Puma Biotechnology (PBYI) 10-K 1 Mar 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Feb. 18, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Trading Symbol	PBYI
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Entity Registrant Name	PUMA BIOTECHNOLOGY, INC.
Entity Central Index Key	0001401667
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Document Annual Report	true
Document Transition Report	false
Entity File Number	001-35703
Entity Tax Identification Number	77-0683487
Entity Address, Address Line One	10880 Wilshire Boulevard
Entity Address, Address Line Two	Suite 2150
Entity Address, City or Town	Los Angeles
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	90024
City Area Code	424
Local Phone Number	248-6500
Entity Incorporation, State or Country Code	DE
Entity Common Stock, Shares Outstanding		40,258,460
Entity Public Float			$ 413.3
ICFR Auditor Attestation Flag	true
Documents Incorporated by Reference	Documents Incorporated by Reference: Portions of the Proxy Statement for the registrant’s 2021 Annual Meeting of Stockholders, or the 2021 Proxy Statement, are incorporated by reference into Part III of the Form 10-K to the extent stated herein.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 85,293	$ 60,037
Marketable securities	8,096	51,607
Accounts receivable, net of allowance for credit loss of $1,000 and $0	25,543	28,896
Inventory, net	3,454	3,170
Prepaid expenses, current	11,262	13,259
Deferred rent	198	154
Restricted cash, current	8,850	8,850
Other current assets	3,443	323
Total current assets	146,139	166,296
Lease right-of-use assets, net	16,404	18,522
Property and equipment, net	2,481	3,304
Intangible assets, net	74,140	40,461
Restricted cash, long-term	3,311	4,323
Prepaid expenses and other, long-term	1,745	1,999
Total assets	244,220	234,905
Current liabilities:
Accounts payable	12,076	19,183
Accrued expenses, current	61,325	69,030
Accrued in-licensed rights, current	20,993
Post-marketing commitment liability, current	2,481
Lease liabilities, current	3,094	2,624
Current portion of long-term debt	14,286
Total current liabilities	114,255	90,837
Accrued expenses, long-term	25,963
Lease liabilities, long-term	19,549	22,643
Post-marketing commitment liability, long-term	6,379	9,000
Long-term debt	84,025	94,962
Total liabilities	250,171	217,442
Commitments and contingencies (Note 14)
Stockholders' (deficit) equity:
Common stock - $.0001 par value per share; 100,000,000 shares authorized; 40,086,387 shares issued and outstanding at December 31, 2020 and 39,203,304 issued and outstanding at December 31, 2019	4	4
Additional paid-in capital	1,331,676	1,295,033
Accumulated other comprehensive income		62
Accumulated deficit	(1,337,631)	(1,277,636)
Total stockholders' (deficit) equity	(5,951)	17,463
Total liabilities and stockholders' (deficit) equity	$ 244,220	$ 234,905

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Allowance for credit loss	$ 1,000	$ 0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	40,086,387	39,203,304
Common stock, shares outstanding	40,086,387	39,203,304

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue:
Total revenue	$ 225,110	$ 272,260	$ 250,991
Operating costs and expenses:
Cost of sales	39,374	36,815	34,621
Selling, general and administrative	118,488	141,639	146,171
Research and development	97,650	132,851	164,854
Total operating costs and expenses	255,512	311,305	345,646
Loss from operations	(30,402)	(39,045)	(94,655)
Other income (expenses):
Interest income	489	2,847	1,796
Interest expense	(14,046)	(15,019)	(10,985)
Legal verdict expense	(16,196)	(16,350)	(9,000)
Loss on debt extinguishment		(8,103)
Other income (expenses)	367	128	(714)
Total other expenses	(29,386)	(36,497)	(18,903)
Loss before income taxes	(59,788)	(75,542)	(113,558)
Income tax expense	(207)	(53)	(17)
Net loss	(59,995)	(75,595)	(113,575)
Net loss applicable to common stockholders	$ (59,995)	$ (75,595)	$ (113,575)
Net loss per share of common stock—basic and diluted	$ (1.52)	$ (1.95)	$ (2.99)
Weighted-average shares of common stock outstanding—basic and diluted	39,576,107	38,768,653	37,942,411
Product Revenue, Net
Revenue:
Total revenue	$ 196,728	$ 211,619	$ 200,491
License Revenue
Revenue:
Total revenue	22,700	60,250	$ 50,500
Royalty Revenue
Revenue:
Total revenue	$ 5,682	$ 391

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (59,995)	$ (75,595)	$ (113,575)
Other comprehensive (loss) income:
Unrealized (loss) gain on available-for-sale securities, net of tax of $0, $0, and $0	(65)	72	(12)
Reclassifications of gain on available-for-sale securities, included in “Other income (expenses)”, net of tax of $0, $0, and $0	3	2
Comprehensive loss	$ (60,057)	$ (75,521)	$ (113,587)

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Unrealized (loss) gain on available-for-sale securities, tax	$ 0	$ 0	$ 0
Reclassifications of gain on available-for-sale securities, included in “Other income (expense)”, tax	$ 0	$ 0	$ 0

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' (Deficit) Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Receivables from Exercises of Options	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning Balance at Dec. 31, 2017	$ 53,302	$ 4	$ 1,142,213	$ (449)		$ (1,088,466)
Beginning Balance (in shares) at Dec. 31, 2017		37,594,851
Stock-based compensation	86,939		86,939
Shares issued or restricted stock units vested under employee stock plans	7,652		7,203	$ 449
Shares issued or restricted stock units vested under employee stock plans (in shares)		730,186
Unrealized gain (loss) on available-for-sale securities	(12)				$ (12)
Net loss	(113,575)					(113,575)
Ending Balance at Dec. 31, 2018	34,306	$ 4	1,236,355		(12)	(1,202,041)
Ending Balance (in shares) at Dec. 31, 2018		38,325,037
Stock-based compensation	57,327		57,327
Shares issued or restricted stock units vested under employee stock plans	1,351		1,351
Shares issued or restricted stock units vested under employee stock plans (in shares)		878,267
Reclassification of gain on available-for-sale securities	2				2
Unrealized gain (loss) on available-for-sale securities	72				72
Net loss	(75,595)					(75,595)
Ending Balance at Dec. 31, 2019	$ 17,463	$ 4	1,295,033		62	(1,277,636)
Ending Balance (in shares) at Dec. 31, 2019	39,203,304	39,203,304
Stock-based compensation	$ 36,575		36,575
Shares issued or restricted stock units vested under employee stock plans	68		68
Shares issued or restricted stock units vested under employee stock plans (in shares)		883,083
Reclassification of gain on available-for-sale securities	3				3
Unrealized gain (loss) on available-for-sale securities	(65)				$ (65)
Net loss	(59,995)					(59,995)
Ending Balance at Dec. 31, 2020	$ (5,951)	$ 4	$ 1,331,676			$ (1,337,631)
Ending Balance (in shares) at Dec. 31, 2020	40,086,387	40,086,387

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities:
Net loss	$ (59,995)	$ (75,595)	$ (113,575)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	10,033	8,077	7,384
Stock-based compensation	36,575	57,327	86,939
Provision for credit loss expense	1,000	0
Disposal of property and equipment		54
Loss on impairment of asset		1,183
Loss on debt extinguishment		8,047
Debt modification fee			289
Changes in operating assets and liabilities:
Accounts receivable, net	2,353	(8,123)	(11,103)
Inventory, net	(284)	(545)	(596)
Prepaid expenses and other	2,251	568	(840)
Other current assets	(3,120)	1,464	(1,787)
Accounts payable	(7,107)	(1,526)	(7,008)
Accrued expenses and other	19,251	22,599	15,783
Deferred rent	(44)	(154)	409
Post-marketing commitment liability	(140)	9,000
Net cash provided by (used in) operating activities	773	22,376	(24,105)
Investing activities:
Purchase of property and equipment	(46)	(306)	(439)
Expenditures for leasehold improvements			(170)
Purchase of available-for-sale securities	(29,826)	(127,198)	(107,502)
Sale of available-for-sale securities		28,135
Maturity of available-for-sale securities	73,275	104,532	50,488
Purchase of intangible assets	(20,000)
Net cash provided by (used in) investing activities	23,403	5,163	(57,623)
Financing activities:
Net proceeds from shares issued under employee stock plans	68	1,351	7,652
Proceeds from debt	8,444	25,000	105,000
Payment of debt	(8,444)	(80,000)
Payment of debt extinguishment costs		(7,793)
Payment of debt issuance costs		(5,625)	(4,201)
Net cash provided by (used in) financing activities	68	(67,067)	108,451
Net increase (decrease) in cash, cash equivalents and restricted cash	24,244	(39,528)	26,723
Cash, cash equivalents and restricted cash, beginning of period	73,210	112,738	86,015
Cash, cash equivalents and restricted cash, end of period	97,454	73,210	112,738
Supplemental disclosures of non-cash investing and financing activities:
Intangibles in accrued expenses	20,000
Property and equipment purchases in accounts payable		25
Supplemental disclosure of cash flow information:
Interest paid	9,703	11,739	8,055
Income taxes paid	$ 207	$ 53	$ 17

Business and Basis of Presentat

Business and Basis of Presentation	12 Months Ended
	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Business and Basis of Presentation	Note 1—Business and Basis of Presentation: Business: 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. 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 breast cancer and HER2 mutated cancers. The Company believes 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, such as breast cancer, cervical cancer, lung cancer or other solid tumors. The Company has two 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. Basis of Presentation: 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/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/amplified breast cancer and who are less than one year from the completion of prior adjuvant trastuzumab-based therapy. 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, 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 Company has reported a net loss of approximately $60.0 million and cash flows from operations of approximately $0.8 million for the year ended December 31, 2020. The Company’s commercialization, research and development or marketing efforts may require funding in addition to the cash and cash equivalents totaling approximately $85.3 million and marketable securities totaling approximately $8.1 million available at December 31, 2020. The Company believes that its existing cash and cash equivalents and marketable securities as of December 31, 2020 and proceeds that will become available to the Company through product sales and sub-license payments are sufficient to satisfy its operating cash needs for at least one year after the filing of the Annual Report on Form 10-K in which these financial statements are included. The Company continues to remain dependent on its ability to obtain sufficient 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 global 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 loan and security 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 December 31, 2020, the Company’s financing has primarily been proceeds from product , royalty, and license revenue, public offerings of its common stock, private equity placements, and borrowings under its loan and security agreement.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Significant Accounting Policies	Note 2—Significant Accounting Policies: The significant accounting policies followed in the preparation of these consolidated financial statements are as follows: Principles of Consolidation: 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. Certain prior year amounts have been reclassified to conform to the current year presentation, the effect of which was not material to the Company’s consolidated financial statements. Segment Reporting: Management has determined that the Company operates in one business segment, which is the development and commercialization of innovative products to enhance cancer care. Use of Estimates: 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. Change in Estimate: During the three-month period ended September 30, 2020, the Company changed its estimate of the legal verdict expense and the associated legal expense accrual for the Hsu v. Puma Biotechnology, Inc., et al. Our estimate of the legal verdict expense and the associated legal expense accrual for the Hsu lawsuit remained unchanged for the quarter ended December 31, 2020. Net Loss per Share of Common Stock: Basic net loss per share of common stock is computed by dividing net loss applicable 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 options, 2,116,250 shares issuable upon exercise of a warrant, and 1,991,125 shares underlying RSUs that were subject to vesting and were anti - dilutive. For the year ended December 31, 2018, potentially dilutive securities excluded from the calculations were shares issuable upon exercise of options, 2,116,250 shares issuable upon exercise of a warrant, and shares underlying RSUs that were subject to vesting and were anti - dilutive. Revenue Recognition: Under ASC Topic 606, Revenue from Contracts with Customers Product Revenue, Net: 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. 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, no such costs were incurred during the year ended December 31, 2020. For the period ended December 31, 2020, two major customers represented approximately 33% and 21%, respectively, of the Company’s total product revenue. For the period ended December 31, 2019, two major customers accounted for approximately 34% and 22%, respectively, of the Company’s total product revenue. For the period ended December 31, 2018, two major customers accounted for approximately 39% and 25%, respectively, of the Company’s total product revenue. Reserves for Variable Consideration: Revenue from product sales is 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 ASU 2013-1, Balance Sheet (Topic 210): Clarifying the Scope of Disclosures about Offsetting Assets and Liabilities 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 occur in a future period for the estimates detailed below as of December 31, 20 20 and, therefore, the transaction price was not reduced further during the year ended December 31, 20 20 . 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. Trade Discounts and Allowances: 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 receivables, 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 statement of operations. Product Returns: 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 revenue in the period the related product revenue is recognized, as well as a reduction to accounts receivables, 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. Provider Chargebacks and Discounts: 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 that the related revenue is recognized, resulting in a reduction of product revenue 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 . Government Rebates: 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 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. Payor Rebates: 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: 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. License Revenue: 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. The Company’s payment terms range between the execution date of the sub-license agreement and 45 days. 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 upfront payments when each sub-license agreement was executed and potential additional 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. For the year ended December 31, 2020, pursuant to the sub-license agreements, the Company recognized as license revenue, upfront payments totaling $0.5 million and development-based milestone payments totaling $22.2 million. The beginning balance of accounts receivable, net on the Company’s consolidated balance sheet for license revenue from the sub-license agreements for the twelve months ended December 31, 2020 was $2.5 million. As of December 31, 2020, $2.5 million in license revenue from the sub-license agreements is included in accounts receivable, net and $1.0 million in the allowance for credit loss on the consolidated balance sheet Royalty Revenue: 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. 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. The Company’s payment terms range between 30 and 90 days. Legal Contingencies and Expense: 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 14-Commitments and Contingencies). Royalty Expenses: Royalties incurred in connection with the Company’s license agreement with Pfizer, as disclosed in Note 14 — Research and Development Expenses: Research and development, or R&D, expenses are charged to operations as incurred. The major components of research and development costs include clinical manufacturing costs, clinical trial expenses, consulting and other 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 research and development costs. Stock-Based Compensation: Stock option awards : ASC Topic 718, Compensation-Stock Compensation Restricted stock units: 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 in the statement of operations. 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 “trued-up” upon the actual forfeiture of a 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 : Warrants (refer to Note 11 for further details) granted to employees and non-employees are normally valued at the fair value of the instrument on the grant date and are recognized in the 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 past eight years of 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. Income Taxes: The Company follows ASC Topic 740, Income Taxes 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 December 31, 2020, the Company’s uncertain tax position includes a reserve for its R&D credits. Financial Instruments 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. Cash and Cash Equivalents: The Company classifies all highly liquid instruments with an original maturity of three months or less as cash equivalents. Restricted Cash: Restricted cash represents cash held at financial institutions that are 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 December 31, 2020 and 2019, the Company had restricted cash in the amount of $12.2 million and $13.2 million, respectively. Investment Securities: 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’ (deficit) 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, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments Assets Measured at Fair Value on a Recurring Basis: ASC Topic 820, Fair Value Measurement Level 1: Quoted prices in active markets for identical assets or liabilities. Level 2: Quoted prices for similar assets or liabilities in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations in which all significant inputs are observable in active markets. Level 3: Valuations derived from valuation techniques in which one or more significant inputs are unobservable. Following are the major categories of assets measured at fair value on a recurring basis as of December 31, 2020 and 2019, using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3) (in thousands): 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, 2019 Level 1 Level 2 Level 3 Total Cash equivalents $ 41,295 $ — $ — $ 41,295 Corporate bonds — 41,557 — 41,557 U.S. government securities 10,050 — — 10,050 Totals $ 51,345 $ 41,557 $ — $ 92,902 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 short-term investments (in thousands): 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 $ 79,813 $ — $ — $ 79,813 Maturity Amortized Unrealized Estimated December 31, 2019 (in years) cost Gains Losses fair value Cash equivalents $ 41,295 $ — $ — $ 41,295 Corporate bonds Less than 1 41,507 50 — 41,557 U.S. government securities Less than 1 10,038 12 — 10,050 Totals $ 92,840 $ 62 $ — $ 92,902 Concentration of Risk: 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 December 31, 2020, were approximately $101.8 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 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 credit loss primarily based on the credit worthiness of its customers, historical payment patterns, aging of receivable balances and general economic conditions. The Company recorded $1.0 million and $0 as an allowance for credit loss and the related credit loss expense in the years ended December 31, 2020 and 2019, respectively. The Company’s success depends on its ability to successfully commercialize NERLYNX. The Company currently has a single product with 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 contractors. The Company is using the same 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 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 contractors to manufacture the commercial supply of drugs. Inventory: 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 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 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. 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 research and development expense when selected for use in a clinical trial. Starter kits, provided to patients prior to insurance approval, are expensed by the Company to s elling, general and administrative expense as incurred. As of December 31, 2020, the Company’s inventory balance consisted primarily of raw materials purchased subsequent to FDA approval of NERLYNX. Property and Equipment, Net: Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the useful lives of the assets, which is general

Accounts Receivable, Net

Accounts Receivable, Net	12 Months Ended
	Dec. 31, 2020
Accounts Receivable Net [Abstract]
Accounts Receivable, Net	Note 3—Accounts Receivable, Net: Accounts receivable, net consisted of the following (in thousands): December 31, 2020 December 31, 2019 Trade accounts receivable $ 21,515 $ 26,180 License revenue receivable 2,500 2,500 Royalty revenue receivable 2,528 216 Total accounts receivable $ 26,543 $ 28,896 Allowance for credit losses (1,000 ) — Total accounts receivable, net $ 25,543 $ 28,896 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 under a sub-license agreement. 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 years ended December 31, 2020 and 2019. For all accounts receivable, the Company recognized credit losses based on lifetime expected losses. In determining estimated credit losses, the Company evaluated its historical loss rates, current economic conditions and reasonable and supportable forecasts of future economic conditions. During the fourth quarter of 2020, the Company became aware of new information regarding the collectability of the amount owed from a sub-licensee relating to license revenue recognized during the third quarter of 2019. Based on this new information, the Company determined that a portion of the receivable may be uncollectible and the Company recorded a credit loss expense of $1.0 million to selling, general and administration expense in the consolidated statements of operations for the year ended December 31, 2020. The Company recorded $1.0 million and $0 as a credit loss expense in the years ended December 31, 2020 and 2019, respectively. The rollforward of the allowance for credit losses is as follows: Allowance for credit losses (in thousands): Beginning balance at January 1, 2020 $ — Impact of adopting ASC 326 — Provision for credit loss expense (1,000 ) Accounts receivable written-off — Recoveries — Total ending allowance balance as December 31, 2020 $ (1,000 )

Prepaid Expenses and Other

Prepaid Expenses and Other	12 Months Ended
	Dec. 31, 2020
Prepaid Expense And Other Assets [Abstract]
Prepaid Expenses and Other	Note 4—Prepaid Expenses and Other: Prepaid expenses and other consisted of the following at December 31 (in thousands): December 31, 2020 December 31, 2019 Current: CRO services $ 1,550 $ 4,810 Other clinical development 2,718 2,043 Insurance 3,708 3,452 Professional fees 651 544 Other 2,635 2,410 11,262 13,259 Long-term: CRO services 518 400 Other clinical development 437 468 Other 790 1,131 1,745 1,999 Totals $ 13,007 $ 15,258 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 Assets

Other Current Assets	12 Months Ended
	Dec. 31, 2020
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Other Current Assets	Note 5—Other Current Assets: Other current assets consisted of the following at December 31 (in thousands): December 31, 2020 December 31, 2019 Deposit for manufacturing costs $ 3,376 $ — Other 67 323 Totals $ 3,443 $ 323 Other current asset amounts consist primarily of capitalized sublease commission and a sublease tenant improvement allowances, net of amortization.

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Property and Equipment	Note 6—Property and Equipment: Property and equipment consisted of the following at December 31 (in thousands): December 31, 2020 December 31, 2019 Leasehold improvements $ 3,779 $ 3,779 Computer equipment 2,192 2,698 Telephone equipment 302 340 Furniture and fixtures 2,359 2,346 8,632 9,163 Less: accumulated depreciation (6,151 ) (5,859 ) Totals $ 2,481 $ 3,304 For the years ended December 31, 2020, 2019, and 2018, the Company incurred depreciation expense of $0.9 million, $0.9 million, and $1.1 million, respectively.

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases	Note 7—Leases: In December 2011, the Company entered into a non-cancelable operating lease for office space in Los Angeles, California, which lease 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 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 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 $4.7 million and $0.4 million, respectively, for the year ended December 31, 2020. Rent expense for each of the respective years ended December 31, 2019 and 2018 was approximately $4.7 million. 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 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 The future minimum lease payments under ASC 842 as of December 31, 2020 were as follows (in thousands): Amount 2021 5,365 2022 5,483 2023 5,631 2024 5,805 2025 5,983 Thereafter 1,509 Total minimum lease payments $ 29,776 Less: imputed interest (7,133 ) Total lease liabilities $ 22,643 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 $0.4 million, $0.2 million and $0 for the years ended December 31, 2020, 2019 and 2018, respectively, in other income (expenses) in the consolidated statements of operations. The future minimum lease payments to be received as of December 31, 2020 were as follows (in thousands): Amount 2021 $ 467 2022 481 2023 495 2024 510 2025 525 Thereafter 133 Total $ 2,611 Supplemental cash flow information related to leases for the year ended December 31, 2020: Operating cash flows used for operating leases (in thousands) $ 5,569 Right-of-use assets obtained in exchange for new operating lease liabilities — Weighted average remaining lease term (in years) 5.2 Weighted average discount rate 10.9 %

Intangible Assets

Intangible Assets	12 Months Ended
	Dec. 31, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible Assets	Note 8—Intangible Assets: Intangible assets consisted of the following at December 31 (in thousands): December 31, 2020 December 31, 2019 Acquired and in-licensed rights $ 90,000 $ 50,000 Less: accumulated amortization (15,860 ) (9,539 ) Total intangible asset, net $ 74,140 $ 40,461 Estimated future intangible amortization expense as of December 31, 2020 is as follows (in thousands): 2021 $ 8,015 2022 8,015 2023 8,015 2024 8,015 2025 8,015 Thereafter 34,065 Totals $ 74,140

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2020
Payables And Accruals [Abstract]
Accrued Expenses	Note 9—Accrued Expenses: Accrued expenses consisted of the following at December 31 (in thousands): December 31, 2020 December 31, 2019 Current: Accrued legal verdict expense $ 22,724 $ 31,350 Accrued royalties 8,604 8,866 Accrued CRO services 3,474 8,502 Accrued variable consideration 9,014 7,978 Accrued bonus 7,788 1,618 Accrued compensation 4,820 4,138 Accrued other clinical development 1,904 2,546 Accrued professional fees 1,420 1,775 Accrued legal fees 383 266 Accrued manufacturing costs 752 869 Accrued other 442 1,122 61,325 69,030 Long-term: Accrued legal verdict expense 24,822 — Accrued CRO services 908 — Accrued other 233 — 25,963 — Totals $ 87,288 $ 69,030 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 represents an estimate of $22.7 million that may be owed to the plaintiff as a result of the jury verdict in Eshelman v. Puma Biotechnology, Inc., et al. Long-term accrued legal verdict expense represents the Company’s estimate of Hsu v. Puma Biotechnology, Inc., et al

Debt

Debt	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Debt	Note 10—Debt: Long-term debt consisted of the following at December 31, 2020 (in thousands): December 31, 2020 Maturity Date Total debt $ 100,000 June 1, 2024 Accretion of final interest payment 3,313 Less: current portion of long-term debt (14,286 ) Less: deferred financing costs (5,002 ) Total long-term debt, net $ 84,025 In October 2017, the Company entered into a loan and security agreement with Silicon Valley Bank, or 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, the Company 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 borrowed under the Original Credit Facility, and (ii) an aggregate amount of $30.0 million that the Company drew in December 2018, which was available under the Amended Credit Facility as a result of achieving a specified minimum revenue milestone. The Company was in compliance with all applicable financial covenants during the entire term of the Amended Credit Facility. Prior to the amendment and restatement of the loan and security agreement in June 2019, which provided for a new credit facility, or the New Credit Facility, the term loans under the Amended Credit Facility bore interest at an annual rate equal to the greater of (i) 8.25% 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 accrued, plus (b) 3.5%. The Company was required to make monthly interest-only payments on each term loan 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 July 1, 2020. Commencing on July 1, 2020, and continuing on the first calendar day of each calendar month thereafter, the Company would have been required to make consecutive equal monthly payments of principal, together with applicable interest, in arrears to each original lender, calculated pursuant to the Amended Credit Facility. All unpaid principal and accrued and unpaid interest with respect to each term loan would have been due and payable in full on May 1, 2023. Upon repayment of the term loans, the Company was also required to make a final payment to the Original Lenders equal to 7.5% of the original principal amount of term loans funded. The Company was also permitted to prepay the outstanding principal balance of any term loan under the Amended Credit Facility, in whole but not in part, subject to a prepayment fee of 3.0% of the amount prepaid if the prepayment were to occur through and including the first anniversary of the funding date of such term loan, 2.0% of any amount prepaid if the prepayment were to occur 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 were to occur after the second anniversary of the funding date of such term loan and prior to May 1, 2023. On June 28, 2019, or the Effective Date, the Company entered into the New Credit Facility with Oxford, as collateral agent, and the lenders party thereto from time to time, including Oxford, pursuant to which the Company 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, 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. No additional capacity remains available to the Company under the New Credit Facility. The New Credit Facility is secured by substantially all of the 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 limits the 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 bear 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 precedes the month in which the interest will accrue, plus (b) 3.5%. The Company is 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 will make 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 is due and payable in full on June 1, 2024, or the Maturity Date. Upon repayment of such term loans, the Company is 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 December 31, 2020 was 12.75%. At the Company’s option, the Company may prepay the outstanding principal balance of any term loan in whole but not in part, subject to a prepayment fee of 3.0% of the amount prepaid if the prepayment occurs through and including the first anniversary of the funding date of such term loan, 2.0% of the amount prepaid if the prepayment occurs 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 occurs after the second anniversary of the funding date of such term loan and prior to the Maturity Date. The New Credit Facility 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 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 will be established for each subsequent fiscal year by mutual agreement of the Company, Oxford, as collateral agent, and the new lenders. The negative covenants 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 includes events of default, the occurrence and continuation of which could cause interest to be charged at the rate that is otherwise applicable plus 5.0% and would provide Oxford, as collateral 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 New Credit Facility, including the Company’s cash. These events of default include, among other things, the Company’s failure to pay principal or interest due under the New Credit Facility, a breach 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 remains 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 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 December 31, 2020, there were $100.0 million in principal amounts The future minimum principal payments under the New Credit Facility as of December 31, 2020 were as follows (in thousands): Amount 2021 $ 14,286 2022 34,286 2023 34,286 2024 17,142 Thereafter — Total $ 100,000 Deferred Financing Costs Deferred financing costs consisted of the following (in thousands): December 31, 2020 December 31, 2019 Deferred financing costs $ 8,668 $ 8,668 Less: accumulated amortization (3,666 ) (1,701 ) Included in long-term debt $ 5,002 $ 6,967 Deferred financing costs 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 consolidated statements of operations. For the years ended December 31, 2020, 2019 and 2018, the Company recorded approximately $2.0 million, $1.5 million and $0.9 million, respectively, of interest expense related to the amortization of debt issuance costs in the consolidated statements of operations.

Stockholders_ (Deficit) Equity

Stockholders’ (Deficit) Equity	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Stockholders’ (Deficit) Equity	Note 11—Stockholders’ (Deficit) Equity: Common Stock: The Company issued 18,202, 87,625, and 200,743 shares of common stock upon exercise of stock options during the years ended December 31, 2020, 2019 and 2018, respectively. The Company issued 864,881, 790,642 Authorized Shares: The Company has 100,000,000 shares of stock authorized for issuance, all of which are common stock, par value $0.0001 per share. Warrants: 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. Stock Options and Restricted Stock Units: The Company’s 2011 Incentive Award Plan, 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 As of December 31, 2020, 5,620,045 shares of the Company’s common stock are issuable upon the exercise of outstanding awards granted under the 2011 Plan and 2,387,923 shares of the Company’s common stock are available for future issuance under the 2011 Plan. The Company awarded only “plain vanilla options” as determined by the SEC Staff Accounting Bulletin 107, or Share Based Payment 2020 2019 Dividend yield 0.0% 0.0% Expected volatility 100.6% 99.9% Risk-free interest rate 0.9% 2.5% Expected life in years 5.81 5.76 The Company’s 2017 Employment Inducement Incentive Award Plan, 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 restricted stock units, 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 Stock-based compensation expense was as follows for the years ended December 31 (in thousands): For the Year Ended December 31, 2020 2019 2018 Stock-based compensation: Options - Selling, general, and administrative $ 3,937 $ 9,044 $ 14,063 Research and development 3,018 7,452 26,456 Restricted stock units - Selling, general, and administrative 13,841 18,848 20,851 Research and development 15,779 21,983 25,569 Total stock-based compensation expense $ 36,575 $ 57,327 $ 86,939 Activity with respect to options granted under the 2011 and 2017 Plan is summarized as follows: Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2017 6,134,513 $ 87.91 7.2 $ 220,060 Granted 315,566 $ 59.13 9.3 Forfeited (183,837 ) $ 51.96 Exercised (200,743 ) $ 35.88 $ 5,063 Expired (356,955 ) $ 116.96 Outstanding at December 31, 2018 5,708,544 $ 87.49 6.1 $ 7,762 Granted 340,241 $ 15.40 8.6 Forfeited (128,406 ) $ 38.71 Exercised (87,625 ) $ 15.42 $ 995 Expired (790,429 ) $ 104.76 Outstanding at December 31, 2019 5,042,325 $ 82.42 5.2 $ 1,951 Granted 700,853 $ 10.03 9.2 Exercised (18,202 ) $ 3.75 $ 119 Expired (715,634 ) $ 90.51 Outstanding at December 31, 2020 5,009,342 $ 71.42 5.1 $ 3,458 Nonvested at December 31, 2020 899,672 $ 11.18 9.1 1,106 Exercisable 4,109,670 $ 84.61 4.3 $ 2,352 At December 31, 2020, total estimated unrecognized compensation cost related to non-vested stock options granted prior to that date was approximately $5.9 million, which is expected to be recognized over a weighted-average period of 1.9 years. At December 31, 2020, the total estimated unrecognized compensation cost related to non-vested RSUs was approximately $16.6 million, which is expected to be recognized over a weighted-average period of 1.5 years. The weighted-average grant date fair value of options granted during the years ended December 31, 2020, 2019 and 2018, was $7.81, $12.08 and $45.62 per share, respectively. The weighted average grant date fair value of RSUs awarded during the year ended December 31, 2020, 2019 and 2018 was $10.47, $14.72, and $41.42, respectively. Stock Option Rollforward Shares Weighted Average Grant-Date Fair Value Nonvested shares at December 31, 2018 779,292 $ 33.75 Granted 340,241 12.08 Vested/Issued (551,933 ) 33.56 Forfeited (128,406 ) 26.27 Nonvested shares at December 31, 2019 439,194 19.38 Granted 700,853 7.81 Vested/Issued (240,375 ) 25.57 Nonvested shares at December 31, 2020 899,672 $ 8.71 Restricted Stock Unit Rollforward Shares Weighted Average Grant-Date Fair Value Nonvested shares at December 31, 2017 1,637,662 $ 85.58 Granted 1,175,231 41.42 Vested/Issued (529,443 ) 79.98 Forfeited (444,780 ) 80.99 Nonvested shares at December 31, 2018 1,838,670 60.08 Granted 1,472,417 14.72 Vested/Issued (790,642 ) 62.98 Forfeited (529,320 ) 51.63 Nonvested shares at December 31, 2019 1,991,125 27.63 Granted 1,234,616 10.47 Vested/Issued (864,881 ) 36.86 Forfeited (506,655 ) 21.72 Nonvested shares at December 31, 2020 1,854,205 $ 13.51

401(k) Savings Plan

401(k) Savings Plan	12 Months Ended
	Dec. 31, 2020
Postemployment Benefits [Abstract]
401(k) Savings Plan	Note 12—401(k) Savings Plan: During 2012, the Company adopted a 401(k) savings plan for the benefit of its employees. The Company is required to make matching contributions to the 401(k) plan equal to 100% of the first 3% 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 $1.4 million, $1.5 million and $ 1.9 million for the years ended December 31, 2020, 2019 and 2018, respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Note 13—Income Taxes: Income tax expense was as follows for the years ended December 31 (in thousands): 2020 2019 2018 Current: Federal $ — $ — $ — State 124 53 17 Foreign 83 — — 207 53 17 Deferred: Federal — — — State — — — — — — Total $ 207 $ 53 $ 17 The provision for income taxes in the accompanying consolidated statements of operations differs from the amount calculated by applying the statutory income tax rate to loss from continuing operations before income taxes. Approximately $13.2 million of tax expense for the year ended December 31, 2020 is due to stock-based compensation expense shortfall and the expiration of vested stock options. Approximately $5.2 million of the tax benefit for the year-ended December 31, 2020 is due to R&D tax credits, net of an approximate $1.3 million reserve related to unrecognized tax benefits for the method of allocation of expenses used in the R&D tax credits calculation.. The primary components of such differences are as follows as of December 31 (in thousands): 2020 2019 2018 Tax computed at the federal statutory rate $ (12,540 ) $ (15,830 ) $ (23,771 ) State taxes (2,304 ) (2,453 ) (2,791 ) Foreign taxes 83 — — Permanent items 13,660 21,834 10,932 R&D credits (5,231 ) (14,946 ) (5,630 ) Prior year adjustment (2,116 ) (2,792 ) 15,750 Change in valuation allowance 8,655 14,240 5,527 Total provision $ 207 $ 53 $ 17 Temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes give rise to the Company’s deferred income taxes. The components of the Company’s net deferred tax assets are as follows as of December 31 (in thousands): 2020 2019 Deferred tax assets: Net operating loss carryforwards $ 261,472 $ 260,555 Business credit carryforwards 55,574 50,343 Compensation 58,112 60,967 Accrued legal verdict 11,880 7,624 Carryforward of disallowed interest 3,093 2,839 Accrued expenses 561 9 Lease liabilities 5,657 6,145 Other deferred tax assets 804 13 Subtotal 397,153 388,495 Deferred tax liabilities: Lease right-of-use assets (4,099 ) (4,505 ) Inventory (21 ) — Other deferred tax liabilities (464 ) (76 ) Subtotal (4,584 ) (4,581 ) Total deferred tax assets 392,569 383,914 Valuation allowance (392,569 ) (383,914 ) Net deferred tax assets $ — $ — As the ultimate realization of the potential benefits of the Company’s deferred tax assets is considered unlikely by management, the Company has offset the deferred tax assets attributable to those potential benefits through valuation allowances. Accordingly, the Company did not recognize any benefit from income taxes in the accompanying consolidated statements of operations to offset its pre-tax losses. The valuation allowance increased $8.7 million and $14.2 million for the years ended December 31, 2020 and 2019, respectively. At December 31, 2020, the Company had federal and state net operating loss carryforwards, respectively, of approximately $961.0 million and $884.3 million, which will begin to expire in 2033. At December 31, 2020, the Company also has federal research and development credit carryforwards of approximately $37.1 million. If not utilized, the carryforwards will begin to expire in 2033. The Company has state research and development credit carryforwards of approximately $21.7 million which do not expire. Pursuant to the Internal Revenue Code, Sections 382 and 383, use of the Company’s net operating loss and credit carryforwards could be limited if a cumulative change in ownership of more than 50% occurs within a three-year period. The Company has not yet performed an assessment on the potential limitation on net operating loss and credit carryforwards. The following is a tabular reconciliation of the total amounts of unrecognized tax benefits at December 31 (in thousands): 2020 2019 2018 Unrecognized tax benefits - January 1 $ 1,968 $ 8,777 $ 7,151 Gross decreases - tax positions in a prior period — (8,422 ) — Gross increases - tax positions in a current period 1,308 1,613 1,626 Unrecognized tax benefits - December 31 $ 3,276 $ 1,968 $ 8,777 During the year ended December 31, 2019, the Company completed an R&D credit study. As a result of the study, the Company assessed that the Company qualified under safe harbor rules, which when applied consistently results in a more conservative approach of calculating the amount of R&D credit. The Company concluded that a release of uncertain tax benefits was appropriate and released a portion of previously recorded uncertain tax positions reserve. There were no releases of uncertain tax position reserves in the year ended December 31, 2020. Current year increases in the R&D credit relate to R&D support department costs that were allocated to various research projects based upon a reasonable methodology. The uncertain tax position is related to the method of allocating these costs. The Company files tax returns as prescribed by the tax laws of the jurisdictions in which it operates. In the normal course of business, the Company is subject to examination by the federal and state jurisdictions where applicable. There are currently no pending income tax examinations. The Company’s tax years for 2009 and forward are subject to examination by the federal and California tax authorities due to the carryforward of unutilized net operating losses and research and development credits.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 14—Commitments and Contingencies: License Agreement: 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 the Licensor’s sole expense. At the Company’s request, Pfizer 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 be responsible 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 (i) reduce the royalty rate payable by the Company to Pfizer on sales of licensed products; (ii) 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 (iii) 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 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 milestone payment under the license agreement with Pfizer. The Letter Agreement permits the Company to make the milestone payment in installments with portions of the amount payable to Pfizer (including interest) made in June and November 2020 for approximately $20.6 million in the aggregate and the remaining portion to be made in September 2021 for approximately $21.9 million. Unpaid portions of the milestone payment will accrue interest at 6.25% per annum until paid. The installment payments and accrued interest are included in accrued in-licensed rights on the accompanying consolidated balance 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 (i) the last to expire licensed patent covering the applicable licensed product in such country, or (ii) 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. Clinical Trial Contracts: The Company engages with clinical research organizations and contract manufacturing organizations, or CMOs, in addition to engaging in contracts for the management of its ongoing clinical trials and pre-commercialization efforts. The Company may cancel these agreements with a 30 to 45 day written notice to the outside vendor. The Company would be obligated to pay for services rendered up to that point. The contracts also contain variable costs that are hard to predict as they are based on such things as patients enrolled and clinical trial sites, which can vary, and therefore, are not included in the table below. The contracts held by the Company as of December 31, 2020, are summarized as follows (in thousands): Indication Estimated Contractual Obligation as of December 31, 2020 Months Remaining on Contract HER2 Overexpressed/Amplified Breast Cancer (Extension) $ 5,242 12 HER2 Overexpressed/Amplified Breast Cancer (Licensor Legacy Clinical Trials) 371 3 HER2 Mutated Breast Cancer and HER2 Mutated Breast Cancer with Brain Metastases 456 24 Metastatic & Adjuvant Breast Cancer 10,399 5 Pre-Clinical Research 22,003 14 Post-Clinical Research 1,256 11 HER2 Mutated Solid Tumors 2,645 10 Other 24,849 15 Total $ 67,221 Included in the above are payments to be made when milestones are reached. As of December 31, 2020, Company obligations for potential milestone payments totaled approximately $18.4 million. This amount will be paid by the Company if all milestones are reached and would reduce the overall contractual obligation if one or more milestone is never reached. Legal Proceedings The Company and certain of its executive officers were named as defendants in the lawsuits detailed below. 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. Currently, the Company has accrued estimated losses of $24.8 million related to Hsu v. Puma Biotechnology, Inc., et al., and $22.7 million related to Eshelman v. Puma Biotechnology, Inc., et al. as detailed below. For certain legal expenses related to the verdicts listed below, the Company has received reimbursements from its insurers. Hsu v. Puma Biotechnology, Inc., et al. On June 3, 2015, Hsingching Hsu, individually and on behalf of all others similarly situated, filed a class action lawsuit against the Company and certain of its 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 the Company’s 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, 2019 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, on October 9, 2020, the claims administrator submitted its supplemental claims report. The claims report reflects approximately $50.5 million in claimed damages. The Company disagrees with the amount of claimed damages. On November 27, 2020, the Court issued an order setting out the process for challenging claims. Pursuant to that order, defendants must decide by March 29, 2021 which claims they intend to challenge, and for which claims the Company needs more information to determine whether or not it will challenge those claims. Based on a review of specific claims and subject to the outcome of the claims challenge process, the Company believes that total claimed damages after all claims challenges have been adjudicated could range from $ 24.8 million to $ million. The total amount of aggregate class-wide damages still remains uncertain and will be ascertained only after 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 yet been entered. Eshelman v. Puma Biotechnology, Inc., et al. In February 2016, Fredric N. Eshelman filed a lawsuit against the Company’s Chief Executive Officer and President, Alan H. Auerbach, and the Company 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 Mr. Auerbach and the Company 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 the Company took place from March 11 to March 15, 2019. At trial, the jury found the Company liable and awarded Dr. Eshelman $15.9 million in compensatory damages and $6.5 million in punitive damages. The Company strongly disagrees 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. The Company has 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 prejudgment interest. In the Court’s March 2 ruling, it denied the motion for attorneys’ fees but granted the request for prejudgment 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. The Company estimates the high end of potential damages in the matter could be approximately $27.7 million; however, the actual amount of damages payable by the Company is still uncertain and will be ascertained only after completion of the appeal and any subsequent proceedings, and such amount could be greater than the amount of expense already recognized or the high end of the estimate. Due to the appeal, the Company secured a bond for the potential damages, which is collateralized by an automatically renewable stand-by letter of credit in the amount of $8.9 million. The stand-by letter of credit is collateralized by a high-yield savings account, which is classified as restricted cash, current on the accompanying consolidated balance sheets. The United States Court of Appeals for the Fourth Circuit has tentatively calendared the oral argument of the Company’s appeal during the month of May 2021. CANbridge Licensing Dispute On July 28, 2020, the Company filed a request for arbitration against CANbridge Biomed Limited, or CANbridge, before the ICC International Court of Arbitration. The Company asserted that CANbridge violated the terms of the Company’s agreement with CANbridge in which it granted CANbridge an exclusive sublicense to develop and commercialize NERLYNX throughout greater China. The Company sought an arbitral award, as well as damages, costs, and attorneys’ fees. On August 26, 2020, CANbridge filed its response to the Company’s request for arbitration and brought counterclaims, seeking damages, costs and attorneys’ fees. On February 24, 2021, the parties resolved their dispute, with each side agreeing to dismiss their respective claims in the arbitration. The settlement is limited to claims asserted in the arbitration, or that are related to the claims asserted in the arbitration. Legal Malpractice Suit On September 17, 2020, the Company filed a lawsuit against Hedrick Gardner Kincheloe & Garofalo, L.L.P. and David L. Levy, the attorneys who previously represented the Company in Eshelman v. Puma Biotechnology, Inc., et al. Eshelman v. Puma Biotechnology, Inc., et al Eshelman v. Puma Biotechnology, Inc., et al.

Quarterly Financial Data

Quarterly Financial Data	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data	Note 15—Quarterly Financial Data: Quarterly financial data (in thousands except share and per share data): (unaudited) Three Months Ended March 31, June 30, September 30, December 31, 2020 Revenues $ 51,217 $ 70,582 $ 50,754 $ 52,557 Net (loss) income (16,933 ) 3,395 (31,463 ) (14,994 ) Net (loss) income attributable to common stock (16,933 ) 3,395 (31,463 ) (14,994 ) Net (loss) income per share—basic $ (0.43 ) $ 0.09 $ (0.79 ) $ (0.38 ) Net (loss) income per share—diluted $ (0.43 ) $ 0.08 $ (0.79 ) $ (0.38 ) Weighted-average shares of common stock outstanding—basic 39,291,162 39,432,030 39,695,444 39,881,131 Weighted-average shares of common stock outstanding—diluted 39,291,162 39,997,571 39,695,444 39,881,131 2019 Revenues $ 99,067 $ 53,919 $ 56,352 $ 62,922 Net loss (10,087 ) (37,424 ) (16,885 ) (11,199 ) Net loss attributable to common stock (10,087 ) (37,424 ) (16,885 ) (11,199 ) Net loss per share—basic and diluted $ (0.26 ) $ (0.97 ) $ (0.44 ) $ (0.29 ) Weighted-average shares of common stock outstanding—basic and diluted 38,481,824 38,647,775 38,893,757 39,043,706 2018 Revenues $ 66,516 $ 50,767 $ 62,629 $ 71,079 Net loss (24,345 ) (44,335 ) (14,201 ) (30,694 ) Net loss attributable to common stock (24,345 ) (44,335 ) (14,201 ) (30,694 ) Net loss per share—basic and diluted $ (0.65 ) $ (1.17 ) $ (0.37 ) $ (0.80 ) Weighted-average shares of common stock outstanding—basic and diluted 37,699,024 37,819,767 38,043,174 38,201,056

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent Events	Note 16—Subsequent Events: Pierre Fabre Amendment and CANbridge Termination of License Agreement and Related Agreements On February 24, 2021, the Company entered into a second amendment, or the Second Pierre Fabre Amendment, to the sub-license agreement with Pierre Fabre Medicament SAS, or Pierre Fabre, to extend Pierre Fabre’s commercial rights for NERLYNX to Greater China, which includes mainland China, Taiwan, Hong Kong and Macao. Under the terms of the Second Pierre Fabre Amendment, the Company will receive an upfront payment of $50.0 million, as well as additional regulatory and sales-based milestone payments that could add up to an additional $240.0 million. These milestones will be based solely on regulatory and sales achievements in Greater China. In addition, the Company is entitled to receive double-digit tiered royalties on the sales of NERLYNX in Greater China. Also on February 24, 2021, the Company and CANbridge BIOMED Limited, or CANbridge, have mutually agreed to terminate the sub-license agreement, by and between the Company and CANbridge, to commercialize NERLYNX in Greater China and all other related agreements. Subject to the terms of a termination agreement between CANbridge and the Company, the Company agreed to pay CANbridge a one-time termination fee of $20.0 million to return all rights to NERLYNX in Greater China back to the Company and assist with the transfer of such rights to the Company.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation: 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. Certain prior year amounts have been reclassified to conform to the current year presentation, the effect of which was not material to the Company’s consolidated financial statements.
Segment Reporting	Segment Reporting: Management has determined that the Company operates in one business segment, which is the development and commercialization of innovative products to enhance cancer care.
Use of Estimates	Use of Estimates: 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.
Change in Estimate	Change in Estimate: During the three-month period ended September 30, 2020, the Company changed its estimate of the legal verdict expense and the associated legal expense accrual for the Hsu v. Puma Biotechnology, Inc., et al. Our estimate of the legal verdict expense and the associated legal expense accrual for the Hsu lawsuit remained unchanged for the quarter ended December 31, 2020.
Net Loss per Share of Common Stock	Net Loss per Share of Common Stock: Basic net loss per share of common stock is computed by dividing net loss applicable 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 options, 2,116,250 shares issuable upon exercise of a warrant, and 1,991,125 shares underlying RSUs that were subject to vesting and were anti - dilutive. For the year ended December 31, 2018, potentially dilutive securities excluded from the calculations were shares issuable upon exercise of options, 2,116,250 shares issuable upon exercise of a warrant, and shares underlying RSUs that were subject to vesting and were anti - dilutive.
Revenue Recognition	Revenue Recognition: Under ASC Topic 606, Revenue from Contracts with Customers Product Revenue, Net: 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. 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, no such costs were incurred during the year ended December 31, 2020. For the period ended December 31, 2020, two major customers represented approximately 33% and 21%, respectively, of the Company’s total product revenue. For the period ended December 31, 2019, two major customers accounted for approximately 34% and 22%, respectively, of the Company’s total product revenue. For the period ended December 31, 2018, two major customers accounted for approximately 39% and 25%, respectively, of the Company’s total product revenue. Reserves for Variable Consideration: Revenue from product sales is 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 ASU 2013-1, Balance Sheet (Topic 210): Clarifying the Scope of Disclosures about Offsetting Assets and Liabilities 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 occur in a future period for the estimates detailed below as of December 31, 20 20 and, therefore, the transaction price was not reduced further during the year ended December 31, 20 20 . 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. Trade Discounts and Allowances: 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 receivables, 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 statement of operations. Product Returns: 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 revenue in the period the related product revenue is recognized, as well as a reduction to accounts receivables, 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. Provider Chargebacks and Discounts: 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 that the related revenue is recognized, resulting in a reduction of product revenue 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 . Government Rebates: 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 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. Payor Rebates: 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: 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. License Revenue: 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. The Company’s payment terms range between the execution date of the sub-license agreement and 45 days. 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 upfront payments when each sub-license agreement was executed and potential additional 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. For the year ended December 31, 2020, pursuant to the sub-license agreements, the Company recognized as license revenue, upfront payments totaling $0.5 million and development-based milestone payments totaling $22.2 million. The beginning balance of accounts receivable, net on the Company’s consolidated balance sheet for license revenue from the sub-license agreements for the twelve months ended December 31, 2020 was $2.5 million. As of December 31, 2020, $2.5 million in license revenue from the sub-license agreements is included in accounts receivable, net and $1.0 million in the allowance for credit loss on the consolidated balance sheet Royalty Revenue: 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. 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. The Company’s payment terms range between 30 and 90 days.
Legal Contingencies and Expense	Legal Contingencies and Expense: 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 14-Commitments and Contingencies).
Royalty Expenses	Royalty Expenses: Royalties incurred in connection with the Company’s license agreement with Pfizer, as disclosed in Note 14 —
Research and Development Expenses	Research and Development Expenses: Research and development, or R&D, expenses are charged to operations as incurred. The major components of research and development costs include clinical manufacturing costs, clinical trial expenses, consulting and other 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 research and development costs.
Stock-Based Compensation	Stock-Based Compensation: Stock option awards : ASC Topic 718, Compensation-Stock Compensation Restricted stock units: 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 in the statement of operations. 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 “trued-up” upon the actual forfeiture of a 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 : Warrants (refer to Note 11 for further details) granted to employees and non-employees are normally valued at the fair value of the instrument on the grant date and are recognized in the 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 past eight years of 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.
Income Taxes	Income Taxes: The Company follows ASC Topic 740, Income Taxes 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 December 31, 2020, the Company’s uncertain tax position includes a reserve for its R&D credits.
Financial Instruments	Financial Instruments 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.
Cash and Cash Equivalents	Cash and Cash Equivalents: The Company classifies all highly liquid instruments with an original maturity of three months or less as cash equivalents.
Restricted Cash	Restricted Cash: Restricted cash represents cash held at financial institutions that are 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 December 31, 2020 and 2019, the Company had restricted cash in the amount of $12.2 million and $13.2 million, respectively.
Investment Securities	Investment Securities: 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’ (deficit) 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, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments
Assets Measured at Fair Value on a Recurring Basis	Assets Measured at Fair Value on a Recurring Basis: ASC Topic 820, Fair Value Measurement Level 1: Quoted prices in active markets for identical assets or liabilities. Level 2: Quoted prices for similar assets or liabilities in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations in which all significant inputs are observable in active markets. Level 3: Valuations derived from valuation techniques in which one or more significant inputs are unobservable. Following are the major categories of assets measured at fair value on a recurring basis as of December 31, 2020 and 2019, using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3) (in thousands): 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, 2019 Level 1 Level 2 Level 3 Total Cash equivalents $ 41,295 $ — $ — $ 41,295 Corporate bonds — 41,557 — 41,557 U.S. government securities 10,050 — — 10,050 Totals $ 51,345 $ 41,557 $ — $ 92,902 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 short-term investments (in thousands): 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 $ 79,813 $ — $ — $ 79,813 Maturity Amortized Unrealized Estimated December 31, 2019 (in years) cost Gains Losses fair value Cash equivalents $ 41,295 $ — $ — $ 41,295 Corporate bonds Less than 1 41,507 50 — 41,557 U.S. government securities Less than 1 10,038 12 — 10,050 Totals $ 92,840 $ 62 $ — $ 92,902
Concentration of Risk	Concentration of Risk: 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 December 31, 2020, were approximately $101.8 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 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 credit loss primarily based on the credit worthiness of its customers, historical payment patterns, aging of receivable balances and general economic conditions. The Company recorded $1.0 million and $0 as an allowance for credit loss and the related credit loss expense in the years ended December 31, 2020 and 2019, respectively. The Company’s success depends on its ability to successfully commercialize NERLYNX. The Company currently has a single product with 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 contractors. The Company is using the same 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 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 contractors to manufacture the commercial supply of drugs.
Inventory	Inventory: 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 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 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. 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 research and development expense when selected for use in a clinical trial. Starter kits, provided to patients prior to insurance approval, are expensed by the Company to s elling, general and administrative expense as incurred. As of December 31, 2020, the Company’s inventory balance consisted primarily of raw materials purchased subsequent to FDA approval of NERLYNX.
Property and Equipment, Net	Property and Equipment, Net: Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the 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. 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.
Leases	Leases: 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 . in the extent or manner in which the asset is being used. The Company 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 are 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 7 — 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 December 31, 2020 was 10.9%. The Company decided to cease the use of a portion of its leased office space in 2019 . In connection with the decreased need for the right to use the ROU asset, the Company entered into a sublease for the underlying asset, in which the sublease income is less than the original lease payments, indicating impairment. In performing the recoverability test on the effective date, the undiscounted future estimated cash flows and carrying value were identified for the subleased portion of the leased building, as an individual asset group, defined under ASC 360. A reduction to the carrying value of the ROU asset of approximately $ 1.2 million was recorded, representing the fair value amount in excess of the carrying value , with a corresponding impairment charge recorded as selling, general and administration expense, in the consolidated statements of operations for the year ended December 31, 20 19 . There were no indications for impairment during the year ended December 31, 2020.
License Fees and Intangible Assets	License Fees and Intangible Assets: 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 non-clinical 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 asset group 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 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 14-Commitments and Contingencies). The Company capitalized the milestone payments as an intangible asset and is amortizing the asset 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 asset of $6.3 million, $3.9 million and $3.9 million for the years ended December 31, 2020, 2019 and 2018, respectively. As of December 31, 2020, estimated future amortization expense related to the Company’s intangible asset was approximately $8.0 million for each year starting 2021 through 2029, and $2.0 million for 2030.
Recently Issued Accounting Standards	Recently Issued Accounting Standards: In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. ASU 2016-13 requires that credit losses be reported using an expected losses model rather than the incurred losses model that is currently used, and establishes additional disclosures related to credit risks. For trade accounts receivable, the Company recognizes credit losses based on lifetime expected losses. For available-for-sale debt securities with unrealized losses, this standard now requires allowances to be recorded instead of reducing the amortized cost of the investment. These amendments under ASU 2016-13 are effective for interim and annual fiscal periods beginning after December 15, 2019. The Company adopted ASU 2016-13, and the adoption did not have a material effect on the Company’s current financial position, results of operations or financial statement disclosures. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement . As of January 1, 2020, the Company adopted the amendments in ASU 2018-13, which modifies the disclosure requirements on fair value measurements. The removed and modified disclosures were adopted on a retrospective basis and the new disclosures were adopted on a prospective basis. The adoption of ASU 2018-13 did not have a material effect on the Company’s current financial position, results of operations or financial statement disclosures. In December 2019, the FASB issued ASU No 2019-12, Income Taxes (Topic 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 removes 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 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. The Company does not expect ASU 2019-12 to have a material effect on the Company’s current financial position, results of operations or financial statement disclosures.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Assets Measured at Fair Value on Recurring Basis	Following are the major categories of assets measured at fair value on a recurring basis as of December 31, 2020 and 2019, using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3) (in thousands): 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, 2019 Level 1 Level 2 Level 3 Total Cash equivalents $ 41,295 $ — $ — $ 41,295 Corporate bonds — 41,557 — 41,557 U.S. government securities 10,050 — — 10,050 Totals $ 51,345 $ 41,557 $ — $ 92,902
Summary of Short-term Investments	The following tables summarize the Company’s short-term investments (in thousands): 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 $ 79,813 $ — $ — $ 79,813 Maturity Amortized Unrealized Estimated December 31, 2019 (in years) cost Gains Losses fair value Cash equivalents $ 41,295 $ — $ — $ 41,295 Corporate bonds Less than 1 41,507 50 — 41,557 U.S. government securities Less than 1 10,038 12 — 10,050 Totals $ 92,840 $ 62 $ — $ 92,902

Accounts Receivable, Net (Table

Accounts Receivable, Net (Tables)	12 Months Ended
	Dec. 31, 2020
Accounts Receivable Net [Abstract]
Schedule of Accounts Receivable, Net	Accounts receivable, net consisted of the following (in thousands): December 31, 2020 December 31, 2019 Trade accounts receivable $ 21,515 $ 26,180 License revenue receivable 2,500 2,500 Royalty revenue receivable 2,528 216 Total accounts receivable $ 26,543 $ 28,896 Allowance for credit losses (1,000 ) — Total accounts receivable, net $ 25,543 $ 28,896
Schedule of Allowance for Credit Losses	The rollforward of the allowance for credit losses is as follows: Allowance for credit losses (in thousands): Beginning balance at January 1, 2020 $ — Impact of adopting ASC 326 — Provision for credit loss expense (1,000 ) Accounts receivable written-off — Recoveries — Total ending allowance balance as December 31, 2020 $ (1,000 )

Prepaid Expenses and Other (Tab

Prepaid Expenses and Other (Tables)	12 Months Ended
	Dec. 31, 2020
Prepaid Expense And Other Assets [Abstract]
Components of Prepaid Expenses and Other	Prepaid expenses and other consisted of the following at December 31 (in thousands): December 31, 2020 December 31, 2019 Current: CRO services $ 1,550 $ 4,810 Other clinical development 2,718 2,043 Insurance 3,708 3,452 Professional fees 651 544 Other 2,635 2,410 11,262 13,259 Long-term: CRO services 518 400 Other clinical development 437 468 Other 790 1,131 1,745 1,999 Totals $ 13,007 $ 15,258

Other Current Assets (Tables)

Other Current Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Schedule of Other Current Assets	Other current assets consisted of the following at December 31 (in thousands): December 31, 2020 December 31, 2019 Deposit for manufacturing costs $ 3,376 $ — Other 67 323 Totals $ 3,443 $ 323

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Property and Equipment	Property and equipment consisted of the following at December 31 (in thousands): December 31, 2020 December 31, 2019 Leasehold improvements $ 3,779 $ 3,779 Computer equipment 2,192 2,698 Telephone equipment 302 340 Furniture and fixtures 2,359 2,346 8,632 9,163 Less: accumulated depreciation (6,151 ) (5,859 ) Totals $ 2,481 $ 3,304

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Future Minimum Lease Payments Under ASC 842	The future minimum lease payments under ASC 842 as of December 31, 2020 were as follows (in thousands): Amount 2021 5,365 2022 5,483 2023 5,631 2024 5,805 2025 5,983 Thereafter 1,509 Total minimum lease payments $ 29,776 Less: imputed interest (7,133 ) Total lease liabilities $ 22,643
Future Minimum Lease Payments to be Received	The future minimum lease payments to be received as of December 31, 2020 were as follows (in thousands): Amount 2021 $ 467 2022 481 2023 495 2024 510 2025 525 Thereafter 133 Total $ 2,611
Supplemental Cash Flow Information Related to Leases	Supplemental cash flow information related to leases for the year ended December 31, 2020: Operating cash flows used for operating leases (in thousands) $ 5,569 Right-of-use assets obtained in exchange for new operating lease liabilities — Weighted average remaining lease term (in years) 5.2 Weighted average discount rate 10.9 %

Intangible Assets (Tables)

Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets	Intangible assets consisted of the following at December 31 (in thousands): December 31, 2020 December 31, 2019 Acquired and in-licensed rights $ 90,000 $ 50,000 Less: accumulated amortization (15,860 ) (9,539 ) Total intangible asset, net $ 74,140 $ 40,461
Schedule of Estimated Future Intangible Amortization Expense	Estimated future intangible amortization expense as of December 31, 2020 is as follows (in thousands): 2021 $ 8,015 2022 8,015 2023 8,015 2024 8,015 2025 8,015 Thereafter 34,065 Totals $ 74,140

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2020
Payables And Accruals [Abstract]
Accrued Expenses	Accrued expenses consisted of the following at December 31 (in thousands): December 31, 2020 December 31, 2019 Current: Accrued legal verdict expense $ 22,724 $ 31,350 Accrued royalties 8,604 8,866 Accrued CRO services 3,474 8,502 Accrued variable consideration 9,014 7,978 Accrued bonus 7,788 1,618 Accrued compensation 4,820 4,138 Accrued other clinical development 1,904 2,546 Accrued professional fees 1,420 1,775 Accrued legal fees 383 266 Accrued manufacturing costs 752 869 Accrued other 442 1,122 61,325 69,030 Long-term: Accrued legal verdict expense 24,822 — Accrued CRO services 908 — Accrued other 233 — 25,963 — Totals $ 87,288 $ 69,030

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Schedule of Long Term Debt	Long-term debt consisted of the following at December 31, 2020 (in thousands): December 31, 2020 Maturity Date Total debt $ 100,000 June 1, 2024 Accretion of final interest payment 3,313 Less: current portion of long-term debt (14,286 ) Less: deferred financing costs (5,002 ) Total long-term debt, net $ 84,025
Future Minimum Principal Payments Under New Credit Facility	The future minimum principal payments under the New Credit Facility as of December 31, 2020 were as follows (in thousands): Amount 2021 $ 14,286 2022 34,286 2023 34,286 2024 17,142 Thereafter — Total $ 100,000
Schedule of Deferred Financing Costs	Deferred financing costs consisted of the following (in thousands): December 31, 2020 December 31, 2019 Deferred financing costs $ 8,668 $ 8,668 Less: accumulated amortization (3,666 ) (1,701 ) Included in long-term debt $ 5,002 $ 6,967

Stockholders_ (Deficit) Equity

Stockholders’ (Deficit) Equity (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Fair Value Options Weighted-Average Assumptions	The Company awarded only “plain vanilla options” as determined by the SEC Staff Accounting Bulletin 107, or Share Based Payment 2020 2019 Dividend yield 0.0% 0.0% Expected volatility 100.6% 99.9% Risk-free interest rate 0.9% 2.5% Expected life in years 5.81 5.76
Stock-based Compensation Expense	Stock-based compensation expense was as follows for the years ended December 31 (in thousands): For the Year Ended December 31, 2020 2019 2018 Stock-based compensation: Options - Selling, general, and administrative $ 3,937 $ 9,044 $ 14,063 Research and development 3,018 7,452 26,456 Restricted stock units - Selling, general, and administrative 13,841 18,848 20,851 Research and development 15,779 21,983 25,569 Total stock-based compensation expense $ 36,575 $ 57,327 $ 86,939
Activity with Respect to Options Granted	Activity with respect to options granted under the 2011 and 2017 Plan is summarized as follows: Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2017 6,134,513 $ 87.91 7.2 $ 220,060 Granted 315,566 $ 59.13 9.3 Forfeited (183,837 ) $ 51.96 Exercised (200,743 ) $ 35.88 $ 5,063 Expired (356,955 ) $ 116.96 Outstanding at December 31, 2018 5,708,544 $ 87.49 6.1 $ 7,762 Granted 340,241 $ 15.40 8.6 Forfeited (128,406 ) $ 38.71 Exercised (87,625 ) $ 15.42 $ 995 Expired (790,429 ) $ 104.76 Outstanding at December 31, 2019 5,042,325 $ 82.42 5.2 $ 1,951 Granted 700,853 $ 10.03 9.2 Exercised (18,202 ) $ 3.75 $ 119 Expired (715,634 ) $ 90.51 Outstanding at December 31, 2020 5,009,342 $ 71.42 5.1 $ 3,458 Nonvested at December 31, 2020 899,672 $ 11.18 9.1 1,106 Exercisable 4,109,670 $ 84.61 4.3 $ 2,352
Stock Options	The weighted-average grant date fair value of options granted during the years ended December 31, 2020, 2019 and 2018, was $7.81, $12.08 and $45.62 per share, respectively. Shares Weighted Average Grant-Date Fair Value Nonvested shares at December 31, 2018 779,292 $ 33.75 Granted 340,241 12.08 Vested/Issued (551,933 ) 33.56 Forfeited (128,406 ) 26.27 Nonvested shares at December 31, 2019 439,194 19.38 Granted 700,853 7.81 Vested/Issued (240,375 ) 25.57 Nonvested shares at December 31, 2020 899,672 $ 8.71
Restricted Stock Units	The weighted average grant date fair value of RSUs awarded during the year ended December 31, 2020, 2019 and 2018 was $10.47, $14.72, and $41.42, respectively. Shares Weighted Average Grant-Date Fair Value Nonvested shares at December 31, 2017 1,637,662 $ 85.58 Granted 1,175,231 41.42 Vested/Issued (529,443 ) 79.98 Forfeited (444,780 ) 80.99 Nonvested shares at December 31, 2018 1,838,670 60.08 Granted 1,472,417 14.72 Vested/Issued (790,642 ) 62.98 Forfeited (529,320 ) 51.63 Nonvested shares at December 31, 2019 1,991,125 27.63 Granted 1,234,616 10.47 Vested/Issued (864,881 ) 36.86 Forfeited (506,655 ) 21.72 Nonvested shares at December 31, 2020 1,854,205 $ 13.51

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of Income Tax Expense	Income tax expense was as follows for the years ended December 31 (in thousands): 2020 2019 2018 Current: Federal $ — $ — $ — State 124 53 17 Foreign 83 — — 207 53 17 Deferred: Federal — — — State — — — — — — Total $ 207 $ 53 $ 17
Schedule of Income Tax Reconciliation	The primary components of such differences are as follows as of December 31 (in thousands): 2020 2019 2018 Tax computed at the federal statutory rate $ (12,540 ) $ (15,830 ) $ (23,771 ) State taxes (2,304 ) (2,453 ) (2,791 ) Foreign taxes 83 — — Permanent items 13,660 21,834 10,932 R&D credits (5,231 ) (14,946 ) (5,630 ) Prior year adjustment (2,116 ) (2,792 ) 15,750 Change in valuation allowance 8,655 14,240 5,527 Total provision $ 207 $ 53 $ 17
Components of Net Deferred Tax Assets	The components of the Company’s net deferred tax assets are as follows as of December 31 (in thousands): 2020 2019 Deferred tax assets: Net operating loss carryforwards $ 261,472 $ 260,555 Business credit carryforwards 55,574 50,343 Compensation 58,112 60,967 Accrued legal verdict 11,880 7,624 Carryforward of disallowed interest 3,093 2,839 Accrued expenses 561 9 Lease liabilities 5,657 6,145 Other deferred tax assets 804 13 Subtotal 397,153 388,495 Deferred tax liabilities: Lease right-of-use assets (4,099 ) (4,505 ) Inventory (21 ) — Other deferred tax liabilities (464 ) (76 ) Subtotal (4,584 ) (4,581 ) Total deferred tax assets 392,569 383,914 Valuation allowance (392,569 ) (383,914 ) Net deferred tax assets $ — $ —
Reconciliation of Unrecognized Tax Benefits	The following is a tabular reconciliation of the total amounts of unrecognized tax benefits at December 31 (in thousands): 2020 2019 2018 Unrecognized tax benefits - January 1 $ 1,968 $ 8,777 $ 7,151 Gross decreases - tax positions in a prior period — (8,422 ) — Gross increases - tax positions in a current period 1,308 1,613 1,626 Unrecognized tax benefits - December 31 $ 3,276 $ 1,968 $ 8,777

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Summary of Clinical Research Organization Contracts	The contracts also contain variable costs that are hard to predict as they are based on such things as patients enrolled and clinical trial sites, which can vary, and therefore, are not included in the table below. The contracts held by the Company as of December 31, 2020, are summarized as follows (in thousands): Indication Estimated Contractual Obligation as of December 31, 2020 Months Remaining on Contract HER2 Overexpressed/Amplified Breast Cancer (Extension) $ 5,242 12 HER2 Overexpressed/Amplified Breast Cancer (Licensor Legacy Clinical Trials) 371 3 HER2 Mutated Breast Cancer and HER2 Mutated Breast Cancer with Brain Metastases 456 24 Metastatic & Adjuvant Breast Cancer 10,399 5 Pre-Clinical Research 22,003 14 Post-Clinical Research 1,256 11 HER2 Mutated Solid Tumors 2,645 10 Other 24,849 15 Total $ 67,221

Quarterly Financial Data (Table

Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data	Quarterly financial data (in thousands except share and per share data): (unaudited) Three Months Ended March 31, June 30, September 30, December 31, 2020 Revenues $ 51,217 $ 70,582 $ 50,754 $ 52,557 Net (loss) income (16,933 ) 3,395 (31,463 ) (14,994 ) Net (loss) income attributable to common stock (16,933 ) 3,395 (31,463 ) (14,994 ) Net (loss) income per share—basic $ (0.43 ) $ 0.09 $ (0.79 ) $ (0.38 ) Net (loss) income per share—diluted $ (0.43 ) $ 0.08 $ (0.79 ) $ (0.38 ) Weighted-average shares of common stock outstanding—basic 39,291,162 39,432,030 39,695,444 39,881,131 Weighted-average shares of common stock outstanding—diluted 39,291,162 39,997,571 39,695,444 39,881,131 2019 Revenues $ 99,067 $ 53,919 $ 56,352 $ 62,922 Net loss (10,087 ) (37,424 ) (16,885 ) (11,199 ) Net loss attributable to common stock (10,087 ) (37,424 ) (16,885 ) (11,199 ) Net loss per share—basic and diluted $ (0.26 ) $ (0.97 ) $ (0.44 ) $ (0.29 ) Weighted-average shares of common stock outstanding—basic and diluted 38,481,824 38,647,775 38,893,757 39,043,706 2018 Revenues $ 66,516 $ 50,767 $ 62,629 $ 71,079 Net loss (24,345 ) (44,335 ) (14,201 ) (30,694 ) Net loss attributable to common stock (24,345 ) (44,335 ) (14,201 ) (30,694 ) Net loss per share—basic and diluted $ (0.65 ) $ (1.17 ) $ (0.37 ) $ (0.80 ) Weighted-average shares of common stock outstanding—basic and diluted 37,699,024 37,819,767 38,043,174 38,201,056

Business and Basis of Present_2

Business and Basis of Presentation - Additional Information (Detail) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2020USD ($)Subsidiary	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Number of subsidiaries | Subsidiary													2
Net loss	$ (14,994)	$ (31,463)	$ 3,395	$ (16,933)	$ (11,199)	$ (16,885)	$ (37,424)	$ (10,087)	$ (30,694)	$ (14,201)	$ (44,335)	$ (24,345)	$ (59,995)	$ (75,595)	$ (113,575)
Net cash used in operating activities													773	22,376	$ (24,105)
Cash and cash equivalents	85,293				60,037								85,293	60,037
Marketable securities	$ 8,096				$ 51,607								$ 8,096	$ 51,607

Significant Accounting Polici_4

Significant Accounting Policies - Additional Information (Detail)	3 Months Ended												12 Months Ended
	Dec. 31, 2020USD ($)$ / shares	Sep. 30, 2020USD ($)$ / shares	Jun. 30, 2020USD ($)$ / shares	Mar. 31, 2020USD ($)$ / shares	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2020USD ($)Segment$ / sharesshares	Dec. 31, 2019USD ($)shares	Dec. 31, 2018USD ($)shares
Significant Accounting Policies [Line Items]
Number of segments | Segment													1
Legal verdict expense													$ 16,196,000	$ 16,350,000	$ 9,000,000
Accrued legal verdict expense, long-term	$ 24,822,000												24,822,000
Revenue recognized	52,557,000	$ 50,754,000	$ 70,582,000	$ 51,217,000	$ 62,922,000	$ 56,352,000	$ 53,919,000	$ 99,067,000	$ 71,079,000	$ 62,629,000	$ 50,767,000	$ 66,516,000	225,110,000	272,260,000	250,991,000
Net loss	$ (14,994,000)	$ (31,463,000)	$ 3,395,000	$ (16,933,000)	(11,199,000)	$ (16,885,000)	$ (37,424,000)	$ (10,087,000)	$ (30,694,000)	$ (14,201,000)	$ (44,335,000)	$ (24,345,000)	(59,995,000)	(75,595,000)	(113,575,000)
Net loss per share | $ / shares	$ (0.38)	$ (0.79)	$ 0.09	$ (0.43)
Incremental costs expenses	$ 0												0
Restricted cash	12,200,000				13,200,000								12,200,000	13,200,000
Credit loss on available for sale securities	0												0
Cash and cash equivalents and restricted cash in excess of insured limits	101,800,000												101,800,000
Allowance for doubtful accounts	$ 1,000,000				$ 0								$ 1,000,000	0
Lessee, operating lease, existence of option to extend													true
Lessee, operating lease, option to extend, description													Options to extend or terminate a lease are considered in the lease term to the extent that the option is reasonably certain of exercise.
Lessee, operating lease, existence of option to terminate													true
Lessee, operating lease, option to terminate, description													Options to extend or terminate a lease are considered in the lease term to the extent that the option is reasonably certain of exercise.
Average incremental borrowing rate	10.90%												10.90%
Reduction in carrying value of right of use asset													$ 1,200,000
Amortization expenses related to intangible assets													6,300,000	3,900,000	3,900,000
Estimated future amortization expense related to intangible assets, 2021	$ 8,015,000												8,015,000
Estimated future amortization expense related to intangible assets, 2022	8,015,000												8,015,000
Estimated future amortization expense related to intangible assets, 2023	8,015,000												8,015,000
Estimated future amortization expense related to intangible assets, 2024	8,015,000												8,015,000
Estimated future amortization expense related to intangible assets, 2025	8,015,000												8,015,000
Estimated future amortization expense related to intangible assets, 2026	8,000,000												8,000,000
Estimated future amortization expense related to intangible assets, 2027	8,000,000												8,000,000
Estimated future amortization expense related to intangible assets, 2028	8,000,000												8,000,000
Estimated future amortization expense related to intangible assets, 2029	8,000,000												8,000,000
Estimated future amortization expense related to intangible assets, 2030	2,000,000												$ 2,000,000
Computer Hardware and Software
Significant Accounting Policies [Line Items]
Estimated useful lives													3 years
Phone Equipment
Significant Accounting Policies [Line Items]
Estimated useful lives													3 years
Furniture and Fixtures
Significant Accounting Policies [Line Items]
Estimated useful lives													7 years
Letter of Credit
Significant Accounting Policies [Line Items]
Lease expiration year													2026
Sub-license Agreements
Significant Accounting Policies [Line Items]
Development-based milestone payments													$ 22,200,000
Potential milestone payments receivable	536,500,000												536,500,000
License Revenue
Significant Accounting Policies [Line Items]
Revenue recognized													22,700,000	60,250,000	$ 50,500,000
Revenue recognized from beginning balance													2,500,000
License Revenue | Sub-license Agreements
Significant Accounting Policies [Line Items]
Revenue recognized													$ 500,000
License Revenue | Maximum
Significant Accounting Policies [Line Items]
Revenue recognition, payment terms													45 days
License Revenue | Accounts Receivable, Net | Sub-license Agreements
Significant Accounting Policies [Line Items]
Revenue recognized													$ 2,500,000
License Revenue | Allowance for Credit Loss | Sub-license Agreements
Significant Accounting Policies [Line Items]
Revenue recognized													1,000,000
Royalty Revenue
Significant Accounting Policies [Line Items]
Revenue recognized													$ 5,682,000	$ 391,000
Royalty Revenue | Maximum
Significant Accounting Policies [Line Items]
Revenue recognition, payment terms													90 days
Royalty Revenue | Minimum
Significant Accounting Policies [Line Items]
Revenue recognition, payment terms													30 days
Customer Concentration Risk | Total Revenues | CVS/Caremark
Significant Accounting Policies [Line Items]
Concentration risk percentage													33.00%	34.00%	39.00%
Customer Concentration Risk | Total Revenues | Accredo/Acaria
Significant Accounting Policies [Line Items]
Concentration risk percentage													21.00%	22.00%	25.00%
Minimum
Significant Accounting Policies [Line Items]
Revenue recognition, payment terms													10 days
Maximum
Significant Accounting Policies [Line Items]
Revenue recognition, payment terms													68 days
Amortization period recognized													1 year
Employee Stock Option
Significant Accounting Policies [Line Items]
Anti-dilutive securities excluded from the calculation of diluted earnings per share | shares													5,009,342	5,042,325	5,708,544
Warrants
Significant Accounting Policies [Line Items]
Anti-dilutive securities excluded from the calculation of diluted earnings per share | shares													2,116,250	2,116,250	2,116,250
Restricted Stock Units
Significant Accounting Policies [Line Items]
Anti-dilutive securities excluded from the calculation of diluted earnings per share | shares													1,854,205	1,991,125	1,838,670
Change in Estimate for Legal Verdict Expense and Accrual
Significant Accounting Policies [Line Items]
Change in accounting estimate, description													During the three-month period ended September 30, 2020, the Company changed its estimate of the legal verdict expense and the associated legal expense accrual for the Hsu v. Puma Biotechnology, Inc., et al. class action lawsuit. The previous estimate was based on data and assumptions that were the best available information at the time. In September and October 2020, the Company obtained additional data, previously unavailable, from the claims report and amended claims report filed with the Court. Our estimate of the legal verdict expense and the associated legal expense accrual for the Hsu lawsuit remained unchanged for the quarter ended December 31, 2020. The new data indicate that the settlement is expected to be larger than previously estimated. As a result, the Company has changed its estimate of the legal accrual on a prospective basis beginning in the third quarter of 2020
Legal verdict expense													$ 15,700,000
Accrued legal verdict expense, long-term	$ 15,700,000												15,700,000
Revenue recognized													0
Net loss													$ 15,700,000
Net loss per share | $ / shares													$ 0.40

Assets Measured at Fair Value o

Assets Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	$ 71,717	$ 41,295
Totals	79,813	92,902
Commercial paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	8,096
Corporate bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities		41,557
U.S. government securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities		10,050
Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	59,919	41,295
Totals	59,919	51,345
Level 1 | U.S. government securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities		10,050
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	11,798
Totals	19,894	41,557
Level 2 | Commercial paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	$ 8,096
Level 2 | Corporate bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities		$ 41,557

Summary of Short-term Investmen

Summary of Short-term Investments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]
Cash equivalents, Amortized cost	$ 85,293	$ 60,037
Marketable securities, Amortized cost	79,813	92,840
Marketable securities, Unrealized Gains		62
Marketable securities, Estimated fair value	79,813	92,902
Cash equivalents
Schedule Of Available For Sale Securities [Line Items]
Cash equivalents, Amortized cost	71,717	41,295
Cash equivalents, Estimated fair value	$ 71,717	$ 41,295
Commercial paper
Schedule Of Available For Sale Securities [Line Items]
Marketable securities, Maturity (in years)	Less than 1
Marketable securities, Amortized cost	$ 8,096
Marketable securities, Estimated fair value	$ 8,096
Corporate bonds
Schedule Of Available For Sale Securities [Line Items]
Marketable securities, Maturity (in years)		Less than 1
Marketable securities, Amortized cost		$ 41,507
Marketable securities, Unrealized Gains		50
Marketable securities, Estimated fair value		$ 41,557
U.S. government securities
Schedule Of Available For Sale Securities [Line Items]
Marketable securities, Maturity (in years)		Less than 1
Marketable securities, Amortized cost		$ 10,038
Marketable securities, Unrealized Gains		12
Marketable securities, Estimated fair value		$ 10,050

Accounts Receivable, Net - Sche

Accounts Receivable, Net - Schedule of Accounts Receivable, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts Receivable Net [Abstract]
Trade accounts receivable	$ 21,515	$ 26,180
License revenue receivable	2,500	2,500
Royalty revenue receivable	2,528	216
Total accounts receivable	26,543	28,896
Allowance for credit losses	(1,000)	0
Total accounts receivable, net	$ 25,543	$ 28,896

Accounts Receivable, Net - Addi

Accounts Receivable, Net - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Accounts Notes And Loans Receivable [Line Items]
Provision for credit loss expense	$ 1,000	$ 0
Selling, General and Administration Expense
Accounts Notes And Loans Receivable [Line Items]
Provision for credit loss expense	$ 1,000

Accounts Receivable, Net - Sc_2

Accounts Receivable, Net - Schedule of Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Accounts Notes And Loans Receivable [Line Items]
Allowance for credit losses, Beginning balance	$ 0
Provision for credit loss expense	(1,000)	$ 0
Allowance for credit losses, Ending balance	$ (1,000)	$ 0

Components of Prepaid Expenses

Components of Prepaid Expenses and Other (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Prepaid Expenses [Line Items]
Prepaid expenses and other, current	$ 11,262	$ 13,259
Prepaid expenses and other, long-term	1,745	1,999
Totals	13,007	15,258
CRO services
Prepaid Expenses [Line Items]
Prepaid expenses and other, current	1,550	4,810
Prepaid expenses and other, long-term	518	400
Other clinical development
Prepaid Expenses [Line Items]
Prepaid expenses and other, current	2,718	2,043
Prepaid expenses and other, long-term	437	468
Insurance
Prepaid Expenses [Line Items]
Prepaid expenses and other, current	3,708	3,452
Professional fees
Prepaid Expenses [Line Items]
Prepaid expenses and other, current	651	544
Other
Prepaid Expenses [Line Items]
Prepaid expenses and other, current	2,635	2,410
Prepaid expenses and other, long-term	$ 790	$ 1,131

Schedule of Other Current Asset

Schedule of Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Deposit for manufacturing costs	$ 3,376
Other	67	$ 323
Totals	$ 3,443	$ 323

Property and Equipment (Detail)

Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 8,632	$ 9,163
Less: accumulated depreciation	(6,151)	(5,859)
Totals	2,481	3,304
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property, Plant and Equipment, Gross	3,779	3,779
Computer Equipment
Property Plant And Equipment [Line Items]
Property, Plant and Equipment, Gross	2,192	2,698
Telephone Equipment
Property Plant And Equipment [Line Items]
Property, Plant and Equipment, Gross	302	340
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 2,359	$ 2,346

Property and Equipment - Additi

Property and Equipment - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Depreciation expense	$ 0.9	$ 0.9	$ 1.1

Leases - Additional Information

Leases - Additional Information (Detail) $ in Millions	1 Months Ended			12 Months Ended
	Feb. 28, 2019ft²	Jun. 30, 2012ft²	Dec. 31, 2011ft²	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Leases [Line Items]
Lessee, operating lease, existence of option to extend				true
Fixed lease expense				$ 4.7
Variable lease expense				0.4
Rent expense					$ 4.7	$ 4.7
Operating sublease income				0.4	$ 0.2	$ 0
Los Angeles, California
Leases [Line Items]
Percentage of increase in annual rent	3.00%
Existing square feet of subleased property | ft²	12,429
Sublease expiration month and year	2026-03
Lease Agreement executed on December 2011
Leases [Line Items]
Office lease, lease term			7 years
Existing square feet of leased property | ft²			65,656
Lease expiration month and year			2026-03
Percentage of increase in annual rent			3.00%
Office space, lease extension Stand-by letter of credit				2
Lease Agreement executed on June 2012
Leases [Line Items]
Existing square feet of leased property | ft²		29,470
Lease expiration month and year		2026-03
Percentage of increase in annual rent		3.00%
Office space, lease extension Stand-by letter of credit				$ 1.1
Lessee, operating lease, existence of option to extend		true
Lease option to extend, term		5 years

Future Minimum Lease Payments U

Future Minimum Lease Payments Under ASC 842 (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Leases [Abstract]
2021	$ 5,365
2022	5,483
2023	5,631
2024	5,805
2025	5,983
Thereafter	1,509
Total minimum lease payments	29,776
Less: imputed interest	(7,133)
Total lease liabilities	$ 22,643

Future Minimum Lease Payments t

Future Minimum Lease Payments to be Received (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Leases [Abstract]
2021	$ 467
2022	481
2023	495
2024	510
2025	525
Thereafter	133
Total	$ 2,611

Supplemental Cash Flow Informat

Supplemental Cash Flow Information Related to Leases (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Leases [Abstract]
Operating cash flows used for operating leases (in thousands)	$ 5,569
Weighted average remaining lease term (in years)	5 years 2 months 12 days
Weighted average discount rate	10.90%

Schedule of Intangible Assets (

Schedule of Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Acquired and in-licensed rights	$ 90,000	$ 50,000
Less: accumulated amortization	(15,860)	(9,539)
Total intangible asset, net	$ 74,140	$ 40,461

Schedule of Estimated Future In

Schedule of Estimated Future Intangible Amortization Expense (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Finite Lived Intangible Assets Future Amortization Expense [Abstract]
2021	$ 8,015
2022	8,015
2023	8,015
2024	8,015
2025	8,015
Thereafter	34,065
Totals	$ 74,140

Accrued Expenses (Detail)

Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current:
Accrued legal verdict expense	$ 22,724	$ 31,350
Accrued royalties	8,604	8,866
Accrued CRO services	3,474	8,502
Accrued variable consideration	9,014	7,978
Accrued bonus	7,788	1,618
Accrued compensation	4,820	4,138
Accrued other clinical development	1,904	2,546
Accrued professional fees	1,420	1,775
Accrued legal fees	383	266
Accrued manufacturing costs	752	869
Accrued other	442	1,122
Accrued expenses, current	61,325	69,030
Long-term:
Accrued legal verdict expense	24,822
Accrued CRO services	908
Accrued other	233
Accrued expenses, long-term	25,963
Totals	$ 87,288	$ 69,030

Accrued Expenses - Additional I

Accrued Expenses - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Accrued Expenses [Line Items]
Current accrued legal verdict expense, estimate owed	$ 22,724,000	$ 31,350,000
Accrued legal verdict expense	24,822,000
Eshelman v. Puma Biotechnology, Inc.
Accrued Expenses [Line Items]
Current accrued legal verdict expense, estimate owed	22,700,000
Eshelman v. Puma Biotechnology, Inc. | Maximum
Accrued Expenses [Line Items]
Claimed damages amount	27,700,000
Hsu v. Puma Biotechnology, Inc.
Accrued Expenses [Line Items]
Claimed damages amount	50,500,000
Accrued legal verdict expense	24,800,000
Accrued estimated losses	$ 24,800,000

Debt - Schedule of Long Term De

Debt - Schedule of Long Term Debt (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Total debt	$ 100,000
Accretion of final interest payment	3,313
Less: current portion of long-term debt	(14,286)
Less: deferred financing costs	(5,002)	$ (6,967)
Total long-term debt, net	$ 84,025
Total debt, maturity date	Jun. 1, 2024

Debt - Additional Information (

Debt - Additional Information (Detail) - USD ($)	Jun. 28, 2019	May 31, 2018	Oct. 31, 2017	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Interest expense related to amortization of debt issuance costs				$ 2,000,000	$ 1,500,000	$ 900,000
Silicon Valley Bank and Oxford Finance LLC | Term Loan
Debt Instrument [Line Items]
Line of credit facility, effective date				2017-10
Amount borrowed under credit facility		$ 125,000,000	$ 50,000,000
Term loan, maximum borrowing capacity		155,000,000
Payment of existing credit facility		50,000,000
Line of credit facility available upon achievement of specified minimum revenue milestone		$ 30,000,000
Interest rate, description				Prior to the amendment and restatement of the loan and security agreement in June 2019, which provided for a new credit facility, or the New Credit Facility, the term loans under the Amended Credit Facility bore interest at an annual rate equal to the greater of (i) 8.25% 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 accrued, plus (b) 3.5%. The Company was required to make monthly interest-only payments on each term loan 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 July 1, 2020
Annual interest rate		8.25%
Redemption period start date		Jul. 1, 2020
Line of credit facility closing date		May 1, 2023
Percentage of original principal amount payable in final payment		7.50%
Silicon Valley Bank and Oxford Finance LLC | Term Loan | First Anniversary of Funding
Debt Instrument [Line Items]
Prepayment fee, percentage		3.00%
Silicon Valley Bank and Oxford Finance LLC | Term Loan | Between First Anniversary and Second Anniversary
Debt Instrument [Line Items]
Prepayment fee, percentage		2.00%
Silicon Valley Bank and Oxford Finance LLC | Term Loan | After Second Anniversary and Prior to May 1, 2023
Debt Instrument [Line Items]
Prepayment fee, percentage		1.00%
Silicon Valley Bank and Oxford Finance LLC | Term Loan | Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate		3.50%
Oxford | Secured Promissory Notes
Debt Instrument [Line Items]
Term loan, maximum borrowing capacity	$ 100,000,000
Payment of existing credit facility	$ 155,000,000
Interest rate, description				The term loans under the New Credit Facility bear 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 precedes the month in which the interest will accrue, plus (b) 3.5%. The Company is 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.
Annual interest rate	9.00%
Redemption period start date	Aug. 1, 2021
Line of credit facility closing date	Jun. 1, 2024
Percentage of original principal amount payable in final payment	7.50%
Aggregate principal amount	$ 100,000,000
Additional capacity remains available under new credit facility	$ 0
Percentage of issued and outstanding capital stock of its subsidiary pledged	65.00%
Effective interest rate				12.75%
Percentage of additional interest rate to be charged on the event of default	5.00%
Amount of indebtedness or judgments against company to be considered as threshold limit for default	$ 500,000
Principal amounts outstanding				$ 100,000,000
Oxford | Secured Promissory Notes | First Anniversary of Funding
Debt Instrument [Line Items]
Prepayment fee, percentage	3.00%
Oxford | Secured Promissory Notes | Between First Anniversary and Second Anniversary
Debt Instrument [Line Items]
Prepayment fee, percentage	2.00%
Oxford | Secured Promissory Notes | After Second Anniversary and Prior to Maturity Date
Debt Instrument [Line Items]
Prepayment fee, percentage	1.00%
Oxford | Secured Promissory Notes | Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate	3.50%

Debt - Future Minimum Principal

Debt - Future Minimum Principal Payments Under New Credit Facility (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Total long-term debt, net	$ 84,025
Secured Promissory Notes
Debt Instrument [Line Items]
2021	14,286
2022	34,286
2023	34,286
2024	17,142
Total long-term debt, net	$ 100,000

Debt - Schedule of Deferred Fin

Debt - Schedule of Deferred Financing Costs (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Deferred financing costs	$ 8,668	$ 8,668
Less: accumulated amortization	(3,666)	(1,701)
Included in long-term debt	$ 5,002	$ 6,967

Stockholders' (Deficit) Equity

Stockholders' (Deficit) Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Oct. 31, 2011
Stockholders Equity Note [Line Items]
Issuance of common stock on exercise of option	18,202	87,625	200,743
Common stock issued upon vesting of RSUs	864,881	790,642	529,443
Common stock, shares authorized	100,000,000	100,000,000
Common stock, par value	$ 0.0001	$ 0.0001
Warrant expiration date	Oct. 4, 2021
Issuance of common stock on exercise of option	5,009,342	5,042,325	5,708,544	6,134,513
Weighted-average grant date fair value of options granted	$ 7.81	$ 12.08	$ 45.62
Non Vested Stock Options
Stockholders Equity Note [Line Items]
Estimated unrecognized compensation cost related to non-vested stock options granted	$ 5.9
Estimated unrecognized compensation cost related to non-vested stock options granted, Weighted-average period of recognition	1 year 10 months 24 days
Restricted Stock Units
Stockholders Equity Note [Line Items]
Common stock issued upon vesting of RSUs	864,881	790,642	529,443
Issuance of common stock on exercise of vesting of RSUs granted	1,234,616	1,472,417	1,175,231
Estimated unrecognized compensation cost related to non-vested stock options granted	$ 16.6
Estimated unrecognized compensation cost related to non-vested stock options granted, Weighted-average period of recognition	1 year 6 months
Weighted-average grant date fair value of RSUs	$ 10.47	$ 14.72	$ 41.42
2011 Plan
Stockholders Equity Note [Line Items]
Stock options, award vesting period	3 years
Common stock shares reserved for issuance	12,529,412
Issuance of common stock on exercise of option	5,620,045
Common stock shares available for future issuance	2,387,923
2017 Employment Inducement Incentive Award Plan
Stockholders Equity Note [Line Items]
Stock options, award vesting period	3 years
Common stock shares reserved for issuance	2,000,000
Issuance of common stock on exercise of option	1,243,502
Common stock shares available for future issuance	434,540
Issuance of common stock on exercise of vesting of RSUs granted	1,243,502
Maximum | 2011 Plan
Stockholders Equity Note [Line Items]
Stock options granted, term	10 years
Maximum | 2017 Employment Inducement Incentive Award Plan
Stockholders Equity Note [Line Items]
Stock options granted, term	10 years
Common Stock
Stockholders Equity Note [Line Items]
Issuance of common stock on exercise of option	18,202	87,625	200,743
Shares of common stock that could be acquired by warrant	2,116,250
Common stock price	$ 16
Common Stock | Alan Auerbach | Minimum
Stockholders Equity Note [Line Items]
Minimum ownership percentage of outstanding shares of common stock the president need to maintain after issuance of warrants					20.00%

Stockholders' (Deficit) Equit_2

Stockholders' (Deficit) Equity - Fair Value Options Weighted-Average Assumptions (Detail) - Employee and Nonemployee Stock Option	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend yield	0.00%	0.00%
Expected volatility	100.60%	99.90%
Risk-free interest rate	0.90%	2.50%
Expected life in years	5 years 9 months 21 days	5 years 9 months 3 days

Stockholders' (Deficit) Equit_3

Stockholders' (Deficit) Equity - Stock-based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based compensation expense	$ 36,575	$ 57,327	$ 86,939
Employee Stock Option | Selling, general and administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based compensation expense	3,937	9,044	14,063
Employee Stock Option | Research and development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based compensation expense	3,018	7,452	26,456
Restricted Stock Units | Selling, general and administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based compensation expense	13,841	18,848	20,851
Restricted Stock Units | Research and development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based compensation expense	$ 15,779	$ 21,983	$ 25,569

Stockholders' (Deficit) Equit_4

Stockholders' (Deficit) Equity - Activity with Respect to Options Granted (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Shares
Beginning balance, shares	5,042,325	5,708,544	6,134,513
Granted, shares	700,853	340,241	315,566
Forfeited, shares		(128,406)	(183,837)
Exercised, shares	(18,202)	(87,625)	(200,743)
Expired, shares	(715,634)	(790,429)	(356,955)
Ending balance, shares	5,009,342	5,042,325	5,708,544	6,134,513
Nonvested, shares	899,672	439,194	779,292
Exercisable, shares	4,109,670
Weighted Average Exercise Price
Beginning Balance, Weighted Average Exercise Price	$ 82.42	$ 87.49	$ 87.91
Granted, Weighted Average Exercise Price	10.03	15.40	59.13
Forfeited, Weighted Average Exercise Price		38.71	51.96
Exercised, Weighted Average Exercise Price	3.75	15.42	35.88
Expired, Weighted Average Exercise Price	90.51	104.76	116.96
Ending Balance, Weighted Average Exercise Price	71.42	$ 82.42	$ 87.49	$ 87.91
Nonvested, Weighted Average Exercise Price	11.18
Exercisable, Weighted Average Exercise Price	$ 84.61
Weighted Average Remaining Contractual Term (years)
Weighted Average Remaining Contractual Term (years)	5 years 1 month 6 days	5 years 2 months 12 days	6 years 1 month 6 days	7 years 2 months 12 days
Granted, Weighted Average Remaining Contractual Term (years)	9 years 2 months 12 days	8 years 7 months 6 days	9 years 3 months 18 days
Nonvested, Weighted Average Remaining Contractual Term (years)	9 years 1 month 6 days
Exercisable, Weighted Average Remaining Contractual Term (years)	4 years 3 months 18 days
Aggregate Intrinsic Value
Shares, Outstanding, Aggregate Intrinsic Value	$ 3,458	$ 1,951	$ 7,762	$ 220,060
Exercised, Aggregate Intrinsic Value	119	$ 995	$ 5,063
Nonvested, Aggregate Intrinsic Value	1,106
Exercisable, Aggregate Intrinsic Value	$ 2,352

Stockholders' (Deficit) Equit_5

Stockholders' (Deficit) Equity - Stock Options (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Shares
Nonvested shares, Beginning balance	439,194	779,292
Granted, shares	700,853	340,241	315,566
Vested/Issued, shares	(240,375)	(551,933)
Forfeited, shares		(128,406)
Nonvested shares, Ending balance	899,672	439,194	779,292
Weighted Average Grant-Date Fair Value
Nonvested, Beginning balance, Weighted Average Grant-Date Fair Value	$ 19.38	$ 33.75
Granted, Weighted Average Grant-Date Fair Value	7.81	12.08	$ 45.62
Vested/Issued, Weighted Average Grant-Date Fair Value	25.57	33.56
Forfeited, Weighted Average Grant-Date Fair Value		26.27
Nonvested, Ending balance, Weighted Average Grant-Date Fair Value	$ 8.71	$ 19.38	$ 33.75

Stockholders' (Deficit) Equit_6

Stockholders' (Deficit) Equity - Restricted Stock Units (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Shares
Vested/Issued, shares	(864,881)	(790,642)	(529,443)
Restricted Stock Units
Shares
Nonvested shares, Beginning balance	1,991,125	1,838,670	1,637,662
Granted, shares	1,234,616	1,472,417	1,175,231
Vested/Issued, shares	(864,881)	(790,642)	(529,443)
Forfeited, shares	(506,655)	(529,320)	(444,780)
Nonvested shares, Ending balance	1,854,205	1,991,125	1,838,670
Weighted Average Grant-Date Fair Value
Nonvested, Beginning balance, Weighted Average Grant-Date Fair Value	$ 27.63	$ 60.08	$ 85.58
Granted, Weighted Average Grant-Date Fair Value	10.47	14.72	41.42
Vested/Issued, Weighted Average Grant-Date Fair Value	36.86	62.98	79.98
Forfeited, Weighted Average Grant-Date Fair Value	21.72	51.63	80.99
Nonvested, Ending balance, Weighted Average Grant-Date Fair Value	$ 13.51	$ 27.63	$ 60.08

401(K) Savings Plan - Additiona

401(K) Savings Plan - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Employer matching contribution expenses	$ 1.4	$ 1.5	$ 1.9
First 3% of each Participant's Contributions
Defined Benefit Plan Disclosure [Line Items]
Company's matching contributions to the 401(k)plan	100.00%
Second 2% of each Participant's Contributions
Defined Benefit Plan Disclosure [Line Items]
Company's matching contributions to the 401(k)plan	50.00%

Schedule of Income Tax Expense

Schedule of Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
State	$ 124	$ 53	$ 17
Foreign	83
Total current	207	53	17
Deferred:
Total	$ 207	$ 53	$ 17

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Contingency [Line Items]
Tax expense due to stock-based compensation expense	$ 13,200
Income tax benefit due to R&D tax credits	5,200
Unrecognized tax benefits	1,308	$ 1,613	$ 1,626
Increase in valuation allowance	$ 8,700	$ 14,200
Federal operating loss carryforwards, expiration beginning year	2033
State operating loss carryforwards, expiration beginning year	2033
Federal
Income Tax Contingency [Line Items]
Operating loss carryforwards	$ 961,000
Federal | Research and development credit carryforwards
Income Tax Contingency [Line Items]
Tax credit carryforwards	$ 37,100
Tax credit carryforwards, expiration beginning year	2033
State
Income Tax Contingency [Line Items]
Operating loss carryforwards	$ 884,300
State | Research and development credit carryforwards
Income Tax Contingency [Line Items]
Tax credit carryforwards	$ 21,700

Schedule of Income Tax Reconcil

Schedule of Income Tax Reconciliation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Tax computed at the federal statutory rate	$ (12,540)	$ (15,830)	$ (23,771)
State taxes	(2,304)	(2,453)	(2,791)
Foreign taxes	83
Permanent items	13,660	21,834	10,932
R&D credits	(5,231)	(14,946)	(5,630)
Prior year adjustment	(2,116)	(2,792)	15,750
Change in valuation allowance	8,655	14,240	5,527
Total	$ 207	$ 53	$ 17

Components of Net Deferred Tax

Components of Net Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets
Net operating loss carryforwards	$ 261,472	$ 260,555
Business credit carryforwards	55,574	50,343
Compensation	58,112	60,967
Accrued legal verdict	11,880	7,624
Carryforward of disallowed interest	3,093	2,839
Accrued expenses	561	9
Lease liabilities	5,657	6,145
Other deferred tax assets	804	13
Subtotal	397,153	388,495
Deferred tax liabilities:
Lease right-of-use assets	(4,099)	(4,505)
Inventory	(21)
Other deferred tax liabilities	(464)	(76)
Subtotal	(4,584)	(4,581)
Total deferred tax assets	392,569	383,914
Valuation allowance	(392,569)	(383,914)
Net deferred tax assets	$ 0	$ 0

Reconciliation of Unrecognized

Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Unrecognized tax benefits - January 1	$ 1,968	$ 8,777	$ 7,151
Gross decreases - tax positions in a prior period		(8,422)
Gross increases - tax positions in a current period	1,308	1,613	1,626
Unrecognized tax benefits - December 31	$ 3,276	$ 1,968	$ 8,777

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($)	Jul. 28, 2020	Mar. 02, 2020	Jan. 29, 2019	Sep. 30, 2021	Nov. 30, 2020	Dec. 31, 2020	Oct. 09, 2020
Commitments And Contingencies Disclosure [Line Items]
License agreement, expected milestone payment						$ 187,500,000
License agreement, installment milestone payment					$ 20,600,000
Percentage of unpaid portion of milestone payments interest rate						6.25%
Company obligations for potential milestone payments for CRO Contracts						$ 18,400,000
Hsingching Hsu
Commitments And Contingencies Disclosure [Line Items]
Accrued estimated losses						24,800,000
Loss contingency damages awarded percent of total claim			5.00%
Loss contingency claimed damages awarded per share			$ 87.20
Loss contingency claimed damages amount							$ 50,500,000
Eshelman v. Puma Biotechnology, Inc.
Commitments And Contingencies Disclosure [Line Items]
Accrued estimated losses						22,700,000
Attorneys fees		$ 3,000,000
Total judgment value		$ 26,300,000
Stand-by letter of credit, amount						8,900,000
Eshelman v. Puma Biotechnology, Inc. | Compensatory
Commitments And Contingencies Disclosure [Line Items]
Damages awarded, value						15,900,000
Eshelman v. Puma Biotechnology, Inc. | Punitive
Commitments And Contingencies Disclosure [Line Items]
Damages awarded, value						$ 6,500,000
CANbridge Life Sciences
Commitments And Contingencies Disclosure [Line Items]
Arbitration filed date
Minimum | Hsingching Hsu
Commitments And Contingencies Disclosure [Line Items]
Accrued estimated losses							24,800,000
Minimum | CRO services
Commitments And Contingencies Disclosure [Line Items]
Written notice of termination, period						30 days
Maximum | Hsingching Hsu
Commitments And Contingencies Disclosure [Line Items]
Accrued estimated losses							$ 51,400,000
Damages awarded per share			$ 4.50
Maximum | Eshelman v. Puma Biotechnology, Inc.
Commitments And Contingencies Disclosure [Line Items]
Claimed damages amount						$ 27,700,000
Maximum | CRO services
Commitments And Contingencies Disclosure [Line Items]
Written notice of termination, period						45 days
Forecast
Commitments And Contingencies Disclosure [Line Items]
License agreement, installment milestone payment				$ 21,900,000

Summary of Clinical Research Or

Summary of Clinical Research Organization Contracts (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Research And Development Arrangement Contract To Perform For Others [Line Items]
Estimated Contractual Obligation	$ 67,221
HER2 Overexpressed/Amplified Breast Cancer (Extension)
Research And Development Arrangement Contract To Perform For Others [Line Items]
Estimated Contractual Obligation	$ 5,242
Months Remaining on Contract	12 months
HER2 Overexpressed/Amplified Breast Cancer (Licensor Legacy Clinical Trials)
Research And Development Arrangement Contract To Perform For Others [Line Items]
Estimated Contractual Obligation	$ 371
Months Remaining on Contract	3 months
HER2 Mutated Breast Cancer and HER2 Mutated Breast Cancer with Brain Metastases
Research And Development Arrangement Contract To Perform For Others [Line Items]
Estimated Contractual Obligation	$ 456
Months Remaining on Contract	24 months
Metastatic & Adjuvant Breast Cancer
Research And Development Arrangement Contract To Perform For Others [Line Items]
Estimated Contractual Obligation	$ 10,399
Months Remaining on Contract	5 months
Pre-Clinical Research
Research And Development Arrangement Contract To Perform For Others [Line Items]
Estimated Contractual Obligation	$ 22,003
Months Remaining on Contract	14 months
Post-Clinical Research
Research And Development Arrangement Contract To Perform For Others [Line Items]
Estimated Contractual Obligation	$ 1,256
Months Remaining on Contract	11 months
HER2 Mutated Solid Tumors
Research And Development Arrangement Contract To Perform For Others [Line Items]
Estimated Contractual Obligation	$ 2,645
Months Remaining on Contract	10 months
Other
Research And Development Arrangement Contract To Perform For Others [Line Items]
Estimated Contractual Obligation	$ 24,849
Months Remaining on Contract	15 months

Quarterly Financial Data (Detai

Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Revenue recognized	$ 52,557	$ 50,754	$ 70,582	$ 51,217	$ 62,922	$ 56,352	$ 53,919	$ 99,067	$ 71,079	$ 62,629	$ 50,767	$ 66,516	$ 225,110	$ 272,260	$ 250,991
Net loss	(14,994)	(31,463)	3,395	(16,933)	(11,199)	(16,885)	(37,424)	(10,087)	(30,694)	(14,201)	(44,335)	(24,345)	(59,995)	(75,595)	(113,575)
Net (loss) income attributable to common stock	$ (14,994)	$ (31,463)	$ 3,395	$ (16,933)	$ (11,199)	$ (16,885)	$ (37,424)	$ (10,087)	$ (30,694)	$ (14,201)	$ (44,335)	$ (24,345)	$ (59,995)	$ (75,595)	$ (113,575)
Net (loss) income per share—basic	$ (0.38)	$ (0.79)	$ 0.09	$ (0.43)
Net (loss) income per share—diluted	$ (0.38)	$ (0.79)	$ 0.08	$ (0.43)
Weighted-average shares of common stock outstanding—basic	39,881,131	39,695,444	39,432,030	39,291,162
Weighted-average shares of common stock outstanding—diluted	39,881,131	39,695,444	39,997,571	39,291,162
Net loss per share—basic and diluted					$ (0.29)	$ (0.44)	$ (0.97)	$ (0.26)	$ (0.80)	$ (0.37)	$ (1.17)	$ (0.65)	$ (1.52)	$ (1.95)	$ (2.99)
Weighted-average shares of common stock outstanding—basic and diluted					39,043,706	38,893,757	38,647,775	38,481,824	38,201,056	38,043,174	37,819,767	37,699,024	39,576,107	38,768,653	37,942,411

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - Subsequent Event $ in Millions	Feb. 24, 2021USD ($)
Pierre Fabre | Second Pierre Fabre Amendment to Sub-License Agreement
Subsequent Event [Line Items]
Upfront payment received	$ 50
Pierre Fabre | Second Pierre Fabre Amendment to Sub-License Agreement | Maximum
Subsequent Event [Line Items]
Regulatory and sales-based milestone payments	240
CANbridge Life Sciences | CANbridge Termination of Sub-License Agreement
Subsequent Event [Line Items]
One-time termination fee	$ 20