PUMA BIOTECHNOLOGY, INC.

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PART I – FINANCIAL INFORMATION:	1
Item 1.	Financial Statements (Unaudited):	1
	Condensed Consolidated Balance Sheets as of ~~June~~September 30, 2021 and December 31, 2020	1
	Condensed Consolidated Statements of Operations for the Three and ~~Six~~Nine Months Ended ~~June~~September 30, 2021 and 2020	2
	Condensed Consolidated Statements of Comprehensive ~~Income (Loss)~~Loss for the Three and ~~Six~~Nine Months Ended ~~June~~September 30, 2021 and 2020	3
	Condensed Consolidated Statements of ~~Stockholders’ Equity (Deficit)~~Stockholders’ Deficit for the Three and ~~Six~~Nine Months Ended ~~June~~September 30, 2021 and 2020	4
	Condensed Consolidated Statements of Cash Flows for the ~~Six~~Nine Months Ended ~~June~~September 30, 2021 and 2020	6
	Notes to the Unaudited Condensed Consolidated Financial Statements	7
Item 2.	~~Management’s~~Management’s Discussion and Analysis of Financial Condition and Results of Operations	2934
Item 3.	Quantitative and Qualitative Disclosures About Market Risk	4149
Item 4.	Controls and Procedures	4149
PART II – OTHER INFORMATION:	4250
Item 1.	Legal Proceedings	42
		50
Item 1A.	Risk Factors	4351
Item 2.	Unregistered Sales of Equity Securities and Use of Proceeds	4351
Item 3.	Defaults Upon Senior Securities	4351
Item 4.	Mine Safety Disclosures	4351
Item 5.	Other Information	4351
Item 6.	Exhibits	4452
Signatures	4553

CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

This Quarterly Report on Form 10-Q, or this Quarterly Report, contains forward-looking statements within the meaning of Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act. Any statements about our expectations, beliefs, plans, objectives, assumptions, future events or performance are not historical facts and may be forward looking. These forward-looking statements include, but are not limited to, statements about:

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the commercialization of ~~NERLYNX~~^®NERLYNX® (neratinib);

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the development of our drug candidates, including when we expect to undertake, initiate and complete clinical trials of our product ~~candidates~~;candidates;

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the impact of the global COVID-19 pandemic, and measures to control the spread of COVID-19, on business, financial condition, results of operations and ongoing trials;

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the anticipated timing of regulatory filings;

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the regulatory approval of our drug candidates;

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our use of clinical research organizations and other contractors;

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our ability to find collaborative partners for research, development and commercialization of potential products;

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efforts of our sub-licensees to obtain regulatory approval and commercialize NERLYNX in areas outside the United States;

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our ability to market any of our products;

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our expectations regarding our costs and expenses;

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our anticipated capital requirements and estimates regarding our needs for additional financing;

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our ability to compete against other companies and research institutions;

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our ability to secure adequate protection for our intellectual property;

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our intention and ability to vigorously defend against any litigation to which we are or may become party;

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our estimates for damages that we may be required to pay in connection with the class action lawsuit to which we are a party;

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our ability to attract and retain key personnel; and

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our ability to obtain adequate financing.

These statements are often, but not always, made through the use of words or phrases such as “anticipate,” “estimate,” “plan,” “project,” “continuing,” “ongoing,” “expect,” “believe,” “intend” and similar words or phrases. Accordingly, these statements involve estimates, assumptions and uncertainties that could cause actual results to differ materially from those expressed in them. Discussions containing these forward-looking statements may be found throughout this Quarterly Report, including, in Part I, the section entitled “Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations.” These forward-looking statements involve risks and uncertainties, including the risks discussed in Part I, Item 1A. “Risk Factors” of our Annual Report on Form 10-K for the year ended December 31, 2020 that could cause our actual results to differ materially from those in the forward-looking statements. Such risks should be considered in evaluating our prospects and future financial performance. We undertake no obligation to update the forward-looking statements or to reflect events or circumstances after the date of this document.

Table of Contents

Part I – FINANCIAL INFORMATION

Item 1. Financial Statements

PUMA BIOTECHNOLOGY, INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED BALANCE SHEETS

(in thousands, except share data)

(unaudited)

	June 30, 2021			December 31, 2020			*September 30, 2021*			*December 31, 2020*
ASSETS
Current assets:
Cash and cash equivalents	$	89,848		$	85,293		$	63,947		$	85,293
Marketable securities		19,127			8,096			23,596			8,096
Accounts receivable, net of allowance for credit loss of $0 and $1,000		30,549			25,543			23,799			25,543
Inventory, net		7,620			3,454			7,206			3,454
Prepaid expenses, current		11,279			11,262			9,074			11,262
Restricted cash, current		8,850			8,850			8,850			8,850
Other current assets		478			3,641			451			3,641
Total current assets		167,751			146,139			136,923			146,139
Lease right-of-use assets, net		15,247			16,404			14,641			16,404
Property and equipment, net		2,099			2,481			1,924			2,481
Intangible assets, net		70,133			74,140			68,129			74,140
Restricted cash, long-term		3,311			3,311			3,311			3,311
Prepaid expenses and other, long-term		1,457			1,745			1,359			1,745
Total assets	$	259,998		$	244,220		$	226,287		$	244,220
LIABILITIES AND STOCKHOLDERS' (DEFICIT) EQUITY
*LIABILITIES AND STOCKHOLDERS' DEFICIT*
Current liabilities:
Accounts payable	$	11,166		$	12,076		$	20,047		$	12,076
Accrued expenses, current		66,988			61,325			90,782			61,325
Accrued in-licensed rights, current		21,613			20,993			0			20,993
Post-marketing commitment liability, current		3,368			2,481			1,978			2,481
Lease liabilities, current		3,336			3,094			3,454			3,094
Current portion of long-term debt		31,429			14,286			0			14,286
Total current liabilities		137,900			114,255			116,261			114,255
Accrued expenses, long-term		1,177			25,963			1,212			25,963
Lease liabilities, long-term		17,823			19,549			16,911			19,549
Post-marketing commitment liability, long-term		4,923			6,379			6,023			6,379
Long-term debt		68,706			84,025			96,802			84,025
Total liabilities		230,529			250,171			237,209			250,171
Commitments and contingencies (Note 13)
Stockholders' equity (deficit):
Common stock - $.0001 par value per share; 100,000,000 shares authorized; 40,733,928 shares issued and outstanding at June 30, 2021 and 40,086,387 issued and outstanding at December 31, 2020		4			4
Stockholders' deficit:
Common stock - $.0001 par value per share; 100,000,000 shares authorized; 40,860,842 shares issued and outstanding at September 30, 2021 and 40,086,387 issued and outstanding at December 31, 2020								4			4
Additional paid-in capital		1,355,775			1,331,676			1,360,057			1,331,676
Accumulated other comprehensive loss		(1	)		—			(2	)		0
Accumulated deficit		(1,326,309	)		(1,337,631	)		(1,370,981	)		(1,337,631	)
Total stockholders' equity (deficit)		29,469			(5,951	)
Total liabilities and stockholders' equity (deficit)	$	259,998		$	244,220
Total stockholders' deficit								(10,922	)		(5,951	)
Total liabilities and stockholders' deficit							$	226,287		$	244,220

See Accompanying Notes to the Unaudited Condensed Consolidated Financial Statements

CONDENSED CONSOLIDATED STATEMENTS OF ~~STOCKHOLDERS’ EQUITY (DEFICIT)~~STOCKHOLDERS’ DEFICIT

~~See Accompanying Notes to the Unaudited Condensed Consolidated Financial Statements~~

See Accompanying Notes to the Unaudited Condensed Consolidated Financial Statements

Puma Biotechnology, Inc., or the Company, is a biopharmaceutical company based in Los Angeles, California with a focus on the development and commercialization of innovative products to enhance cancer care. The Company in-licenses from Pfizer, Inc., or Pfizer, the global development and commercialization rights to PB272 (neratinib, oral), PB272 (neratinib, intravenous) and PB357, as well as certain related compounds. Neratinib is a potent irreversible tyrosine kinase inhibitor that blocks signal transduction through the epidermal growth factor receptors HER1,HER2 and HER4. Currently, the Company is primarily focused on the development and commercialization of the oral version of neratinib, and its most advanced drug candidates are directed at the treatment of ~~HER2-positive~~HER2-positive breast cancer and HER2 mutated cancers. The Company believes that neratinib has clinical application in the treatment of several other cancers as well, including other tumor types that over-express or have a mutation in HER2 or EGFR, such as breast cancer, cervical cancer, lung cancer or other solid tumors.

The Company has 2 subsidiaries, Puma Biotechnology Ltd., a United Kingdom company, and Puma Biotechnology, B.V., a Netherlands company. These subsidiaries were established for the purpose of legal representation in the United Kingdom and the European Union.

The Company has incurred significant operating losses since its inception. The Company believes that it will continue to incur net losses and may incur negative net cash flows from operating activities through the drug development process and global commercialization. In 2017, the Company received U.S. Food and Drug Administration, or FDA, approval for its first product, NERLYNX® (neratinib), formerly known as PB272 (neratinib, oral), for the extended adjuvant treatment of adult patients with early stage ~~HER2-overexpressed/~~HER2-overexpressed/amplified breast cancer following adjuvant trastuzumab-based therapy. Following FDA approval in July 2017, NERLYNX became available by prescription in the United States, and the Company commenced commercialization.

In February 2020, NERLYNX was also approved by the FDA in combination with capecitabine for the treatment of adult patients with advanced or metastatic HER2-positive breast cancer who have received two or more prior anti-HER2-based regimens in the metastatic setting.

In 2018, the European Commission, or EC, granted marketing authorization for NERLYNX in the European Union for the extended adjuvant treatment of adult patients with early stage hormone receptor positive ~~HER2-overexpressed/~~HER2-overexpressed/amplified breast cancer and who are less than one year from the completion of prior adjuvant trastuzumab-based therapy.

In February 2020, NERLYNX was also approved by the FDA in combination with capecitabine for the treatment of adult patients with advanced or metastatic HER2-positive breast cancer who have received two or more prior anti-HER2-based regimens in the metastatic setting.

The Company is required to make substantial payments to Pfizer upon the achievement of certain milestones and has contractual obligations for clinical trial contracts.

The Company has entered into other exclusive sub-license agreements with various parties to pursue regulatory approval, if necessary, and commercialize NERLYNX, if approved, in many regions outside the United States, including Europe (excluding Russia and Ukraine), Australia, Canada, China, Southeast Asia, Israel, Mexico, South Korea, and various countries and territories in Central and South America. The Company plans to continue to pursue commercialization of NERLYNX in other countries outside the United States, if approved.

The condensed consolidated financial statements have been prepared assuming the Company will continue to operate as a going concern, which contemplates the realization of assets and settlement of liabilities in the normal course of business, and does not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classifications of liabilities that may result from uncertainty related to its ability to continue as a going concern within one year from the date of issuance of these condensed consolidated financial statements. However due to the factors described below, there is substantial doubt about the Company's ability to continue as a going concern for the twelve months following the issuance date of the unaudited condensed consolidated financial statements for three and nine months ended September 30, 2021.

The Company has reported a net loss of approximately ~~$5.1~~$44.7 million and net ~~income~~loss of approximately ~~$11.3~~$33.4 million for the three and ~~six~~nine months ended ~~June~~September 30, 2021, respectively, and cash flows from operations of approximately ~~$15.6~~$26.1 million for the ~~six~~nine months ended ~~June~~September 30, ~~2021.~~ 2021. The Company’s commercialization, research and development or marketing efforts may require funding in addition to the cash and cash equivalents totaling approximately ~~$89.8~~$63.9 million and marketable securities totaling approximately~~$19.1~~ $23.6 million available at ~~June~~September 30, ~~2021. The Company believes that its existing cash and cash equivalents and marketable securities as of June 30,~~ 2021 ~~and proceeds that will become available to~~. As a result, the Company ~~through product sales and sub-license payments are sufficient~~ is likely to satisfy its operating cash and needs for at least one year after the filing of the Quarterly Report on Form 10-Q in which these financial statements are included. The Company continues to remain dependent on its ability need to obtain ~~sufficient~~additional funding to sustain operations and continue to successfully commercialize neratinib in the United States. While the Company has been successful in raising capital in the past, there can be no assurance that it will be able to do so in the future. The Company’s ability to obtain funding may be adversely impacted by uncertain market conditions, including the ~~COVID-19~~COVID-19 pandemic, the Company’s success in commercializing neratinib, unfavorable decisions of regulatory authorities or adverse clinical trial results. The outcome of these matters cannot be predicted at this time. ~~Additionally, the terms of the Company’s Note Purchase Agreement place~~

restrictions on the Company’s ability to operate the business and on the Company’s financial flexibility, and the Company may be unable to achieve the revenue necessary to satisfy the minimum revenue covenants as specified in the agreement.

Since its inception through ~~June~~September 30, 2021, the Company’s financing has ~~primarily been~~consisted of proceeds from product and license revenue, public offerings of its common stock, private equity placements, and borrowings under its prior loan and security agreement, which borrowings were paid off in July 2021 using new borrowings from the issuance of notes under the Company’s Note Purchase Agreement. Additionally, the Company anticipates it may need to make 2 cash payments relating to the settlement of its class action legal matter totaling $54.2 million in the firstsix months of 2022, the payment of which could place the Company in noncompliance with the cash covenant of the Company's financial debt covenants, which raises substantial doubt about the Company's ability to continue as a going concern. For additional detail regarding the current status of the Company's class action litigation, see Note 9, Accrued Expenses.

The significant accounting policies followed in the preparation of these unaudited consolidated financial statements are as follows:

The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.

Management has determined that the Company operates in 1one business segment, which is the development and commercialization of innovative products to enhance cancer care.

The preparation of consolidated financial statements in conformity with U.S. generally accepted accounting principles, or GAAP, requires management to make estimates and assumptions that affect reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities at the date of the balance sheet, and reported amounts of revenues and expenses for the period presented. Accordingly, actual results could differ from those estimates.

Significant estimates include estimates for variable consideration for which reserves were established. These estimates are included in the calculation of net revenues and include trade discounts and allowances, product returns, provider chargebacks and discounts, government rebates, payor rebates, and other incentives, such as voluntary patient assistance, and other allowances that are offered within contracts between the Company and its customers, payors, and other indirect customers relating to the Company’s sale of its products.

Basic net ~~income (loss)~~loss per share of common stock is computed by dividing net ~~income (loss)~~loss available to common stockholders by the weighted-average number of shares of common stock outstanding during the periods presented, as required by Accounting Standards Codification, or ASC, 260,Earnings per Share. For purposes of calculating diluted net ~~income (loss)~~loss per share of common stock, the denominator includes both the weighted-average number of shares of common stock outstanding and the number of dilutive common stock equivalents, such as stock options, restricted stock units, or RSUs, and warrants. A common stock equivalent is not included in the denominator when calculating diluted earnings per common share if the effect of such common stock equivalent would be anti-dilutive and a net loss is reported.

Our potentially dilutive securities include potential common shares related to our stock options and restricted stock units granted in connection with the 2011 and 2017 Plans. Diluted earnings per share (“Diluted EPS”) considers the impact of potentially dilutive securities except in periods in which there is a loss because the inclusion of the potential common shares would have an anti-dilutive effect. Diluted EPS excludes the impact of potential common shares related to our stock options in periods in which the option exercise price is greater than the average market price of our common stock for the period.

The 2,116,250 shares underlying the warrant will not have an impact on our diluted net income (loss) per share until the average market price of our common stock exceeds the exercise price of $16 per share. Refer to Note 11 for further details about the warrant.

A reconciliation of the numerators and denominators of the basic and diluted net ~~income (loss)~~loss per share of common stock computations is as follows (in thousands, except per share amounts):

Under ASC Topic 606,Revenue from Contracts with Customers, or ASC 606, the Company recognizes revenue when its customer obtains control of the promised goods or services, in an amount that reflects the consideration which the entity expects to be entitled in exchange for those goods or services. The Company had no contracts with customers until the FDA approved NERLYNX on July 17, 2017. Subsequent to receiving FDA approval, the Company entered into a limited number of arrangements with specialty pharmacies and specialty distributors in the United States to distribute NERLYNX. These arrangements are the Company’s initial contracts with customers. The Company has determined that these sales channels with customers are similar.

The Company sells NERLYNX to a limited number of specialty pharmacies and specialty distributors in the United States. These customers subsequently resell the Company’s products to patients and certain medical centers or hospitals. In addition to distribution agreements with these customers, the Company enters into arrangements with health care providers and payors that provide for government mandated and/or privately negotiated rebates, chargebacks and discounts with respect to the purchase of the Company’s products.

The Company recognizes revenue on product sales when the specialty pharmacy or specialty distributor, as applicable, obtains control of the Company's product, which occurs at a point in time (upon delivery). Product revenue is recorded net of applicable reserves for variable consideration, including discounts and allowances. The Company’s payment terms range between 10 and 68 ~~days~~. days.

Shipping and handling costs for product shipments occur prior to the customer obtaining control of the goods and are recorded in cost of sales.

If taxes should be collected from customers relating to product sales and remitted to governmental authorities, they will be excluded from revenue. The Company expenses incremental costs of obtaining a contract when incurred if the expected amortization period of the asset that the Company would have recognized is one year or less. However, 0no such costs were incurred during the ~~six~~nine months ended ~~June~~September 30, 2021 and ~~2020.~~2020.

Revenue from product sales are recorded at the net sales price (transaction price), which includes estimates of variable consideration for which reserves are established. Components of variable consideration include trade discounts and allowances, product returns, provider chargebacks and discounts, government rebates, payor rebates, and other incentives, such as voluntary patient assistance, and other allowances that are offered within contracts between the Company and its customers, payors, and other indirect customers relating to the Company’s sale of its products. These reserves, as detailed below, are based on the related sales, and

are classified as reductions of accounts receivable, net when the right of offset exists in accordance with Accounting Standards Update ("or "ASU") ASU ~~2013-1,~~ 2013-1,Balance Sheet (Topic ~~210)~~210): Clarifying the Scope of Disclosures about Offsetting Assets and Liabilities,or as a current liability. These estimates take into consideration a range of possible outcomes that are probability-weighted in accordance with the expected value method in ASC 606 for relevant factors such as current contractual and statutory requirements, specific known market events and trends, industry data, and forecasted customer buying and payment patterns. Overall, these reserves reflect the Company’s best estimates of the amount of consideration to which it is entitled based on the terms of the respective underlying contracts.

The amount of variable consideration that is included in the transaction price may be constrained, and is included in the net sales price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized under the contract will not occur in a future period. The Company’s analyses also contemplated application of the constraint in accordance with the guidance, under which it determined a significant reversal of revenue would not be probable to occur in a future period for the estimates detailed below as of ~~June~~September 30, 2021 and, therefore, the transaction price was not reduced further during the quarter ended ~~June~~September 30, ~~2021.~~2021. Actual amounts of consideration ultimately received may differ from the Company’s estimates. If actual results in the future vary from the Company’s estimates, the Company will adjust these estimates, which would affect net product revenue and earnings in the period such variances become known.

The Company generally provides customers with discounts, which include incentive fees that are explicitly stated in the Company’s contracts and are recorded as a reduction of revenue in the period the related product revenue is recognized. The reserve for discounts is established in the same period that the related revenue is recognized, together with reductions to accounts receivable, net on the consolidated balance sheets. In addition, the Company compensates its customers for sales order management, data, and distribution services. The Company has determined such services received to date are not distinct from the Company’s sale of products to its customers and, therefore, these payments have been recorded as a reduction of revenue within the consolidated statements of operations.

Consistent with industry practice, the Company offers the specialty pharmacies and specialty distributors that are its customers limited product return rights for damaged and expiring product, provided it is within a specified period around the product expiration date as set forth in the applicable individual distribution agreement. The Company estimates the amount of its product sales that may be returned by its customers and records this estimate as a reduction of product revenue, net in the period the related product revenue is recognized, as well as a reduction to accounts receivable, net on the consolidated balance sheets. The Company currently estimates product returns using its own sales information, including its visibility into the inventory remaining in the distribution channel. The Company has an insignificant amount of returns to date and believes that returns of its products will continue to be minimal.

Chargebacks for fees and discounts to providers represent the estimated obligations resulting from contractual commitments to sell products to qualified healthcare providers at prices lower than the list prices charged to its customers who directly purchase the product from the Company. Customers charge the Company for the difference between what they pay for the product and the ultimate selling price to the qualified healthcare providers. The reserve for chargebacks is established in the same period the related revenue is recognized, resulting in a reduction of product revenue, net and a reduction to accounts receivable, net on the consolidated balance sheets. Chargeback amounts are generally determined at the time of resale to the qualified healthcare provider by customers, and the Company generally issues credits for such amounts within a few weeks of the customer’s notification to the Company of the resale. Chargebacks consist of credits the Company expects to issue for units that remain in the distribution channel at each reporting period-end that the Company expects will be sold to qualified healthcare providers and chargebacks that customers have claimed, but for which the Company has not yet issued a ~~payment~~.payment.

The Company is subject to discount obligations under state Medicaid programs and Medicare. These reserves are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue, net and the establishment of a current liability, which is included in accrued expenses on the consolidated balance sheets. The Company’s liability for these rebates consists of invoices received for claims from prior quarters that have not been paid or for which an invoice has not yet been received, estimates of claims for the current quarter, and estimates of future claims that will be made for product that has been recognized as revenue, but which remains in the distribution channel at the end of each reporting period.

The Company contracts with certain private payor organizations, primarily insurance companies and pharmacy benefit managers, for the payment of rebates with respect to utilization of its products. The Company estimates these rebates and records such estimates in the same period the related revenue is recognized, resulting in a reduction of product revenue, net and the establishment of a current liability, which is included in accrued expenses on the consolidated balance sheets.

Other incentives the Company offers include voluntary patient assistance programs, such as the co-pay assistance program, which are intended to provide financial assistance to qualified commercially insured patients with prescription drug co-payments required by payors. The calculation of the accrual for co-pay assistance is based on an estimate of claims and the cost per claim that the Company expects to receive associated with product that has been recognized as revenue, but remains in the distribution channel at the end of each reporting period. The adjustments are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability, which is included as a component of accrued expenses on the consolidated balance sheets.

The Company also recognizes license revenue under certain of the Company’s sub-license agreements that are within the scope of ASC 606. The terms of these agreements may contain multiple performance obligations, which may include licenses and research and development activities. The Company evaluates these agreements under ASC 606 to determine the distinct performance obligations. Non-refundable, upfront fees that are not contingent on any future performance and require no consequential continuing involvement by the Company, are recognized as revenue when the license term commences and the licensed data, technology or product is delivered. The Company defers recognition of non-refundable upfront license fees if the performance obligations are not satisfied.

Prior to recognizing revenue, the Company makes estimates of the transaction price, including variable consideration that is subject to a constraint. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur and when the uncertainty associated with the variable consideration is subsequently resolved.

If there are multiple distinct performance obligations, the Company allocates the transaction price to each distinct performance obligation based on its relative standalone selling price. The standalone selling price is generally determined based on the prices charged to customers or using expected cost-plus margin. Revenue is recognized by measuring the progress toward complete satisfaction of the performance obligations using an input measure.

Since 2018, the Company has entered into sub-license agreements with certain sub-licensees in territories outside of the United States. These sub-licensing agreements grant certain intellectual property rights and set forth various respective obligations with respect to actions such as development, pursuit and maintenance of regulatory approvals, commercialization and supply of NERLYNX in the sub-licensees’ respective territories.

License fees under the sub-license agreements include ~~one-time~~one-time upfront payments when each sub-license agreement was executed and potential additional ~~one-time~~one-time milestone payments due to the Company upon successful completion of certain performance obligations, such as achieving regulatory approvals or sales target thresholds, and potential double-digit royalties on sales of the licensed product, calculated as a percentage of net sales of the licensed product throughout each sub-licensee’s respective territory.

As of ~~June~~September 30, 2021, the total potential milestone payments that would be due to the Company upon achievement of all respective performance obligations under the sub-license agreements is approximately ~~$581.5~~$581.3 million. At this time, the Company cannot estimate if or when these milestone-related performance obligations might be achieved.

For sub-license agreements that are within the scope of ASC 606, the Company recognizes revenue when the related sales occur in accordance with the sales-based royalty exception under ASC ~~606-10-55-65.~~606-10-55-65.

Royalty revenue consists of consideration earned related to international sales of NERLYNX made by the Company’s sub-licensees in their respective territories. The Company recognizes royalty revenue when the performance obligations have been satisfied. Royalty revenue was ~~$4.3~~$2.8 million and ~~$6.6~~$9.5 million for the three and ~~six~~nine months ended ~~June~~September 30, 2021, respectively.

For legal contingencies, the Company accrues a liability for an estimated loss if the potential loss from any claim or legal proceeding is considered probable and the amount can be reasonably estimated. Legal fees and expenses are expensed as incurred based on invoices or estimates provided by legal counsel. The Company periodically evaluates available information, both internal and external, relative to such contingencies and adjusts the accrual as necessary. The Company determines whether a contingency should be disclosed by assessing whether a material loss is deemed reasonably possible. In determining whether a loss should be accrued, the Company evaluates, among other factors, the degree of probability of an unfavorable outcome and the ability to make a reasonable estimate of the amount of the loss (see Note ~~13-Commitments~~13, Commitments and Contingencies).

Royalties incurred in connection with the Company’s license agreement with Pfizer, as disclosed in Note 13—13—Commitments and Contingencies, are expensed to cost of sales as revenue from product sales is recognized.

Research and development expenses, or R&D Expenses, are charged to operations as incurred. The major components of R&D Expenses include clinical manufacturing costs, clinical trial expenses, consulting and other ~~third-party~~third-party costs, salaries and employee benefits, stock-based compensation expense, supplies and materials, and allocations of various overhead costs. Clinical trial expenses include, but are not limited to, investigator fees, site costs, comparator drug costs, and clinical research organization, or CRO, costs. In the normal course of business, the Company contracts with third parties to perform various clinical trial activities in the ongoing development of potential products. The financial terms of these agreements are subject to negotiation and variations from contract to contract and may result in uneven payment flows. Payments under the contracts depend on factors such as the achievement of certain events, the successful enrollment of patients and the completion of portions of the clinical trial or similar conditions. The Company’s accruals for clinical trials are based on estimates of the services received and efforts expended pursuant to contracts with numerous clinical trial sites, cooperative groups and CROs. As actual costs become known, the Company adjusts its accruals in that period.

In instances where the Company enters into agreements with third parties for clinical trials and other consulting activities, upfront amounts are recorded to prepaid expenses and other in the accompanying consolidated balance sheets and expensed as services are performed or as the underlying goods are delivered. If the Company does not expect the services to be rendered or goods to be delivered, any remaining capitalized amounts for non-refundable upfront payments are charged to expense immediately. Amounts due under such arrangements may be either fixed fee or fee for service, and may include upfront payments, monthly payments and payments upon the completion of milestones or receipt of deliverables.

Costs related to the acquisition of technology rights and patents for which development work is still in process are charged to operations as incurred and considered a component of R&D Expenses.

ASC Topic 718,Compensation-Stock Compensation, or ASC 718, requires the fair value of all share-based payments to employees and nonemployees, including grants of stock options, to be recognized in the statement of operations over the requisite service period. Under ASC 718, employee and nonemployee option grants are generally valued at the grant date and those valuations do not change once they have been established. The fair value of each option award is estimated on the grant date using the Black-Scholes Option Pricing Method. As allowed by ASC 718, the Company’s estimate of expected volatility is based on its average volatilities using its past eight years of publicly traded history. The risk-free rate for periods within the contractual life of the option is based on the U.S. Treasury yield curve in effect at the time of grant valuation. Option forfeitures are estimated when the option is granted to reduce the option expense to be recognized over the life of the award. The estimated forfeiture rate considers historical employee turnover rates stratified into employee pools, actual forfeiture experience and other factors. The option expense is adjusted upon the actual forfeiture of a stock option grant and the Company periodically revises the estimated forfeiture rate in subsequent periods if actual forfeitures differ from those estimates. Due to its limited history of stock option exercises, the Company uses the simplified method to determine the expected life of the option grants. Compensation expense related to modified stock options is measured based on the fair value for the awards as of the modification date. Any incremental compensation expense arising from the excess of the fair value of the awards on the modification date compared to the fair value of the awards immediately before the modification date is recognized at the modification date or ratably over the requisite service period, as appropriate.

RSUs are valued on the grant date and the fair value of the RSUs is equal to the market price of the Company’s common stock on the grant date. The RSU expense is recognized over the requisite service period. When the requisite service period begins prior to the grant date (because the service inception date occurs prior to the grant date), the Company is required to begin recognizing compensation cost before there is a measurement date (i.e., the grant date). The service inception date is the beginning of the requisite service period. If the service inception date precedes the grant date, accrual of compensation cost for periods before the grant date shall be based on the fair value of the award at the reporting date. In the period in which the grant date occurs, cumulative compensation cost shall be adjusted to reflect the cumulative effect of measuring compensation cost based on fair value at the grant date rather than the fair value previously used at the service inception date (or any subsequent reporting date). RSU forfeitures are estimated when the RSU is granted to reduce the RSU expense to be recognized over the life of the award. The estimated forfeiture rate considers historical employee turnover rates stratified into employee pools, actual forfeiture experience and other factors. The RSU expense is adjusted upon the actual forfeiture of an RSU grant and the Company periodically revises the estimated forfeiture rate in subsequent periods if actual forfeitures differ from those estimates. Compensation expense related to modified restricted stock units is measured based on the fair value for the awards as of the modification date. Any incremental compensation expense arising from the excess of the fair value of the awards on the modification date compared to the fair value of the awards immediately before the modification date is recognized at the modification date or ratably over the requisite service period, as appropriate.

Warrants (refer to Note 11 for further details) granted to employees and nonemployees are normally valued at the fair value of the instrument on the grant date and are recognized in the condensed statement of operations over the requisite service period. When the requisite service period precedes the grant date and a market condition exists in the warrant, the Company values the warrant using the Monte Carlo Simulation Method. When the terms of the warrant become fixed, the Company values the warrant using the Black-Scholes Option Pricing Method. As allowed by ASC 718, the Company’s estimate of expected volatility is based on its average volatilities using its publicly traded history. The risk-free rate for periods within the contractual life of the warrant is based on the U.S. Treasury yield curve in effect at the time of grant valuation. In determining the value of the warrant until the terms are fixed, the Company factors in the probability of the market condition occurring and several possible scenarios. When the requisite service period precedes the grant date and is deemed to be complete, the Company records the fair value of the warrant at the time of issuance as an equity stock-based compensation transaction. The grant date is determined when all pertinent information, such as exercise price and quantity are known. Compensation expense related to warrant modifications is measured based on the fair value of the warrant as of the modification date. Any incremental compensation expense arising from the excess of the fair value of the warrant on the modification date compared to the fair value of the warrant immediately before the modification date is recognized at the modification date or ratably over the requisite service period, as appropriate.

The Company follows ASC Topic 740,Income Taxes, or ASC 740, which requires recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the consolidated financial statements or tax returns. Under this method, deferred tax assets and liabilities are based on the differences between the consolidated financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Deferred tax assets are reduced by a valuation allowance to the extent management concludes it is more likely than not that the asset will not be realized. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled.

The standard addresses the determination of whether tax benefits claimed or expected to be claimed on a tax return should be recorded in the consolidated financial statements. Under ASC 740, the Company may recognize the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the tax authorities, based on the technical merits of the position. The tax benefits recognized in the consolidated financial statements from such a position should be measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. ASC 740 also provides guidance on de-recognition, classification, interest and penalties on income taxes, accounting in interim periods and requires increased disclosures. As of ~~June~~September 30, 2021, the Company’s uncertain tax position reserves include a reserve for its R&D credits.

The carrying value of financial instruments, such as cash equivalents, accounts receivable and accounts payable, approximate their fair value because of their short-term nature. The carrying value of long-term debt approximates its fair value as the principal amounts outstanding are subject to variable interest rates that are based on market rates, which are regularly reset.

The Company classifies all highly liquid instruments with an original maturity of three months or less as cash equivalents.

Restricted cash represents cash held at financial institutions that is pledged as collateral for stand-by letters of credit for lease and legal verdict commitments. The lease-related letters of credit will lapse at the end of the respective lease terms through 2026. At each of ~~June~~September 30, 2021 and December 31, 2020, the Company had restricted cash in the amount of $12.2 million.

The Company classifies all investment securities (short-term and long-term) as available-for-sale, as the sale of such securities may be required prior to maturity to implement management’s strategies. These securities are carried at fair value, with the unrealized gains and losses reported as a component of accumulated other comprehensive income (loss) in stockholders’ equity until realized. Realized gains and losses from the sale of available-for-sale securities, if any, are determined on a specific identification basis. In accordance with ASU ~~2016-13,~~ 2016-13,Financial Instruments – Credit Losses (Topic ~~326)~~326): Measurement of Credit Losses on Financial Instruments, credit losses on available-for-sale securities are reported using an expected loss model and recorded to an allowance. Premiums and discounts are amortized or accreted over the life of the related security as an adjustment to yield using the straight-line method. Interest income is recognized when earned.

ASC Topic 820,Fair Value Measurement, or ASC 820, provides a single definition of fair value and a common framework for measuring fair value as well as disclosure requirements for fair value measurements used in financial statements. Under ASC 820, fair value is determined based upon the exit price that would be received by a company to sell an asset or paid by a company to transfer a liability in an orderly transaction between market participants, exclusive of any transaction costs. Fair value measurements are determined by either the principal market or the most advantageous market. The principal market is the market with the greatest level of activity and volume for the asset or liability. Absent a principal market to measure fair value, the Company uses the most advantageous market, which is the market from which the Company would receive the highest selling price for the asset or pay the lowest price to settle the liability, after considering transaction costs. However, when using the most advantageous market, transaction costs are only considered to determine which market is the most advantageous and these costs are then excluded when applying a fair value measurement. ASC 820 creates a ~~three-level~~three-level hierarchy to prioritize the inputs used in the valuation techniques to derive fair values. The basis for fair value measurements for each level within the hierarchy is described below, with Level 1 having the highest priority and Level 3 having the lowest.

Following are the major categories of assets measured at fair value on a recurring basis as of ~~June~~September 30, 2021 and December 31, 2020, using quoted prices in active markets for identical assets (Level 1)1), significant other observable inputs (Level 2)2), and significant unobservable inputs (Level 3)3) (in thousands):

The Company’s investments in commercial paper, corporate bonds and U.S. government securities are exposed to price fluctuations. The fair value measurements for commercial paper, corporate bonds and U.S. government securities are based upon the quoted prices of similar items in active markets multiplied by the number of securities owned.

The following tables summarize the Company’s cash equivalents and short-term investments (in thousands):

Financial instruments, which potentially subject the Company to concentrations of credit risk, principally consist of cash and cash equivalents, marketable securities, and accounts receivable, net. The Company’s cash and cash equivalents and restricted cash in excess of the Federal Deposit Insurance Corporation and the Securities Investor Protection Corporation insured limits at ~~June~~September 30, 2021, were approximately ~~$102.0~~$75.9 million. The Company does not believe it is exposed to any significant credit risk due to the quality nature of the financial instruments in which the money is held. Pursuant to the Company’s internal investment policy, investments must be rated ~~A-1/P-1~~A-1/P-1 or better by Standard and Poor’s Rating Service and Moody’s Investors Service at the time of purchase.

The Company sells its products in the United States primarily through specialty pharmacies and specialty distributors. Therefore, wholesale distributors and large pharmacy chains account for a large portion of its accounts receivables, net and product revenues, net. The creditworthiness of its customers is continuously monitored, and the Company has internal policies regarding customer credit limits. The Company estimates an allowance for doubtful accounts primarily based on the credit worthiness of its customers, historical payment patterns, aging of receivable balances and general economic conditions. The Company recorded a recovery of $1.0 million credit loss and $1.0 million as an allowance for credit loss for the periods ended ~~June~~September 30, 2021 and December 31, 2020, respectively.

The Company’s success depends on its ability to successfully commercialize NERLYNX. The Company currently has a single product and limited commercial sales experience, which makes it difficult to evaluate its current business, predict its future prospects and forecast financial performance and growth. The Company has invested a significant portion of its efforts and financial resources in the development and commercialization of the lead product, NERLYNX, and expects NERLYNX to constitute the vast majority of product revenue for the foreseeable future.

The Company relies exclusively on third parties to formulate and manufacture NERLYNX and its drug candidates. The commercialization of NERLYNX and any other drug candidates, if approved, could be stopped, delayed or made less profitable if those third parties fail to provide sufficient quantities of product or fail to do so at acceptable quality levels or prices. The Company has no experience in drug formulation or manufacturing and does not intend to establish its own manufacturing facilities. The Company lacks the resources and expertise to formulate or manufacture NERLYNX and other drug candidates. While the drug candidates were being developed by Pfizer, both the drug substance and drug product were manufactured by ~~third-party~~third-party contractors. The Company is using the same ~~third-party~~third-party contractors to manufacture, supply, store and distribute drug supplies for clinical trials and the commercialization of NERLYNX. If the Company is unable to continue its relationships with one or more of these ~~third-party~~third-party contractors, it could experience delays in the development or commercialization efforts as it locates and qualifies new manufacturers. The Company intends to rely on one or more ~~third-party~~third-party contractors to manufacture the commercial supply of drugs.

The Company values its inventories at the lower of cost and estimated net realizable value. The Company determines the cost of its inventories, which includes amounts related to materials and manufacturing overhead, on a ~~first-in, first-out~~first-in, first-out basis. The Company performs an assessment of the recoverability of capitalized inventory during each reporting period, and it writes down any excess and obsolete inventories to their estimated realizable value in the period in which the impairment is first identified. Such impairment

charges, should they occur, are recorded within ~~the~~ cost of sales in the condensed consolidated statements of operations. The determination of whether inventory costs will be realizable requires estimates by management. If actual market conditions are less favorable than projected by management, additional write-downs of inventory may be ~~required, which would be recorded as a cost of sales in the consolidated statements of operations.~~required.

The Company capitalizes inventory costs associated with the Company’s products after regulatory approval, if any, when, based on management’s judgment, future commercialization is considered probable and the future economic benefit is expected to be realized. Inventory that can be used in either the production of clinical or commercial product is recorded as R&D Expenses when selected for use in a clinical trial. Starter kits, provided to patients prior to insurance approval, are expensed by the Company to selling, general and administrative expense as incurred.

As of ~~June~~September 30, 2021, the Company’s inventory balance consisted primarily of raw materials purchased subsequent to FDA approval of NERLYNX.

Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, which is generally three years for computer hardware and software, three years for phone equipment, and seven years for furniture and fixtures. Leasehold improvements are amortized using the straight-line method over the lesser of the useful life or the lease term. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation are eliminated from the accounts and any resulting gain or loss is credited or charged to operations. Repairs and maintenance costs are expensed as ~~incurred~~.incurred.

The Company reviews its long-lived assets used in operations for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable, as required by ASC Topic 360,Property, Plant, and Equipment, or ASC 360. The Company performs a recoverability test by comparing the sum of the estimated undiscounted cash flows over the life of the asset to its carrying value on the consolidated balance sheet. If the undiscounted cash flows used in the recoverability test are less than the carrying value, the Company would then determine the fair value of the long-lived asset and recognize an impairment loss for the amount in excess of the carrying value.

ASC Topic 842,Leases, as adopted in the first quarter of 2019, requires lessees to recognize most leases on the balance sheet with a corresponding right-of-use asset, or ROU asset. ROU assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. The assets and lease liabilities are recognized at the lease commencement date based on the estimated present value of fixed lease payments over the lease term. ROU assets are evaluated for impairment using the long-lived assets impairment guidance, as required by ASC 360. A significant indication of impairment of an ROU asset would include a change in the extent or manner in which the asset is being used. The Company must make assumptions which underlie the most significant and subjective estimates in determining whether any impairment exists. Those estimates, and the underlying assumptions, include estimates of future cash flow utilizing market lease rates and determination of fair value. If an ROU asset related to an operating lease is impaired, the carrying value of the ROU asset post-impairment should be amortized on a straight-line basis through the earlier of the end of the useful life of the ROU asset or the end of the lease term. Post impairment, a lessee must calculate the amortization of the ROU asset and interest expense on the lease liability separately, although the sum of the two continues to be presented as a single lease cost. If a lease is planned to be abandoned with no intention of subleasing, the ROU asset should be assessed for impairment.

Leases will be classified as financing or operating, which will drive the expense recognition pattern. The Company elects to exclude short-term leases if and when the Company has them. For additional information, see Note 6,—Leases.

The Company leases office space and copy machines, all of which are operating leases. Most leases include the option to renew and the exercise of the renewal options is at the Company’s sole discretion. Options to extend or terminate a lease are considered in the lease term to the extent that the option is reasonably certain of exercise. The leases do not include options to purchase the leased property. The depreciable life of assets and leasehold improvements is limited by the expected lease term. Covenants imposed by the leases include letters of credit required to be obtained by the lessee.

The incremental borrowing rate, or IBR, represents the rate of interest the Company would expect to pay on a collateralized basis to borrow an amount equal to the lease payments under similar terms. When determinable, the Company uses the rate implicit in the lease to determine the present value of lease payments. As the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The Company’s average IBR for existing leases as of ~~June~~September 30, 2021 is 10.9%.

The Company expenses amounts paid to acquire licenses associated with products under development when the ultimate recoverability of the amounts paid is uncertain and the technology has no alternative future use when acquired. Acquisitions of technology licenses are charged to expense or capitalized based upon the asset achieving technological feasibility in accordance with management’s assessment regarding the ultimate recoverability of the amounts paid and the potential for alternative future use. The Company has determined that technological feasibility for its product candidates is reached when the requisite regulatory approvals are obtained to make the product available for sale. The Company capitalizes technology licenses upon reaching technological feasibility.

The Company maintains definite-lived intangible assets related to the license agreement with Pfizer. These assets are amortized over their remaining useful lives, which are estimated based on the shorter of the remaining patent life or the estimated useful life of the underlying product. Intangible assets are amortized using the economic consumption method if anticipated future revenues can be reasonably estimated. The straight-line method is used when future revenues cannot be reasonably estimated. Amortization costs are recorded as part of cost of sales.

The Company assesses its intangible assets for impairment if indicators are present or changes in circumstance suggest that impairment may exist. Events that could result in an impairment, or trigger an interim impairment assessment, include the receipt of additional clinical or nonclinical data regarding one of the Company’s drug candidates or a potentially competitive drug candidate, changes in the clinical development program for a drug candidate, or new information regarding potential sales for the drug. If impairment indicators are present or changes in circumstance suggest that impairment may exist, the Company performs a recoverability test by comparing the sum of the estimated undiscounted cash flows of each intangible asset to its carrying value on the consolidated balance sheet. If the undiscounted cash flows used in the recoverability test are less than the carrying value, the Company would determine the fair value of the intangible asset and recognize an impairment loss if the carrying value of the intangible asset exceeds its fair value. In connection with the FDA approval of NERLYNX in July 2017, the Company triggered a ~~one-time~~one-time milestone payment pursuant to its license agreement with Pfizer. In June 2020, the Company entered into a letter agreement with Pfizer relating to the method of payment associated with a milestone payment under the Company’s license agreement with Pfizer (see Note ~~13-Commitments~~13, Commitments and Contingencies). The Company capitalized the milestones as intangible assets and is amortizing the assets to cost of sales on a straight-line basis over the estimated useful life of the licensed patent through 2030. The Company recorded amortization expense related to its intangible assets of $2.0 million and ~~$4.0~~$6.0 million for the three and ~~six~~nine months ended ~~June~~September 30, 2021, respectively. As of ~~June~~September 30, 2021, estimated future amortization expense related to the Company’s intangible assets was approximately ~~$4.0~~$2.0 million for the remainder of 2021 and ~~$8.0~~$8.0 million for each year starting 2022 through 2029, and $2.0 million for ~~2030~~.2030.

During the ~~six~~nine months ended ~~June~~September 30, 2021, the Company agreed to settle its ongoing arbitration proceeding with CANbridge BIOMED Limited, or CANbridge, relating to an agreement in which the Company granted CANbridge an exclusive sub-license to develop and commercialize NERLYNX throughout greater China. The Company and CANbridge agreed to drop their respective claims against one another. At the same time, the Company entered into a separate transaction in which it agreed to pay CANbridge a ~~one-time~~one-time termination fee of $20.0 million in exchange for it returning to the Company all rights to NERLYNX in greater China. The Company expensed the $20.0 million ~~one-time~~one-time termination fee to cost of sales in the ~~six~~nine months ended ~~June~~September 30, ~~2021.~~2021.

In December 2019, the Financial Accounting Standards Board, or FASB issued ASU No ~~2019-12,~~ 2019-12,Income Taxes (Topic ~~740)~~740): Simplifying the Accounting for Income Taxes, as part of its Simplification Initiative to reduce the cost and complexity in accounting for income taxes. The amendments in ASU ~~2019-12~~2019-12 remove certain exceptions related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. ASU ~~2019-12~~2019-12 also amends other aspects of the guidance to help simplify and promote consistent application of GAAP. The guidance is effective for interim and annual periods beginning after December 15, 2020, with early adoption permitted. ASU ~~2019-12~~2019-12 did not have a material effect on the Company’s current financial position, results of operations or financial statement disclosures.

In October 2020, the FASB issued ASU2020-10, Codification Improvements, which updates various codification topics by clarifying or improving disclosure requirements to align with SEC regulations. The Company adopted ASU2020-10 as of the reporting period beginning January 1, 2021. ASU ~~2020-10~~2020-10 did not have a material effect on the Company’s current financial position, results of operations or financial statement disclosures.

Trade accounts receivable consist entirely of amounts owed from the Company’s customers related to product sales. License revenue receivable represents an amount owed from ~~a sub-licensee~~sub-licensees under a sub-license ~~agreement.~~agreements. Royalty revenue receivable represents amounts owed related to royalty revenue recognized based on the Company’s sub-licensees’ sales in their respective territories in the periods ended ~~June~~September 30, 2021 and December 31, ~~2020.~~2020.

For all accounts receivable, the Company recognized credit losses based on lifetime expected losses to selling, general and administrative expense in the consolidated statements of operations. In determining estimated credit losses, the Company evaluated its historical loss rates, current economic conditions and reasonable and supportable forecasts of future economic conditions. The Company recorded a recovery of $1.0 million in credit loss and $1.0 million as a credit loss expense for the periods ended ~~June~~September 30, 2021 and December 31, 2020, respectively. The rollforward of the allowance for credit losses is as follows:

Other current prepaid amounts consist primarily of deposits, signing bonuses, licenses, subscriptions and software. Other long-term prepaid amounts consist primarily of deposits, signing bonuses, licenses, subscriptions, software, a capitalized sublease commission and a sublease tenant improvement allowance, net of amortization.

Other current asset amounts consist primarily of a deposit, capitalized sublease commission and a sublease tenant improvement allowance, net of amortization.

In December 2011, the Company entered into a non-cancelable operating lease for office space in Los Angeles, California, which was subsequently amended in November 2012, December 2013, March 2014, July 2015, and December 2017. The initial term of the lease was for seven years and commenced on December 10, 2011. As amended, the Company rents approximately 65,656 square feet. The term of the lease runs until March 2026, and rent amounts payable by the Company increase approximately 3% per year. Concurrent with the execution of the lease, the Company provided the landlord an automatically renewable stand-by letter of credit in the amount of $2.0 million. The stand-by letter of credit is collateralized by a high-yield savings account, which is classified as restricted cash, long-term on the accompanying consolidated balance sheets.

In June 2012, the Company entered into a long-term lease agreement for office space in South San Francisco, California, which was subsequently amended in May 2014 and July 2015. As amended, the Company rents approximately 29,470 square feet. The term of this lease runs until March 2026, with the option to extend for an additional ~~five-year~~five-year term, and rents payable by the Company increase approximately 3% per year. The Company provided the landlord an automatically renewable stand-by letter of credit in the amount of $1.1 million. The stand-by letter of credit is collateralized by a high-yield savings account, which is classified as restricted cash, long-term on the accompanying consolidated balance sheets. The Company also leases copier equipment for use in the office spaces. Components of lease expense include fixed lease expense and variable lease expense of approximately ~~$2.3~~$3.5 million and ~~$0.2~~$0.3 million, respectively, for each of the ~~six~~nine months ended ~~June~~September 30, 2021 and ~~June~~September 30, ~~2020.~~2020. For purposes of determining straight-line rent expense, the lease term is calculated from the date the Company first takes possession of the facility, including any periods of free rent and any renewal option periods that the Company is reasonably certain of exercising. The Company’s office and equipment leases generally have contractually specified minimum rent and annual rent increases that are included in the measurement of the ROU asset and related lease liability. Additionally, under these lease arrangements, the Company may be required to pay directly, or reimburse the lessors, for real estate taxes, insurance, utilities, maintenance and other operating costs. Such amounts are generally variable and therefore not included in the measurement of the ROU asset and related lease liability but are instead recognized as variable lease expense in selling, general and administrative costs in the consolidated statements of operations when they are ~~incurred~~.incurred.

~~Supplemental cash flow information related to leases for the three months ended June 30, 2021:~~

The future minimum lease payments under ASC 842 as of ~~June~~September 30, 2021 were as follows (in thousands):

In February 2019, the Company entered into a long-term sublease agreement for 12,429 square feet of the office space in Los Angeles, California. The term of the lease runs until March 2026 and rent amounts payable to the Company increase approximately 3% per year. The Company recorded operating sublease income of $0.1 million and ~~$0.2~~$0.3 million for the three and ~~six~~nine months ended ~~June~~September 30, 2021, respectively, in other income (expenses) in the consolidated statements of operations.

The future minimum lease payments to be received as of ~~June~~September 30, 2021 were as follows (in thousands):

Property and equipment, net consisted of the following (in ~~thousands~~)thousands):

For the three and ~~six~~nine months ended ~~June~~September 30, 2021, the Company incurred depreciation expense of $0.2 million and ~~$0.4~~$0.6 million, respectively.

For the three and ~~six~~nine months ended ~~June~~September 30, 2021, the Company incurred amortization expense of $2.0 million and ~~$4.0~~$6.0 million, respectively.In June 2020, the Company entered into a letter agreement with Pfizer relating to the method of payment associated with a ~~one-time~~one-time milestone payment under the Company’s license agreement with Pfizer(~~see~~ (see Note ~~13-Commitments~~13, Commitments and ~~Contingencies~~)Contingencies). The estimated remaining useful life of the intangible assets as of ~~June~~September 30, 2021 is ~~8.8~~8.5 years.

Accrued CRO services, accrued other clinical development expenses, and accrued legal fees represent the Company’s estimates of such costs and are recognized as incurred. Accrued royalties represent royalties incurred in connection with the Company’s license agreement with Pfizer. Accrued compensation includes accrued commissions and accrued vacation, which is accrued at the rate the employee earns vacation and reduced as vacation is used by the employee. Accrued variable consideration represents estimates of adjustments to product revenue, net for which reserves are established.

Current accrued legal verdict expense includes an estimate of $2.8 million that may be owed to the plaintiff as a result of the jury verdict in Eshelman v. Puma Biotechnology, Inc., et al. The ~~Company~~Company's best estimates ~~the high end~~ of potential damages in the matter could be approximately $2.8 ~~million;~~million, which also represents our estimate as the most likely outcome; however, the actual amount of damages payable by the Company is still uncertain and will be ascertained only after completion of the appeal process and subsequent proceedings on remand, and such amount could be greater than the amount of expense already recognized or the high end of the estimate. During the ~~quarter~~nine months ended ~~June~~September 30, 2021, the Company revised its estimate from $22.9 million to $2.8 million, a decrease of $20.1 million, based on changes in the facts and circumstances surrounding this case and recent developments. The Company continues to classify the accrual as a current liability due to the uncertainty of the timing and amount of the payment. See Part II Item 1. “Legal Proceedings” of this Quarterly Report for a more detailed description of recent developments.

Additionally, current accrued legal verdict expense includes the Company’s estimate of ~~$30.0~~$54.2 million that may be owed to class action participants as a result of the jury verdict in Hsu v. Puma Biotechnology, Inc., et al. ~~While the final claims report received in~~ ~~Hsu~~ reflects a total of $50.5 million in claimed damages, the Company intends to challenge these claims and estimates that actual claims could be as low as $30.0 million. The actual amount and timing of payment of damages in ~~Hsu~~ ~~is uncertain and will be ascertained only after an extensive claims challenge process, the completion of post-trial proceedings and the exhaustion of any appeals.~~ During the ~~quarter~~nine months ended ~~June~~September 30, 2021 the Company revised its estimate from ~~$24.9~~$24.8 million to ~~$30.0~~$54.5 million, an increase of ~~$5.1~~$29.7 million, based on changes in the facts and circumstances surrounding this case and recent developments. ~~The Company continues to classify the accrual as a current liability due to the uncertainty of the timing of the payment. Actual damages in the~~ ~~Hsu~~ ~~matter may be higher than the Company’s estimate.~~ See Part II Item 1. “Legal Proceedings” of this Quarterly Report for a more detailed description of recent developments.

Other current accrued expenses consist primarily of business license fees, one half of the portion of employer Social Security payroll taxes deferred under the Coronavirus Aid, Relief, and Economic Security Act, or the CARES Act, and other taxes, insurance and marketing fees.

Other long-term accrued expenses consist primarily of one half of the portion of employer Social Security payroll taxes deferred under the CARES Act, accrued compensation and deposit from a sublessee.

In October 2017, the Company entered into a loan and security agreement with Silicon Valley Bank ("SVB"), as administrative agent, and the lenders party thereto from time to time, or the Original Lenders, including Oxford Finance, LLC, ("Oxford"), and SVB. Pursuant to the terms of the credit facility provided for by the loan and security agreement, or the Original Credit Facility, we borrowed $50.0 million. In May 2018, the Company entered into an amendment to the loan and security agreement, which provided for an amended credit facility, or the Amended Credit Facility. Under the Amended Credit Facility, the Original Lenders agreed to make term loans available to the company in an aggregate amount of $155.0 million, consisting of (i) an aggregate amount of $125.0 million, the proceeds of which, in part, were used to repay the $50.0 million outstanding under the Original Credit Facility, and (ii) an aggregate amount of $30.0 million that was drawn in December 2018, which was available under the Amended Credit Facility as a result of achieving a specified minimum revenue milestone.

On June 28, 2019, or the Effective Date, the Company entered into an amendment and restatement of ~~its~~the loan and security agreement, which provided for a new credit facility, or the New Credit Facility, with ~~Oxford Finance, LLC, or~~ Oxford, as collateral agent, and the lenders party thereto from time to time, including Oxford, pursuant to which the Company repaid ~~its~~the $155.0 million outstanding ~~debt,~~under the Amended Credit Facility, as well as all applicable exit and prepayment fees, owed to the ~~lenders~~Original Lenders under ~~its prior credit facility,~~the Amended Credit Facility, using cash on hand and $100.0 million in new borrowings from the New Credit Facility. Under the New Credit Facility, the Company issued to Oxford new and/or replacement secured promissory notes in an aggregate principal amount for all such promissory notes of $100.0 million evidencing the New Credit Facility. ~~NaN additional money remains available to the Company under the New Credit Facility.~~

The New Credit Facility was secured by substantially all of the ~~Company’s~~Company's personal property other than ~~its~~ intellectual property. The Company also pledged 65% of the issued and outstanding capital stock of its subsidiaries, Puma Biotechnology Ltd. and Puma Biotechnology B.V. The New Credit Facility limited the ~~Company’s~~Company's ability to grant any interest in ~~its~~ intellectual property to certain permitted licenses and permitted encumbrances set forth in the agreement.

The term loans under the New Credit Facility bore interest at an annual rate equal to the greater of (i) 9.0% and (ii) the sum of (a) the “prime rate,” as reported in The Wall Street Journal on the last business day of the month that immediately preceded the month in which the interest will accrue, plus (b) 3.5%. The Company was required to make monthly interest-only payments on each term loan under the New Credit Facility commencing on the first calendar day of the calendar month following the funding date of such term loan, and continuing on the first calendar day of each calendar month thereafter through August 1,2021, or the Amortization Date. Commencing on the Amortization Date, and continuing on the first calendar day of each calendar month thereafter, the Company would have made consecutive equal monthly payments of principal, together with applicable interest, in arrears to each lender under the New Credit Facility, calculated pursuant to the New Credit Facility. All unpaid principal and accrued and unpaid interest with respect to each term loan under the New Credit Facility was due and payable in full on June 1,2024, or the Maturity Date. Upon repayment of such term loans, the Company was also required to make a final payment to the lenders equal to 7.5% of the aggregate principal amount of such term loans outstanding as of the Effective Date.

AtCompany had the ~~Company’s~~ option ~~the Company was able~~ to prepay the outstanding principal balance of any term loan in whole but not in part, subject to a prepayment fee of 3.0% of any amount prepaid if the prepayment occurred through and including the first anniversary of the funding date of such term loan, 2.0% of the amount prepaid if the prepayment occurred after the first anniversary of the funding date of such term loan through and including the second anniversary of the funding date of such term loan, and 1.0% of the amount prepaid if the prepayment occurred after the second anniversary of the funding date of such term loan and prior to the Maturity Date.

On July 23, 2021, the Company used proceeds from the Athyrium Note Purchase Agreement to repay the amounts outstanding under the New Credit Facility, ~~included~~together with applicable exit and prepayment fees, and terminated the New Credit Facility.

The Company issued senior notes for an aggregate principal amount of $100.0 million pursuant to the note purchase agreement dated July 23, 2021, by and among the Company, its subsidiaries, Athyrium Opportunities IV Co-Invest 1 LP (“Athyrium”), as Administrative Agent, and certain other investor parties (the “Note Purchase Agreement”), with an initial maturity date of July 23, 2026 (the “Athyrium Notes”). The Athyrium Notes were issued for face amount of $100.0 million net of an original issue discount of $1.5 million. The Athyrium Notes also require a 2.0% exit payment to be made on each payment of principal. The borrowings under the Athyrium Notes, together with cash on hand, were used to repay the Company’s outstanding indebtedness, including the applicable exit and prepayment fees owed to lenders under its Oxford Credit Facility. The Company can borrow up to an additional $25.0 million under the Note Purchase Agreement. The Athyrium Notes are secured by substantially all the Company’s assets. The Company incurred $1.9 million of deferred financing costs with the borrowing.

The Athyrium Notes bear interest at an annual rate equal to the sum of (i) 8.0% and (ii) three-month London Interbank Offering Rate (LIBOR) rate where the three-month LIBOR rate cannot be less than 1.5% or greater than 3.5%. (or a comparable or successor rate that gives due consideration to the then prevailing rate used by commercial banks in the United States which rate is reasonably determined by Athyrium). Interest is payable quarterly on the last business day of March, June, September and December each year. Beginning June 30, 2024, principal payments are required to be made quarterly at 11.11% of the original face amount with the remaining balance paid at maturity. Each principal payment will also include 2.0% exit payment.

At the Company’s option, the Company may prepay the outstanding principal balance of the notes in whole or in part, subject to a prepayment fee of 2.0% of the amount prepaid if the prepayment occurs on or prior to the second anniversary of the issuance date of such notes, plus the present value of remaining interest that would have accrued through and including the second anniversary date, and 2.0% of the amount prepaid if the prepayment occurs after the second anniversary but on or prior to the third anniversary of the issuance date of such notes. In addition, under the Note Purchase Agreement, the Company will be subject to mandatory prepayments of the net cash proceeds received in connection with a Disposition or Involuntary Disposition (as defined), an Extraordinary Receipt (as defined) or a Debt Issuance (as defined).

The Athyrium Notes include affirmative and negative covenants applicable to the ~~Company, its current subsidiaries and any subsidiaries the Company would have created in the future.~~Company. The affirmative covenants ~~included,~~include, among others, covenants requiring the Company to maintain its legal existence and governmental approvals, deliver certain financial reports, maintain insurance coverage, and satisfy certain requirements regarding deposit accounts. The ~~Company was also required to achieve certain product revenue targets, measured as of the last day of each fiscal quarter on a trailing year-to-date basis. New minimum revenue~~

~~levels were to be established for each subsequent fiscal year by mutual agreement of the Company, Oxford, as collateral agent, and the lenders under the New Credit Facility. The~~ negative covenants ~~included,~~include, among others, restrictions on the Company’s transferring collateral, incurring additional indebtedness, engaging in mergers or acquisitions, paying dividends or making other distributions, making investments, creating liens, selling assets and suffering a change in control, in each case subject to certain exceptions.

~~The New Credit Facility also included events of default,~~ Additionally, the ~~occurrence and continuation of which could have caused interest to be charged at the rate that would otherwise have been applicable plus 5.0% and would have provided Oxford, as collateral agent,~~Company may not make legal payments in connection with the ~~right~~Eshelman or class actionlegal matters exceeding a certain threshold without first raising sufficient additional capital above the threshold. The Company is also required to ~~exercise remedies against~~achieve certain minimum product revenue targets, measured as of the ~~Company and the collateral securing the New Credit Facility, including foreclosure against the property securing the New Credit Facility, including the Company’s cash. These events~~last day of ~~default included, among other things, the Company’s failure to pay principal or interest due under the New Credit Facility,~~each fiscal quarter on a ~~breach~~trailing year-to-date basis. As of certain covenants under the New Credit Facility, the Company’s insolvency, a material adverse change, the occurrence of any default under certain other indebtedness in an amount greater than $500,000 and one or more judgments against the Company in an amount greater than $500,000 individually or in the aggregate that remained unsatisfied, unvacated, or unstayed for a period of 10 days after its entry.

On ~~February 27, 2020, the Company~~ ~~and Oxford~~ ~~amended the New Credit Facility~~ ~~to establish the Company’s minimum revenue thresholds~~ ~~for the~~ ~~trailing~~ ~~year-to-date periods ending~~ ~~March 31, June 30,~~ September 30, ~~and December 31, 2020 and~~2021, the ~~fiscal year 2021.~~ On August 5, 2020 the Company and Oxford amended the New Credit Facility to amend the minimum revenue thresholds for the trailing year-to-date periods ending September 30 and December 31, 2020. On February 3, 2021, the Company and Oxford amended the New Credit Facility to establish the Company’s minimum revenue thresholds for the trailing year-to-date periods ending March 31, June 30, September 30 and December 31, 2021.

~~As of June 30, 2021, there were $100.0 million in term loans~~principal balance outstanding under the ~~New Credit Facility,~~Athyrium Notes was $100.0 million, representing all of the Company’s long-term ~~debt outstanding as of that date, and the~~debt. The Company was in compliance with all applicable covenants under the ~~New Credit Facility.~~Athyrium Notes.

The future minimum principal and exit payments under the ~~New Credit Facility~~Athyrium Notes as of ~~June~~September 30, 2021 were as follows (in thousands):

~~Deferred financing~~Debt issuance costs ~~consisted~~and discounts consist of the following (in thousands):

~~Deferred financing~~Debt issuance costs and discounts are financing costs related to the Company’s outstanding debt. Amortization of debt issuance costs is expensed using the effective interest method and is included in interest expense in the condensed consolidated statement of operations. For the ~~six~~nine months ended ~~June~~September 30, 2021 and 2020, the Company recorded approximately ~~$1.1~~$1.5 million and ~~$0.9~~$1.4 million, respectively, of interest expense related to the amortization of debt issuance costs in the consolidated statements of operations.

In July 2021, the Company entered into a Note Purchase Agreement with a new lender, and used the gross proceeds of $100.0 million, along with cash on hand, to retire the entire principal balance outstanding, plus related outstanding interest and early payment fees under the New Credit Facility. See Note 14 – Subsequent Events.

The Company issued 0 and ~~500~~12,000 shares of common stock upon exercise of stock options during the ~~six~~nine months ended ~~June~~September 30, 2021 and 2020, respectively. The Company issued ~~647,541~~774,455 and ~~423,113~~505,627 shares of common stock upon vesting of RSUs during the ~~six~~nine months ended ~~June~~September 30, 2021 and 2020, respectively.

The Company has 100,000,000 shares of stock authorized for issuance, all of which are common stock, par value $0.0001 per share.

In October 2011, the Company issued an anti-dilutive warrant to Alan Auerbach, the Company’s founder and Chief Executive Officer. The warrant was issued to provide Mr. Auerbach with the right to maintain ownership of at least 20% of the Company’s common stock in the event that the Company raised capital through the sale of its securities in the future.

In connection with the closing of a public offering in October 2012, the exercise price and number of shares underlying the warrant issued to Mr. Auerbach were established and, accordingly, the final value of the warrant became fixed. Pursuant to the terms of the warrant, Mr. Auerbach may exercise the warrant to acquire 2,116,250 shares of the Company’s common stock at $16 per share until October 4,2021. On April 1, 2021, the Company’s Board of Directors approved an amendment to the terms of the warrant by extending the term until October 4, 2026. The amendment was approved by the Company’s stockholders on June 15, 2021.

As a result of this amendment, the Company recorded additional stock-based compensation in the amount of $0 and $13.6 million which was included in selling, general and administrative expense for the three and ~~six~~nine months ended ~~June~~September 30, ~~2021.~~2021. The fair value of the additional stock-based compensation was estimated using the Black-Scholes Option Pricing Method (see Note 2)2, Significant Accounting Policies) with the following assumptions as of June 15, 2021, the date of modification:

The Company’s 2011 Incentive Award Plan, as amended, or the 2011 Plan, was adopted by the Company’s Board of Directors on September 15, 2011. Pursuant to the 2011 Plan, the Company may grant incentive stock options and nonqualified stock options, as well as other forms of equity-based compensation. Incentive stock options may be granted only to employees, while consultants, employees, officers and directors are eligible for the grant of nonqualified options under the 2011 Plan. The maximum term of stock options granted under the 2011 Plan is 10 years and the awards generally vest over a ~~three-year~~three-year period. The exercise price of incentive stock options granted under the 2011 Plan must be at least equal to the fair value of such shares on the date of grant. On April 1, 2021, the Board of Directors adopted an amendment to the 2011 Plan to increase the number of shares of the Company’s common stock reserved for issuance thereunder by 2,000,000 shares. The amendment was approved by the Company’s stockholders on June 15, 2021. As of ~~June~~September 30, 2021, a total of 14,529,412 shares of the Company’s common stock have been reserved for issuance under the 2011 Plan.

All of the options awarded by the Company have been “plain vanilla options” as determined by the SEC Staff Accounting Bulletin 107 - Share Based Payment. As of ~~June~~September 30, 2021 ~~6,159,570~~, 5,537,638 shares of the Company’s common stock are issuable upon the exercise of outstanding stock options and vesting of RSUs granted under the 2011 Plan and ~~3,361,888~~3,919,963 shares of the Company’s common stock are available for future issuance under the 2011 Plan. The fair value of options granted to employees and nonemployees was estimated using the Black-Scholes Option Pricing Method (see Note 2)2, Significant Accounting Policies) with the following weighted-average assumptions used during the ~~six~~nine months ended ~~June 30:~~September 30:

The Company’s 2017 Employment Inducement Incentive Award Plan, as amended, or the 2017 Plan, was adopted by the Company’s Board of Directors on April 27,2017.Pursuant to the 2017 Plan, the Company may grant stock options and RSUs, as well as other forms of equity-based compensation to employees, as an inducement to join the Company. The maximum term of stock options granted under the 2017 Plan is 10 years and the awards generally vest over a ~~three-year~~three-year period. The exercise price of stock options granted under the 2017 Plan must be at least equal to the fair market value of such shares on the date of grant. On July 15 2021, the Board of Directors adopted an amendment to the 2017 Plan to increase the number of shares of the Company's common stock reserved for issuance thereunder by 1,000,000 shares. As of ~~June~~September 30, 2021, a total of ~~2,000,000~~3,000,000 shares of the Company’s common stock have been reserved for issuance under the 2017 Plan. As of ~~June~~September 30, 2021 ~~1,158,256~~, 1,112,103 shares of the Company’s common stock are issuable upon the exercise of outstanding stock options and vesting of RSUs granted under the 2017 Plan and ~~358,755~~1,341,851 shares of the Company’s common stock are available for future issuance under the 2017 Plan.

On July 15, 2021, the Board of Directors adopted an amendment to the 2017 Plan to increase the number of shares of the Company’s common stock reserved for issuance thereunder by 1,000,000 shares. See Note 14 – Subsequent Events.

Activity with respect to options granted under the 2011 Plan and 2017 Plan is summarized as follows:

At ~~June~~September 30, 2021, total estimated unrecognized employee compensation cost related to non-vested stock options granted prior to that date was approximately ~~$7.0~~$6.4 million, which is expected to be recognized over a weighted-average period of ~~2.0~~1.9 years. At ~~June~~September 30, 2021, the total estimated unrecognized employee compensation cost related to non-vested RSUs was approximately ~~$21.8~~$15.3 million, which is expected to be recognized over a weighted-average period of ~~1.84~~1.7 years. The weighted-average grant date fair value of options granted during the ~~six~~nine months ended ~~June~~September 30, 2021 and 2020 was ~~$8.32~~$7.90 and ~~$7.86~~$7.81 per share, respectively. The weighted average grant date fair value of RSUs awarded during the ~~six~~nine months ended ~~June~~September 30, 2021 and 2020 was ~~$11.92~~$11.73 and ~~$10.61~~$10.57 per share, respectively.

During 2012, the Company adopted a ~~401(k)~~401(k) savings plan for the benefit of its employees. The Company is required to make matching contributions to the ~~401(k)~~401(k) plan equal to 100% of the first3% of wages deferred by each participating employee and 50% on the next 2% of wages deferred by each participating employee. The Company incurred expenses for employer matching contributions of approximately ~~$1.0~~$1.3 million and ~~$0.7~~$1.1 millionfor the ~~six~~nine months ended ~~June~~September 30, 2021 and 2020, respectively.

Contractual obligations represent future cash commitments and liabilities under agreements with third parties, and exclude contingent liabilities for which the Company cannot reasonably predict future payment. The Company’s contractual obligations result primarily from obligations for various contract manufacturing organizations and clinical research organizations, which include potential payments we may be required to make under our agreements. The contracts also contain variable costs and milestones that are hard to predict as they are based on such things as patients enrolled and clinical trial sites. The timing of payments and actual amounts paid under contract manufacturing organization, or CMO, and CRO agreements may be different depending on the timing of receipt of goods or services or changes to agreed-upon terms or amounts for some obligations. Also, those agreements are cancelable upon written notice by the Company and, therefore, not long-term liabilities.

In August 2011, the Company entered into an agreement pursuant to which Pfizer agreed to grant it a worldwide license for the development, manufacture and commercialization of PB272 neratinib (oral), PB272 neratinib (intravenous) and PB357, and certain related compounds. The license is exclusive with respect to certain patent rights owned by or licensed to Pfizer. Under the agreement, the Company is obligated to commence a new clinical trial for a product containing one of these compounds within a specified period of time and to use commercially reasonable efforts to complete clinical trials and to achieve certain milestones as provided in a development plan. From the closing date of the agreement through December 31, 2011, Pfizer continued to conduct the existing clinical trials on behalf of the Company at Pfizer’s sole expense. At the Company’s request, Pfizer has agreed to continue to perform certain services in support of the existing clinical trials at the Company’s expense. These services will continue through the completion of the transitioned clinical trials. The license agreement “capped” the out of pocket expense the Company would incur to complete the then existing clinical trials. All agreed upon costs incurred by the Company above the “cost cap” would be reimbursed by Pfizer. The Company exceeded the “cost cap” during the fourth quarter of 2012. In accordance with the license agreement, the Company billed Pfizer for agreed upon costs above the “cost cap” until December 31, 2013.

On July 18, 2014, the Company entered into an amendment to the license agreement with Pfizer. The amendment amends the agreement to ~~(1)~~(1) reduce the royalty rate payable by the Company to Pfizer on sales of licensed products; ~~(2)~~(2) release Pfizer from its obligation to pay for certain out-of-pocket costs incurred or accrued on or after January 1, 2014 to complete certain ongoing clinical studies; and ~~(3)~~(3) provide that Pfizer and the Company will continue to cooperate to effect the transfer to the Company of certain records, regulatory filings, materials and inventory controlled by Pfizer as promptly as reasonably practicable.

As consideration for the license, the Company is required to make substantial payments upon the achievement of certain milestones totaling approximately $187.5 million if all such milestones are achieved. In connection with the FDA approval of NERLYNX in July of 2017, the Company triggered a ~~one-time~~one-time milestone payment pursuant to the agreement. In June 2020, the Company entered into a letter agreement, or the Letter Agreement, with Pfizer relating to the method of payment associated with a ~~one-time~~one-time milestone payment under the license agreement with Pfizer. The Letter Agreement ~~permits~~permitted the Company to make the milestone payment in installments with the remaining amount payable to Pfizer (including interest) ~~to be made in September 2021 for approximately $21.9 million. Unpaid portions of the~~. The milestone payment ~~will accrue~~accrued interest at 6.25% per ~~annum until paid.~~ annum. The milestone payment including accrued interest of $1.8 million was paid in full in September 2021. The installment payments and accrued interest ~~are~~were included in accrued in-licensed rights on the accompanying consolidated balance ~~sheets~~.sheets. The Company may trigger additional milestone payments in the future. Should the Company commercialize any more of the compounds licensed from Pfizer or any products containing any of these compounds, the Company will be obligated to pay to Pfizer annual royalties at a fixed rate in the low-to-mid teens of net sales of all such products, subject to certain reductions and offsets in some circumstances. The Company’s royalty obligation continues, on a product-by-product and country-by-country basis, until the later of ~~(1)~~(1) the last to expire licensed patent covering the applicable licensed product in such country, or ~~(2)~~(2) the earlier of generic competition for such licensed product reaching a certain level in such country or expiration of a certain time period after first commercial sale of such licensed product in such country. In the event that the Company sublicenses the rights granted to the Company under the license agreement with Pfizer to a third party, the same milestone and royalty payments are required. The Company can terminate the license agreement at will, or for safety concerns, in each case upon specified advance notice.

The Company and certain of its executive officers were named as defendants in ~~the lawsuits detailed~~ ~~in Part II Item 1. “Legal Proceedings” of this Quarterly Report.~~certain lawsuits. The Company records a liability in the consolidated financial statements for loss contingencies when a loss is known or considered probable and the amount can be reasonably estimated. If the reasonable estimate of a known or probable loss is a range, and no amount within the range is a better estimate than any other, the minimum amount of the range is accrued. If a loss is reasonably possible but not known or probable, and can be reasonably estimated, the estimated loss or range of loss is disclosed. When determining the estimated loss or range of loss, significant judgment is required to estimate the amount and timing of a loss to be recorded.

On October 29, 2021, the parties to the Company's class action lawsuit, Hsu v. Puma Biotechnology, Inc., et al., informed the court that they had reached a settlement in principle, and the court entered judgment in the amount of claimed damages and prejudgment interest totaling approximately $54.2 million. On November 2, 2021, the court dismissed the case in light of the parties' settlement, retaining jurisdiction only for settlement approval. The parties' settlement in principle provides that there will be no judgment for liability entered against the Company or its chief executive officer, Alan Auerbach, and provides for payment by the Company of approximately $54.2 million in 2 installments, to be paid in January and June of 2022. The settlement in principle is subject to execution of a formal settlement agreement to be negotiated among the parties, which agreement will be submitted to the court for approval.

On ~~July 23,~~November 2, 2021, ~~or the NPA Effective Date,~~ the Company ~~repaid~~implemented a restructuring of the ~~$100.0 million~~organization in ~~term loans outstanding under its prior credit facility, as well as all accrued interest, applicable exit, prepayment and legal fees owed~~part due to the ~~lenders under its prior credit facility in an amount~~impact of approximately $9.2 million, using cash on hand and $100.0 million in new borrowings from the issuance of notes under the note purchase agreement, or the Note Purchase Agreement, that the Company entered into on the NPA Effective Date with Athyrium Opportunities IV Co-Invest 1 LP, or, together with its affiliates, Athyrium, as administrative agent, and the purchasers party thereto from time to time, or the Purchasers, including Athyrium. Additionally, the Company wrote off approximately $3.9 million in deferred financing costs associated with its prior credit facility as a result of the transaction in July 2021.

Pursuant to the Note Purchase Agreement, the Purchasers agreed to purchase from the Company, and the Company agreed to issue to such Purchasers, notes payable by the Company. On the NPA Effective Date, the Company issued to the Purchasers notes in an aggregate principal amount for all such notes of $100.0 million. Subject to satisfaction of certain conditions set forth in the Note Purchase Agreement, $25.0 million in additional notes remains available to the Company under the Note Purchase Agreement.

The obligations of the Company under the Note Purchase Agreement are secured by substantially all of the Company’s assets, including its intellectual property. The Company also pledged 65% of the issued and outstanding capital stock of its subsidiaries, Puma Biotechnology Ltd. and Puma Biotechnology B.V.

The notes issued under the Note Purchase Agreement bear interest at an annual rate equal to the sum of (a) 8.0% and (b) Adjusted Three-Month LIBOR for such Interest Period (as defined in the Note Purchase Agreement). The Company is required to make quarterly interest payments on each note issued under the Note Purchase Agreement commencing on the last business day of September 2021 and continuing on the last business day of each March, June, September and December through June 30, 2024, or the NPA Amortization Date. Commencing on the NPA Amortization Date, and continuing on the last day of each March, June,

September and December thereafter, the Company will make consecutive equal quarterly payments of principal, together with applicable interest, in arrears to each Purchaser, calculated pursuant to the Note Purchase Agreement. All unpaid principal and accrued and unpaid interest with respect to each note issued under the Note Purchase Agreement is due and payable in full on July 23, 2026, or the NPA Maturity Date. At the Company’s option, the Company may prepay the outstanding principal balance of all or any portion of the principal amount of the notes, subject to a prepayment fee equal to (i) a make-whole amount if the prepayment occurs on or prior to the second anniversary of the NPA Effective Date and (ii) 2.0% of the amount prepaid if the prepayment occurs after the second anniversary of the NPA Effective Date by on or prior to the third anniversary of the NPA Effective Date. Upon prepayment or repayment of all or any portion of the principal amount of the notes (whether on the NPA Maturity Date or otherwise), the Company is also required to pay an exit fee to the Purchasers equal to 2.00% of the aggregate principal amount of such notes prepaid or repaid.

The Note Purchase Agreement includes affirmative and negative covenants applicable to the Company, its current subsidiaries, and any subsidiaries the Company creates in the future. The affirmative covenants include, among others, covenants requiring the Company to maintain its legal existence and governmental approvals, deliver certain financial reports, maintain insurance coverage and satisfy certain requirements regarding deposit accounts. The Company must also (i) maintain a minimum amount of unrestricted cash in deposit accounts subject to a control agreement in favor of Athyrium at any time and (ii) achieve at least a specified minimum amount of revenue (based on a combination of both sales of NERLYNX in the United States and royalty revenues received by the Company for sales of NERLYNX outside the United States), measured as of the last day of each four consecutive fiscal quarter period. The negative covenants include, among others, restrictionsCOVID-19 on the Company’s ~~transferring collateral, incurring additional indebtedness, engaging~~sales. The restructuring includes a reduction in ~~mergers or acquisitions, paying dividends or making other distributions, making investments, creating liens, selling assets~~headcount of approximately 13% consisting primarily of commercial and ~~suffering a change~~research personnel. The Company anticipates that it will incur approximately $1.2 million in ~~control,~~severance related costs which includes salary, insurance premiums, and sales commissions. This cost will be recorded in ~~each case subject~~the fourth quarter of 2021. The Company believes that all payments related to ~~certain exceptions.~~this plan will be made by March 31, 2022.

The Note Purchase Agreement also includes events of default, the occurrence and continuation of which could cause interest to be charged at the rate that is otherwise applicable plus 2.0% and would provide Athyrium, as administrative agent, with the right to exercise remedies against the Company and the collateral securing the new credit facility, including foreclosure against the property securing the obligations of the Company under the Note Purchase Agreement, including its cash. These events of default include, among other things, the Company’s failure to pay principal or interest due under the Note Purchase Agreement, a breach of certain covenants under the Note Purchase Agreement, the Company’s insolvency, a material adverse change, the occurrence of any default under certain other indebtedness in an amount greater than $750,000 and one or more judgments against the Company in an amount greater than $750,000 individually or in the aggregate that remains discharged or otherwise satisfied, in each case, as further described in the Note Purchase Agreement.

The foregoing description of the Note Purchase Agreement and the notes is only a summary of the material terms thereof, and does not purport to be complete. The description is qualified in its entirety by reference to the Note Purchase Agreement and the form of note, which will be filed as exhibits to the Company’s Quarterly Report on Form 10-Q for the quarter ending September 30, 2021.

On July 15, 2021, the Company's Board of Directors adopted an amendment to the 2017 Plan to increase the number of shares of the Company’s common stock reserved for issuance thereunder by 1,000,000 shares.

The following discussion and analysis of our financial condition and results of operations should be read in conjunction with our unaudited condensed consolidated financial statements and the notes thereto included in Item 1 in this Quarterly Report on Form 10-Q, or this Quarterly Report. The following discussion should also be read in conjunction with our audited consolidated financial statements and the notes thereto and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” included in our Annual Report on Form 10-K for the year ended December 31, 2020.

Unless otherwise provided in this Quarterly Report, references to the “Company,” “we,” “us,” and “our” refer to Puma Biotechnology, Inc., a Delaware corporation, together with its wholly owned subsidiaries.

We are a biopharmaceutical company with a focus on the development and commercialization of innovative products to enhance cancer care. We ~~in-license~~in-licensed from Pfizer, Inc., or Pfizer, the global development and commercialization rights to PB272 (neratinib, oral), PB272 (neratinib, intravenous) and PB357. Neratinib is a potent irreversible tyrosine kinase inhibitor, or TKI, that blocks signal transduction through the human epidermal growth factor receptors, HER1, HER2 and HER4. Currently, we are primarily focused on the development and commercialization of the oral version of neratinib, ~~and~~ our most advanced drug ~~candidates are~~candidate is directed at the treatment of HER2-positive breast cancer and HER2 mutated cancers. We believe neratinib has clinical application in the treatment of several other cancers as well, including other tumor types that over-express or have a mutation in HER2 or EGFR, such as breast cancer, cervical cancer, lung cancer or other solid tumors.

Prior to 2017, our efforts and resources had been focused primarily on acquiring and developing our pharmaceutical technologies, raising capital and recruiting personnel. In 2017, the U.S. Food and Drug Administration, or FDA, approved NERLYNX, formally known as PB272 (neratinib, oral), for the extended adjuvant treatment of adult patients with early stage HER2-overexpressed/amplified breast cancer following adjuvant trastuzumab-based therapy. In February 2020, NERLYNX was also approved by the FDA in combination with capecitabine for the treatment of adult patients with advanced or metastatic HER2-positive breast cancer who have received two or more prior anti-HER2-based regimens in the metastatic setting. In 2018, the European Commission, or EC, granted marketing authorization for NERLYNX in the European Union for the extended adjuvant treatment of adult patients with early-stage hormone receptor positive HER2-overexpressed/amplified breast cancer and who are less than one year from the completion of prior adjuvant trastuzumab-based therapy.

We have entered into exclusive sub-license agreements with various parties to pursue regulatory approval, if necessary, and commercialize NERLYNX, if approved, in numerous regions outside the United States, including Europe (excluding Russia and Ukraine), Australia, Canada, China, Southeast Asia, Israel, Mexico, South Korea, and various countries and territories in Central and South ~~America~~.America. We plan to continue to pursue commercialization of NERLYNX in other countries outside the United States, if approved.

~~During the three months ended June 30,~~In July 2021, ~~Puma~~our Canadian partner, Knight Therapeutics, Inc., received ~~FDA~~Health Canada’s approval ~~for~~of an alternate dosing regimen (two-week dose escalation) to be incorporated into the ~~U.S.~~ prescribing information. ~~In addition,~~

On July 23, 2021, we entered into a note purchase agreement with Athyrium Opportunities IV Co-Invest 1 LP ("Athyrium") for an aggregate principal amount of $100.0 million. The borrowings under the ~~FDA approved~~Athyrium Note Purchase Agreement ("Athyrium Notes"), together with cash on hand, were used to repay the ~~commercial distribution of a new SKU (133 count)~~outstanding indebtedness, including the applicable exit and prepayment fees owed to ~~support use of this regimen. In June 2021,~~lenders under our Oxford Credit facility. See Note 10, Debt for further details regarding both the Company’s Canadian partner, Knight Therapeutics, Inc., received Health Canada’s approval of NERLYNX in combination with capecitabine for the treatment of adult patients with advanced or metastatic HER2-positive breast cancer who have received two or more prior anti-HER2-based regimens in the metastatic setting.Athyrium Notes and Oxford Loan and Security Agreement.

Our expenses to date have been related to hiring staff, commencing company-sponsored clinical trials and the build out of our corporate infrastructure and, since 2017, the commercial launch of NERLYNX. Accordingly, our success depends not only on the safety and efficacy of our product candidates, but also on our ability to finance product development. To date, our major sources of working capital have been proceeds from product and license revenue, public offerings of our common stock, proceeds from our credit facility and sales of our common stock in private placements.

Our priorities during the COVID-19 pandemic continue to be focused on protecting the health and safety of our employees while delivering on our mission to develop and commercialize innovative products to enhance cancer care. Substantially all geographic regions in which our U.S. sales force operates have imposed restrictions and may in the future change or impose additional restrictions to control or limit the spread of COVID-19 and its variants. These restrictions include, but are not limited to “shelter-in-place” orders, quarantines, testing requirements or similar orders or restrictions. These types of restrictions may deter or prevent cancer patients from traveling to see their doctors and result in a decline in revenue for NERLYNX, our only commercial product. Additionally, the impact of COVID-19 has significantly reduced the ability of our commercial team and our sales force to travel and interact personally with physicians and members of the extended healthcare team. This has reduced our commercial team’s access to

healthcare providers, and a large portion of its promotional activities are now being conducted virtually. Although we have seen some recent easing of local restrictions, these have been inconsistent and have not led to a broad relaxation of requirements. These types of restrictions have adversely impacted our ability to engage with our customers and have adversely impacted sales of NERLYNX, and they may continue to do so. The respective commercial teams affiliated with certain companies to which we sub-license the commercial rights to NERLYNX, and on which we rely for our international sales, have chosen or have been forced to take similar action, and other sub-licensees of NERLYNX may choose or be forced to take similar action in the future. Furthermore, the COVID-19 pandemic has resulted in dramatic increases in unemployment rates, which may result in a substantial number of people becoming uninsured or underinsured. Any of these developments may have an adverse effect on our revenue. We have observed disruptions in patient enrollments in the United States and in our Phase II SUMMIT basket trial. If the COVID-19 pandemic continues to spread in the geographies in which we are conducting clinical trials, we may experience additional disruptions in those clinical trials, which could have a material adverse impact on our clinical trial plans and timelines.

Our ability to continue to operate without any significant negative impacts will in part depend on the length and severity of the COVID-19 pandemic and our ability to protect our employees and our supply chain. We continue to follow and monitor recommended actions of government and health authorities to protect our employees worldwide. For the ~~six~~nine months ended ~~June~~September 30, 2021, we and our key third-party suppliers and manufacturers were able to broadly maintain operations. We rely exclusively on third-party manufacturers to manufacture NERLYNX.

On October 29, 2021, the parties to our class action lawsuit informed the court that they had reached a settlement in principle, and the court entered judgment in the amount of claimed damages and prejudgment interest totaling approximately $54.2 million. On November 2, 2021, the court dismissed the case in light of the parties' settlement, retaining jurisdiction only for settlement approval. The parties' settlement in principle provides that there will be no judgment for liability entered against us or Mr. Auerbach, and provides for payment by us of approximately $54.2 million in two installments, to be paid in January and June of 2022. The settlement in principle is subject to execution of a formal settlement agreement to be negotiated among the parties, which agreement will be submitted to the court for approval. For additional detail regarding the class action lawsuit, see Part II. Item 1. Legal Proceedings in this Quarterly Report on Form 10-Q.

We intend to satisfy our near-term liquidity requirements through a combination of our existing cash and cash equivalents and marketable securities as of ~~June~~September 30, 2021 and proceeds that will become available to us through product sales, royalties and sub-license milestone payments. However, this intention is based on assumptions that may prove to be wrong. Changes may occur that would consume our available capital faster than anticipated, including the length and severity of the COVID-19 pandemic and measures taken to control the spread of COVID-19, as well as changes in and progress of our development activities, the impact of commercialization efforts, acquisitions of additional drug candidates and changes in regulation. Some of these developments have had and may continue to have an adverse effect on our revenue and thus could have an adverse effect on our ability to satisfy the minimum revenue covenants in our Note Purchase Agreement.

Our consolidated financial statements as of and for the three and nine months ended September 30, 2021 have been prepared on the basis that we will continue as a going concern, which contemplates the realization of assets and satisfaction of liabilities in the normal course of business. Based on our cash and marketable securities balances, recurring losses since inception and recent developments in our class action litigation, there is substantial doubt about our ability to continue as a going concern, due to our minimum cash financial covenant. Our ability to continue as a going concern is dependent upon our ability to raise additional capital to sustain operations and continue to commercialize neratinib. We cannot assure you that such funding will be available on commercially reasonable terms, or at all.

As of the date of the filing of this Quarterly Report, we believe there have been no material changes to our critical accounting policies and estimates during the ~~six~~nine months ended ~~June~~September 30, 2021 from our accounting policies at December 31, 2020, as reported in our Annual Report on Form 10-K for the fiscal year ended December 31, 2020. We accounted for the following related to sub-license agreements and our legal contingencies and expense during the ~~six~~nine months ended ~~June~~September 30, 2021:

We recognize license revenue under certain of our sub-license agreements that are within the scope of ASC 606. The terms of these agreements may contain multiple performance obligations, which may include licenses and research and development activities. We evaluate these agreements under ASC 606 to determine the distinct performance obligations. Non-refundable, up-front fees that are not contingent on any future performance and require no consequential continuing involvement by us, are recognized as revenue when the license term commences and the licensed data, technology or product is delivered. We defer recognition of non-refundable upfront license fees if the performance obligations are not satisfied.

Prior to recognizing revenue, we make estimates of the transaction price, including variable consideration that is subject to a constraint. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur and when the uncertainty associated with the variable consideration is subsequently resolved. Variable consideration may include nonrefundable upfront license fees, payments for research and development activities, reimbursement of certain third-party costs, payments based upon the achievement of specified milestones, and royalty payments based on product sales derived from the collaboration.

If there are multiple distinct performance obligations, we allocate the transaction price to each distinct performance obligation based on its relative standalone selling price. The standalone selling price is generally determined based on the prices charged to customers or using expected cost-plus margin. Revenue is recognized by measuring the progress toward complete satisfaction of the performance obligations.

For legal contingencies, we accrue a liability for an estimated loss if the potential loss from any claim or legal proceeding is considered probable and the amount can be reasonably estimated. Legal fees and expenses are expensed as incurred based on invoices or estimates provided by legal counsel. We periodically evaluate available information, both internal and external, relative to such contingencies and adjust the accrual as necessary. We determine whether a contingency should be disclosed by assessing whether a

material loss is deemed reasonably possible. In determining whether a loss should be accrued, we evaluate, among other factors, the degree of probability of an unfavorable outcome and the ability to make a reasonable estimate of the amount of the loss (see Note ~~13-Commitments~~13, Commitments and Contingencies in the accompanying notes to the financial statements).

Product revenue, net consists of revenue from sales of NERLYNX. We sell NERLYNX to a limited number of specialty pharmacies and specialty distributors in the United States. We record revenue at the net sales price, which includes an estimate for variable consideration for which reserves are established. Variable consideration consists of trade discounts and allowances, product returns, provider chargebacks and discounts, government rebates and other incentives.

License revenue consists of consideration earned for performance obligations satisfied pursuant to our sub-license agreements.

Royalty revenue consists of consideration earned related to product sales made by our sub-licensees in their respective territories pursuant to our sub-license agreements.

Cost of sales consists of third-party manufacturing costs, freight, and indirect overhead costs associated with sales of NERLYNX. Cost of sales also includes period costs related to royalty charges payable to Pfizer, the amortization of milestone payments made to Pfizer, certain inventory manufacturing services, inventory adjustment charges, unabsorbed manufacturing and overhead costs, and manufacturing variances.

Selling, general and administrative expenses, or SG&A Expenses, consist primarily of salaries and payroll-related costs, stock-based compensation expense, professional fees, business insurance, rent, general legal activities, credit loss expense and other corporate expenses. We expense SG&A Expenses as they are incurred.

Research and development expenses, or R&D Expenses, include costs associated with services provided by consultants who conduct and perform clinical services on our behalf and contract organizations for the manufacturing of clinical ~~materials and clinical trials.~~materials. During the three and ~~six~~nine months ended ~~June~~September 30, 2021 and 2020, our R&D Expenses consisted primarily of clinical research organization, or CRO, fees; fees paid to consultants; salaries and related personnel costs; and stock-based compensation. We expense our R&D Expenses as they are incurred. Internal R&D Expenses primarily consist of payroll-related costs and also include equipment costs, travel expenses and supplies.

Three Months Ended ~~June~~September 30, 2021 Compared to Three Months Ended ~~June~~September 30, 2020

For the three months ended ~~June~~September 30, 2021, total revenue was approximately ~~$53.4~~$46.2 million, compared to ~~$70.6~~$50.8 million for the three months ended ~~June~~September 30, 2020.

Product revenue, net was approximately ~~$48.9~~$43.4 million for the three months ended ~~June~~September 30, 2021, compared to ~~$48.8~~$49.3 million for the three months ended ~~June~~September 30, 2020. ~~The increase~~This decrease in product revenue, net was primarily attributable to a volume decrease of approximately 18.0% in bottles of NERLYNX sold and an increase in reserves for variable consideration from approximately 15.8% of product revenue for the three months ended September 30, 2020 compared to approximately 19.4% of product revenue, for the three months ended September 30, 2021 offset by increases in the gross selling price that occurred in the third quarter of 2020 and in the first and third quarter of 2021; offset by a volume decrease of approximately 10.0% in bottles of NERLYNX sold, and an increase in reserves for variable consideration from approximately 14.4% of product revenue, net for the three months ended June 30, 2020 to approximately 17.7% of product revenue, net for the three months ended

~~June 30,~~ 2021. The increase in reserves for variable consideration is primarily due to an increase in Medicaid claims and government chargebacks as a percentage of gross revenue.

Royalty revenue was approximately ~~$0.3~~$2.8 million for the three months ended ~~June~~September 30, 2021, compared to ~~approximately $20.7~~$1.4 million for the three months ended June 30, 2020. During the three months ended June 30, 2020, the Company recognized one-time license revenue of $20.7 million for an upfront payment and for satisfaction of two performance-based milestones related to sub-license agreements.

~~Royalty revenue was approximately $4.3 million for the three months ended June 30, 2021, compared to $1.1 million for the three months ended June~~September 30, 2020. The increase was due to increased product sales by our sub-licensees as they continue to commercialize NERLYNX in additional territories.

Cost of sales was approximately ~~$12.0~~$10.3 million for the three months ended ~~June~~September 30, 2021, compared to ~~$9.4~~$9.9 million for the three months ended ~~June~~September 30, 2020. The increase was primarily attributable to the increase in the amortization of the intangible asset under our license agreement with Pfizer and increased royalty expense due to Pfizer.

For the three months ended ~~June~~September 30, 2021, SG&A Expenses were approximately ~~$39.4~~$26.1 million, compared to approximately ~~$29.3~~$29.6 million for the three months ended ~~June~~September 30, 2020. SG&A Expenses for the three months ended ~~June~~September 30, 2021 and 2020 were as follows:

For the three months ended ~~June~~September 30, 2021, SG&A Expenses ~~increased~~decreased by approximately ~~$10.1~~$3.5 million compared to the same period in 2020, primarily attributable to the following:

●

a decrease in professional fees and expenses of approximately $1.7 million, consisting of approximately $1.3 million of lower consultant expenses associated with marketing and commercialization support, and a decrease of approximately $0.4 million in legal fees;

~~an increase~~●

a decrease in stock-based compensation expense of approximately ~~$12.0~~$1.2 million primarily due to ~~the $13.6 million incremental expense resulting from the modification to the term of Mr. Auerbach’s warrant and approximately $1.2 million from new grants, partially offset by the~~a decrease of approximately $2.2 million for stock awards that have fully vested and a decrease of approximately ~~$0.6~~$0.3 million ~~from~~for stock awards ~~forfeited; and~~

●

~~an increase in travel and meetings of approximately $0.5 million as some travel restrictions due to the COVID-19 pandemic have been lifted.~~

~~These increases were partially offset by:~~

●

a decrease in professional fees and expenses of approximately $0.9 million, consisting primarily of a decrease of approximately $1.1 million for professional fees, primarily related to decreased consultancy efforts related to marketing and commercialization support,forfeited, partially offset by an increase of approximately ~~$0.2~~$1.3 million ~~in insurance premiums~~from new grants; and ~~legal fees in connection with various lawsuits;~~

●

~~a decrease in other expenses of $0.8 million due to lower bad debt expenses, partially offset by higher sponsorship fees; and~~

●

a decrease in payroll and related costs of approximately ~~$0.7 million.~~$0.8 million resulting from a reduction in headcount.

Table of Contents

Research and development expenses:

For the three months ended ~~June~~September 30, 2021, R&D Expenses were approximately ~~$18.6~~$18.8 million, compared to approximately ~~$24.7~~$23.3 million for the three months ended ~~June~~September 30, 2020. R&D Expenses for the three months ended ~~June~~September 30, 2021 and 2020 were as follows:

Research and development expenses	For the Three Months Ended				Change						For the Three Months Ended				Change
(in thousands)	June 30,				$			%			September 30,				$			%
	2021		2020		2021/2020			2021/2020			2021		2020		2021/2020			2021/2020
Clinical trial expense	$	6,982	$	7,062	$	(80	)		-1.1	%	$	8,396	$	8,257	$	139			1.7	%
Internal R&D		8,209		9,894		(1,685	)		-17.0	%		7,761		9,441		(1,680	)		-17.8	%
Consultant and contractors		1,940		1,835		105			5.7	%		1,347		2,183		(836	)		-38.3	%
Stock-based compensation		1,507		5,900		(4,393	)		-74.5	%		1,332		3,463		(2,131	)		-61.5	%
	$	18,638	$	24,691	$	(6,053	)		-24.5	%	$	18,836	$	23,344	$	(4,508	)		-19.3	%

For the three months ended ~~June~~September 30, 2021, R&D Expenses decreased by approximately ~~$6.1~~$4.5 million compared to the same period in 2020, primarily attributable to the following:

●

a decrease in stock-based compensation expense of approximately ~~$4.4~~$2.1 million primarily due to a decrease of ~~approximately $3.8~~$2.3 million for stock awards that have fully vested and a decrease of approximately ~~$1.1~~$0.3 million ~~from~~for stock ~~award forfeitures,~~awards forfeited, partially offset by an increase of ~~approximately~~ $0.5 million from new ~~grants~~grants; and ~~other immaterial fluctuations; and~~

●

a decrease in Internal R&D of approximately $1.7 million, primarily due to a ~~decrease in payroll and payroll-related expenses as a result of a~~ reduction in ~~headcount~~.headcount.

Other income (expenses):

Other income (expenses)	For the Three Months Ended						Change						For the Three Months Ended						Change
(in thousands)	June 30,						$			%			September 30,						$			%
	2021			2020			2021/2020			2021/2020			2021			2020			2021/2020			2021/2020
Interest income	$	121		$	66		$	55			83.3	%	$	13		$	22		$	(9	)		-40.9	%
Interest expense		(3,518	)		(3,784	)		266			-7.0	%		(3,121	)		(3,627	)		506			-14.0	%
Legal verdict (expense) credit		14,902			(93	)		14,995			-16123.7	%
Legal verdict expense														(24,498	)		(15,855	)		(8,643	)		54.5	%
Loss on debt extinguishment														(8,146	)		—			(8,146	)		-100.0	%
Other income		60			77			(17	)		-22.1	%		71			128			(57	)		-44.5	%
	$	11,565		$	(3,734	)	$	15,299			-409.7	%	$	(35,681	)	$	(19,332	)	$	(16,349	)		84.6	%

Interest expense:

For the three months ended ~~June~~September 30, 2021,, we recognized approximately ~~$3.5~~$3.1 million in interest expense, compared to ~~$3.8~~$3.6 million of interest expense for the three months ended ~~June~~September 30, ~~2020~~. 2020. The decrease in interest expense was primarily the result of the interest expense for the milestone payments being paid to Pfizer in installments.

Legal verdict ~~(expense) credit:~~expense:

For the three months ended ~~June~~September 30, 2021, we ~~reduced our~~recorded additional legal expense ~~accrual by $20.0~~of $24.5 million ~~with respect~~primarily related to ~~the~~ ~~Eshelman v. Puma Biotechnology, Inc., et al.~~ ~~judgment, and we increased~~ our ~~legal expense accrual by $5.1 million with respect to the~~ ~~Hsu v. Puma Biotechnology, Inc., et.al~~ ~~judgment, which resulted in a $14.9 million net credit in legal verdict expense~~outstanding class action matter. See Item 1. "Legal Proceedings" for ~~the period.~~further details.

Loss on debt extinguishment:

For the three months ended September 30, 2021, we recognized approximately $8.1 million in loss on debt extinguishment related to our debt refinancing during July 2021. See Item 2 "Liquidity and Capital Resources".

Table of Contents

~~Six~~Nine Months Ended ~~June~~September 30, 2021 Compared to ~~Six~~Nine Months Ended ~~June~~September 30, 2020

Total revenue:

For the ~~six~~nine months ended ~~June~~September 30, 2021, total revenue was approximately ~~$151.6~~$197.8 million, compared to ~~$121.8~~$172.6 million for the ~~six~~nine months ended ~~June~~September 30, 2020.

Product revenue, net:

Product revenue, net was approximately ~~$94.7~~$138.1 million for the ~~six~~nine months ended ~~June~~September 30, 2021, compared to ~~$97.4~~$146.7 million for the ~~six~~nine months ended ~~June~~September 30, 2020. The decrease in product revenue, net was attributable to a volume decrease of approximately

~~15.0%~~ 16.0% in bottles of NERLYNX sold, and an increase in reserves for variable consideration from approximately ~~15.3%~~15.5% of product revenue for the ~~six~~nine months ended ~~June~~September 30, 2020 to approximately ~~18.3%~~18.5% of product revenue for the ~~six~~nine months ended ~~June~~September 30, 2021. The increase in reserves for variable consideration is primarily due to an increase in Medicaid claims and government chargebacks as a percentage of gross revenue. The decrease in product revenue, net was partially offset by an increase in gross selling price that occurred in the third quarter of 2020 and in the first and third quarter of 2021.

License revenue:

License revenue was approximately $50.3 million for the ~~six~~nine months ended ~~June~~September 30, 2021, compared to approximately $22.7 million for the ~~six~~nine months ended ~~June~~September 30, 2020. The increase in license revenue is due to a large, upfront payment in connection with an amendment to a sub-license agreement entered into during the ~~six~~nine months ended ~~June~~September 30, 2021.

Royalty revenue:

Royalty revenue was approximately ~~$6.6~~$9.5 million for the ~~six~~nine months ended ~~June~~September 30, 2021, compared to ~~$1.7~~$3.1 million for the ~~six~~nine months ended ~~June~~September 30, 2020. The increase was due to increased product sales by our sub-licensees as they continue to commercialize NERLYNX in additional territories.

Cost of sales:

Cost of sales was approximately ~~$41.5~~$51.8 million for the ~~six~~nine months ended ~~June~~September 30, 2021, compared to ~~$18.5~~$28.4 million for the ~~six~~nine months ended ~~June~~September 30, 2020. The increase in cost of sales was primarily attributable to a $20.0 million one-time license termination fee ~~the increase~~ in ~~the amortization~~February 2021.

Table of ~~the intangible asset under our license agreement with Pfizer and increased royalty expense due to Pfizer.~~Contents

Selling, general and administrative expenses:

For the ~~six~~nine months ended ~~June~~September 30, 2021, SG&A Expenses were approximately ~~$67.7~~$93.8 million, compared to approximately ~~$60.3~~$89.9 million for the ~~six~~nine months ended ~~June~~September 30, 2020. SG&A Expenses for the ~~six~~nine months ended ~~June~~September 30, 2021 and 2020 were as follows:

Selling, general, and administrative expenses	For the Six Months Ended				Change						For the Nine Months Ended				Change
(in thousands)	June 30,				$			%			September 30,				$			%
	2021		2020		2021/2020			2021/2020			2021		2020		2021/2020			2021/2020
Payroll and related costs	$	20,599	$	21,384	$	(785	)		-3.7	%	$	30,113	$	31,658	$	(1,545	)		-4.9	%
Professional fees and expenses		20,416		20,981		(565	)		-2.7	%		30,028		32,252		(2,224	)		-6.9	%
Travel and meetings		2,042		2,933		(891	)		-30.4	%		3,380		4,023		(643	)		-16.0	%
Facilities and equipment costs		2,795		2,864		(69	)		-2.4	%		4,175		4,276		(101	)		-2.4	%
Stock-based compensation		20,333		9,422		10,911			115.8	%		23,281		13,523		9,758			72.2	%
Other		1,563		2,700		(1,137	)		-42.1	%		2,855		4,150		(1,295	)		-31.2	%
	$	67,748	$	60,284	$	7,464			12.4	%	$	93,832	$	89,882	$	3,950			4.4	%

For the ~~six~~nine months ended ~~June~~September 30, 2021, SG&A Expenses increased by approximately ~~$7.5~~$3.9 million compared to the same period in 2020, primarily attributable to the following:

●

an increase in stock-based compensation expense of approximately ~~$10.9~~$9.8 million primarily due to the $13.6 million incremental expense resulting from the modification toof the term of Mr. Auerbach’s warrant, and an increase of ~~$2.6~~approximately $3.4 million from new grants, partially offset by a decrease of approximately ~~$4.2~~$5.9 million for ~~stock awards that have~~ fully vested grants and a decrease of approximately ~~$1.1~~$1.3 million ~~from stock~~for awards forfeited.

This increase was partially offset by:

●

~~a decrease in other expense of $1.1 million due to lower sponsorships, software, educational and training costs for the commercial team;~~

●

~~a decrease in travel and meetings of approximately $0.9 million related to travel restrictions due to the COVID-19 pandemic;~~

●

~~a decrease in payroll and related costs of approximately $0.8 million; and~~

●

a decrease in professional fees and expenses of approximately ~~$0.6~~$2.2 million, consisting ~~primarily of decreases~~ of approximately ~~$1.8~~$3.1 million for professional fees, primarily related to decreased consultancy efforts related to marketing and commercialization support, and lower audit and IT related expenses of approximately $0.2 million, partially offset by an increase of approximately ~~$0.1~~$0.4 million in insurance premiums and an increase of approximately ~~$1.1~~$0.7 million in legal fees in connection with various ~~lawsuits.~~lawsuits;

●

a decrease in payroll and related costs of approximately $1.5 million due to a reduction in headcount;

●

a decrease in other expenses of approximately $1.3 million due to a recovery of bad debt expense of $1.0 million and other miscellaneous costs; and

●

a decrease in travel and meeting related costs of approximately $0.6 million resulting from COVID travel restrictions.

Table of Contents

Research and development expenses:

For the ~~six~~nine months ended ~~June~~September 30, 2021, R&D expenses were approximately ~~$38.9~~$57.7 million, compared to approximately ~~$50.1~~$73.5 million for the ~~six~~nine months ended ~~June~~September 30, 2020. R&D expenses for the ~~six~~nine months ended ~~June~~September 30, 2021 and 2020 were as follows:

Research and development expenses	For the Six Months Ended				Change						For the Nine Months Ended				Change
(in thousands)	June 30,				$			%			September 30,				$			%
	2021		2020		2021/2020			2021/2020			2021		2020		2021/2020			2021/2020
Clinical trial expense	$	13,108	$	15,873	$	(2,765	)		-17.4	%	$	21,504	$	24,130	$	(2,626	)		-10.9	%
Internal R&D		18,469		20,123		(1,654	)		-8.2	%		26,230		29,564		(3,334	)		-11.3	%
Consultant and contractors		3,523		4,035		(512	)		-12.7	%		4,870		6,218		(1,348	)		-21.7	%
Stock-based compensation		3,766		10,115		(6,349	)		-62.8	%		5,098		13,578		(8,480	)		-62.5	%
	$	38,866	$	50,146	$	(11,280	)		-22.5	%	$	57,702	$	73,490	$	(15,788	)		-21.5	%

For the ~~six~~nine months ended ~~June~~September 30, 2021, R&D Expenses decreased by approximately ~~$11.3~~$15.8 million compared to the same period in 2020, primarily attributable to the following:

●

a decrease in stock-based compensation expense of approximately ~~$6.3~~$8.5 million primarily due to a decrease of approximately ~~$6.3~~$8.6 million for ~~stock awards that~~ fully vested grants and a decrease of ~~approximately $1.0~~$1.3 million ~~from stock award forfeitures,~~for awards forfeited, partially offset by an increase of ~~approximately $1.0~~$1.4 million from new ~~grants and other immaterial fluctuations;~~

grants;

●

a decrease in internal R&D expense of approximately $3.3 million resulting from a reduction in headcount;

●

a decrease in clinical trial expenses of approximately ~~$2.8~~$2.6 million ~~primarily~~ due to the close out of certain clinical trials and a reduction in patient enrollments and ~~patient on studies for open studies;~~monitoring costs; and

●

~~a decrease in internal R&D expense of approximately $1.7 million, primarily due to a decrease in payroll and payroll-related expenses; and~~

●

a decrease in consultant and contractor expenses of approximately ~~$0.5~~$1.3 million ~~primarily~~ due to the close out of certain clinical trials.

Other income (expenses):

Other income (expenses)	For the Nine Months Ended						Change
(in thousands)	September 30,						$			%
	2021			2020			2021/2020			2021/2020
Interest income	$	147		$	474		$	(327	)		-69.0	%
Interest expense		(10,089	)		(10,479	)		390			-3.7	%
Legal verdict expense		(9,781	)		(16,041	)		6,260			-39.0	%
Loss on debt extinguishment		(8,146	)		—			(8,146	)		0.0	%
Other income		173			298			(125	)		-41.9	%
	$	(27,696	)	$	(25,748	)	$	(1,948	)		7.6	%

Other income (expenses)

For the Six Months Ended

Change

(in thousands)

June 30,

$

%

2021

2020

2021/2020

2021/2020

Interest income

$
134

$
452

$
(318
)

-70.4
%
Interest expense

(6,968
)

(6,852
)

(116
)

1.7
%
Legal verdict (expense) credit

14,717

(186
)

14,903

-8012.4
%
Other income

102

170

(68
)

-40.0
%

$
7,985

$
(6,416
)

$
14,401

-224.5
%

~~Interest income:~~

Table of Contents

~~For the six months ended~~ ~~June 30, 2021, interest income decreased by approximately $0.3 million compared to the six months ended~~ ~~June 30, 2020. The decrease in interest income reflects less cash invested in money market accounts and high-yield savings accounts in 2021 compared to 2020.~~

~~Interest expense:~~Legal verdict (expense) credit:

For the ~~six~~nine months ended ~~June 30, 2021, we recognized approximately $7.0million in interest expense, compared to $6.9 million of interest expense for the six months ended~~ ~~June 30, 2020~~.

~~Legal verdict (expense) credit:~~

~~For the six months ended June~~September 30, 2021, we reduced our legal expense accrual by approximately $20.0 million with respect to the Eshelman v. Puma Biotechnology, Inc., et al. judgment, and we increased our legal expense accrual by ~~$5.3~~approximately $29.6 million with respect to the Hsu v. Puma Biotechnology, Inc., et.al judgment, which resulted in a ~~$14.7 million~~ net ~~credit in~~ legal verdict expense of $9.8 million for the period.

Loss on debt extinguishment:

For the nine months ended September 30, 2021, we recognized approximately $8.1 million in connection with our repayment and termination of the Oxford Credit Facility, which we replaced with the Athyrium Note. See Item 2. Liquidity and Capital Resources.

Liquidity and Capital Resources

We have reported a net loss of approximately $44.7 million and net loss of approximately $33.4 million for the three and nine months ended September 30, 2021, respectively. As of September 30, 2021, we had approximately $87.5 million in cash and marketable securities. Our commercialization, research and development or marketing efforts may require funding in addition to our current cash and marketable securities. Additionally, in light of recent developments in our class action lawsuit, we may need to make two payments totaling approximately $54.2 million in January and June 2022 in settlement of the litigation. As a result, the combination of these factors together with our cash and marketable securities balances and recurring losses since inception raise substantial doubt about our ability to continue as a going concern.

We may need to obtain additional funding to sustain operations and continue to commercialize neratinib in the United States. Our ability to obtain additional funding may be adversely impacted by a variety of issues including, uncertain market conditions, the COVID-19 pandemic, our success in commercializing neratinib, unfavorable decisions of regulatory authorities, adverse clinical trial results or the outcomes of outstanding or new litigation. We cannot assure you that such funding will be available on commercially reasonable terms, or at all. While we have been successful in raising capital in the past, there can be no assurance that we will be able to do so in the future. Our ability to obtain funding may be adversely impacted by uncertain market conditions, including the COVID-19 pandemic, our success in commercializing neratinib, unfavorable decisions of regulatory authorities or adverse clinical trial results. The outcome of these matters cannot be predicted at this time.

The following table summarizes our liquidity and capital resources as of ~~June~~September 30, 2021 and December 31, 2020, and for the ~~six~~nine months ended ~~June~~September 30, 2021 and 2020, and is intended to supplement the more detailed discussion that follows:

	As of			As of
Liquidity and capital resources (in thousands)	September 30, 2021			December 31, 2020
Cash and cash equivalents	$	63,947		$	85,293
Marketable securities	$	23,596		$	8,096
Working capital	$	20,662		$	31,884
Stockholders' deficit	$	(10,922	)	$	(5,951	)

	Nine Months Ended			Nine Months Ended
	September 30, 2021			September 30, 2020
Cash provided by (used in):
Operating activities	$	26,085		$	6,408
Investing activities		(15,502	)		22,580
Financing activities		(31,929	)		45
Net increase (decrease) in cash, cash equivalents and restricted cash	$	(21,346	)	$	29,033

As of

As of

Liquidity and capital resources (in thousands)

June 30, 2021

December 31, 2020

Cash and cash equivalents

$
89,848

$
85,293

Marketable securities

$
19,127

$
8,096

Working capital

$
29,851

$
31,884

Stockholders' equity (deficit)

$
29,469

$
(5,951
)

Six Months Ended

Six Months Ended

June 30, 2021

June 30, 2020

Cash provided by (used in):

Operating activities

$
15,587

$
4,688

Investing activities

(11,032
)

25,158

Financing activities

—

2

Net increase in cash, cash equivalents and restricted cash

$
4,555

$
29,848

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~~Operating Activities:~~

~~For the six months ended June 30,~~On November 2, 2021, we ~~reported net income~~implemented a restructuring of the organization in part due to the impact of COVID-19 on our sales. The restructuring includes a reduction in headcount of approximately ~~$11.3~~13% consisting primarily of commercial and research personnel. We anticipate approximately $1.2 million ~~compared~~in severance related costs which includes salary, insurance premiums, and sales commissions. This cost will be recorded in the fourth quarter of 2021. We believe that all payments related to ~~a net loss of approximately $13.5 million for the same period in 2020. Additionally, cash provided~~this plan will be made by ~~operating activities for the six months ended June 30, 2021 was approximately $15.6 million compared to approximately $4.7 million of cash provided by operating activities for the same period in 2020.~~March 31, 2022.

Operating Activities:

Cash provided by operating activities for the ~~six~~nine months ended ~~June~~September 30, 2021 consisted of a net ~~income~~loss of approximately ~~$11.3~~$33.4 million, offset by a decrease of approximately $39.5 million of non-cash items, including stock-based compensation, depreciation and amortization, loss on extinguishment of debt of approximately $3.8 million related to the write off of debt issuance costs and provision for credit loss expense. These decreases were partially offset by an increase in accrued expenses and other of approximately ~~$18.5~~$3.7 million, an increase in inventory of approximately ~~$4.2~~$3.8 million, and an increase in our post-marketing commitment liability of approximately $0.9 million which were partially offset by decreases of approximately $5.8 million in accounts receivable, net ~~of approximately $4.0 million,~~and other current assets, and an increase of approximately ~~$1.2~~$8.0 million in accounts ~~payable and in other immaterial fluctuations, and an increase~~payable.

Cash provided by operating activities for the nine months ended September 30, 2020 consisted of ~~$1.0~~a net loss of approximately $45.0 million, ~~due to a recovery of credit loss expense; partially~~ offset by ~~a decrease of~~ approximately ~~$30.0~~$34.2 million of non-cash items, such as stock-based compensation and depreciation and amortization, an increase in accrued expense and other of approximately $21.0 million, a decrease in prepaid expenses and other ~~current assets~~ of approximately ~~$3.2 million.~~

~~Cash provided by operating activities for the six months ended June 30, 2020 consisted of a net loss of approximately $13.5~~$4.4 million, ~~offset by approximately $23.7 million of non-cash items, such as stock-based compensation~~ and ~~depreciation and amortization,~~ a decrease in accounts receivable, net of approximately ~~$4.9 million, and other immaterial changes of $0.1 million;~~$1.8 million. These increases were partially offset by a decrease in accounts payable of approximately $6.7 million, an increase in other current assets of approximately $3.1 million and ~~a decrease in accounts payable of approximately $7.4 million.~~other immaterial changes.

Investing Activities:

During the ~~six~~nine months ended ~~June~~September 30, 2021, cash used in investing activities was approximately ~~$11.0~~$15.5 million, compared to net cash provided by investing activities of ~~$25.2~~$22.6 million for the same period in 2020.

Cash used in investing activities during the ~~six~~nine months ended ~~June~~September 30, 2021 consisted of approximately ~~$19.1~~$38.1 million of in purchases available-for-sale securities, partially offset by maturities of approximately ~~$8.1~~$22.6 million of available-for-sale securities.

Net cash provided by investing activities during the ~~six~~nine months ended ~~June~~September 30, 2020 consisted of approximately ~~$51.5~~$57.0 million of maturities of available-for-sale securities, partially offset by the purchase of ~~available for sale~~available-for-sale securities of approximately ~~$16.4~~$24.4 million and an increase in intangible assets relating to the milestone achieved under the Company’s license agreement with Pfizer of $10.0 million.

Financing Activities:

During the ~~six~~nine months ended ~~June~~September 30, 2021, net cash used in financing activities was $31.9 million. During July 2021, we used approximately $8.5 million for the payment of prepayment costs, end of loan payment costs and other extinguishment costs related to our credit facility with Oxford, and approximately $1.9 million in payment of debt issuance costs related to the ~~same period in 2020, cash~~Athyrium Notes, and $20.0 million was ~~materially unchanged by financing activities. However, during April 2020, we borrowed and fully repaid approximately $8.4 million~~used for installment payments relating to the milestone achieved under our license agreement with ~~no penalty or interest from Silicon Valley Bank, or SVB, under the Paycheck Protection Program, or PPP,~~Pfizer of ~~the Coronavirus Aid, Relief, and Economic Security Act.~~$20.00 million.

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Oxford Loan and Security Agreement:

In October 2017, we entered into a loan and security agreement with SVB, as administrative agent, and the lenders party thereto from time to time, or the Original Lenders, including Oxford Finance, LLC, or Oxford, and SVB. Pursuant to the terms of the credit facility provided for by the loan and security agreement, or the Original Credit Facility, we borrowed $50.0 million.In May 2018, we entered into an amendment to the loan and security agreement, which provided for an amended credit facility, or the Amended Credit Facility. Under the Amended Credit Facility, the Original Lenders agreed to make term loans available to us in an aggregate amount of $155.0 million, consisting of (i) an aggregate amount of $125.0 million, the proceeds of which, in part, were used to repay the $50.0 million we borrowed under the Original Credit Facility, and (ii) an aggregate amount of $30.0 million that we drew in December 2018, which was available under the Amended Credit Facility as a result of achieving a specified minimum revenue milestone.

On June 28, 2019, or the Effective Date, we entered into an amendment and restatement of the loan and security agreement, which provided for a new credit facility, or the New Credit Facility, with Oxford, as collateral agent, and the lenders party thereto from time to time, including Oxford, pursuant to which we repaid the $155.0 million outstanding under the Amended Credit Facility, as well as all applicable exit and prepayment fees, owed to the Original Lenders under the Amended Credit Facility, using cash on hand and $100.0 million in new borrowings from the New Credit Facility. Under the New Credit Facility, we issued to Oxford new and/or replacement secured promissory notes in an aggregate principal amount for all such promissory notes of $100.0 million evidencing the New Credit Facility. ~~No additional money remains available to us under the New Credit Facility.~~

The New Credit Facility was secured by substantially all of our personal property other than our intellectual property. We also pledged 65% of the issued and outstanding capital stock of our subsidiaries, Puma Biotechnology Ltd. and Puma Biotechnology B.V. The New Credit Facility limited our ability to grant any interest in our intellectual property to certain permitted licenses and permitted encumbrances set forth in the agreement.

The term loans under the New Credit Facility bore interest at an annual rate equal to the greater of (i) 9.0% and (ii) the sum of (a) the “prime rate,” as reported in The Wall Street Journal on the last business day of the month that immediately preceded the month in which the interest will accrue, plus (b) 3.5%. We were required to make monthly interest-only payments on each term loan under the New Credit Facility commencing on the first calendar day of the calendar month following the funding date of such term loan, and continuing on the first calendar day of each calendar month thereafter through August 1, 2021, or the Amortization Date. Commencing on the Amortization Date, and continuing on the first calendar day of each calendar month thereafter, we would have made consecutive equal monthly payments of principal, together with applicable interest, in arrears to each lender under the New Credit Facility, calculated pursuant to the New Credit Facility. All unpaid principal and accrued and unpaid interest with respect to each term loan under the New Credit Facility was due and payable in full on June 1, 2024, or the Maturity Date. Upon repayment of such term loans, we were also required to make a final payment to the lenders equal to 7.5% of the aggregate principal amount of such term loans outstanding as of the Effective Date. ~~The effective interest rate as of June 30, 2021 was 12.75%.~~

At our option, we were able to prepay the outstanding principal balance of any term loan in whole but not in part, subject to a prepayment fee of 3.0% of any amount prepaid if the prepayment occurred through and including the first anniversary of the funding date of such term loan, 2.0% of the amount prepaid if the prepayment occurred after the first anniversary of the funding date of such term loan through and including the second anniversary of the funding date of such term loan, and 1.0% of the amount prepaid if the prepayment occurred after the second anniversary of the funding date of such term loan and prior to the Maturity Date.

The New Credit Facility included affirmative and negative covenants applicable to us, our current subsidiaries and any subsidiaries we would have created in the future. The affirmative covenants included, among others, covenants requiring us to maintain our legal existence and governmental approvals, deliver certain financial reports, maintain insurance coverage and satisfy certain requirements regarding deposit accounts. We were also required to achieve certain product revenue targets, measured as of the last day of each fiscal quarter on a trailing year-to-date basis. New minimum revenue levels were to be established for each subsequent fiscal year by mutual agreement of us, Oxford, as collateral agent, and the lenders under the New Credit Facility. The negative covenants included, among others, restrictions on our transferring collateral, incurring additional indebtedness, engaging in mergers or acquisitions, paying dividends or making other distributions, making investments, creating liens, selling assets and suffering a change in control, in each case subject to certain exceptions.

The New Credit Facility also included events of default, the occurrence and continuation of which could have caused interest to be charged at the rate that would otherwise have been applicable plus 5.0% and would have provided Oxford, as collateral agent, with the right to exercise remedies against us and the collateral securing the New Credit Facility, including foreclosure against the property securing the New Credit Facility, including our cash. These events of default included, among other things, our failure to pay principal or interest due under the New Credit Facility, a breach of certain covenants under the New Credit Facility, our insolvency, a material adverse change, the occurrence of any default under certain other indebtedness in an amount greater than $500,000 and one or more judgments against us in an amount greater than $500,000 individually or in the aggregate ~~that remained unsatisfied, unvacated, or unstayed for a period of 10 days after its entry~~.

On February 27, 2020, we entered into an amendment of the New Credit Facility with Oxford to establish our minimum revenue thresholds for the trailing year to date periods ending March 31, June 30, September 30, and December 31, 2020 and the fiscal year 2021. On August 5, 2020, we entered into an amendment of the New Credit Facility with Oxford to amend the minimum revenue thresholds for the trailing year to date periods ending September 30 and December 31, 2020. On February 3, 2021, we entered into an amendment of the New Credit Facility with Oxford to establish our minimum revenue thresholds for the trailing year to date periods ending March 31, June 30, September 30 and December 31, 2021.

Table of June 30, 2021, there were $100.0 million in term loans outstanding under the New Credit Facility, representing all of our long-term debt outstanding as of that date, and we were in compliance with all applicable covenants under the New Credit Facility.Contents

Athyrium Note Purchase Agreement:

On July 23, 2021, or the NPA Effective Date, we repaid the $100.0 million in term loans outstanding under the New Credit Facility, as well as all accrued interest, applicable exit, prepayment and legal fees owed to the lenders under the New Credit Facility in an amount of approximately $9.2 million, using cash on hand and $100.0 million in new borrowings from the issuance of notes under the note purchase agreement, or the ~~Note Purchase Agreement,~~Athyrium Notes, that we entered into on the NPA Effective Date with Athyrium Opportunities IV Co-Invest 1 LP, or, together with its affiliates, Athyrium, as administrative agent, and the purchasers party thereto from time to time, or the Purchasers, including Athyrium.

Pursuant to the ~~Note Purchase Agreement,~~Athyrium Notes, the Purchasers agreed to purchase from us, and we agreed to issue to such Purchasers, notes payable by us. On the NPA Effective Date, we issued to the Purchasers notes in an aggregate principal amount for all such notes of $100.0 million. Subject to satisfaction of certain conditions set forth in the ~~Note Purchase Agreement,~~Athyrium Notes, $25.0 million in additional notes remains available to us under the ~~Note Purchase Agreement.~~Athyrium Notes.

The obligations of usthe Company under the ~~Note Purchase Agreement~~Athyrium Notes are secured by substantially all of our assets, including our intellectual property. We also pledged 65% of the issued and outstanding capital stock of our subsidiaries, Puma Biotechnology Ltd. and Puma Biotechnology B.V.

The notes ~~issued under the Note Purchase Agreement~~ bear interest at an annual rate equal to the sum of (a) 8.0% and (b) Adjusted Three-Month LIBOR for such Interest Period (as defined in the ~~Note Purchase Agreement)~~Athyrium Notes). We are required to make quarterly interest payments on each note issued under the ~~Note Purchase Agreement~~Athyrium Notes commencing on the last business day of September 2021, and continuing on the last business day of each March, June, September and December through June 30, 2024, or the NPA Amortization Date. Commencing on the NPA Amortization Date, and continuing on the last day of each March, June, September and December thereafter, we will make consecutive equal quarterly payments of principal, together with applicable interest, in arrears to each Purchaser, calculated pursuant to the ~~Note Purchase Agreement.~~Athyrium Notes. All unpaid principal and accrued and unpaid interest with respect to each note issued under the ~~Note Purchase Agreement~~Athyrium Notes is due and payable in full on July 23, 2026, or the NPA Maturity Date. At our option, we may prepay the outstanding principal balance of all or any portion of the principal amount of the notes, subject to a prepayment fee equal to (i) a make-whole amount if the prepayment occurs on or prior to the second anniversary of the NPA Effective Date and (ii) 2.0% of the amount prepaid if the prepayment occurs after the second anniversary of the NPA Effective Date by on or prior to the third anniversary of the NPA Effective Date. Upon prepayment or repayment of all or any portion of the principal amount of the notes (whether on the NPA Maturity Date or otherwise), we are also required to pay an exit fee to the Purchasers equal to 2.00% of the aggregate principal amount of such notes prepaid or repaid.

The ~~Note Purchase Agreement includes~~Athyrium Notes include affirmative and negative covenants applicable to us, our current subsidiaries and any subsidiaries we create in the future. The affirmative covenants include, among others, covenants requiring us to maintain our legal existence and governmental approvals, deliver certain financial reports, maintain insurance coverage and satisfy certain requirements regarding deposit accounts. We must also (i) maintain a minimum amount of unrestricted cash in deposit accounts subject to a control agreement in favor of Athyrium at any time and (ii) achieve at least a specified minimum amount of revenue (based on a combination of both sales of NERLYNX in the United States and royalty revenues received by us for sales of NERLYNX outside the United States), measured as of the last day of each four consecutive fiscal quarter period. The negative covenants include, among others,

restrictions on our transferring collateral, incurring additional indebtedness, engaging in mergers or acquisitions, paying dividends or making other distributions, making investments, creating liens, selling assets and suffering a change in control, in each case subject to certain exceptions.

Table of Contents

The ~~Note Purchase Agreement~~Athyrium Notes also ~~includes~~include events of default, the occurrence and continuation of which could cause interest to be charged at the rate that is otherwise applicable plus 2.0% and would provide Athyrium, as administrative agent, with the right to exercise remedies against us and the collateral securing the new credit facility, including foreclosure against the property securing the obligations of us under the ~~Note Purchase Agreement,~~Athyrium Notes, including our cash. These events of default include, among other things, our failure to pay principal or interest due under the ~~Note Purchase Agreement,~~Athyrium Notes, a breach of certain covenants under the ~~Note Purchase Agreement,~~Athyrium Notes, our insolvency, a material adverse change, the occurrence of any default under certain other indebtedness in an amount greater than $750,000 and one or more judgments against us in an amount greater than $750,000 individually or in the aggregate that remains discharged or otherwise satisfied, in each case, as further described in the ~~Note Purchase Agreement.~~Athyrium Notes.

~~The foregoing description~~As of the Note Purchase Agreement and the notes is only a summary of the material terms thereof, and does not purport to be complete. The description is qualified in its entirety by reference to the Note Purchase Agreement and the form of note, which will be filed as exhibits to our Quarterly Report on Form 10-Q for the quarter ending September 30, ~~2021.~~2021, there were $102.0 million in term loans outstanding under the Athyrium Notes, representing all of our long-term debt outstanding as of that date, and we were in compliance with all applicable covenants.

Current and Future Financing Needs:

We did not receive or record any product revenues until the third quarter of 2017. We have spent, and expect to continue to spend, substantial amounts in connection with implementing our business strategy, including our planned product development efforts, our clinical trials, our research and development efforts and our commercialization efforts.

We may choose to begin new research and development efforts or we may choose to launch additional marketing efforts. These efforts may require funding in addition to the cash and cash equivalents totaling approximately ~~$89.8~~$63.9 million and ~~$19.1~~$23.6 million in marketable securities available at ~~June~~September 30, 2021. While our consolidated financial statements have been prepared on a going concern basis, we expect to continue incurring significant losses for the foreseeable future and will need to generate significant revenue to sustain operations and successfully commercialize neratinib. While we have been successful in raising financing in the past, there can be no assurance that we will be able to do so in the future. Our ability to obtain funding may be adversely impacted by uncertain market conditions, including the global COVID-19 pandemic, our success in commercializing neratinib, unfavorable decisions of regulatory authorities or adverse clinical trial results. The outcome of these matters cannot be predicted at this time.

In addition, we have based our estimate of capital needs on assumptions that may prove to be wrong. Changes may occur that would consume our available capital faster than anticipated, including the length and severity of the COVID-19 pandemic and measures taken to control the spread of COVID-19, as well as changes in and progress of our development activities, the impact of commercialization efforts, acquisitions of additional drug candidates and changes in regulation. Potential sources of financing include strategic relationships, public or private sales of equity or debt and other sources of funds. We may seek to access the public or private equity markets when conditions are favorable due to our long-term capital requirements. If we raise funds by selling additional shares of common stock or other securities convertible into common stock, the ownership interests of our existing stockholders will be diluted. If we are not able to obtain financing when needed, we may be unable to carry out our business plan. As a result, we may have to significantly limit our operations, and our business, financial condition and results of operations would be materially harmed. In such an event, we will be required to undertake a thorough review of our programs, and the opportunities presented by such programs, and allocate our resources in the manner most prudent.

Non-GAAP Financial Measures

In addition to our operating results, as calculated in accordance with generally accepted accounting principles, or GAAP, we use certain non-GAAP financial measures when planning, monitoring, and evaluating our operational performance. The following table presents our net loss and net loss per share, as calculated in accordance with GAAP, as adjusted to remove the impact of stock-based compensation. For the three and ~~six~~nine months ended ~~June~~September 30, 2021, stock-based compensation represented approximately ~~31.4%~~9.5% and ~~22.6%~~18.7% of our operating expenses, respectively, compared to ~~19.7%~~14.3% and ~~17.7%~~16.6% for the same respective ~~period~~periods in 2020, in each case excluding cost of sales. Our management believes that these non-GAAP financial measures are useful to enhance understanding of our financial performance, are more indicative of our operational performance and facilitate a better comparison among fiscal periods. These non-GAAP financial measures are not, and should not be viewed as, substitutes for GAAP reporting measures.

Table of Contents

Reconciliation of GAAP Net ~~Income (Loss)~~Loss to Non-GAAP Adjusted Net ~~Income~~Loss and

GAAP Net ~~Income (Loss)~~Loss Per Share to Non-GAAP Adjusted Net ~~Income~~Loss Per Share

(in thousands except share and per share data)

For the Three Months Ended June 30,

For the Six Months Ended June 30,

2021

2020

2021

2020

GAAP net income (loss)

$
(5,106
)

$
3,395

$
11,322

$
(13,538
)

Adjustments:

Stock-based compensation -

Selling, general and administrative (1)

16,731

4,730

20,332

9,422

Research and development (2)

1,508

5,900

3,767

10,115

Non-GAAP adjusted net income

$
13,133

$
14,025

$
35,421

$
5,999

GAAP net income (loss) per share—basic

$
(0.13
)

$
0.09

$
0.28

$
(0.34
)

Adjustment to net income (loss) (as detailed above)

0.45

0.27

0.60

0.49

Non-GAAP adjusted basic net income per share

$
0.32

(3)
$
0.36

(4)
$
0.88

(3)
$
0.15

(4)

GAAP net income (loss) per share—diluted

$
(0.13
)

$
0.08

$
0.28

$
(0.34
)

Adjustment to net income (loss) (as detailed above)

0.45

0.27

0.59

0.49

Non-GAAP adjusted diluted net income per share

$
0.32

(5)
$
0.35

(6)
$
0.87

(5)
$
0.15

(6)

(1) To reflect a non-cash charge to operating expense for selling, general, and administrative stock-based compensation.

(2) To reflect a non-cash charge to operating expense for research and development stock-based compensation.

(3) Non-GAAP adjusted basic net income per share was calculated based on 40,479,577 and 40,370,825 weighted-average shares of common stock outstanding for the three and six months ended June 30, 2021, respectively.

(4) Non-GAAP adjusted basic net income per share was calculated based on 39,432,030 and 39,361,596 weighted-average shares of common stock outstanding for the three and six months ended June 30, 2020, respectively.

(5) Non-GAAP adjusted diluted net income per share was calculated based on 40,986,716 and 40,939,688 weighted-average shares of common stock outstanding for the three and six months ended June 30, 2021, respectively.

(6) Non-GAAP adjusted diluted net income per share was calculated based on 39,997,571 and 39,815,867 weighted-average shares of common stock outstanding for the three and six months ended June 30, 2020, respectively.

	For the Three Months Ended September 30,						For the Nine Months Ended September 30,
	2021			2020			2021			2020
GAAP net loss	$	(44,672	)	$	(31,463	)	$	(33,350	)	$	(45,001	)
Adjustments:
Stock-based compensation -
Selling, general and administrative (1)		2,950			4,101			23,282			13,523
Research and development (2)		1,332			3,464			5,099			13,579
Non-GAAP adjusted net loss	$	(40,390	)	$	(23,898	)	$	(4,969	)	$	(17,899	)

GAAP net loss per share—basic	$	(1.09	)	$	(0.79	)	$	(0.82	)	$	(1.14	)
Adjustment to net loss (as detailed above)		0.10			0.19			0.70			0.69
Non-GAAP adjusted basic net loss per share (3) (4)	$	(0.99	)	$	(0.60	)	$	(0.12	)	$	(0.45	)

GAAP net loss per share—diluted	$	(1.09	)	$	(0.79	)	$	(0.82	)	$	(1.14	)
Adjustment to net loss (as detailed above)		0.10			0.19			0.70			0.69
Non-GAAP adjusted diluted net loss per share (5) (6)	$	(0.99	)	$	(0.60	)	$	(0.12	)	$	(0.45	)

⁽¹⁾To reflect a non-cash charge to operating expense for selling, general, and administrative stock-based compensation.

⁽²⁾ To reflect a non-cash charge to operating expense for research and development stock-based compensation.

⁽³⁾ Non-GAAP adjusted basic net loss per share was calculated based on 40,813,609 and 40,520,041 weighted-average shares of common stock outstanding for the three and nine months ended September 30, 2021, respectively.

⁽⁴⁾ Non-GAAP adjusted basic net loss per share was calculated based on 39,695,444 and 39,473,691 weighted-average shares of common stock outstanding for the three and nine months ended September 30, 2020, respectively.

⁽⁵⁾ Non-GAAP adjusted diluted net loss per share was calculated based on 40,813,609 and 40,520,041 weighted-average shares of common stock outstanding for the three and nine months ended September 30, 2021, respectively.

⁽⁶⁾ Non-GAAP adjusted diluted net loss per share was calculated based on 39,695,444 and 39,473,691 weighted-average shares of common stock outstanding for the three and nine months ended September 30, 2020, respectively.

Off-Balance Sheet Arrangements

We do not have any “off-balance sheet agreements,” as defined by SEC regulations.

Contractual Obligations

In June 2020, we entered into a letter agreement, or the Letter Agreement, with Pfizer relating to the method of payment associated with our achievement of a milestone that triggered a $40.0 million payment under our license agreement with Pfizer. The Letter Agreement ~~permits~~permitted us to make the milestone payment in installments with the majority of the amount payable to Pfizer (including interest) ~~to be made in 2021 and the final payment occurring~~ by September ~~30,~~ 2021. ~~Unpaid portions of~~All amounts related to the ~~milestone payment will accrue interest at 6.25% per annum until paid.~~Letter Agreement were paid in full during August 2021.

Other than as described in the preceding paragraph, there have been no material changes outside the ordinary course of business to our contractual obligations and commitments as described in “Management’s Discussion and Analysis of Financial Condition and Results of Operations” in our Annual Report on Form 10-K for the year ended December 31, 2020.

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Item3.

QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

~~QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK~~

Some of the securities that we invest in have market risk in that a change in prevailing interest rates may cause the principal amount of the cash equivalents to fluctuate. Financial instruments that potentially subject us to significant concentrations of credit risk consist primarily of cash and cash equivalents. We invested our excess cash primarily in cash equivalents such as money market investments as of ~~June~~September 30, 2021. The primary objectives of our investment activities are to ensure liquidity and to preserve principal while at the same time maximizing the income we receive from our cash and cash equivalents without significantly increasing risk. Additionally, we established guidelines regarding approved investments and maturities of investments, which are designed to maintain safety and liquidity.

Because of the short-term maturities of our cash equivalents, we do not believe that a 10% increase in interest rates would have a material effect on the realized value of our cash equivalents.

We also have interest rate exposure as a result of borrowings outstanding under our Note Purchase Agreement. As of ~~June~~September 30, 2021, the outstanding principal amount of our borrowings under our prior loan and security agreement was $100.0 million, which has since been repaid in full. As of July 23, 2021, the outstanding principal amount of our borrowings under our Note Purchase Agreement was $100.0 million. Our borrowings under the Note Purchase Agreement bear interest at an annual rate equal to the sum of (a) 8.0% and (b) Adjusted Three-Month LIBOR for such Interest Period (as defined in the Note Purchase Agreement). Changes in LIBOR may therefore affect our interest expense associated with our borrowings under the Note Purchase Agreement.

We maintain disclosure controls and procedures that are designed to ensure that information required to be disclosed in our reports under the Exchange Act, is recorded, processed, summarized and reported within the timelines specified in the SEC’s rules and forms, and that such information is accumulated and communicated to our management, including our Chief Executive Officer and Chief Financial Officer, as appropriate, to allow timely decisions regarding required disclosures. In designing and evaluating the disclosure controls and procedures, management recognized that any controls and procedures, no matter how well designed and operated, can only provide reasonable assurance of achieving the desired control objectives and in reaching a reasonable level of assurance, management necessarily was required to apply its judgment in evaluating the cost-benefit relationship of possible controls and procedures.

Under the supervision and with the participation of our management, including our Chief Executive Officer and Chief Financial Officer, we have evaluated the effectiveness of our disclosure controls and procedures (as defined under Exchange Act Rule 13a-15(e)), as of ~~June~~September 30, 2021. Based on that evaluation, our Chief Executive Officer and Chief Financial Officer have concluded that these disclosure controls and procedures were effective as of ~~June~~September 30, 2021.

There were no changes in our internal control over financial reporting during the three months ended ~~June~~September 30, 2021 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

On June 3, 2015, Hsingching Hsu, individually and on behalf of all others similarly situated, filed a class action lawsuit against us and certain of our executive officers in the United States District Court for the Central District of California (Case No. 8:15-cv-00865-AG-JCG). On October 16, 2015, lead plaintiff Norfolk Pension Fund filed a consolidated complaint on behalf of all persons who purchased our securities between July 22, 2014 and May 29, 2015. A trial on the claims relating to four statements alleged to have been false or misleading was held from January 15 to January 29, 2019. At trial, the jury found that three of the four challenged statements were not false or misleading, and thus found in the defendants’ favor on those claims. The jury found liability as to one statement and awarded a maximum of $4.50 per share in damages, which represents approximately 5% of the total claimed damages of $87.20 per share. On September 9, 2019, the Court entered an order specifying the rate of prejudgment interest to be awarded on any valid claims at the 52-week Treasury Bill rate. On September 8, 2020, ~~the claims administrator submitted its final claims report to the Court~~ and as supplemented on October 9, 2020, the claims administrator submitted its ~~supplemental claims report. The~~final claims report, ~~reflects~~reflecting approximately $50.5 million in claimed ~~damages. We disagree with~~damages, exclusive of prejudgment interest. On October 29, 2021, the parties informed the Court that they had reached a settlement in principle, and the Court entered judgment in the amount of claimed ~~damages.~~ damages and prejudgment interest totaling approximately $54.2 million. On November ~~27, 2020,~~2, 2021, the Court ~~issued an order setting out~~dismissed the ~~process~~case in light of the parties' settlement, retaining jurisdiction only for ~~challenging claims. That process remains on-going. On June 28, 2021, plaintiffs filed a proposed~~settlement approval. The parties' settlement in principle provides that there will be no judgment ~~on certain claims totaling~~for liability entered against Defendants, and provides for payment by us of approximately ~~$41.99~~$54.2 million in ~~damages plus interest~~two installments, to be paid in ~~the amount~~January and June of approximately $2.95 million. Defendants dispute the entry of judgment and the proposed amount of prejudgment interest. Defendants objected to plaintiffs’ proposed judgment on July 19, 2021 and intend to file a motion to exclude certain disputed claims from any judgment. ~~Based on a review of specific claims and~~2022. The settlement in principle is subject to execution of a formal settlement agreement to be negotiated among the outcome of the claims challenge process, we believe that total claimed damages after all claims challenges have been adjudicated could range from $30.0 million to $51.4 million. The total amount of aggregate class-wide damages still remains uncertain andparties, which agreement will be ~~ascertained only after~~submitted to the claims challenge process and the exhaustion of any appeals. It is reasonably possible that the final total damages awarded will differ from these estimates; however, the amount is not estimable at this time. A final judgment has not been entered.court for approval.

In February 2016, Fredric N. Eshelman filed a lawsuit against our Chief Executive Officer and President, Alan H. Auerbach, and us in the United States District Court for the Eastern District of North Carolina (Case No. 7:16-cv-00018-D). The complaint generally alleged that we and Mr. Auerbach made defamatory statements regarding Dr. Eshelman in connection with a proxy contest. In May 2016, Dr. Eshelman filed a notice of voluntary dismissal of the claims against Mr. Auerbach. A trial on the remaining defamation claims against us took place from March 11 to March 15, 2019. At trial, the jury found us liable and awarded Dr. Eshelman $15.9 million in compensatory damages and $6.5 million in punitive damages. We strongly disagree with the verdict and, on April 22, 2019, filed a motion for a new trial or, in the alternative, a reduced damages award. The Court denied that motion on March 2, 2020. We have appealed that ruling and the verdict. Additionally, after trial, the plaintiff filed a motion seeking approximately $3.0 million in attorneys’ fees, as well as pre-judgment interest. In the Court’s March 2 ruling, it denied the motion for attorneys’ fees but granted the request for pre-judgment interest, bringing the total judgment to $26.3 million. On March 30, 2020, the plaintiff filed a notice of cross-appeal and conditional cross-appeal, appealing the Court’s order denying the plaintiff’s request for attorneys’ fees and conditionally cross-appealing a Court ruling that certain communications between Mr. Auerbach and his attorneys were protected by attorney-client privilege and a related evidentiary ruling. On June 23, 2021, the United States Court of Appeals for the Fourth Circuit affirmed the liability verdict in the Eshelman v. Puma Biotechnology, Inc., et al. matter but found the $22.35 million damages award, payable by us, to be excessive in light of the evidence at trial. The Court vacated this award and remanded for a new trial on damages. The Court’s judgment will eliminate the damages award, including interest on the judgment, pending further proceedings on remand. On July 7, 2021, the plaintiff filed a petition for panel or en banc rehearing, which was denied on July 20, 2021. On July 26, 2021, the plaintiff filed a motion to stay issuance of the Fourth Circuit’s mandate pending the filing and resolution of a petition for certiorari in the Supreme Court. The Fourth Circuit denied that motion on July 29, 2021. On October 18, 2021, the plaintiff filed a petition for certiorari with the Supreme Court seeking review of the Fourth Circuit's ruling. We estimate the high end of potential damages in the matter could be approximately $2.8 ~~million.~~million which also represents our estimate as the most likely outcome.

On September 17, 2020, we filed a lawsuit against Hedrick Gardner Kincheloe & Garofalo, L.L.P. and David L. Levy, the attorneys who previously represented us in Eshelman v. Puma Biotechnology, Inc., et al. in the Superior Court of Mecklenburg County, North Carolina. We are alleging legal malpractice based on the defendants’ negligent handling of the defense of us in Eshelman v. Puma Biotechnology, Inc., et al. as detailed above. We are seeking recovery of the entire amount awarded in Eshelman v. Puma Biotechnology, Inc., et al. On November 23, 2020, the defendant filed an answer to the complaint denying the allegations of ~~negligence~~.negligence.

On June 23, 2021, the United States Court of Appeals for the Fourth Circuit set aside the damages award in the Eshelman v. Puma Biotechnology, Inc., et al. matter and remanded the case to the District Court for a new trial on damages. On October 7, 2021, Judge R. Stuart Albright entered a Order staying all proceedings in the legal malpractice case for a period of six months to allow time to resolve the damages issues in the Eshelman case. As a result, the amount of potential damages that may be recovered in the legal malpractice case is uncertain at this time.

On September 22, 2021, we filed a complaint for Patent Infringement againstAstraZeneca (AZ), which markets osimeritinib (TAGRISSO), an irreversible EGFR kinase inhibitor for the treatment of patients with certain non-small cell lung cancers. We hold the rights to U.S. Patent No. 10,603,314 (the 314 patent) and U.S. Patent No. 10,596,162 (the 162 patent), which relate to the treatment of EGFR-mutant mediated lung cancers and filed suit to enforce our patent rights in the ’314 and ’162 patents against AZ for infringement arising out of AZ’s manufacture, use, offer for sale, sale, distribution, and/or importation of osimertinib and TAGRISSO® dosage forms.

We received a Notice Letter dated September 29, 2021 from Sandoz Inc. (“Sandoz”) notifying us of its Abbreviated New Drug Application (ANDA), which contains a Paragraph IV certification against U.S. Patent No. 7,399,865 that is listed, among other patents, in the U.S. Food and Drug Administration (FDA) list of Approved Drug Products with Therapeutic Equivalence Evaluations, for NERLYNX®. Sandoz is seeking to manufacture and market a generic version of NERLYNX® (neratinib) Tablets, 40 mg, in the United States. In response to the Notice Letter, we, with our licensor, have 45 days, which we will calculate from the date above, to file an infringement action against Sandoz in order to avail ourselves of the statutory 30-month stay of final FDA approval of Sandoz’s ANDA. We plan to protect our patent rights to the full extent of the law.

Under Item 1A of our Annual Report on Form 10-K for the year ended December 31, 2020, we identified important factors that could affect our financial performance and could cause our actual results for future periods to differ materially from our anticipated results or other expectations, including those expressed in any forward-looking statements made in this Quarterly Report. ~~There~~Except as described below, there has been no material change in our risk factors subsequent to the filing of our prior reports referenced above. However, the risks described in our reports are not the only risks we face. Additional risks and uncertainties that we currently deem to be immaterial or not currently known to us, as well as other risks reported from time to time in our reports to the SEC, also could cause our actual results to differ materially from our anticipated results or other expectations.

We have been subject to securities litigation in the past, and volatility in the price of our common stock may subject us to securities litigation in the future.

We did not sell any of our equity securities without registration under the Securities Act of 1933, as amended, during the three months ended ~~June~~ September 30, ~~2021~~.2021.

Neither we nor any “affiliated purchasers” within the definition of Rule 10b-18(a)(3) promulgated under the Exchange Act made any purchases of our equity securities during the quarter ended ~~June~~ September 30, ~~2021~~.2021.

Large accelerated filer	☐	Accelerated filer	☒

Non-accelerated filer	☐	Smaller reporting company	☐

Emerging growth company	☐

	*For the Three Months Ended September 30,*						*For the Nine Months Ended September 30,*
	*2021*			*2020*			*2021*			*2020*
Net loss	$	(44,672	)	$	(31,463	)	$	(33,350	)	$	(45,001	)
Other comprehensive loss:
Unrealized loss on available-for-sale securities, net of tax of $0 and $0		(1	)		(1	)		(2	)		(65	)
Reclassifications of gain on available-for-sale securities, included in “Other income (expenses)", net of tax of $0 and $0		0			0			0			3
Comprehensive loss	$	(44,673	)	$	(31,464	)	$	(33,352	)	$	(45,063	)

*For the Three Months Ended September 30, 2021*
							*Accumulated*
					*Additional*		*Other*
	*Common Stock*				*Paid-in*		*Comprehensive*			*Accumulated*
	*Shares*		*Amount*		*Capital*		*Income (Loss)*			*Deficit*			*Total*
Balance at June 30, 2021		40,733,928	$	4	$	1,355,775	$	(1	)	$	(1,326,309	)	$	29,469
Stock-based compensation		—		0		4,282		0			0			4,282
Shares issued or restricted stock units vested under employee stock plans		126,914		0		0		0			0			0
Unrealized loss on available-for-sale securities		—		0		0		(1	)		0			(1	)
Net loss		—		0		0		0			(44,672	)		(44,672	)
Balance at September 30, 2021		40,860,842	$	4	$	1,360,057	$	(2	)	$	(1,370,981	)	$	(10,922	)

For the Three Months Ended September 30, 2020
							*Accumulated*
					*Additional*		*Other*
	*Common Stock*				*Paid-in*		*Comprehensive*			*Accumulated*
	*Shares*		*Amount*		*Capital*		*Income (Loss)*			*Deficit*			*Total*
Balance at June 30, 2020		39,626,917	$	4	$	1,314,572	$	1		$	(1,291,174	)	$	23,403
Stock-based compensation		—		0		7,565		0			0			7,565
Shares issued or restricted stock units vested under employee stock plans		94,014		0		43		0			0			43
Unrealized loss on available-for-sale securities		—		0		0		(1	)		0			(1	)
Net loss		—		0		0		0			(31,463	)		(31,463	)
Balance at September 30, 2020		39,720,931	$	4	$	1,322,180	$	0		$	(1,322,637	)	$	(453	)

*For the Nine Months Ended September 30, 2021*
							*Accumulated*
					*Additional*		*Other*
	*Common Stock*				*Paid-in*		*Comprehensive*			*Accumulated*
	*Shares*		*Amount*		*Capital*		*Income (Loss)*			*Deficit*			*Total*
Balance at December 31, 2020		40,086,387	$	4	$	1,331,676	$	0		$	(1,337,631	)	$	(5,951	)
Stock-based compensation		—		0		28,381		0			0			28,381
Shares issued or restricted stock units vested under employee stock plans		774,455		0		0		0			0			0
Unrealized loss on available-for-sale securities		—		0		0		(2	)		0			(2	)
Net loss		—		0		0		0			(33,350	)		(33,350	)
Balance at September 30, 2021		40,860,842	$	4	$	1,360,057	$	(2	)	$	(1,370,981	)	$	(10,922	)

	For the Three Months Ended June 30,						For the Six Months Ended June 30,						*For the Three Months Ended September 30,*						*For the Nine Months Ended September 30,*
	2021			2020			2021			2020			*2021*			*2020*			*2021*			*2020*
Revenue:
Revenues:
Product revenue, net	$	48,856		$	48,771		$	94,672		$	97,380		$	43,426		$	49,333		$	138,098		$	146,713
License revenue		250			20,700			50,250			22,700			0			0			50,250			22,700
Royalty revenue		4,278			1,111			6,631			1,719			2,819			1,421			9,450			3,140
Total revenue		53,384			70,582			151,553			121,799			46,245			50,754			197,798			172,553
Operating costs and expenses:
Cost of sales		11,969			9,415			41,527			18,491			10,279			9,943			51,806			28,434
Selling, general and administrative		39,410			29,347			67,748			60,284			26,084			29,598			93,832			89,882
Research and development		18,638			24,691			38,866			50,146			18,836			23,344			57,702			73,490
Total operating costs and expenses		70,017			63,453			148,141			128,921			55,199			62,885			203,340			191,806
Income (loss) from operations		(16,633	)		7,129			3,412			(7,122	)
Loss from operations														(8,954	)		(12,131	)		(5,542	)		(19,253	)
Other income (expenses):
Interest income		121			66			134			452			13			22			147			474
Interest expense		(3,518	)		(3,784	)		(6,968	)		(6,852	)		(3,121	)		(3,627	)		(10,089	)		(10,479	)
Legal verdict (expense) credit		14,902			(93	)		14,717			(186	)
Legal verdict expense														(24,498	)		(15,855	)		(9,781	)		(16,041	)
Loss on debt extinguishment														(8,146	)		0			(8,146	)		0
Other income		60			77			102			170			71			128			173			298
Total other income (expenses)		11,565			(3,734	)		7,985			(6,416	)
Net income (loss) before income taxes	$	(5,068	)	$	3,395		$	11,397		$	(13,538	)
Total other expenses														(35,681	)		(19,332	)		(27,696	)		(25,748	)
Net loss before income taxes													$	(44,635	)	$	(31,463	)	$	(33,238	)	$	(45,001	)
Income tax expense	$	(38	)	$	—		$	(75	)	$	—		$	(37	)		0		$	(112	)		0
Net income (loss)	$	(5,106	)	$	3,395		$	11,322		$	(13,538	)
Net income (loss) per share of common stock—basic	$	(0.13	)	$	0.09		$	0.28		$	(0.34	)
Net income (loss) per share of common stock—diluted	$	(0.13	)	$	0.08		$	0.28		$	(0.34	)
Net loss													$	(44,672	)	$	(31,463	)	$	(33,350	)	$	(45,001	)
Net loss per share of common stock—basic													$	(1.09	)	$	(0.79	)	$	(0.82	)	$	(1.14	)
Net loss per share of common stock—diluted													$	(1.09	)	$	(0.79	)	$	(0.82	)	$	(1.14	)
Weighted-average shares of common stock outstanding—basic		40,479,577			39,432,030			40,370,825			39,361,596			40,813,609			39,695,444			40,520,041			39,473,691
Weighted-average shares of common stock outstanding—diluted		40,479,577			39,997,571			40,939,688			39,361,596			40,813,609			39,695,444			40,520,041			39,473,691

For the Three Months Ended June 30, 2021
							Accumulated
					Additional		Other
	Common Stock				Paid-in		Comprehensive			Accumulated
	Shares		Amount		Capital		Income (Loss)			Deficit			Total
Balance at March 31, 2021		40,324,263	$	4	$	1,337,536	$	-		$	(1,321,203	)	$	16,337
Stock-based compensation		—		—		18,239		—			—			18,239
Shares issued or restricted stock units vested under employee stock plans		409,665		—		—		—			—			—
Unrealized loss on available-for- sale securities		—		—		—		(1	)		—			(1	)
Net income		—		—		—		—			(5,106	)		(5,106	)
Balance at June 30, 2021		40,733,928	$	4	$	1,355,775	$	(1	)	$	(1,326,309	)	$	29,469

For the Three Months Ended June 30, 2020
							Accumulated
					Additional		Other
	Common Stock				Paid-in		Comprehensive			Accumulated
	Shares		Amount		Capital		Income (Loss)			Deficit			Total
Balance at March 31, 2020		39,317,221	$	4	$	1,303,940	$	2		$	(1,294,569	)	$	9,377
Stock-based compensation		—		—		10,630		—			—			10,630
Shares issued or restricted stock units vested under employee stock plans		309,696		—		2		—			—			2
Reclassification of gain on available- for-sale securities		—		—		—		—			—			—
Unrealized loss on available-for- sale securities		—		—		—		(1	)		—			(1	)
Net income		—		—		—		—			3,395			3,395
Balance at June 30, 2020		39,626,917	$	4	$	1,314,572	$	1		$	(1,291,174	)	$	23,403

For the Six Months Ended June 30, 2021
							Accumulated
					Additional		Other
	Common Stock				Paid-in		Comprehensive			Accumulated
	Shares		Amount		Capital		Income (Loss)			Deficit			Total
Balance at December 31, 2020		40,086,387	$	4	$	1,331,676	$	—		$	(1,337,631	)	$	(5,951	)
Stock-based compensation		—		—		24,099		—			—			24,099
Shares issued or restricted stock units vested under employee stock plans		647,541		—		—		—			—			—
Unrealized loss on available-for- sale securities		—		—		—		(1	)		—			(1	)
Net income		—		—		—		—			11,322			11,322
Balance at June 30, 2021		40,733,928	$	4	$	1,355,775	$	(1	)	$	(1,326,309	)	$	29,469

For the Six Months Ended June 30, 2020
							Accumulated
					Additional		Other
	Common Stock				Paid-in		Comprehensive			Accumulated
	Shares		Amount		Capital		Income (Loss)			Deficit			Total
Balance at December 31, 2019		39,203,304	$	4	$	1,295,033	$	62		$	(1,277,636	)	$	17,463
Stock-based compensation		—		—		19,537		—			—			19,537
Shares issued or restricted stock units vested under employee stock plans		423,613		—		2		—			—			2
Reclassification of gain on available-for-sale securities		—		—		—		3			—			3
Unrealized loss on available-for- sale securities		—		—		—		(64	)		—			(64	)
Net loss		—		—		—		—			(13,538	)		(13,538	)
Balance at June 30, 2020		39,626,917	$	4	$	1,314,572	$	1		$	(1,291,174	)	$	23,403

June 30, 2021	Level 1		Level 2		Level 3		Total
September 30, 2021									*Level 1*		*Level 2*		*Level 3*		*Total*
Cash equivalents	$	60,703	$	—	$	—	$	60,703	$	46,242	$	0	$	0	$	46,242
Commercial paper		—		14,497		—		14,497		0		16,883		0		16,883
Corporate bonds		—		4,630		—		4,630		0		6,713		0		6,713
Totals	$	60,703	$	19,127	$	—	$	79,830	$	46,242	$	23,596	$	0	$	69,838


December 31, 2020	Level 1		Level 2		Level 3		Total
Cash equivalents	$	59,919	$	11,798	$	—	$	71,717
Commercial paper		—		8,096		—		8,096
Totals	$	59,919	$	19,894	$	—	$	79,813

December 31, 2020	Level 1		Level 2		Level 3		Total
Cash equivalents	$	59,919	$	11,798	$	0	$	71,717
Commercial paper		0		8,096		0		8,096
Totals	$	59,919	$	19,894	$	0	$	79,813

	Maturity	Amortized		Unrealized					Estimated		*Maturity*	*Amortized*		*Unrealized*					*Estimated*
June 30, 2021	(in years)	cost		Gains		Losses			fair value
September 30, 2021											*(in years)*	*cost*		*Gains*		*Losses*			*fair value*
Cash equivalents		$	60,703	$	—	$	—		$	60,703	Cash equivalents	$	46,242	$	—	$	—		$	46,242
Commercial paper	Less than 1		14,497		—		—			14,497	Less than 1		16,883		0		0			16,883
Corporate bonds	Less than 1		4,631		—		(1	)		4,630	Less than 1		6,715		0		(2	)		6,713
Totals		$	79,831	$	—	$	(1	)	$	79,830	Totals	$	69,840	$	0	$	(2	)	$	69,838


	Maturity	Amortized		Unrealized					Estimated
December 31, 2020	(in years)	cost		Gains		Losses			fair value
Cash equivalents		$	71,717	$	—	$	—		$	71,717
Commercial paper	Less than 1		8,096		—		—			8,096
Totals	Less than 1	$	79,813	$	—	$	—		$	79,813

	Maturity	Amortized		Unrealized				Estimated
December 31, 2020	(in years)	cost		Gains		Losses		fair value
Cash equivalents		$	71,717	$	—	$	—	$	71,717
Commercial paper	Less than 1		8,096		0		0		8,096
Totals	Less than 1	$	79,813	$	0	$	0	$	79,813

Allowance for credit losses (in thousands):
Beginning balance at January 1, 2021	$	(1,000	)	$	(1,000	)
Provision for credit loss expense		—			—
Accounts receivable written-off		—			0
Recoveries		1,000			1,000
Total ending allowance balance as June 30, 2021	$	—
Total ending allowance balance as September 30, 2021				$	0

Operating cash flows used for operating leases (in thousands)	$	2,845
Right-of-use assets obtained in exchange for new operating lease liabilities		—
Weighted average remaining lease term (in years)		4.7
Weighted average discount rate		10.9	%

Supplemental cash flow information related to leases for the nine months ended September 30, 2021:
Operating cash flows used for operating leases (in thousands)	$	4,282
Right-of-use assets obtained in exchange for new operating lease liabilities		0
Weighted average remaining lease term (in years)		4.5
Weighted average discount rate		10.9	%

	Amount			*Amount*
2021 (remaining)	$	2,704		$	1,352
2022		5,483			5,483
2023		5,631			5,631
2024		5,805			5,805
2025		5,983			5,983
Thereafter		1,508			1,508
Total minimum lease payments	$	27,114		$	25,762
Less: imputed interest		(5,955	)		(5,397	)
Total lease liabilities	$	21,159		$	20,365

	June 30, 2021			December 31, 2020
Acquired and in-licensed rights	$	90,000		$	90,000
Less: accumulated amortization		(19,867	)		(15,860	)
Total intangible asset, net	$	70,133		$	74,140

	June 30, 2021			Maturity Date
Total debt	$	100,000		June 1, 2024
Accretion of final interest payment		4,051
Less: current portion of long-term debt		(31,429	)
Less: deferred financing costs		(3,916	)
Total long-term debt, net	$	68,706

	*September 30, 2021*			*Maturity Date*
Total debt	$	102,000		July 23, 2026
Less: debt issuance costs and discounts		(5,198	)
Total long-term debt, net	$	96,802

Dividend yield	0.0	%
Expected volatility	87.0	%
Risk-free interest rate	0.8	%
Expected life in years	5.31

	For the Three Months Ended				For the Six Months Ended				*For the Three Months Ended*				*For the Nine Months Ended*
	June 30,				June 30,				*September 30,*				*September 30,*
	2021		2020		2021		2020		*2021*		*2020*		*2021*		*2020*
Stock-based compensation:
Options -
Options:
Selling, general, and administrative	$	964	$	963	$	1,971	$	1,883	$	971	$	1,025	$	2,942	$	2,908
Research and development		50		731		279		1,572		147		723		426		2,295
Restricted stock units -
Restricted stock units:
Selling, general, and administrative		2,180		3,767		4,774		7,539		1,979		3,076		6,753		10,615
Research and development		1,458		5,169		3,488		8,543		1,185		2,741		4,673		11,284
Warrant modification
Warrant modification:
Selling, general, and administrative		13,587		-		13,587		-		0		0		13,587		0
Total stock-based compensation expense	$	18,239	$	10,630	$	24,099	$	19,537	$	4,282	$	7,565	$	28,381	$	27,102

	Shares			Weighted Average Exercise Price		Aggregate Intrinsic Value (in thousands)		*Shares*			*Weighted Average Exercise Price*		*Aggregate Intrinsic Value (in thousands)*
Outstanding at December 31, 2020		5,009,342		$	71.42	$	3,458		5,009,342		$	71.42	$	3,458
Granted		532,027		$	11.71				640,748		$	11.12
Forfeited		(110,183	)	$	12.66				(148,051	)	$	11.16
Exercised		-
Expired		(189,439	)	$	117.98				(744,256	)	$	84.47
Outstanding at June 30, 2021		5,241,747		$	64.91	$	2,528
Nonvested at June 30, 2021		985,497		$	10.93	$	388
Outstanding at September 30, 2021									4,757,783		$	63.13	$	1,079
Nonvested at September 30, 2021									949,366		$	10.67		0
Exercisable		4,256,250		$	77.41	$	2,140		3,808,417		$	76.21	$	1,079

	Shares			Weighted Average Grant-Date Fair Value		*Shares*			*Weighted Average Grant-Date Fair Value*
Nonvested shares at December 31, 2020		899,672		$	8.71		899,672		$	8.71
Granted		532,027			8.32		640,748			7.90
Forfeited		(110,183	)		12.66		(148,051	)		8.32
Vested/Issued		(336,019	)		9.65		(443,003	)		9.52
Nonvested shares at June 30, 2021		985,497		$	8.11
Nonvested shares at September 30, 2021							949,366		$	7.85

Exhibit Number		Description


3.1		Second Amended and Restated Certificate of Incorporation of the Company, as filed with the Secretary of State of the State of Delaware on June 14, 2016 (filed as Exhibit 3.1 to the ~~Company’s~~Company’s Current Report on Form 8-K filed with the SEC on June 15, 2016 and incorporated herein by reference)

3.2		Third Amended and Restated Bylaws of the Company (filed as Exhibit 3.1 to the ~~Company’s~~Company’s Current Report on Form 8-K filed with the SEC on May 28, 2019 and incorporated herein by reference)

10.1+*		Note Purchase Agreement with Athyrium Opportunities IV Co-Invest LP dated July 23, 2021

~~4.1#~~10.2#		Second Amendment to ~~Warrant to Purchase Shares of Common Stock of~~ Puma Biotechnology, Inc. 2017 Incentive Award Plan (filed as Exhibit ~~4.1~~99.12 to the Company's Current Report on Form ~~8-K~~S-8 filed with the SEC on ~~June 17,~~September 16, 2021, and incorporated herein by reference)

~~10.1#~~		Fifth Amendment to Puma Biotechnology, Inc. 2011 Incentive Award Plan (filed as Exhibit 10.1 to the Company's Current Report on Form 8-K filed with the SEC on June 17, 2021, and incorporated herein by reference)

31.1+		Certification of Principal Executive Officer pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 with respect to the ~~registrant’s~~registrant’s Quarterly Report on Form 10-Q for the quarter ended ~~June~~September 30, 2021

31.2+		Certification of Principal Financial Officer pursuant to Section 302 of the Sarbanes-Oxley Act of 2002, with respect to the ~~registrant’s~~registrant’s Quarterly Report on Form 10-Q for the quarter ended ~~June~~September 30, 2021

32.1++		Certification of Principal Executive Officer pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002

32.2++		Certification of Principal Financial Officer pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002

101.INS+		Inline XBRL Instance Document – the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCH+		Inline XBRL Taxonomy Extension Schema Document

101.CAL+		Inline XBRL Taxonomy Extension Calculation Linkbase Document

101.DEF+		Inline XBRL Taxonomy Extension Definition Linkbase Document

101.LAB+		Inline XBRL Taxonomy Extension Label Linkbase Document

101.PRE+		Inline XBRL Taxonomy Extension Linkbase Document

104+		Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101)

+		Filed herewith
++		Furnished herewith
# *		Portions of this exhibit (indicated by asterisks) have been omitted pursuant to Regulation S-K, Item 601(b)(10). Such omitted information is not material and would likely cause competitive harm to the registrant if publicly disclosed.
#		Management contract or compensatory ~~plan or arrangement~~agreement

	PUMA BIOTECHNOLOGY, INC.

Date: ~~August 5,~~November 4, 2021	By:	/s/ Alan H. Auerbach
		Alan H. Auerbach
		President and Chief Executive Officer
		(Principal Executive Officer)

Date: ~~August 5,~~November 4, 2021	By:	/s/ Maximo F. Nougues
		Maximo Nougues
		Chief Financial Officer
		(Principal Financial and Accounting Officer)	~~(Principal Financial and Accounting Officer)~~