Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically ~~and posted on its corporate Web site, if any,~~ every Interactive Data File required to be submitted ~~and posted~~ pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit ~~and post~~ such files). Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section ~~7(a)(2)(B)~~13(a) of the ~~Securities~~Exchange Act. ☒

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒

As of ~~October 31, 2017,~~April 26, 2019, the registrant had ~~12,951,033~~16,443,132 shares of common stock, $0.0001 par value per share, outstanding.

This Quarterly Report on Form 10-Q contains forward-looking statements that involve substantial risks and uncertainties. All statements, other than statements of historical facts, contained in this Quarterly Report on Form 10-Q, including statements regarding our strategy, future operations, future financial position, projected costs, prospects, plans and objectives of management, are forward-looking statements. In some cases, you can identify forward-looking statements by terms such as “may,” “will,” “should,” “design,” “expect,” “seek,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” ~~“contemplate,”~~ “believe,” “estimate,” “predict,” “potential” or “continue” or the negative of these terms or other similar expressions.

These forward-looking statements include, but are not limited to, statements about:

We may not actually achieve the plans, intentions or expectations disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in the forward-looking statements we make. Factors that could cause actual results or events to differ materially from the forward-looking statements that we make include, but are not limited to, the following:

You should read this Quarterly Report on Form 10-Q and the documents that we have filed as exhibits to this Quarterly Report on Form 10-Q completely and with the understanding that our actual future results may be materially different from what we expect. You should also read carefully the factors described in ~~the section “Risk Factors” of this Quarterly Report on Form 10-Q and~~ “Item 1A. Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, ~~2016~~2018, as filed with the Securities and Exchange Commission on March 11, 2019, to better understand the risks and uncertainties inherent in our business and underlying any forward-looking statements. You are advised, however, to consult any further disclosures we make on related subjects in our subsequent Quarterly Reports on Form 10-Q, Current Reports on Form 8-K, press releases, and our website. Any forward-looking statements that we make in this Quarterly Report on Form 10-Q speak only as of the date of this Quarterly Report on Form 10-Q, and we undertake no obligation to update such statements to reflect events or circumstances after the date of this Quarterly Report on Form 10-Q or to reflect the occurrence of unanticipated events.

	September 30,			December 31,			March 31,			December 31,
	2017			2016			2019			2018
ASSETS	(unaudited)						(unaudited)
Current assets:
Cash and cash equivalents	$	17,539		$	10,684		$	16,750		$	14,724
Marketable securities		34,640			14,046			29,857			32,914
Prepaid expenses and other current assets		850			840			1,218			1,649
Total current assets		53,029			25,570			47,825			49,287
Marketable securities, long-term		—			752			10,873			16,804
Property and equipment, net		534			522			2,307			2,319
Operating lease right-of-use assets								2,915			—
Restricted cash		250			—			234			234
Other assets		35			35			198			167
Total	$	53,848		$	26,879		$	64,352		$	68,811
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current liabilities:
Accounts payable	$	1,773		$	1,519		$	1,986		$	1,880
Accrued expenses and other current liabilities		2,312			1,982			1,693			2,367
Operating lease liabilities, current								269			—
Total current liabilities		4,085			3,501			3,948			4,247
Warrant liabilities		17,807			6,333			5,690			8,511
Operating lease liabilities, noncurrent								3,141			—
Other long-term liabilities		32			27			27			193
Total liabilities		21,924			9,861			12,806			12,951
Commitments and contingencies (Note 8)
Commitments and contingencies (Note 9)
Stockholders’ equity:
Preferred stock, $0.0001 par value—authorized, 10,000,000 shares at September 30, 2017 and December 31, 2016; no shares issued or outstanding at September 30, 2017 and December 31, 2016		—			—
Common stock, $0.0001 par value—authorized, 200,000,000 shares at September 30, 2017 and December 31, 2016; 12,697,038 and 9,416,238 shares issued and outstanding at September 30, 2017 and December 31, 2016, respectively		1			1
Preferred stock, $0.0001 par value—authorized, 10,000,000 shares at March 31, 2019 and December 31, 2018; no shares issued or outstanding at March 31, 2019 and December 31, 2018								—			—
Common stock, $0.0001 par value—authorized, 200,000,000 shares at March 31, 2019 and December 31, 2018; 16,442,532 and 16,434,614 shares issued and outstanding at March 31, 2019 and December 31, 2018, respectively								2			2
Additional paid-in capital		109,682			68,559			158,928			157,931
Accumulated deficit		(77,752	)		(51,535	)		(107,263	)		(102,068	)
Other comprehensive loss		(7	)		(7	)
Accumulated other comprehensive loss								(121	)		(5	)
Total stockholders’ equity		31,924			17,018			51,546			55,860
Total	$	53,848		$	26,879		$	64,352		$	68,811

	For the Three Months Ended September 30,						For the Nine Months Ended September 30,						For the Three Months Ended March 31,
	2017			2016			2017			2016			2019			2018
Grant revenue	$	—		$	—		$	—		$	352
Operating expenses:
Research and development		3,221			2,723			9,152			11,247		$	5,567		$	3,977
General and administrative		1,968			1,452			5,811			4,136			2,810			2,223
Total operating expenses		5,189			4,175			14,963			15,383			8,377			6,200
Loss from operations		(5,189	)		(4,175	)		(14,963	)		(15,031	)		(8,377	)		(6,200	)
Other income (expense):
Other income:
Interest income		141			27			220			65			361			134
Change in fair value of warrant liabilities		(5,780	)		—			(11,474	)		—			2,821			1,202
Net loss		(10,828	)		(4,148	)		(26,217	)		(14,966	)		(5,195	)		(4,864	)
Unrealized (loss) gain on marketable securities		(10	)		(3	)		(7	)		18
Unrealized loss on marketable securities														(116	)		—
Comprehensive loss	$	(10,838	)	$	(4,151	)	$	(26,224	)	$	(14,948	)	$	(5,311	)	$	(4,864	)
Net loss per common share – basic and diluted	$	(0.85	)	$	(0.53	)	$	(2.48	)	$	(2.18	)
Weighted-average number of shares outstanding – basic and diluted		12,696,986			7,759,630			10,555,461			6,856,876
Net loss per common share - basic and diluted													$	(0.32	)	$	(0.37	)
Weighted-average number of shares outstanding - basic and diluted														16,436,970			12,991,532

	Common Stock				Additional Paid-in		Accumulated			Other Comprehensive			Total Stockholders’
	Shares		Amount		Capital		Deficit			Income (loss)			Equity
Balance at December 31, 2018		16,434,614	$	2	$	157,931	$	(102,068	)	$	(5	)	$	55,860
Stock-based compensation		—		—		913		—			—			913
Issuance of common stock for services rendered		7,918		—		84		—			—			84
Net unrealized loss on marketable securities		—		—		—		—			(116	)		(116	)
Net loss		—		—		—		(5,195	)		—			(5,195	)
Balance at March 31, 2019		16,442,532	$	2	$	158,928	$	(107,263	)	$	(121	)	$	51,546

	Common Stock				Additional Paid-in		Accumulated			Other Comprehensive			Total Stockholders’
	Shares		Amount		Capital		Deficit			Income (loss)			Equity
Balance at December 31, 2017		12,961,993	$	1	$	113,984	$	(79,214	)	$	(23	)	$	34,748
Stock-based compensation		—		—		634		—			—			634
Issuance of common stock for services rendered		1,831		—		24		—			—			24
Issuance of common stock in connection with at-the-market offering, net of issuance costs of $125		190,055		—		2,827		—			—			2,827
Net unrealized gain on marketable securities		—		—		—		(23	)		23			—
Net loss		—		—		—		(4,864	)		—			(4,864	)
Balance at March 31, 2018		13,153,879	$	1	$	117,469	$	(84,101	)	$	—		$	33,369

	For the Nine Months Ended September 30,						For the Three Months Ended March 31,
	2017			2016			2019			2018
Cash flows from operating activities:
Net loss	$	(26,217	)	$	(14,966	)	$	(5,195	)	$	(4,864	)
Adjustments for:
Depreciation and amortization		115			87			83			45
Operating lease right-of-use asset amortization								65			—
Change in fair value of warrant liabilities		11,474			—			(2,821	)		(1,202	)
Non-cash investment income (losses)		(50	)		28
Non-cash investment income (expense)								(12	)		35
Non-cash stock-based compensation		1,483			1,015			972			658
Non-cash issuance of common stock and warrants connected to license agreement		—			2,780
Changes in operating assets and liabilities:
Prepaid expenses and other current assets		(10	)		(746	)		431			(29	)
Other assets		—			(35	)		(31	)		(181	)
Accounts payable		254			148			106			(45	)
Accrued expenses and other liabilities		311			(19	)		(411	)		(605	)
Operating lease liabilities								26			—
Net cash used in operating activities		(12,640	)		(11,708	)		(6,787	)		(6,188	)
Cash flows from investing activities:
Proceeds from sale of marketable securities								8,884			13,550
Purchases of marketable securities		(34,397	)		(6,693	)		—			(10,000	)
Proceeds from sale of marketable securities		14,605			4,894
Purchases of property and equipment		(127	)		(156	)		(71	)		(250	)
Net cash used in investing activities		(19,919	)		(1,955	)
Net cash provided by investing activities								8,813			3,300
Cash flows from financing activities:
Proceeds from issuance of common stock		42,500			11,339
Payment of finance costs related to issuance of common stock		(2,928	)		(2,128	)
Proceeds from exercise of warrants		—			5,342
Proceeds from exercise of stock options		92			95
Proceeds from issuance of common stock in connection with at-the-market offering, net of issuance costs								—			2,827
Cash provided by financing activities		39,664			14,648			—			2,827
Net increase in cash, cash equivalents and restricted cash		7,105			985
Cash and cash equivalents, beginning of period		10,684			4,347
Net increase (decrease) in cash, cash equivalents and restricted cash								2,026			(61	)
Cash, cash equivalents and restricted cash, beginning of period								14,958			24,133
Cash, cash equivalents and restricted cash, end of period	$	17,789		$	5,332		$	16,984		$	24,072
Supplemental disclosures of cash flow information:
Cash paid for taxes	$	1		$	1		$	—		$	3
Cash paid for interest	$	—		$	—
Supplemental disclosures of noncash financing activities:
Issuance of common stock warrants in connection with initial public offering	$	—		$	218
Cash paid for interest, net							$	—		$	—

Spring Bank Pharmaceuticals, Inc. (the “Company”) is a clinical-stage biopharmaceutical company engaged in the discovery and development of a novel class of therapeutics using a proprietary small molecule ~~nucleic acid hybrid (“SMNH”) chemistry~~nucleotide platform. The Company is developing its most advanced ~~SMNH~~ product candidate, inarigivir soproxil (“inarigivir”) ~~(formerly known as SB 9200)~~, for the treatment of ~~viral diseases.~~chronic hepatitis B virus. Since inception in 2002 and prior to its initial public offering (“IPO”) in May 2016, the Company built its technology platform and product candidate pipeline, ~~using a semi-virtual business model,~~ supported by grants and ~~direct funding from the United States National Institutes of Health (“NIH”) as well as~~ through private financings. In September 2015, the Company formed a wholly owned subsidiary, Sperovie Biosciences, Inc., and in December 2016, the Company formed a wholly owned subsidiary, SBP Securities Corporation.

The Company’s success is dependent upon its ability to successfully complete clinical development and obtain regulatory approval of its product candidates, successfully commercialize approved products, generate revenue, and, ultimately, attain profitable operations. The Company’s operations to date have been primarily limited to ~~financing and staffing the Company and~~ the development of inarigivir, SB 11285, SB 9225 and the Company’s other product candidates.

The accompanying consolidated financial statements have been prepared in accordance with United States (“U.S.”) generally accepted accounting principles (“U.S. GAAP”).

Prior to and in connection with the Company completing its IPO in May 2016, the Company effected a 1-for-4 reverse stock split of its common stock on March 8, 2016. All share and per share amounts and the number of shares of common stock set forth in the financial statements and notes thereto have been retroactively adjusted for all periods presented to give effect to the reverse stock split, including reclassifying an amount equal to the reduction in par value of common stock to additional paid-in capital.

The accompanying interim financial statements as of ~~September 30, 2017~~March 31, 2019 and for the ~~nine~~three months ended ~~September 30, 2017~~March 31, 2019 and ~~2016,~~2018, and related interim information contained within the notes to the financial statements, are unaudited. In management’s opinion, the unaudited interim consolidated financial statements have been prepared on the same basis as the Company’s audited financial statements and include all adjustments (including normal recurring adjustments) necessary for the fair presentation of the Company’s financial position as of ~~September 30, 2017,~~March 31, 2019, results of operations for the ~~nine~~three months ended ~~September 30, 2017~~March 31, 2019 and ~~2016,~~2018, and its cash flows for the ~~nine~~three months ended ~~September 30, 2017~~March 31, 2019 and ~~2016.~~2018. These interim financial statements should be read in conjunction with the Company’s audited financial statements and accompanying notes contained in the Company’s Annual Report on Form 10-K for the year ended December 31, ~~2016,~~2018, as filed with the Securities and Exchange Commission (“SEC”) on ~~February 14, 2017.~~March 11, 2019. The results for the three ~~and nine~~ months ended ~~September 30, 2017~~March 31, 2019 are not necessarily indicative of the results expected for the full fiscal year or any interim period.

As of ~~September 30, 2017,~~March 31, 2019, the Company had an accumulated deficit of ~~$77.8~~$107.3 million and ~~$52.2~~$57.5 million in cash, cash equivalents and marketable securities.

The Company expects to continue to incur significant and increasing losses for the foreseeable future. The Company anticipates that its expenses will increase significantly as it continues to develop inarigivir, SB 11285, SB 9225 and its other product candidates. The Company does not have any committed external source of funds. As a result, the Company will need additional financing to support its continuing operations. Adequate additional funds may not be available to the Company on acceptable terms, or at all. To the extent that the Company raises additional capital through the sale of equity or convertible debt securities, stockholders’ ownership interests will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect common stockholder rights. If the Company raises additional funds through collaborations, strategic alliances or licensing arrangements with third parties, the Company may have to relinquish valuable rights to its technologies, future revenue streams, research programs, or product candidates or grant licenses on terms that may not be favorable to the Company.

The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries, Sperovie Biosciences, Inc. and SBP Securities Corporation. Sperovie Biosciences, Inc. had operations consisting mainly of legal fees associated with intellectual property activities as of ~~September 30, 2017.~~March 31, 2019. SBP Securities Corporation had assets primarily related to investments in marketable securities and operations consisting primarily of interest income as of ~~September 30, 2017.~~March 31, 2019. All intercompany balances and transactions have been eliminated in consolidation.

The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. The Company bases estimates and assumptions on historical experience when available and on various factors that it believes to be reasonable under the circumstances. Significant estimates relied upon in preparing the accompanying financial statements related to the fair value of common stock and warrant liabilities, accounting for stock-based compensation, income taxes, useful lives of long-lived assets, and accounting for certain accruals. The Company evaluates its estimates and assumptions on an ongoing basis. The Company’s actual results may differ from these estimates.

Cash equivalents are stated at fair value and include short-term, highly liquid investments with remaining maturities of 90 days or less at the date of purchase.

~~Restricted cash consists of $250,000 and is held as collateral for the Company’s credit card program. There were no restricted cash as of December 31, 2016.~~

Included in cash and cash equivalents as of ~~September 30, 2017~~March 31, 2019 and December 31, ~~2016~~2018 are money market fund investments of ~~$15,164,000~~$15.4 million and ~~$9,507,000,~~$13.3 million, respectively, which are reported at fair value (Note 5).

As of March 31, 2019 and December 31, 2018, restricted cash consists of approximately $234,000, which is held as a security deposit required in conjunction with a lease agreement entered into in October 2017.

Financial instruments that subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents, restricted cash and marketable securities. Substantially all of the Company’s cash is held at financial institutions that management believes to be of ~~high-credit~~high credit quality. Deposits with these financial institutions may exceed the amount of insurance provided on such deposits; however, these deposits may be redeemed upon demand and, therefore, bear minimal risk.

The Company’s one source of revenue during the three and nine months ended September 30, 2016 was grants from the NIH, representing 100% of total revenue for such periods. The Company did not have any sources of revenue for the three and nine months ended September 30, 2017.

The Company invests excess cash balances in short-term and long-term marketable securities. The Company classifies investments in marketable securities as either held-to-maturity or available-for-sale based on facts and circumstances present at the time of purchase. At each balance sheet date presented, all investments in securities are classified as available-for-sale. The Company reports available-for-sale investments at fair value at each balance sheet date and includes any unrealized holding gains and losses (the adjustment to fair value) in accumulated other comprehensive income (loss), a component of stockholders’ equity. Realized gains and losses are determined using the specific identification method and are included in other income (expense). If any adjustment to fair value reflects a decline in the value of the investment, the Company considers all available evidence to evaluate the extent to which the decline is “other than temporary,” including the intention to sell and, if so, marks the investment to market through a charge to the Company’s consolidated statements of operations and comprehensive loss.

Property and equipment are recorded at cost. Costs associated with maintenance and repairs are expensed as incurred. Depreciation ~~and amortization are~~is provided using the straight-line method over the estimated useful lives:

The Company determines if an arrangement is a lease at inception. Operating leases are included in operating lease right-of-use (“ROU”) assets, other current liabilities and operating lease liabilities in the Company’s consolidated balance sheets.

ROU assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent its obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at commencement date based

on the present value of lease payments over the lease term. As the Company’s leases do not provide an implicit rate, the Company uses an incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. This is the rate the Company would have to pay if borrowing on a collateralized basis over a similar term to each lease. The operating lease ROU asset also includes any lease payments made and excludes lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term.

Long-lived assets to be held and used are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the asset may not be recoverable. When such events occur, the Company compares the carrying amounts of the assets to their undiscounted expected future cash flows. If the undiscounted cash flows are insufficient to recover the carrying value, an impairment loss is recorded for the difference between the carrying value and fair value of the asset. Through ~~September 30, 2017,~~March 31, 2019, no such impairment has occurred.

The Company’s operating leases include rent escalation payment terms and other incentives received from landlords. Deferred rent represents the difference between actual operating lease payments due and straight-line rent expense over the term of the lease, which is recorded in accrued expenses and other current liabilities. The Company had deferred aggregate rent for its research and development facility in Milford, Massachusetts and its headquarters in Hopkinton, Massachusetts of $35,000 and $35,000 as of September 30, 2017 and December 31, 2016, respectively.

The Company recognizes revenue when all of the following criteria are met: there is persuasive evidence of an arrangement, the fee is fixed or determinable, delivery has occurred or services have been rendered and collection of the related receivable is reasonably assured. Generally, these criteria were met and revenue from grants from the NIH, which subsidized certain of the Company’s research projects, as efforts were expended and as eligible project costs were incurred.

Research and development expenses consist primarily of costs incurred for the Company’s research activities, including discovery efforts, and the development of product candidates, which include:

The Company expenses research and development costs as incurred. The Company recognizes external development costs based on an evaluation of the progress to completion of specific tasks using information provided to the Company by its vendors and its clinical investigative sites. Payments for these activities are based on the terms of the individual agreements, which may differ from the pattern of costs incurred, and are reflected in the Company’s consolidated financial statements as prepaid or accrued research and development expenses.

The Company reviews the terms of all warrants issued and classifies the warrants as a component of permanent equity if they are freestanding financial instruments that are legally detachable and separately exercisable, contingently exercisable, do not embody an obligation for the Company to repurchase its own shares, and permit the holders to receive a fixed number of shares of common stock upon exercise. In addition, the warrants must require physical settlement and may not provide any guarantee of value or return. Warrants that meet these criteria are initially recorded at their grant date fair value and are not subsequently remeasured. Warrants that do not meet this criteria are classified as liabilities and remeasured to their fair value at each reporting period.

The Company’s stock-based payments include stock options, performance-based restricted stock units and grants of common stock, including common stock subject to vesting. The Company accounts for all stock-based payment awards granted to employees and nonemployees using a fair value method. ~~The Company’s stock-based payments include stock options and grants of common stock, including common stock subject to vesting.~~ The measurement date for employee awards is the date of grant, and stock-based compensation costs are recognized as expense over the employees’ requisite service period, which is generally the vesting period, on a straight-line basis. The ~~measurement date for nonemployee awards is the date the services are completed, resulting in periodic adjustments to stock-based compensation during the vesting period for changes in~~Company measures the fair value of the ~~awards. Stock-based compensation costs for nonemployees are recognized as expense over~~performance-based restricted stock units relating to the ~~vesting period on~~total share return performance using a ~~straight-line basis.~~Monte Carlo valuation model. The Company adopted ASU 2018-07, Improvements to Nonemployee Share-Based Payment Accounting, effective July 1, 2018, which aligns the accounting treatment of nonemployee awards with

employee awards. Stock-based compensation expense is classified in the accompanying consolidated statements of operations and comprehensive loss based on the department to which the related services are provided.

The Company’s financial instruments consist of cash equivalents, marketable securities, accounts payable and liability classified warrants. The carrying amounts of cash and cash equivalents and accounts payable approximate their fair value due to the short-term nature of those financial instruments. The fair value of the marketable securities and liability classified warrants are remeasured to fair value each reporting period as described in Note 5.

The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. Accounting Standards Codification (“ASC”) 820, Fair Value Measurements and Disclosures (“ASC 820”), establishes a hierarchy of inputs used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the asset or liability and are developed based on the best information available in the circumstances. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of the investment credit quality. The three levels of the fair value hierarchy are described below:

Level 1—Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.

Level 2—Valuations based on quoted prices for similar assets or liabilities in markets that are not active or for which all significant inputs are observable, either directly or indirectly.

Level 3—Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and unobservable.

To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The Company’s assets and liabilities measured at fair value on a recurring basis include cash equivalents, marketable securities and warrant liabilities.

Basic net loss per share is computed by dividing the net loss by the weighted-average number of shares of common stock outstanding for the period. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of shares of common stock and dilutive common stock equivalents outstanding for the period, determined using the treasury-stock method and the as if-converted method, for convertible securities, if inclusion of these instruments is dilutive. ~~As of September 30, 2017~~For the three months ended March 31, 2019 and ~~December 31, 2016,~~2018, both methods are equivalent. ~~Common stock, preferred stock~~Basic and ~~warrant issuances are~~diluted net loss per share is described further in Note 7.2.

Deferred tax assets and liabilities are determined based upon the differences between the financial statement carrying amounts and the tax basis of existing assets and liabilities and for loss and credit carryforwards using enacted tax rates expected to be in effect in the years in which the differences are expected to reverse. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that some portion or all of the deferred tax asset will not be realized.

The Company assesses its income tax positions and records tax benefits based upon management’s evaluation of the facts, circumstances and information available at the reporting date. For those tax positions where it is more likely than not that a tax benefit will be sustained, the Company records the largest amount of tax benefit with a greater than 50% likelihood of being realized upon ultimate settlement with a taxing authority having full knowledge of all relevant information. For those income tax positions where it is not more likely than not that a tax benefit will be sustained, no tax benefit is recognized in the consolidated financial statements. The Company classifies interest and penalties associated with such uncertain tax positions as a component of interest expense. As of ~~September 30, 2017~~March 31, 2019 and December 31, ~~2016,~~2018, the Company has not identified any material uncertain tax positions.

As permitted under Delaware law, the Company indemnifies its officers and directors for certain events or occurrences while the officer or director is, or was, serving at the Company’s request in such capacity.

The Company leases office and laboratory space in Hopkinton, Massachusetts and previously leased research and development space in Milford, Massachusetts under non-cancelable operating leases. The Company has standard indemnification arrangements under these leases that require it to indemnify the landlords against liability for injury, loss, accident, or damage from any claims, actions, proceedings, or costs resulting from certain acts, breaches, violations, or nonperformance under the Company’s lease.

Through ~~September 30, 2017,~~March 31, 2019, the Company had not experienced any losses related to these indemnification obligations and no material claims were outstanding. The Company does not expect significant claims related to these indemnification obligations, and consequently, concluded that the fair value of these obligations is negligible, and no related reserves were established.

Operating segments are identified as components of an enterprise about which separate and discrete financial information is available for evaluation by the chief operating decision maker, the Company’s chief executive officer, in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business in one operating segment and does not track expenses on a program-by-program basis.

In ~~November 2016,~~August 2018, the ~~Financial Accounting Standards Board (“FASB”)~~FASB issued ~~Accounting Standards Update (“ASU”) 2016-18,~~ASU 2018-13, ~~Statement~~Fair Value Measurement (Topic 820), Disclosure Framework – Changes to the Disclosure Requirement for Fair Value Measurement. This ASU removes, modifies and adds certain disclosure requirements of ~~Cash Flows (Topic 230): Restricted Cash~~, which includes provisions intended to clarify how entities present restricted cash and restricted cash equivalents in the statement of cash flows. Companies must show the change in total cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows.ASC Topic 820. The ~~new standard is applied retrospectively and~~ASU is effective for ~~our annual periods beginning after December 15, 2017,~~all entities for fiscal years, and ~~for~~ interim periods within those annual periods, with early adoption permitted. The Company elected early adoption of this standard as of September 30, 2017, the first period in which the Company had restricted cash. The adoption of this standard has resulted in the presentation of the change in cash, cash equivalents and restricted cash on the statement of cash flows in the periods presented.

~~In March 2016, the FASB issued ASU 2016-09,~~ ~~Compensation – Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting~~ (“ASU 2016-09”) to require changes to several areas of employee stock-based compensation payment accounting in an effort to simplify stock-based compensation reporting. The update revises requirements in the following areas: minimum statutory withholding, accounting for income taxes, forfeitures, and intrinsic value accounting for private entities. ASU 2016-09 is effective for annual reporting periodsfiscal years, beginning after December 15, 2016, including interim reporting periods within each annual reporting period. The Company adopted this standard on January 1, 2017. The update revises requirements in the following areas: minimum statutory withholding, accounting for income taxes, and forfeitures. Prior to adoption, the Company applied a 0% forfeiture rate to stock-based compensation, resulting in no cumulative effect adjustment to the opening period. Upon adoption of this standard, the Company’s accounting policy is to recognize forfeitures as they occur.

The update requires the Company to recognize the income tax effect of awards in the income statement when the awards vest or are settled. It also allows the Company to repurchase more of an employee’s shares than it could prior to the update for tax withholding purposes without triggering a liability. The income tax related items had no effect on the current period presentation and the Company maintains a full valuation allowance against its deferred tax assets.

~~In May 2014, the FASB issued ASU No. 2014-09,~~ ~~Revenue from Contracts with Customers~~ (Topic 606) (“ASC 606”), which amends the guidance for revenue recognition to replace numerous industry-specific requirements. ASC 606 implements a five-step process for customer contract revenue recognition that focuses on transfer of control, as opposed to transfer of risk and rewards. ASC 606 also requires enhanced disclosures regarding the nature, amount, timing, and uncertainty of revenues and cash flows from contracts with customers. Other major provisions include ensuring the time value of money is considered in the transaction price, and allowing estimates of variable consideration to be recognized before contingencies are resolved in certain circumstances. The amendments in ASC 606 are effective for reporting periods beginning after December 15, 2016, and early adoption is not permitted. In July 2015, the FASB approved the deferral of adoption by one year. Entities can transition to the standard either retrospectively or as a cumulative-effect adjustment as of the date of adoption. Until the Company expects material revenue to be recognized, the adoption of this standard is not expected to have an impact on the Company’s consolidated financial statements.

~~In January 2016, the FASB issued ASU 2016-01,~~ ~~Recognition and Measurement of Financial Assets and Financial Liabilities, which amends ASC Subtopic 825-10,~~ ~~Financial Instruments - Overall~~, and includes updates on certain aspects of recognition, measurement, presentation and disclosure of financial instruments and applies to all entities that hold financial assets or owe financial liabilities. The new standard is effective for the Company for the annual period beginning after December 15, 2017, with early adoption permitted.31, 2019. The Company is currently evaluating the impact that the adoption of this standard may have on ~~its~~the Company’s consolidated financial statements.

In February 2016, the FASB issued ASU No. 2016-02, Leases (“ASU 2016-02”). ASU 2016-02 ~~Leases (Topic 842), which supersedes the current leasing guidance and upon adoption, will require~~requires lessees to recognize ~~right-of-use assets and lease liabilities~~most leases on ~~the~~their balance sheet ~~for all leases with terms longer than 12 months.~~as a right-of-use asset and a lease liability. Leases are classified as either operating or finance, and classification is based on criteria similar to current lease accounting, but without explicit bright lines. In July 2018, the FASB issued ASU No. 2018-10, “Codification Improvements to Topic 842, Leases” (“ASU 2018-10”), which provides narrow amendments to clarify how to apply certain aspects of the new lease standard, and ASU No. 2018-11, “Leases (Topic 842) – Targeted Improvements” (ASU 2018-11), which addresses implementation issues related to the new lease standard. The ~~new standard~~guidance is effective for ~~the Company for the~~ annual ~~period~~reporting periods beginning after December 15, 2018 and ~~can be~~interim periods within those fiscal years, and early ~~adopted by applying a modified retrospective approach for leases existing~~adoption is permitted. Under this standard, disclosures are required to enable users of financial statements in assessing the amount, timing, and uncertainty of cash flows arising from leases. The standard permits two transition methods, (1) to apply the new lease requirements at ~~and entered into after,~~ the beginning of the earliest ~~comparable~~ period presented, inor (2) to apply the ~~financial statements.~~ new lease requirements at the effective date. Under both transition methods there is a cumulative effect adjustment.

The Company ~~is currently evaluating~~adopted the standard on the effective date of January 1, 2019 by applying the new lease requirements at the effective date. Prior periods continue to be presented based on the accounting standards originally in effect for such periods. The Company also elected the package of practical expedients permitted under the transition guidance within the new standard, which, among other things, allows the Company to carry forward the historical lease classification. The Company will also apply the practical expedient not to separate lease and non-lease components for new and modified leases commencing after adoption. The standard had an impact ~~that~~of approximately $3.0 million on the ~~adoption of this standard may have~~Company’s assets and $3.4 million on its ~~consolidated financial statements.~~

~~In September 2016, the FASB issued ASU 2016-15,~~ ~~Classification~~liabilities, as of ~~Certain Cash Receipts and Cash Payments, which amends ASC Topic 230,~~ ~~Statement of Cash Flows, and includes provisions intended to reduce diversity in practice and provides guidance on eight specific statements of cash flows classification issues. The new standard is effective~~January 1, 2019, for the ~~Company for~~recognition of right-of-use assets and lease liabilities, which are primarily related to the ~~annual period ending after December 15, 2017, and for annual and interim periods thereafter, with early adoption permitted.~~lease of its corporate headquarters in Hopkinton, Massachusetts. The ~~Company is currently evaluating~~standard did not have a material impact on the ~~impact that the adoption~~Company’s results of ~~this standard may have on its consolidated financial statements.~~operations or liquidity.

In July 2017, the FASB issued ASU 2017-11, Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480), Derivatives and Hedging (Topic 815): I. Accounting for Certain Financial Instruments with Down Round Features and II. Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception. Part I applies to entities that issue financial instruments such as warrants, convertible debt or convertible preferred stock that contain down round features. Part II simply replaces the indefinite deferral for certain mandatorily redeemable noncontrolling interests and mandatorily redeemable financial instruments of nonpublic entities contained within Accounting Standards Codification (ASC) Topic 480 with a scope exception and does not impact the accounting for these mandatorily redeemable instruments. This ASU is effective for public companies for the annual reporting periods beginning after December 15, 2018, and interim periods within those annual periods. Early adoption is permitted. The

Company ~~is currently evaluating the impact that~~adopted this standard as of January 1, 2019; however, the adoption of this standard ~~may have on its~~did not impact the Company’s consolidated financial statements.

The following table summarizes the computation of basic and diluted net loss per share of the Company for such periods (in thousands, except share and per share data):

Diluted net loss per common share is the same as basic net loss per common share for all periods presented.

The following potentially dilutive securities outstanding, prior to the use of the treasury stock method or if-converted method, have been excluded from the computation of diluted weighted-average shares outstanding, because such securities had an antidilutive impact due to the losses reported:

	For the Three and Nine Months Ended September 30,				For the Three Months Ended March 31,
	2017		2016		2019		2018
Common stock warrants		1,798,084		153,347		1,662,124		1,787,124
Stock options		977,565		718,065
Stock options, RSUs and Inducement awards						1,919,765		1,261,065

Cash in excess of the Company’s immediate requirements is invested in accordance with the Company’s investment policy that primarily seeks to maintain adequate liquidity and preserve capital.

The following table summarizes the Company’s investments, by category, as of ~~September 30, 2017~~March 31, 2019 and December 31, ~~2016~~2018 (in thousands):

	September 30,			December 31,		March 31,		December 31,
Investments - Current:	2017			2016		2019		2018
Debt securities - available for sale	$	34,640		$	14,046	$	29,857	$	32,914
Total	$	34,640		$	14,046	$	29,857	$	32,914
			��
Investments - Noncurrent:
Debt securities - available for sale	$	—		$	752	$	10,873	$	16,804
Total	$	—		$	752	$	10,873	$	16,804

A summary of the Company’s available-for-sale classified investments as of March 31, 2019 and December 31, 2018 consisted of the following (in thousands):

	At September 30, 2017									At March 31, 2019
	Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value		Cost Basis		Accumulated Unrealized Gains		Accumulated Unrealized Losses			Fair Value
Investments - Current:
Commercial paper	$	14,345	$	—	$	—		$	14,345
Corporate bonds										$	10,063	$	—	$	(30	)	$	10,033
United States treasury securities											19,896		—		(72	)		19,824
Total										$	29,959	$	—	$	(102	)	$	29,857

Investments - Noncurrent:
Corporate bonds		18,309		—		(7	)		18,302	$	4,968	$	—		(13	)	$	4,955
United States treasury securities		1,993		—		—			1,993		5,924		—		(6	)		5,918
Total	$	34,647	$	—	$	(7	)	$	34,640	$	10,892	$	—	$	(19	)	$	10,873

	At December 31, 2016									At December 31, 2018
	Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value		Cost Basis		Accumulated Unrealized Gains		Accumulated Unrealized Losses			Fair Value
Investments - Current:
Agency bonds	$	452	$	—	$	—		$	452
Commercial paper		2,947		—		—			2,947
Corporate bonds		8,499		—		(7	)		8,492	$	16,028	$	—	$	(19	)	$	16,009
United States treasury securities		2,155		—		—			2,155		16,913		—		(8	)		16,905
Total	$	14,053	$	—	$	(7	)	$	14,046	$	32,941	$	—	$	(27	)	$	32,914

Investments - Noncurrent:
Corporate bonds		752		—		—			752	$	4,930	$	2	$	—		$	4,932
United States treasury securities											11,852		20		—			11,872
Total	$	752	$	—	$	—		$	752	$	16,782	$	22	$	—		$	16,804

The amortized cost and fair value of the Company’s available-for-sale investments, by contract maturity, as of ~~September 30, 2017~~March 31, 2019 consisted of the following (in thousands):

	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Due in one year or less	$	34,647	$	34,640	$	29,959	$	29,857
Due after one year through two years		—		—		10,892		10,873
Total	$	34,647	$	34,640	$	40,851	$	40,730

Property and equipment as of ~~September 30, 2017~~March 31, 2019 and December 31, ~~2016~~2018 consisted of the following (in thousands):

	September 30,			December 31,			March 31,			December 31,
	2017			2016			2019			2018
Equipment	$	683		$	576		$	1,152		$	1,064
Furniture and fixtures		144			140			377			400
Leasehold improvements		149			133			1,353			1,347
Total property and equipment		976			849			2,882			2,811
Less: accumulated depreciation and amortization		(442	)		(327	)		(575	)		(492	)
Property and equipment, net	$	534		$	522		$	2,307		$	2,319

Depreciation ~~and amortization~~ expense for the three ~~and nine~~ months ended ~~September 30, 2017~~March 31, 2019 and 2018 was ~~$39,000~~$83,000 and ~~$115,000,~~$45,000, respectively. ~~Depreciation and amortization expense for the three and nine months ended September 30, 2016 was $30,000 and $87,000, respectively.~~

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value are performed in a manner to maximize the use of observable inputs and minimize the use of unobservable inputs.

The Company classified its money market funds and United States treasury securities within Level 1 because their fair values are based on their quoted market prices. The Company classified its commercial paper and ~~fixed income securities~~corporate bonds within Level 2 because their fair values are determined using alternative pricing sources or models that utilized market observable inputs.

A summary of the assets and liabilities that are measured at fair value as of ~~September 30, 2017~~March 31, 2019 and December 31, ~~2016~~2018 is as follows (in thousands):

			Fair Value Measurement at September 30, 2017
	Carrying Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)				Fair Value Measurement at March 31, 2019
Assets:									Carrying Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Money market funds ⁽¹⁾	$	15,164	$	15,164	$	—	$	—	$	15,380	$	15,380	$	—	$	—
Fixed income securities		34,640		—		34,640		—		40,730		—		40,730		—
Total	$	49,804	$	15,164	$	34,640	$	—	$	56,110	$	15,380	$	40,730	$	—

Liabilities:
Warrant liabilities	$	17,807	$	—	$	—	$	17,807	$	5,690	$	—	$	—	$	5,690
Total	$	17,807	$	—	$	—	$	17,807	$	5,690	$	—	$	—	$	5,690

			Fair Value Measurement at December 31, 2016								Fair Value Measurement at December 31, 2018
Assets:	Carrying Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Carrying Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Money market funds ⁽¹⁾	$	9,507	$	9,507	$	—	$	—	$	13,264	$	13,264	$	—	$	—
Fixed income securities		14,798		—		14,798		—		49,718		—		49,718		—
Total	$	24,305	$	9,507	$	14,798	$	—	$	62,982	$	13,264	$	49,718	$	—

Liabilities:
Warrant liabilities	$	6,333	$	—	$	—	$	6,333	$	8,511	$	—	$	—	$	8,511
Total	$	6,333	$	—	$	—	$	6,333	$	8,511	$	—	$	—	$	8,511

The following table reflects the change in the Company’s Level 3 liabilities, which consists of the warrants issued in a private placement in November 2016 (see Note 7), for the period ended ~~September 30, 2017~~March 31, 2019 (in thousands):

Accrued expenses as of ~~September 30, 2017~~March 31, 2019 and December 31, ~~2016~~2018 consisted of the following (in thousands):

	September 30,		December 31,		March 31,		December 31,
	2017		2016		2019		2018
Clinical	$	1,159	$	738	$	960	$	941
Compensation and benefits		750		901		424		830
Accounting and legal		281		279		223		227
Other		122		64		86		369
Total accrued expenses	$	2,312	$	1,982
Total accrued expenses and other current liabilities					$	1,693	$	2,367

Effective February 1, 2016, the Company amended and restated its license agreement with BioHEP Technologies Ltd. (“BioHEP”). In connection with the amendment and restatement, the Company issued 125,000 shares of its common stock to BioHEP and granted to BioHEP a warrant to purchase an additional 125,000 shares of its common stock at an exercise price of $16.00 per share, which warrant will expire on August 1, 2018. The fair value of the common stock as of the date of issuance, $2.0 million, was expensed as research and development costs.

In May 2016, the Company issued and sold in its IPO an aggregate of 944,900 shares of its common stock at $12.00 per share, which included 24,900 shares that represented the exercise of an option to purchase additional shares granted to the underwriters in connection with the IPO. The offering resulted in $8.2 million of net proceeds to the Company, after deducting underwriting discounts and commissions and other offering expenses payable by the Company. Upon the closing of the Company’s IPO, the Company filed an amended and restated certificate of incorporation, which authorized the Company to issue 200,000,000 shares of common stock and 10,000,000 shares of preferred stock. In connection with the closing of the IPO, the Company received approximately $5.3 million in proceeds upon the exercise of previously issued warrants to purchase 641,743 shares of common stock of the Company.

~~Upon the closing of the Company’s IPO, all outstanding shares of the Company’s preferred stock automatically converted into 250,000 shares of the Company’s common stock.~~

In November 2016, the Company entered into a definitive agreement with respect to the private placement of 1,644,737 shares of common stock and warrants to purchase 1,644,737 shares of common stock (the “November Private Placement Warrants”) to a group of accredited investors (the “November Private Placement”). These investors paid $9.12 for each share of common stock and warrant to purchase one share of common stock. The November Private Placement Warrants are exercisable at an exercise price of $10.79 per share and expire on November 23, 2021. The Company completed the November Private Placement on November 23, 2016, resulting in $13.7 million in net proceeds to the Company, after deducting placement agent fees and other offering expenses payable by the Company.

In June 2017, the Company issued and sold in an underwritten public offering an aggregate of 3,269,219 shares of its common stock at $13.00 per share, which included 384,604 shares pursuant to the exercise of an option to purchase additional shares granted to the underwriters in connection with the offering. The offering resulted in ~~$39.6~~$39.7 million of net proceeds to the Company, after deducting underwriting discounts and commissions and other offering expenses payable by the Company.

In August 2017, the Company entered into a Controlled Equity Offering^SMSales Agreement (the “Sales Agreement”) with Cantor Fitzgerald & Co. (“Cantor”), pursuant to which the Company may offer and sell, from time to time through Cantor, shares of the Company’s common stock having an aggregate offering price of up to $50.0 million. The Company ~~will pay~~pays Cantor a commission rate equal to 3.0% of the aggregate gross proceeds from each sale. During the three months ended March 31, 2019, the Company made no sales under the Sales Agreement. During the year ended December 31, 2018, the Company sold an aggregate of 217,329 shares of its common stock pursuant to the Sales Agreement at a weighted-average selling price of $15.42 per share, which resulted in $3.2 million of net proceeds to the Company.

In August 2018, the Company issued and sold in an underwritten public offering an aggregate of 3,246,079 shares of its common stock at $12.50 per share, which included 246,079 shares pursuant to the exercise of an option to purchase additional shares granted to the underwriters in connection with the offering. The offering resulted in $38.0 million of net proceeds, after deducting underwriting discounts and commissions and other offering expenses payable by the Company.

In connection with the amendment and restatement of a license agreement with BioHEP in February 2016, the Company issued a warrant to purchase 125,000 shares of the Company’s common stock to BioHEP (the “BioHEP Warrant”)~~, effective February~~. The BioHEP Warrant had an exercise price of $16.00 per share and expired unexercised on August 1, ~~2016.~~2018. The Company evaluated the terms of the warrant and concluded that it should be equity-classified. The fair value of the warrant, $0.8 million, was estimated on the issuance date using a ~~Black Scholes~~Black-Scholes pricing model based on the following assumptions: an expected term of two and a half years, expected stock price volatility of 71%, a ~~risk free~~risk-free rate of 1.01%, and a dividend yield of 0%. The fair value was expensed as research and development costs.

In connection with the Company’s IPO, the Company issued to the sole book-running manager for the IPO a warrant to purchase 27,600 shares of common stock in May 2016 and a warrant to purchase 747 shares of common stock in June 2016 (together, the “IPO Warrants”). The IPO Warrants are exercisable at an exercise price of $15.00 per share and expire on May 5, 2021. The Company evaluated the terms of the IPO Warrants and concluded that they should be equity-classified. The fair value of the May 2016 IPO Warrants was estimated on the applicable issuance dates using a ~~Black Scholes~~Black-Scholes pricing model based on the following assumptions: an expected term of 4.99 years; expected stock price volatility of 87%; a ~~risk free~~risk-free rate of 1.20%; and a dividend yield of 0%. The fair value of the June 2016 IPO Warrants was estimated on the applicable issuance dates using a ~~Black Scholes~~Black-Scholes pricing model based on the following assumptions: an expected term of 4.92 years; expected stock price volatility of 87%; a ~~risk free~~risk-free rate of 1.23%; and a dividend yield of 0%. The aggregate fair value of the IPO Warrants was approximately $0.2 million.

~~The~~In November 2016, the Company ~~received approximately $5.3 million in proceeds upon~~entered into a definitive agreement with respect to the ~~exercise~~private placement of ~~warrants to purchase 641,743~~1,644,737 shares of ~~its~~ common stock ~~of the Company, which were exercised in connection with the closing of the IPO. Upon the closing of the Company’s IPO, all of the outstanding~~and warrants ~~that were not exercised, except the BioHEP warrant and the IPO Warrants, terminated in accordance with their original terms.~~

~~In connection with the November Private Placement, the Company issued the November Private Placement Warrants~~ to purchase 1,644,737 shares of common stock ~~in November~~(the “November 2016 Private Placement Warrants”) to a group of accredited investors. These investors paid $9.12 for each share of common stock and warrant to purchase one share of common stock. The November 2016 Private Placement Warrants are exercisable at an exercise price of $10.79 per share and expire on November 23, 2021. The Company evaluated the terms of these warrants and concluded that they are liability-classified. In November 2016, the Company recorded the fair value of these warrants of approximately $8.3 million using a ~~Black Scholes~~Black-Scholes pricing model. The

Company must recognize any change in the value of the warrant liability each reporting period in the statement of operations. As of March 31, 2019 and December 31, ~~2016 and September 30, 2017,~~2018, the fair value of the November 2016 Private Placement Warrants was approximately ~~$6.3~~$5.7 million and ~~$17.8~~$8.5 million, respectively (see Note 5).

A summary of the ~~Black Scholes~~Black-Scholes pricing model assumptions used to record the fair value of the warrants is as follows:

~~The following table summarizes~~A summary of the warrant activity for the three months ended March 31, 2019 and for the year ended December 31, ~~2016 and for the nine months ended September 30, 2017:~~

In April 2014, the Company’s Board of Directors approved the 2014 Stock Incentive Plan (the “2014 Plan”). and authorized 750,000 shares of common stock to be issued under the 2014 Plan. The Company’s 2014 Plan provides for the issuance of common stock, stock options and other stock-based awards to employees, officers, directors, consultants, and advisors. ~~As of September 30, 2017, the Board had authorized 750,000 shares of common stock to be issued under the 2014 Plan.~~ The Company’s 2015 Stock Incentive Plan (the “2015 Plan”) became effective immediately prior to the closing of the Company’s IPO on May 11, 2016. Upon the effectiveness of the 2015 Plan, 116,863 shares of common stock that remained available for grant under the 2014 Plan became available for grant under the 2015 Plan, and no further awards were available to be issued under the 2014 Plan.

The Company’s Board of Directors initially adopted the 2015 Plan in December 2015, subject to stockholder approval, and authorized 750,000 shares of Common Stock to be issues und ether 2015 Plan. The 2015 Plan became effective upon the closing of the Company’s IPO on May 11, 2016 after approval by the Company’s stockholders. The 2015 Plan provides for the issuance of common stock, stock options and other stock-based awards to employees, officers, directors, consultants and advisors of the Company. ~~The number~~

In June 2018, upon receipt of ~~shares reserved for issuance under~~stockholder approval at the Company’s 2018 annual meeting, the 2015 Plan iswas amended and restated in its entirety increasing the sum of 750,000 shares of common stock, plus the number of shares equal to the sum of (i) 116,863 shares of common stock, which was the number of shares reserved for issuance under the 2014 Plan that remained available for grant under the 2014 Plan immediately prior to the closing of the Company’s IPO, and (ii) theauthorized number of shares of common stock ~~subject~~reserved for issuance by 800,000 shares (together with the 2014 Plan, the 2015 Plan, the “Stock Incentive Plans”). The Board approved the Amended and Restated 2015 Plan on March 9, 2018. Pursuant to the Amended and Restated 2015 Plan, there are 1,666,863 shares authorized for issuance. In addition, to the extent any outstanding awards under the 2014 Plan ~~that~~ expire, terminate or are otherwise surrendered, cancelled or ~~forfeited.~~ forfeited after the closing of the Company’s IPO, those shares are added to the authorized shares under the Amended and Restated 2015 Plan. The total amount of shares authorized for issuance under both the 2014 Plan and the Amended and Restated 2015 Plan is 2,300,000. As of March 31, 2019, the Company had 401,204 shares available for issuance under the Amended and Restated 2015 Plan.

The exercise price of stock options cannot be less than the fair value of the common stock on the date of grant. Stock options awarded under the ~~2015 Plan~~Stock Incentive Plans expire 10 years after the grant date, unless the Board sets a shorter term. ~~As of September 30, 2017, the Company had 472,087 shares available for issuance under the 2015 Plan.~~There were no stock options granted prior to 2015.

The following table summarizes the option activity under the Stock Incentive Plans for the ~~nine~~three months ended ~~September 30, 2017, under the 2014 Plan~~March 31, 2019 and the ~~2015 Plan (collectively the “Plans”):~~

	Options			Weighted-Average Exercise Price Per Share		Aggregate Intrinsic Value		Options			Weighted-Average Exercise Price Per Share		Aggregate Intrinsic Value
Options outstanding at December 31, 2015		610,481		$	11.99	$	—
Options outstanding at December 31, 2017									988,565		$	10.83	$	2,617,859
Granted		128,334			10.41		—		311,000			12.28		—
Exercised		(10,247	)		9.28		29,550		—			—		—
Cancelled		(24,253	)		9.89		—		—			—		—
Outstanding at December 31, 2016		704,315		$	11.82		—
Outstanding at December 31, 2018									1,299,565			11.18		881,385
Granted		286,500			8.20		—		343,000			10.37		—
Exercised		(10,000	)		9.28		11,228		—			—		—
Cancelled		(3,250	)		12.44		—		(16,500	)		14.78		—
Options outstanding at September 30, 2017		977,565		$	10.78	$	5,923,320
Options exercisable at September 30, 2017		390,417		$	11.67	$	2,019,924
Options outstanding at March 31, 2019									1,626,065		$	10.97	$	969,205
Options exercisable at March 31, 2019									877,941		$	11.27	$	576,923

As of ~~September 30, 2017,~~March 31, 2019, all options ~~granted are expected to vest and the~~outstanding have a weighted-average remaining contractual life of ~~all options is 8.4~~7.9 years. The weighted-average fair value of all stock options granted for the ~~nine~~three months ended ~~September 30, 2017~~March 31, 2019 was ~~$5.67.~~$7.30. Intrinsic value at ~~September 30, 2017~~March 31, 2019 and December 31, 2018 is based on the closing price of the Company’s common stock on that date of ~~$16.84~~$10.49 per ~~share.~~share and $10.39 per share, respectively.

~~Prior to~~In January 2018, the ~~Company’s IPO on May 11, 2016,~~Company issued a stock option award as an inducement grant for the ~~Board determined the estimated fair value~~purchase of an aggregate of 50,000 shares of the Company’s common stock, outside of the Stock Incentive Plans, at an exercise price of $12.02 per share. The inducement grant is excluded from the option activity table above.

In February 2019, the Company issued a stock option award as an inducement grant for the purchase of an aggregate of 40,000 shares of the Company’s common stock, outside of the Stock Incentive Plans, at an exercise price of $10.39 per share. The inducement grant is excluded from the option activity table above.

In January 2019, the Company issued performance-based restricted stock units (“RSUs”) to senior management under the 2015 Plan that represent shares potentially issuable in the future subject to the satisfaction of certain performance milestones as well as a service condition. The vesting of 50% of the RSUs is based upon the Company’s performance relative to a peer group over a two-year performance period, from January 1, 2019 through December 31, 2020, measured by the Company’s relative total shareholder return. The vesting of 25% of the RSUs is based on the achievement of a performance goal milestone as of December 31, 2019 and vesting of the remaining 25% of the RSUs is based upon the achievement of a performance goal milestone as of December 31, 2020.

The Company estimates the fair value of market-based RSUs at the date of grant ~~based on~~using a Monte Carlo valuation methodology and amortizes those fair values over the requisite service period for each separately vesting tranche of the award. The Monte Carlo methodology that the Company uses to estimate the fair value of market-based RSUs at the date of grant incorporates into the valuation the possibility that the market condition may not be satisfied. Provided that the requisite service is rendered, the total fair value of the market-based RSUs at the date of grant must be recognized as compensation expense even if the market condition is not achieved. However, the number of ~~objective~~shares that ultimately vest can vary significantly with the performance of the specified market criteria.

The Company estimates the fair value of performance-based RSUs at the date of grant using the fair value method and ~~subjective factors, including third party valuations. Since~~ the ~~IPO,~~probability that the specified performance criteria will be met. Each quarter the Company updates its assessment of the probability that the specified performance criteria will be achieved and adjusts its estimate of the fair value of the ~~Company’s common stock on~~performance-based RSUs, if necessary. The Company amortizes the ~~date~~fair values of performance-based RSUs over the requisite service period for each separately vesting tranche of the ~~grant is based on~~award. As of March 31, 2019, the closing price per share of the common stock on the NASDAQ Capital Market on the date of grant. The computation of expected volatility is based on the historical volatilities of peer companies. The peer companies include organizations that are in the same industry, with similar size and stage of growth. The Company estimates that it is currently probable that it will achieve the ~~expected life~~clinical milestones included in the PSU performance goals and has recognized the stock-based compensation expense for the RSUs issued as it relates to the milestone base performance goals. The total stock-based compensation recognized for the three months ended March 31, 2019 for the RSUs was approximately $158,000.

The following table is a rollforward of ~~the options granted using the simplified method allowable~~performance-based restricted stock unit activity under the ~~SEC’s Staff Accounting Bulletin No. 107,~~ ~~Share Based Payments. The interest rate is based on~~Stock Incentive Plans for the U.S. Treasury bill rates for U.S. treasury bills with terms commensurate with the expected term of the option grants on the grant date of the option. The Company accounts for stock option forfeitures when they occur.three months ended March 31, 2019:

There were no performance-based restricted stock ~~options granted prior to 2015.~~ units exercisable as of March 31, 2019.

The assumptions the Company used to determine the fair value of stock options granted to employees and directors ~~in 2017~~during the three months ended March 31, 2019 and ~~2016~~2018 are as follows, presented on a weighted-average ~~basis.~~basis:

	Nine Months Ended September 30,						Three Months Ended March 31,
	2017			2016			2019			2018
Risk-free interest rate		2.0	%		1.4	%		2.6	%		2.4	%
Expected term (in years)		6.0			6.1			6.0			6.0
Expected volatility		79.8	%		77.6	%		81.1	%		82.7	%
Expected dividend yield		0	%		0	%		0	%		0	%

The assumptions used to determine the fair value of the performance-based restricted stock units granted to management during the three months ended March 31, 2019 for the performance goal milestone units is based on the market price of the award on the grant date, which was a weighted average fair value for the three months ended March 31, 2019 of $10.35 per share. The fair value of the performance-based restricted stock units granted to management in 2019 for the Company’s relative total share return units is based on the Monte Carlo Simulation method on the grant date, which the weighted average fair value as of the three months ended March 31, 2019 was $6.62 per share.

The following table summarizes the Company’s stock-based compensation expense for the three ~~and nine~~ months ended ~~September 30, 2017~~March 31, 2019 and ~~2016, under the Plans~~2018 (in thousands):

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2017		2016		2017		2016		For the Three Months Ended March 31,
Stock-based compensation:									2019		2018
Research and development	$	121	$	104	$	402	$	286	$	317	$	201
General and administrative		389		274		1,081		729		655		455
Total Stock-based compensation	$	510	$	378	$	1,483	$	1,015	$	972	$	656

The fair value of stock options vested during the ~~nine~~three months ended ~~September 30, 2017~~March 31, 2019 was ~~$1,275,000.~~$1.3 million. At ~~September 30, 2017,~~March 31, 2019, there was ~~$3,875,000~~$5.4 million of unrecognized stock-based compensation expense relating to stock options granted pursuant to the Stock Incentive Plans, which will be recognized over the weighted-average remaining vesting period of ~~2.3~~2.8 years.

The expense recognized is partially dependent upon the Company’s estimate of the number of shares that will ultimately be issued. At March 31, 2019, there was $1.6 million of unrecognized stock-based compensation expense relating to performance-based restricted stock units granted pursuant to the Stock Incentive Plans, which will be recognized over the weighted-average remaining vesting period of 1.8 years.

As of ~~September 30, 2017~~March 31, 2019 and ~~2016,~~December 31, 2018, the Company ~~has~~ reserved the following shares of common stock for ~~potential conversion~~issuance of ~~the~~shares resulting from exercise of outstanding warrants, ~~and outstanding~~ options and performance-based restricted stock units, as well as issuance of shares available for grant under the ~~2015 Plan:~~

~~In April 2015,~~The Company has operating leases for its principal office and laboratory space and the ~~Company entered into~~Company’s former headquarters. The Company’s leases have remaining lease terms of approximately 10 years for its principal office and laboratory space, which includes an ~~amendment~~option to extend the lease for up to 5 years, and approximately 2 years for its former headquarters. The Company’s former headquarters location is subleased through the remainder of the lease term.

Operating lease costs and variable lease costs under the leases for the three months ended March 31, 2019 was approximately $130,000 and $26,000, respectively. Total operating lease costs were offset by $19,000 for sublease income and variable lease cost payments. Total rent expense for the three months ended March 31, 2018 was $73,000, which included payments for a lease of the Company’s research and development facility. The lease term of the research and development facility ~~in Milford, Massachusetts to extend the term~~ended as of ~~the lease through~~ March 31, ~~2018 and expand~~2018.

~~In March 2016, the Company entered into a new~~Company’s maturities of operating lease ~~for its headquarters in Hopkinton, Massachusetts with a lease term through May~~liabilities as of March 31, ~~2021. The total payments due during the term of the lease are approximately $771,000.~~

Rent paid for the three and nine months ended September 30, 2017 was $59,000 and $174,000, respectively. Rent paid for the three and nine months ended September 30, 2016 was $56,000 and $110,000, respectively.

~~Future minimum commitments due under all leases at September 30, 2017 are as follows~~2019 (in thousands):

See subsequent events (Note 10) regarding a new lease commitment that the Company entered into after September 30, 2017. The commitments under the new lease agreement are not included in the table above.

For comparative purposes, the Company’s aggregate future minimum non-cancellable commitments under operating leases as of December 31, 2018 were as follows:

In January 2016, the Company entered into an amended and restated license agreement with BioHEP, which became effective on February 1, 2016.

Under the amended and restated license agreement, the Company agreed to pay BioHEP up to $3.5 million in development and regulatory milestone payments for disease(s) caused by each distinct virus for which the Company develops licensed product(s). BioHEP is also eligible to receive tiered royalties in the low-to-mid single-digits on net product sales of licensed products by the Company and its affiliates and sub licensees, and a specified share of non-royalty sublicensing revenues the Company and its affiliates receive from sub licensees, which share of sublicensing revenues is capped at a maximum aggregate of $2.0 million under all such sublicenses. Milestone and royalty payments associated with the Company’s amended and restated license agreement with BioHEP cannot be reasonably estimated as to whether or when they will occur. As of March 31, 2019, there have been no milestone or royalty payments made to BioHEP.

The Company accrues for contingent liabilities to the extent that the liability is probable and estimable. There are no accruals for contingent liabilities in these consolidated financial statements.

During May 2015, the Company entered into a transition agreement with the Company’s former President and Chief Executive Officer. Under the transition agreement, he continued to serve as the Company’s president and chief executive officer for a transition period that ended on August 17, 2015. Following the transition period, the Company made 18 monthly payments totaling $464,000 and also provided benefits consistent with the coverage that was provided prior to the execution of the transition agreement. There was no remaining unpaid balance relating to this obligation at September 30, 2017.

During the nine months ended September 30, 2016, the Company reimbursed BioHEP, a greater than five percent stockholder as of September 30, 2016, $14,000 for legal expenses that BioHEP incurred in connection with entering into the amended and restated license agreement. The Company incurred no such payments during the nine months ended September 30, 2017.

The Company has evaluated subsequent events through the date on which the consolidated financial statements were issued, to ensure that this submission includes appropriate disclosure of events both recognized in the consolidated financial statements and events which occurred subsequently but were not recognized in the consolidated financial statements.

On October 4, 2017, the Company entered into a lease agreement (the “New Lease”) in Hopkinton, Massachusetts. The premises covered by the New Lease will serve as the Company’s new principal office and laboratory space. The initial term of the New Lease is 125 months beginning on the date on which the landlord substantially completes certain renovations to the premises covered by the New Lease. The Company has the option to extend the New Lease one time for an additional 5-year period. Following an eleven-month rent abatement period, the Company will be obligated to make monthly rent payments in the amount of $34,533, which is subject to increase by approximately 3% annually for the first five years of the New Lease and by approximately 2.5% annually thereafter. The total lease payments due during the term of the lease are approximately $4.4 million. In addition, the Company is responsible under the New Lease for specified costs and charges, including certain operating expenses, utilities, taxes and insurance.

~~You~~The following information should be read in conjunction with the ~~following discussion~~unaudited financial information and ~~analysis~~the notes thereto included in this Quarterly Report on Form 10-Q and the consolidated financial statements and notes thereto for the year ended December 31, 2018, and the related Management’s Discussion and Analysis of Financial Condition and Results of Operations, contained in our Annual Report on Form 10-K filed with the United States Securities and Exchange Commission, or the SEC, on March 11, 2019.

This report contains forward-looking statements that are being made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995, or PSLRA, with the intention of obtaining the benefits of the “safe harbor” provisions of the PSLRA. Forward-looking statements involve risks and uncertainties. In this Quarterly Report on Form 10-Q, words such as “may,” “will,” “expect,” “anticipate,” “estimate,” “intend,” and similar expressions (as well as other words or expressions referencing future events, conditions or circumstances) are intended to identify forward-looking statements.

Our actual results and the timing of certain events may differ materially from the results discussed, projected, anticipated, or indicated in any forward-looking statements. We caution our readers that forward-looking statements are not guarantees of future performance and that our actual results of operations, financial condition and ~~results~~liquidity, and the development of ~~operations together with Part I, Item 1“Financial Statements” and related notes included elsewhere~~the industry in which we operate may differ materially from those expressed or implied by the forward-looking statements contained in this Quarterly Report on Form 10-Q.

We caution readers not to place undue reliance on any forward-looking statements made by us, which speak only as of the date they are made. We disclaim any obligation, except as specifically required by law and the rules of the SEC, to publicly update or revise any such statements to reflect any change in our expectations or in events, conditions or circumstances on which any such statements may be based, or that may affect the likelihood that actual results will differ from those set forth in the forward-looking statements.

We are a clinical-stage biopharmaceutical company engaged in the discovery and development of a novel class of therapeutics for the treatment of viral infections, inflammatory diseases and certain cancers using our proprietary small molecule ~~nucleic acid hybrid, or SMNH, chemistry~~nucleotide platform. ~~Our SMNH~~We design our compounds ~~are small segments of nucleic acids that we design~~ to selectively target and modulate the activity of specific proteins implicated in various disease states. We are developing our ~~most advanced SMNH~~lead product candidate, inarigivir soproxil, ~~(formerly known as SB 9200), which we refer to as~~or inarigivir, for the treatment of ~~certain viral diseases.~~chronic hepatitis B virus, or HBV. We have designed our antiviral product candidates, including inarigivir, to selectively activate within infected hepatic cells the cellular ~~proteins,~~protein, retinoic acid-inducible gene 1 (RIG-I) ~~and nucleotide-binding oligomerization domain-containing protein 2 (NOD2)~~, to inhibit viral replication and to cause the induction of intracellular interferon signaling pathways for antiviral defense. We believe that inarigivir, ~~may~~as a RIG-I agonist, could play an important role in antiviral therapy ~~by modulating~~as a result of its dual mechanism of action that is designed to selectively modulate the body’s immune response ~~through its mechanisms of action to fight~~and inhibit viral ~~infections.~~replication. We are also developing ~~other SMNH~~additional product candidates, including our lead STING (STimulator of INterferon Genes) agonist product candidate, SB 11285, which is an immunotherapeutic agent for the potential treatment of selected ~~cancers through~~cancers.

In April 2017, the ~~activation of the STimulator of INterferon Genes,~~World Health Organization, or ~~STING, pathway.~~

WeWHO, Global Hepatitis Report estimated that 257 million people are currently developing inarigivir for the treatment of chronic hepatitis B virus, or HBV. We are conducting Part A of our Phase 2 ACHIEVE multi-center clinical trial of inarigivir in Canada, Hong Kong, Korea and Taiwan. Part A of the Phase 2 ACHIEVE trial is a randomized, placebo-controlled, multiple ascending dose trial in up to 80 non-cirrhotic patientschronically infected with chronic HBV ~~using doses~~worldwide, and nearly 900,000 people worldwide die every year due to complications from chronic HBV infection despite the availability of ~~25 mg, 50 mg, 100 mg~~vaccines against the virus. There is no approved cure for chronic HBV and ~~200 mg of inarigivir as a monotherapy administered daily for 12 weeks. Following this treatment, all patients will receive treatment with the oral~~currently approved direct-acting antiviral agent tenofovir disoproxil fumarate (marketed by Gilead Sciences, Inc., or Gilead, as Viread®), which we refer to as Viread, as a monotherapy for 12 weeks. Patients will be sequentially enrolled into one of the four dose cohorts and randomized between the inarigivir dose group or placebo on a 4:1 basis. Patients are stratified based on HBeAg positive (+) or negative (–) status. HBeAg is a non-structural protein which is secreted by the virus and whose presence in blood, or HBeAg–positive, is indicative of wild type or non-mutated virus with high levels of viral replication. The loss of HBeAg occurs secondary to mutations in the virus and results in a patient becoming HBeAg negative with a resulting lower level of actively replicating virus. The primary endpoints of Part A of the Phase 2 ACHIEVE clinical trial are safety and antiviral activity, as measured by the change in HBV DNA at week 12 from baseline. Multiple exploratory secondary endpoints include reduction or loss of hepatitis B surface antigen, or HBsAg, and HBeAg, quantitative HBV RNA as a marker for control of virus production and studies of immune activity.

In May 2017, we reported top-line results from the first inarigivir monotherapy dosing cohort of Part A of the Phase 2 ACHIEVE clinical trial indicating that a low dose (25mg) of inarigivir alone showed a favorable safety profile and antiviral activity against HBV DNA and HBsAg. The first inarigivir monotherapy dosing cohort consisted of 11 HBeAg-positive and 9 HBeAg–negative patients, of which 80% were genotype B/C, the most common Asian genotypes. Administration of inarigivir resulted in a statistically ~~significant reduction in HBV DNA at week 12 (unpaired t-test 2.85, p=0.01) compared to placebo, with a mean reduction of 0.6 log~~₁₀ ~~(range 0 to 1.87 log~~₁₀~~) in the inarigivir treatment group. For the secondary endpoint of reduction or loss of HBsAg, 5 of 16 patients (31%) in the inarigivir treatment group had a greater than 0.5 log~~₁₀ ~~reduction at any time point (range 0.52 to 1.01 log~~₁₀~~), compared to none in the placebo group. The 7 HBeAg–negative patients in the inarigivir treatment group had the greatest mean reduction in HBV DNA at 0.9 log~~₁₀~~, and 3 of these 7 patients also had a greater than 0.5 log~~₁₀ reduction in HBsAg. The overall safety profile of inarigivir was favorable with no serious adverse events observed during the 12 week study. Treatment-emergent adverse events ranged from mild to moderate in severity with no interferon-like side effects and were comparable to patients on placebo.

In October 2017, we reported additional results from the first cohort of Part A of the Phase 2 ACHIEVE clinical trial consisting of patient data from 12 weeks of Viread monotherapy treatment that followed 12 weeks of inarigivir (25mg) monotherapy treatment. Treatment with Viread monotherapy during weeks 12-24 of the first cohort induced potent suppression of HBV DNA in all patients including placebo, and 6 of 16 patients (38%) in the inarigivir treatment group had a greater than 0.5 log₁₀ ~~reduction in HBsAg at week 24, which included 3 HBeAg-positive patients. An associated greater than 0.75 log~~₁₀ reduction in HBeAg was seen in 4 of 9 (44%) HBeAg-positive patients in the inarigivir treatment group, compared to zero of four (0%) in the placebo group. We believe this data suggests an enhanced effect of Viread in the inarigivir treated patients and is supportive of the proposed combination strategy that will be evaluated in Part B of the Phase 2 ACHIEVE trial, as discussed below.

We expect to report top-line results from the second inarigivir monotherapy dosing cohort (50mg) of Part A of the Phase 2 ACHIEVE clinical trial in the fourth quarter of 2017, and to report top-line monotherapy results for all patients treated with inarigivir alone in the second half of 2018.

~~Part B of the Phase 2 ACHIEVE clinical trial, which we expect to initiate in the second half of 2018, will consist of 12 weeks of combination treatment with inarigivir (100mg) and Viread. Following this treatment, all patients will receive treatment with Viread as a monotherapy for 12 weeks.~~ We expect to initiate Part B of this clinical trial in the second half of 2018. Both Parts A and B of the Phase 2 ACHIEVE clinical trial are being conducted under our clinical trial supply and collaboration agreement with Gilead.

~~We have entered into multiple collaborations and seek to enter into additional collaborations with third parties that are investigating and/or developing compounds~~therapies for the treatment of chronic HBV lack a broadly sustained response following the discontinuation of treatment.

We are developing inarigivir, an orally-administered investigational selective immunomodulator, as a potential backbone in a combinatorial treatment for chronic HBV, with ~~different pharmacological mechanisms of action than inarigivir. Pursuant~~a goal to ~~this strategy,~~accelerate and substantially increase functional cure rates in ~~2016, we entered into an agreement with Arrowhead Pharmaceuticals, Inc., or Arrowhead, to collaborate on the study of the combined use~~a simple, safe and selective manner. We recently completed our global Phase 2 ACHIEVE trial of inarigivir, and ~~Arrowhead’s small interfering ribonucleic acid, or siRNA, product pipeline for~~in April 2019, we launched two Phase 2 global trials (CATALYST 1 and CATALYST 2) examining the ~~treatment~~administration of chronic HBV. Under this collaboration with Arrowhead, we agreed first to study the co-administration of both agents in preclinical models, with the potential to be added to a clinical study. We have also entered into a material transfer agreementinarigivir 400mg as monotherapy and co-administered with a ~~third party to conduct preclinical experiments examining the co-administration of inarigivir with a capsid inhibitor for the potential treatment of patients infected with~~nucleotide in naïve and virally-suppressed chronic HBV. Additionally, in July 2017, we entered into a clinical trial collaboration with Gilead under which Gilead will fund and conduct a Phase 2 trial examining the co-administration of inarigivir and tenofovir alafenamide (marketed by Gilead as Vemlidy®) in patients infected with chronic HBV. ~~The protocol for this Phase 2~~ ~~clinical~~ ~~trial provides that treatment will consist of 12 weeks of combination therapy with inarigivir (50mg) and Vemlidy. Following this treatment, all patients will receive treatment with Vemlidy as a monotherapy for 12 weeks. We anticipate that Gilead will initiate this clinical trial in the first quarter of 2018.~~

HBV patients. We are also pursuing the development of ~~the~~SB 9225, a co-formulation of inarigivir with ~~Viread and with entecavir (marketed~~tenofovir disoproxil fumarate, or TDF, as ~~Baraclude®), which we refer to~~ as ~~Baraclude, as~~a potential fixed-dose combination ~~products~~product for the treatment of patients with chronic ~~HBV who may benefit from the combined use of~~HBV. In addition to our inarigivir clinical trials, we continue to explore collaborations, including with siRNA compounds targeting hepatitis B surface antigen, or HBsAg, as ~~a potential~~well as other antiviral and immunomodulatory agent, and Baraclude or Viread, as the antiviral agent. We anticipate that the fixed-dose combination product(s) could result in enhanced patient compliance and potentially allow for a more favorable safety profile. We have conducted early development work on a co-formulation of inarigivir with Viread and believe that inarigivir with Viread is compatible in the same formulation.mechanisms. We believe ~~that~~ the immunomodulatory activity ~~provided by~~of inarigivir could become a key component of a future combinatorial treatment offor patients infected with chronic HBV, ~~which could increase~~increasing the percentage of chronic HBV patients who achieve a functional cure.

~~STING Agonist Product Candidates~~In July 2017, we entered into a clinical trial supply and collaboration agreement with Gilead Sciences, Inc., or Gilead, under which Gilead is funding and conducting a Phase 2 clinical trial examining the co-administration of inarigivir and Vemlidy® 25 mg (tenofovir alafenamide) in patients infected with chronic HBV. On August 2, 2018, we announced the expansion of the clinical trial being undertaken by Gilead Sciences, Inc. to include two additional cohorts. The new second cohort of the study will assess

inarigivir 200mg co-administered with Vemlidy, subject to independent regulator assessments of the safety of inarigivir at the 200mg dose. Additionally, a new third cohort has been added to examine the administration of inarigivir 100mg in chronic HBV patients currently treated with nucleoside/tide analogues.

WeIn addition to our inarigivir clinical development program, we are developing SB ~~11285, a novel proprietary~~our lead STING agonist product candidate, SB 11285, as a potential next-generation immunotherapeutic agent for the treatment of selected cancers. Recent published scientific literature indicates that the activation of the STING pathway can result in the induction of cellular interferons and cytokines and promote an aggressive and strong anti-tumor response through the induction of innate and adaptive immune response. In our preclinical studies ~~performed~~ in ~~in vitro~~ ~~systems,~~multiple tumor-derived cell lines, SB 11285 has been observed to cause the induction of ~~interferon and other~~ cytokines consistent with engagement of the target, as well as cell death ~~or apoptosis, of multiple tumor-derived cell lines.~~

~~We continue to conduct~~and apoptosis. Based on our preclinical studies ofperformed to date, SB 11285 has reduced tumor volumes, without dose-limiting toxicities, in multiple ~~in vivo~~ ~~cancer models. In 2017, we have presented data from~~ ~~in vivo~~ ~~studies in the A20 lymphoma, CT26 colon carcinoma, B16 melanoma and orthotopic4T1 breast cancer syngeneic mouse~~rodent tumor models at various industry conferences, including the March 2017 Cancer Immunology and Immunotherapy Keystone Symposia, the June 2017 American Society of Clinical Oncology (ASCO) Annual Meeting and the October 2017 American Association for Cancer Research (AACR) Conference on Tumor Immunology and Immunotherapy.~~SB 11285 was evaluated~~ ~~for~~ ~~tumor growth inhibition and tumor growth delay and has shown that it is highly potent and has a durable anti-tumor response~~ when administered intravenously ~~intratumorally and intraperitoneally across different tumor models. The induction of immune-memory, tumor growth inhibition and abscopal anti-tumor activity upon intra-tumoral administration of~~or intratumorally. These findings lead us to believe that SB 11285 has ~~been observed in~~ the ~~A20 lymphoma model. In addition, in the CT26 colon cancer syngeneic mouse model,~~potential to be administered clinically by either route of administration, and that SB 11285 has exhibited dose-dependent, potent tumor growth inhibition and durable anti-tumor response upon intra-tumoral, intraperitoneal and intravenous routes of administration. In the B16 melanoma model, intravenous and intraperitoneal administration of SB 11285 showed significant inhibition of tumor growth. In the orthotopic 4T1 breast cancer model, intraperitoneal administration of SB 11285 resulted in significant inhibition of primary tumor growth, as well as inhibition of tumor metastasis. In the rat orthotopic bladder cancer model, intravenous administration of SB 11285 resulted in potent, dose-dependent inhibition of tumor growth in bladder. As part of the mechanism of action, immuno-histochemistry combined with flow cytometric analysis of tissues and blood from SB 11285-treated groups were conducted which revealed the presence of activated immune cells, including CD8+ T cells, natural killer (NK) cells and macrophages critical for anti-tumor activity. ~~We believe these preclinical studies demonstrate the potential for both intra-tumoral and systemic administration of SB 11285~~may be used to target a variety of tumors ~~which could potentially~~at various anatomic sites and, if approved, has the potential to be used in combination with other therapeutic ~~modalities.~~

modalities to enhance efficacy. We ~~intend to continue the development of SB 11285 as a potentially important addition to the current standard of care in the treatment of~~ ~~various~~ ~~cancers~~anticipate that we believe could increase the treatment responses in patients. We intend to continue to advance the SB 11285 program with preclinical, toxicology, and process development efforts. Subject to the results of these pr~~eclinical studies, we hope to~~will submit an investigational new drug ~~application,~~ or ~~IND, and/or a~~ clinical trial application ~~or CTA,~~ for SB 11285 in ~~mid-2018, and,~~ ~~if cleared, commence Phase Ib/II clinical trials in liver cancer in~~ the second ~~half~~quarter of ~~2018.~~

~~In August 2017, we entered into~~2019, and, if approved, initiate a preclinical research collaboration with a third party to examine the potential for the conjugation of selected compounds from our STING agonist platform with selected proprietary antibodies from the third-party’s immune-oncology portfolio.

~~On October 4, 2017, we entered into a lease agreement, or the New Lease,~~Phase 1b clinical trial in Hopkinton, Massachusetts. The premises covered by the New Lease will serve as our new principal office and laboratory space. The initial term of the New Lease is 125 months beginning on the date on which the landlord substantially completes certain renovations to the premises covered by the New Lease. We have the option to extend the New Lease one time for an additional 5-year period. The total lease payments due during the term of the lease are approximately $4.4 million.

To date, we have devoted substantially all of our resources to research and development efforts, including conducting clinical trials for our product candidates, protecting our intellectual property and providing general and administrative support for these operations. We have not generated any revenue to date other than from grants from the National Institutes of Health, or NIH. No additional funding remains available to us under any grant for the development of any of our product candidates. We have funded our operations primarily through proceeds received from private placements of convertible notes, common stock and/or warrants; the exercise of options and warrants; NIH grant funding; and public offerings of securities.

We have incurred significant annual net operating losses in every year since our inception and expect to continue to incur significant expenses and net operating losses for the foreseeable future. Our net losses ~~were $10.8 million and $26.2 million~~ for the three ~~and nine~~ months ended ~~September 30, 2017, respectively,~~March 31, 2019 and ~~$17.4~~2018 were $5.2 million ~~for the year ended December 31, 2016.~~and $4.9 million, respectively. As of ~~September 30, 2017,~~March 31, 2019, we had an accumulated deficit of ~~$77.8~~$107.3 million. Our net losses may fluctuate significantly from quarter to quarter and year to year. We expect to continue to incur significant expenses and increasing operating losses for the next several years.

We anticipate that our expenses will increase significantly as we continue to develop inarigivir, SB 11285 and our other product candidates. See “—Liquidity and Capital Resources—Funding Requirements.” As a result, we will need additional financing to support our continuing operations. Until such time as we can generate significant revenue from product sales, if ever, we expect to finance our operations through a combination of public or private equity or debt financings, including our at-the-market offering program with Cantor Fitzgerald & Co., or other sources, which may include collaborations with third parties. Arrangements with collaborators or others may require us to relinquish rights to certain of our technologies or product candidates. Adequate additional financing may not be available to us on acceptable terms, or at all. Our inability to raise capital as and when needed would have a negative impact on our financial condition and our ability to pursue our business strategy. We will need to generate significant revenue to achieve and sustain profitability, and we may never be able to do so.

As of ~~September 30, 2017,~~March 31, 2019, we had ~~$52.2~~$57.5 million in cash, cash equivalents and marketable securities. We expect that our cash, cash equivalents and marketable securities as of ~~September 30, 2017~~March 31, 2019 will enable us to fund our operating expenses and capital expenditure requirements ~~through~~into the ~~end~~second quarter of 2019. However, we anticipate that our existing cash, cash equivalents, restricted cash and marketable securities will not be sufficient to fund additional development of inarigivir beyond our Phase 2 ACHIEVE clinical trial.2021. See “—Liquidity and Capital Resources.”

~~Historically, we have generated~~We do not expect to generate revenue from ~~grants from the NIH~~product sales unless and until we successfully complete development and obtain regulatory approval for ~~the~~one or more of our product candidates, which we expect will take a number of years and is subject to significant uncertainty. We have no manufacturing facilities, and all of our manufacturing activities are contracted out to third parties. Additionally, we currently utilize third-party contract research organizations, or CROs, to carry out our clinical development ~~of inarigivir. The NIH grants provided funding of $6.8 million between October 2003~~activities, and ~~April 2016. As of September 30, 2017, no additional funding remains available to us under any grant~~we do not yet have a sales organization. If we obtain regulatory approval for ~~the development of~~ any of our product ~~candidates.~~candidates, we expect to incur significant commercialization expenses related to product sales, marketing, manufacturing and distribution. Accordingly, we will seek to continue to fund our operations through public or private equity or debt financings or other sources including geographic partnerships. However, we may be unable to raise additional funds or enter into other arrangements when needed on favorable terms or at all. Our failure to raise capital or enter into such other arrangements as and when needed would have a negative impact on our financial condition and our ability to develop our products.

Our operating expenses since inception have consisted primarily of research and development expense and general and administrative costs.

Research and development expenses consist primarily of costs incurred for our research activities, including our discovery efforts, and the development of our product candidates, which include:

We expense research and development costs as incurred. We recognize external development costs based on an evaluation of the progress to completion of specific tasks using information provided to us by our vendors and our clinical investigative sites. Payments for these activities are based on the terms of the individual agreements, which may differ from the pattern of costs incurred, and are reflected in our consolidated financial statements as prepaid or accrued research and development expenses.

Our ~~primary focus of~~direct research and development ~~since inception~~expenses are not currently tracked on a program-by-program basis. Our primary focus has been on the research and development of inarigivir. Our direct research and development expenses consist primarily of external costs, such as fees paid to investigators, consultants and CROs in connection with our preclinical studies and clinical trial and regulatory fees. We do not allocate employee-related costs and other indirect costs to specific research and development programs because our primary focus has been on the ~~discovery~~research and development of inarigivir. ~~Our direct research and development expenses are not currently tracked on a program-by-program basis.~~

The successful development of our product candidates is highly uncertain. Accordingly, at this time, we cannot reasonably estimate the nature, timing and costs of the efforts that will be necessary to complete the ~~remainder of the~~ development of ~~these~~any of our product candidates. We are also unable to predict when, if ever, we will generate revenues from inarigivir or any of our other ~~current or potential~~ product candidates. This is due to the numerous risks and uncertainties associated with developing medicines, including the uncertainties of:

A change in the outcome of any of these variables with respect to any of our product candidates would significantly change the costs and timing associated with the development of that product candidate.

Research and development activities are central to our business model. Product candidates in later stages of clinical development generally have higher development costs than those in earlier stages of clinical development, primarily due to the increased size and duration of later-stage clinical trials. We expect that our research and development expenses will continue to increase in the foreseeable future as we ~~continue~~initiate clinical trials for certain product candidates and pursue later stages of clinical development of ~~our~~other product candidates. However, we do not believe that it is possible at this time to accurately project total program-specific expenses through commercialization. There are numerous factors associated with the successful commercialization of any of our product candidates, including future trial design and various regulatory requirements, many of which cannot be determined with accuracy at this time based on our stage of development. Additionally, future commercial and regulatory factors beyond our control will impact our clinical development programs and plans.

General and administrative expenses consist primarily of salaries and other related costs, including stock-based compensation, for personnel in our executive, finance, corporate and business development and administrative functions. General and administrative expenses also include legal fees relating to patent and corporate matters; professional fees for accounting, auditing, tax and consulting services; insurance costs; travel expenses; and facility-related expenses, which include direct depreciation costs and allocated expenses for rent and maintenance of facilities and other operating costs.

We anticipate that our general and administrative expenses will increase in the future as we increase our headcount to support the expected growth in our research and development activities and the potential commercialization of our product candidates. We also expect to ~~continue to~~ incur ~~significant~~increased expenses associated with being a public company, including increased costs of accounting, audit, legal, regulatory and tax-related services associated with maintaining compliance with exchange listing and SEC requirements, director and officer insurance ~~costs,~~premiums, and investor and public relations costs.

Other income (expense) consists of interest income earned on our cash, cash equivalents, restricted cash and marketable ~~securities and the gain/loss on~~securities.

Change in fair value of warrant liabilities consists of a gain or (loss) related to the change in the fair value of the ~~warrant liabilities.~~warrants issued in connection with our private placement offering in November 2016, resulting from a change factors such as a change in our stock price and a change in expected stock price volatility.

Our consolidated financial statements are prepared in accordance with generally accepted accounting principles in the United States of America. The preparation of our consolidated financial statements and related disclosures requires us to make estimates and assumptions that affect the reported amount of assets, liabilities, revenue, costs and expenses and related disclosures. We believe that the estimates and assumptions involved in the accounting policies described therein may have the greatest potential impact on our consolidated financial statements and, therefore, consider these to be our critical accounting policies. We evaluate our estimates and assumptions on an ongoing basis. Our actual results may differ from these estimates under different assumptions and conditions.

As part of the process of preparing our consolidated financial statements, we are required to estimate our accrued research and development expenses. This process involves reviewing open contracts and purchase orders, communicating with our personnel to identify services that have been performed on our behalf and estimating the level of service performed and the associated costs

incurred for the services when we have not yet been invoiced or otherwise notified of the actual costs. The majority of our service providers invoice us in arrears for services performed, on a predetermined schedule or when contractual milestones are met; however, some require advanced payments. We make estimates of our accrued expenses as of each balance sheet date in our consolidated financial statements based on facts and circumstances known to us at that time. Examples of estimated accrued research and development expenses include fees paid to:

We base our expenses related to preclinical studies and clinical trials on our estimates of the services received and efforts expended pursuant to quotes and contracts with multiple CROs that conduct and manage clinical trials on our behalf. The financial terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows. There may be instances in which payments made to our vendors will exceed the level of services provided and result in a prepayment of the clinical expense. Payments under some of these contracts depend on factors such as the successful enrollment of patients and the completion of clinical trial milestones. In accruing service fees, we estimate the time period over which services will be performed, enrollment of patients, number of sites activated and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from our estimate, we adjust the accrual or amount of prepaid expense accordingly. Although we do not expect our estimates to be materially different from amounts actually incurred, our understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in us reporting amounts that are too high or too low in any particular period. To date, we have not made any material adjustments to our prior estimates of accrued research and development expenses.

~~In connection with entering into the amended and restated license agreement with BioHEP effective February 1,~~ Issued in 2016 we issued to BioHEP a warrant to purchase 125,000 shares of our common stock at a purchase price of $16.00 per share. We evaluated the terms of the warrant and concluded that it should be equity-classified. The fair value of the warrant, $0.8 million and was expensed as research and development costs.

In connection with our initial public offering, or IPO, we issued the sole book-running manager for the IPO warrants to purchase 28,347 shares of common stock at an exercise price of $15.00 per share, which we refer to collectively as the IPO warrants. We evaluated the terms of the IPO warrants and concluded that they should be equity-classified. The aggregate fair value of the IPO warrants was $0.2 million. See Note 7 of the notes to the unaudited financial statements included elsewhere in this Quarterly Report on Form 10-Q.

In connection with our private placement offering in November 2016, or the November private placement, we issued warrants to purchase 1,644,737 shares of common stock, which we refer to ~~a group of accredited investors. The~~as the November 2016 Warrants. These warrants ~~will be~~are exercisable ~~beginning May 24, 2017~~ at an exercise price of $10.79 per share. We evaluated the terms of ~~the~~these warrants and concluded that they should be liability-classified. In November 2016, we recorded the fair value of these warrants of approximately $8.3 million. We recognize any change in the value of the warrant liability each reporting period in the statement of operations. As of ~~September 30, 2017,~~March 31, 2019, the fair value of the warrants was approximately ~~$17.8~~$5.7 million, which is ~~an increase~~a decrease of ~~$11.5~~$2.8 million from the fair value of approximately ~~$6.3~~$8.5 million as of December 31, ~~2016.~~2018. See Note 7 of the notes to the unaudited financial statements included elsewhere in this Quarterly Report on Form 10-Q.

We issue stock-based awards to employees and non-employees, generally in the form of stock options or performance-based restricted stock units. We account for our stock-based compensation awards in accordance with Financial Accounting Standards Board, (FASB) ASC Topic 718, Compensation—Stock Compensation, or ASC 718. ASC 718 requires all stock-based payments to employees, including grants of employee stock options and modifications to existing stock awards, to be recognized in the statements of operations and comprehensive loss based on their fair values. We adopted ASU 2018-07, Improvements to Nonemployee Share-Based Payment Accounting, effective July 1, 2018, which aligns the accounting treatment of nonemployee awards with employee awards. Described below is the methodology we have utilized in measuring stock-based compensation expense. Stock option, common stock and restricted stock values are determined based on a blend of our stock price and the quoted market price of our comparable public companies.

We measure stock options and other stock-based awards granted to employees, nonemployees and directors based on the fair value on the date of grant and recognize the corresponding compensation expense of those awards, ~~net of estimated forfeitures,~~ over the requisite service period, which is generally the vesting period of the respective award. Generally, we issue stock options and performance based restricted stock ~~awards~~units with ~~only~~ service-based vesting conditions and record the expense for these awards using the straight-line method.

~~We measure stock options~~ Each quarter we update our assessment of the probability that the specified performance criteria will be achieved and ~~other stock-based awards granted to consultants and nonemployees based on~~adjust our estimate of the fair value of the ~~award on the date at which the related service is complete.~~performance-based RSUs if necessary. We ~~recognize this~~adopted ASU No. 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting, or ASU 2016-09, effective January 1,

2017. Prior to adoption, share-based compensation expense ~~over the period during which services~~was recognized on a straight-line basis, net of estimated forfeitures, such that expense was recognized only for share-based awards that are ~~rendered by such consultants~~expected to vest. A forfeiture rate was estimated annually and ~~nonemployees until completed. At the end~~revised, if necessary, in subsequent periods if actual forfeitures differed from initial estimates. Following adoption of ~~each financial reporting period prior to completion of the service,~~ASU 2016-09, we ~~remeasure the fair value of these awards using the then-current fair value of our common stock~~no longer apply a forfeiture rate and ~~updated assumption inputs in the Black-Scholes option-pricing model.~~instead will account for forfeitures as they occur.

We estimate the fair value of each stock option grant using the Black-Scholes option-pricing model. Use of this model requires that we make assumptions as to the fair value of our common stock, the volatility of our common stock, the expected term of our stock options, the risk-free interest rate for a period that approximates the expected term of our stock options and our expected dividend yield. Because we lack company-specific historical and implied volatility information due in part to the limited time in which we have operated as a publicly traded company, we estimate our expected volatility based on the historical volatility of a group of publicly traded peer companies. We expect to continue to do so until such time as we have adequate historical data regarding the volatility of our traded stock price. We use the simplified method prescribed by the SEC’s Staff Accounting Bulletin No. 107, Share-Based Payment, to calculate the expected term of options granted to employees and directors. We base the expected term of options granted to consultants and nonemployees on the contractual term of the options. We determine the risk-free interest rate by reference

to the United States Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is based on the fact that we have never paid cash dividends and do not expect to pay any cash dividends in the foreseeable future. We measure the fair value of the performance-based restricted stock units relating to the total share return performance using a Monte Carlo valuation model.

There were no stock options granted prior to 2015. We recognize forfeitures as they occur and the compensation expense is reversed in the period that the forfeiture occurs.

~~In 2015,~~ The assumptions we ~~began issuing stock options~~used to employees, directors and consultants. During the periods ended September 30, 2017 and 2016, we issued common stock to consultants and advisors as compensation for services and recognized expense equal todetermine the fair value of granted stock options in three months ended March 31, 2019 and 2018 are as follows:

These assumptions represented our best estimates, but the ~~shares issued.~~ estimates involve inherent uncertainties and the application of our judgment. As a result, if factors change and we use significantly different assumptions or estimates, our stock-based compensation expense could be materially different. We recognize compensation expense for only the portion of awards that are expected to vest.

We expect the impact of our stock-based compensation expense for stock options and performance based restricted stock units granted to employees and non-employees to grow in future periods due to the potential increases in the fair value of our common stock and the increase in the number of grants as a result of an increase in headcount.

The following table summarizes the classification of our stock-based compensation expenses recognized in our consolidated statements of operations and comprehensive loss (in thousands):

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,				For the Three Months Ended March 31,
	2017		2016		2017		2016
Stock-based compensation:									2019		2018
Research and development	$	121	$	104	$	402	$	286	$	317	$	201
General and administrative		389		274		1,081		729		655		455
	$	510	$	378	$	1,483	$	1,015
Total Stock-based compensation									$	972	$	656

In April 2012, the Jumpstart Our Business Startups Act of 2012, or the JOBS Act, was enacted. Section 107 of the JOBS Act provides that an “emerging growth company,” or EGC, can take advantage of the extended transition period provided in Section 7(a)(2)(B) of the Securities Act for complying with new or revised accounting standards. Thus, an EGC can delay the adoption of certain accounting standards until those standards would otherwise apply to private companies. We have irrevocably elected not to avail ourselves of this extended transition period and, as a result, we ~~will~~ adopt new or revised accounting standards on the relevant dates on which adoption of such standards is required for other public companies.

Subject to certain conditions, as an EGC, we intend to rely on certain exemptions afforded by the JOBS Act, including the exemption from: certain requirements related to the disclosure of executive compensation in our periodic reports and proxy statements, and the requirement that we hold a nonbinding advisory vote on executive compensation and any golden parachute

payments; the requirement that the auditors provide an attestation report on our system of internal controls over financial reporting pursuant to Section 404(b) of the Sarbanes-Oxley Act; and complying with any requirement that may be adopted by the Public Company Accounting Oversight Board, or PCAOB, regarding mandatory audit firm rotation or a supplement to the auditor’s report providing additional information about the audit and the financial statements, known as the auditor discussion and analysis. We will remain an EGC until the earliest of the last day of the fiscal year in which we have total annual gross revenues of approximately $1.07 billion or more; the last day of the fiscal year following the fifth anniversary of the date of the completion of the closing of ~~an IPO;~~our IPO, which is December 31, 2021; the date on which we have issued more than $1 billion in nonconvertible debt during the previous three years; or the date on which we are deemed to be a large accelerated filer under the rules of the ~~Securities and Exchange Commission, or the~~ SEC.

Comparison of the Three ~~and Nine~~ Months Ended ~~September 30, 2017~~March 31, 2019 and ~~2016~~2018

The following table summarizes our results of operations for the three ~~and nine~~ months ended ~~September 30, 2017~~March 31, 2019 and ~~2016~~2018 (in thousands):

For the Three Months Ended September 30,

Increase

For the Nine Months Ended September 30,

Increase

2017

2016

(Decrease)

2017

2016

(Decrease)

Grant revenue

$
—

$
—

$
—

$
—

$
352

$
(352
)
Operating expenses:

Research and development

3,221

2,723

498

9,152

11,247

(2,095
)
General and administrative

1,968

1,452

516

5,811

4,136

1,675

Total operating expenses

5,189

4,175

1,014

14,963

15,383

(420
)
Loss from operations

(5,189
)

(4,175
)

(1,014
)

(14,963
)

(15,031
)

68

Other income

141

27

114

220

65

155

Change in fair value of warrant liabilities

(5,780
)

—

(5,780
)

(11,474
)

—

(11,474
)
Net loss

$
(10,828
)

$
(4,148
)

$
(6,680
)

$
(26,217
)

$
(14,966
)

$
(11,251
)

~~Grant revenue~~. There was no grant revenue for the three months ended September 2017 and 2016. There was no grant revenue for the nine months ended September 30, 2017 compared to $0.4 million for the nine months ended September 30, 2016. The decrease was primarily due to the completion of our last NIH grant as of April 30, 2016. As of September 30, 2017, no additional funding remained available to us under any grant for the development of any of our product candidates.

Research and development expenses ~~were $3.2 million for~~during the three months ended ~~September 30, 2017, compared to $2.7~~March 31, 2019 and 2018 were $5.6 million ~~for~~and $4.0 million, respectively. The increase of $1.6 million during the three months ended ~~September 30, 2016. The increase of $0.5 million~~March 31, 2019 was due primarily to an increase in spending on preclinical studies and clinical ~~trial related~~trial-related activities for inarigivir and preclinical studies for SB 11285 ~~in the three months ended September 30, 2017.~~

~~Research and development expenses were $9.1~~of $1.0 million, for the nine months ended September 30, 2017, compared to $11.2 million for the nine months ended September 30, 2016. The decrease of $2.1 million was due primarily to $2.7 million in non-cash charges primarily in connection with our amended and restated license agreement with BioHEP; offset by an increase of $0.4 million in spending on preclinical studies and clinical trial related activities for inarigivir and SB 11285 in the nine months ended September 30, 2017 and an increase in additional salaries and benefits ~~of $0.2 million~~ associated with higher research and development headcount ~~in the nine months ended September 30, 2017.~~ of $0.3 million, laboratory supplies of $0.1 million, non-cash charges for stock-based compensation of $0.1 million and other research and development costs of $0.1 million.

General and administrative expenses ~~were $2.0 million for~~during the three months ended ~~September 30, 2017, compared to $1.5~~March 31, 2019 and 2018 were $2.8 million ~~for~~and $2.2 million, respectively. The increase of $0.6 million during the three months ended ~~September 30, 2016. This increase of $0.5 million~~March 31, 2019 was primarily due to an increase in non-cash charges for ~~stock based~~stock-based compensation of ~~$0.1~~$0.2 million, ~~additional~~legal costs of $0.2 million, salaries and benefits of $0.1 million ~~associated with higher headcount of non-research~~ and development employees in the three months ended September 30, 2017, an increase of $0.1 million for public company related expenses in the three months ended September 30, 2017, an increase of $0.1 million for consulting related costs during the three months ended September 30, 2017 and an increase of $0.1 million for other general and administrative costs ~~in the three months ended September 30, 2017.~~

General and administrative expenses were $5.8 million for the nine months ended September 30, 2017, compared to $4.1 million for the nine months ended September 30, 2016. This increase of $1.7 million was primarily due to an increase in non-cash charges for stock based compensation of $0.4 million, additional salaries and benefits of $0.7 million associated with higher headcount of non-research and development employees in the nine months ended September 30, 2017, $0.6 million for public company related expenses incurred during the nine months ended September 30, 2017 and $0.1 million for additional rent expense for the nine months ended September 30, 2017; offset by a decrease of $0.1 ~~million for legal and consulting related costs during the nine months ended September 30, 2017.~~million.

Other income. Other income ~~for~~during the three ~~and nine~~ months ended ~~September 30, 2017~~March 31, 2019 and ~~2016~~2018 is solely comprised of interest income. Interest income ~~for~~during the three ~~and nine~~ months ended ~~September 30, 2017~~March 31, 2019 and 2018 was ~~$141,000~~$0.3 million and ~~$220,000,~~$0.1 million, respectively, and was primarily related to the interest earned on marketable securities. ~~Interest~~The increase in interest income ~~for~~during the ~~nine~~three months ended ~~September 30, 2016~~March 31, 2019 was ~~$27,000 and $65,000, respectively, and was primarily related~~due to ~~the interest earned on~~a higher average balance of marketable securities.

Change in fair value of warrant liabilities. Change in fair value of warrant liabilities ~~for~~during the three ~~and nine~~ months ended ~~September 30, 2017~~March 31, 2019 and 2018 was ~~$5.8~~a loss of $2.8 million and ~~$11.5~~$1.2 million, ~~respectively, and~~respectively. The change in value each period was solely related to ~~an increase~~the change in the fair value of the ~~warrants from~~November 2016 Warrants, primarily as a result of the ~~November private placement, primarily due to the increase~~change in ~~the Company’s~~our stock ~~price. There were no warrant liabilities during the three~~price and ~~nine months ended September 30, 2016.~~stock price volatility.

From our inception through ~~September 30, 2017,~~March 31, 2019, we have financed our operations through proceeds received from private placements of convertible notes, common stock and/or ~~warrants;~~warrants, the exercise of options and ~~warrants;~~warrants, NIH grant ~~funding;~~funding and public offerings of securities. As of ~~September 30, 2017,~~March 31, 2019, we had cash, cash equivalents and marketable securities totaling ~~$52.2~~$57.5 million and an accumulated deficit of ~~$77.8~~$107.3 million.

In August 2018, we issued and sold in an underwritten public offering an aggregate of 3,246,079 shares of our common stock at $12.50 per share, which included 246,079 shares pursuant to the exercise of an option to purchase additional shares granted to the underwriters in connection with the offering. The shares issued in this offering were registered under the Securities Act pursuant to our Registration Statement on Form S-3 (Registration No. 333-218399) that was declared effective by the SEC on June 12, 2017, which we refer to as the S-3 Registration Statement, and a prospectus supplement and base prospectus filed on August 9, 2018. The offering resulted in $38.0 million of net proceeds, after deducting underwriting discounts and commissions and other offering expenses payable by us.

In August 2017, we entered into a Controlled Equity Offering^SM Sales Agreement, or Sales Agreement, with Cantor Fitzgerald & Co., or Cantor, pursuant to which we may offer and sell, from time to time through Cantor, shares of our common stock having an aggregate offering price of up to $50.0 million. We ~~will~~ pay Cantor a commission rate equal to 3.0% of the aggregate gross proceeds from each sale. Shares sold under the Sales Agreement ~~will be~~are offered and sold pursuant to our S-3 Registration Statement ~~on Form S-3 (Registration No. 333-218399) that was declared effective by the SEC on June 12, 2017, or the Registration Statement,~~, and a prospectus supplement and accompanying base prospectus that we filed with the ~~SEC~~Securities and Exchange Commission on August 18, 2017.

~~In June 2017,~~ During the three months ended March 31, 2019, we ~~issued and~~made no sales under the Sales Agreement. During the year ended December 31, 2018, we sold ~~in an underwritten public offering~~ an aggregate of ~~3,269,219~~217,329 shares of our common stock under the Sales Agreement at ~~$13.00~~a weighted average selling price of $15.42 per share, which included 384,604 shares pursuant to the exercise of an option to purchase additional shares granted to the underwriters in connection with the offering. The shares issued in this offering were registered under the Securities Act pursuant to the Registration Statement. The offering resulted in ~~$39.6~~$3.2 million of net ~~proceeds, after deducting underwriting discounts and commissions and other offering expenses payable by us.~~

In November 2016, we entered into a definitive agreement with a group of accredited investors resulting in a private placement of 1,644,737 shares of our common stock and warrants to purchase 1,644,737 shares of common stock, which we refer to as the November private placement. These investors paid $9.12 for each share of common stock and warrant to purchase one share of common stock. The warrants will be exercisable beginning May 24, 2017 with a term of five years at an exercise price of $10.79. We completed the November private placement on November 23, 2016, resulting in approximately $15.0 million in gross proceeds. ~~Net proceeds from this issuance after deducting placement agent fees and other offering-related expenses were $13.7 million.~~

In May 2016, we completed our IPO and sold an aggregate of 944,900 shares of common stock at a price to the public of $12.00 per share, which included 24,900 shares pursuant to the exercise of an option to purchase additional shares granted to the underwriters in connection with the IPO. The offering resulted in $8.2 million of net proceeds, after deducting underwriting discounts and commissions and other offering expenses payable by us. In connection with the closing of the IPO, we received approximately $5.3 million in proceeds upon the exercise of previously issued warrants to purchase 641,743 shares of common stock.

The following table summarizes sources and uses of cash for each of the periods presented (in thousands):

	For the Nine Months Ended September 30,						For the Three Months Ended March 31,
	2017			2016			2019			2018
Net cash used in operating activities	$	(12,640	)	$	(11,708	)	$	(6,787	)	$	(6,188	)
Net cash used in investing activities		(19,919	)		(1,955	)
Net cash provided by investing activities								8,813			3,300
Net cash provided by financing activities		39,664			14,648			—			2,827
Net increase in cash, cash equivalents and restricted cash	$	7,105		$	985
Net increase (decrease) in cash, cash equivalents and restricted cash							$	2,026		$	(61	)

Net cash used in operating activities. The use of cash in both periods resulted primarily from our net losses adjusted for non-cash charges and changes in components of working capital. Net cash used in operating activities during the three months ended March 31, 2019 and 2018 was ~~$12.6~~$6.8 million and ~~$11.7~~$6.2 million, ~~during the nine months ended September 30, 2017 and 2016,~~ respectively. The increase in cash used in operating activities ~~for~~during the ~~nine~~three months ended ~~September 30, 2017~~March 31, 2019 compared to ~~September 30, 2016~~the three months ended March 31, 2018 of $0.6 million was primarily due to an increase in the net loss of ~~$11.3~~$0.3 million ~~which were~~ offset by a decrease in prepaid expenses and other current assets of $0.5 million, other assets of $0.1 million, accounts payable of $0.1 million and accrued expenses and other current and non-current liabilities of ~~$1.2~~$0.2 million. In addition, there was an increase in the non-cash change in the fair value of the warrant liability of ~~$11.5~~$1.6 million, the non-cash stock-based compensation of $0.3 million and ~~an increase in~~the non-cash ~~stock based compensation~~operating lease right-of-use asset amortization of $0.5 million, which was offset by a decrease in non-cash common stock and warrant valuation expense related to the BioHEP license agreement of $2.8 million for the nine months ended September 30, 2017.$0.1 million.

Net cash used in investing activities. Net cash ~~used in~~provided by investing activities ~~was $19.9 million for~~during the ~~nine~~three months ended ~~September 30, 2017 compared to $2.0~~March 31, 2019 and 2018 was $8.8 million ~~for~~and $3.3 million, respectively. The cash provided by investing activities during the ~~nine~~three months ended ~~September 30, 2016. The cash used in investing activities of $19.9 million in the nine months ended September 30, 2017~~March 31, 2019 was primarily the result of ~~$14.6~~$8.9 million in proceeds from the sale of marketable securities, which was offset by ~~$34.4 million for the purchase of marketable securities and~~ $0.1 million for the purchase of property and equipment. The cash ~~used in~~provided by investing activities ~~of $2.0 million for~~during the ~~nine~~three months ended ~~September 30, 2016~~March 31, 2018 was ~~mainly due to~~primarily the result of $13.6 million in proceeds ~~of $4.9 million~~ from the sale of marketable securities, which was offset by ~~$6.7~~$10.0 million for the purchase of marketable securities and ~~$0.2~~$0.3 million for the purchase of property and ~~equipment for the nine months ended September 30, 2016.~~equipment.

Net cash provided by financing activities. There were no financing activities during the three months ended March 31, 2019. Net cash provided by financing activities during the three months ended March 31, 2018 was ~~$39.7~~$2.8 million and ~~$14.6 million during the nine months ended September 30, 2017 and 2016, respectively. The cash provided by financing activities in the nine months ended September 30, 2017~~ was primarily the result of ~~$42.5 million of gross~~net proceeds from our at-the-market offering program under the ~~common stock offering and $0.1 million of proceeds from the exercise of stock options, offset by $2.9 million of offering expenses. The cash provided by~~Sales Agreement.

financing activities in the nine months ended September 30, 2016 was primarily the result of $11.3 million of gross proceeds received from our IPO, cash of $5.3 million for the exercise of warrants in connection with the closing of our IPO and $0.1 million for the exercise of stock options, offset by $2.1 million in underwriting discounts and offering expenses related to our IPO.

We expect to continue to incur significant and increasing losses for the foreseeable future. We anticipate these losses to increase as our expenses increase, and we expect that our expenses will increase if and as we:

We expect that our existing cash, cash equivalents and marketable securities as of ~~September 30, 2017~~ March 31, 2019 will enable us to fund our operating expenses and capital expenditure requirements ~~through~~into the ~~end~~second quarter of 2019. However, we anticipate that our existing cash, cash equivalents and marketable securities will not be sufficient to fund additional development of inarigivir beyond our Phase 2 ACHIEVE clinical trial in patients with chronic HBV. 2021. We have based this estimate on assumptions that may prove to be wrong, and we may use our available capital resources sooner than we currently expect. Because of the numerous risks and uncertainties associated with the development of ~~inarigivir and SB 11285,~~our product candidates, we are unable to estimate the amounts of increased capital outlays and operating expenses associated with completing the research and development of our product candidates. Our future capital requirements, both near and long-term, will depend on many factors, including, but not limited ~~to:~~to:

Identifying potential product candidates and conducting preclinical testing and clinical trials is a time-consuming, expensive and uncertain process that takes years to complete, and we may never generate the necessary data or results required to obtain marketing approval and achieve product sales. In addition, our product candidates, if approved, may not achieve commercial success. Our commercial revenues, if any, will be derived from sales of products that we do not expect to be commercially available for many years, if ever. Accordingly, we will need to obtain substantial additional funds to achieve our business objectives.

Adequate additional funds may not be available to us on acceptable terms, or at all. We do not currently have any committed external source of funds. ~~We have an effective shelf registration statement on Form S-3 (File No. 333-218399~~), which we refer to as the Registration Statement. In August 2017, we entered into the Sales Agreement with Cantor pursuant to which we may offer and sell, from time to time through Cantor, shares of our common stock having an aggregate offering price of up to $50.0 million. Shares sold under the Sales Agreement will be offered and sold pursuant to the Registration Statement and a prospectus supplement and accompanying base prospectus that we filed with the SEC on August 18, 2017. As of ~~September 30, 2017,~~March 31, 2019, we had up to ~~$107.5~~$59.6 million in securities available for future issuance under the S-3 Registration Statement, which ~~includes $50.0~~included $42.7 million in shares issuable pursuant to ~~the~~our at-the-market program and our Sales Agreement with Cantor. To the extent that we raise additional capital through the sale of equity or convertible debt securities, the ownership interests of our stockholders will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect the rights of our common stockholders. Additional debt financing and equity financing, if available, may involve agreements that include covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends and may require the issuance of warrants, which could potentially dilute the ownership interests of our stockholders.

If we raise additional funds through collaborations, strategic alliances or licensing arrangements with third parties, we may have to relinquish valuable rights to our technologies, future revenue streams, research programs, or product candidates or grant licenses on terms that may not be favorable to us. If we are unable to raise additional funds through equity or debt financings when needed, we may be required to delay, limit, reduce or terminate our product development programs or any future commercialization efforts or grant rights to develop and market product candidates that we would otherwise prefer to develop and market ourselves.

~~The following table summarizes our contractual obligations at September 30, 2017, and the effect such obligations are expected to have on our liquidity and cash flow in future periods (in thousands):~~

~~In addition to the amounts shown in the above table, we~~We have contractual obligations pursuant to our amended and restated license agreement with BioHEP. Under this agreement, we have agreed to pay up to $3.5 million in development and regulatory milestone payments to BioHEP for each distinct viral indication for which we develop licensed product(s). BioHEP is also eligible to

receive tiered royalties in the low-to-mid single-digits on net product sales of licensed products by us and our affiliates and sub licensees, and a specified share of non-royalty sublicensing revenues we and our affiliates receive from sub licensees, which share of sublicensing revenues is capped at a maximum aggregate of $2.0 million under all such sublicenses. Milestone and royalty payments associated with our amended and restated license agreement with BioHEP have not been included in the above table of contractual obligations as we cannot reasonably estimate if or when they will occur.

~~On October 4, 2017, we entered into a New Lease. The premises covered by the New Lease will serve as our new principal office and laboratory space. The initial term~~ As of ~~the New Lease is 125 months beginning on the date on which the landlord substantially completes certain renovations~~March 31, 2019, there have been no milestone or royalty payments made to the premises covered by the New Lease, which we expect to occur in approximately April 2018. Following an eleven-month rent abatement period, we will be obligated to make monthly rent payments in the amount of $34,533, which is subject to increase by approximately 3% annually for the first five years of the New Lease and by approximately 2.5% annually thereafter. The total lease payments due during the term of the lease are approximately $4.4 million. In addition, we are responsible under the New Lease for specified costs and charges, including certain operating expenses, utilities, taxes and insurance. BioHEP.

We enter into contracts in the normal course of business with third party service providers for clinical trials, preclinical research studies and testing, manufacturing and other services and products for operating purposes. We have not included our payment obligations under these contracts in the table as these contracts generally provide for termination upon notice, and therefore we believe that our non-cancelable obligations under these agreements are not material. We could also enter into additional research, manufacturing, supplier and other agreements in the future, which may require up-front payments and even long-term commitments of cash.

We did not have during the periods presented, and we do not currently have, any off-balance sheet arrangements, as defined in the rules and regulations of the SEC.

In ~~November 2016,~~August 2018, the ~~Financial Accounting Standards Board, or~~ FASB issued ~~Accounting Standards Update, or~~ ASU ~~No. 2016-18,~~2018-13, ~~Statement~~Fair Value Measurement (Topic 820), Disclosure Framework – Changes to the Disclosure Requirement for Fair Value Measurement. This ASU removes, modifies and adds certain disclosure requirements of ~~Cash Flows (Topic 230): Restricted Cash~~, which includes provisions intended to clarify how entities present restricted cash and restricted cash equivalents in the statement of cash flows. Companies must show the change in total cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows.ASC Topic 820. The ~~new standard is applied retrospectively and~~ASU is effective for ~~our annual periods beginning after December 15, 2017,~~all entities for fiscal years, and ~~for~~ interim periods within those annual periods, with early adoption permitted. We elected early adoption of this standard as of September 30, 2017, the first period in which we had restricted cash. The adoption of this standard has resulted in the presentation of the change in cash, cash equivalents and restricted cash on the statement of cash flows in the periods presented.

~~In March 2016, the FASB issued ASU 2016-09,~~ ~~Compensation – Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting~~ (“ASU 2016-09”) to require changes to several areas of employee stock-based compensation payment accounting in an effort to simplify stock-based compensation reporting. The update revises requirements in the following areas: minimum statutory withholding, accounting for income taxes, forfeitures, and intrinsic value accounting for private entities. ASU 2016-09 is effective for our annual reporting periodsfiscal years, beginning after December 15, 2016, including interim reporting periods within each annual reporting period. We adopted this standard on January 1, 2017. The update revises our requirements in the following areas: minimum statutory withholding, accounting for income taxes, and forfeitures. Prior to adoption, we applied a 0% forfeiture rate to stock-based compensation, resulting in no cumulative effect adjustment to the opening period. Upon adoption of this standard, our accounting policy is to recognize forfeitures as they occur.

The update requires us to recognize the income tax effect of awards in the income statement when the awards vest or are settled. It also allows us to repurchase more of an employee’s shares than we could prior to the update for tax withholding purposes without triggering a liability. The income tax related items had no effect on the current period presentation and we maintain a full valuation allowance against our deferred tax assets.

~~In May 2014, the FASB issued ASU 2014-09,~~ ~~Revenue from Contracts with Customers~~ (Topic 606), or ASC 606, which amends the guidance for revenue recognition to replace numerous industry-specific requirements. ASC 606 implements a five-step process for customer contract revenue recognition that focuses on transfer of control, as opposed to transfer of risk and rewards. ASC 606 also requires enhanced disclosures regarding the nature, amount, timing, and uncertainty of revenues and cash flows from contracts with customers. Other major provisions include ensuring the time value of money is considered in the transaction price, and allowing estimates of variable consideration to be recognized before contingencies are resolved in certain circumstances. The amendments in ASC 606 are effective for reporting periods beginning after December 15, 2016, and early adoption is not permitted. In July 2015, FASB approved the deferral of adoption by one year. Entities can transition to the standard either retrospectively or as a cumulative-effect adjustment as of the date of adoption. Until we expect material revenue to be recognized, the adoption of this standard is not expected to have an impact on our consolidated financial statements.

~~In January 2016, the FASB issued ASU 2016-01,~~ ~~Recognition and Measurement of Financial Assets and Financial Liabilities, which amends Accounting Standards Codification, or ASC, Subtopic 825-10,~~ ~~Financial Instruments - Overall~~, and includes updates on certain aspects of recognition, measurement, presentation and disclosure of financial instruments and applies to all entities that hold financial assets or owe financial liabilities. The new standard is effective for our annual period beginning after December 15, 2017, with early adoption permitted.31, 2019. We are currently evaluating the impact that the adoption of this standard may have on our consolidated financial statements.

In February 2016, the FASB issued ASU No. 2016-02, Leases (“ASU 2016-02”). ASU 2016-02 ~~Leases (Topic 842), which supersedes the current leasing guidance and upon adoption, will require~~requires lessees to recognize ~~right-of-use assets and lease liabilities~~most leases on ~~the~~their balance sheet ~~for all leases with terms longer than 12 months.~~as a right-of-use asset and a lease liability. Leases are classified as either operating or finance, and classification is based on criteria similar to current lease accounting, but without explicit bright lines. In July 2018, the FASB issued ASU No. 2018-10, “Codification Improvements to Topic 842, Leases” (“ASU 2018-10”), which provides narrow amendments to clarify how to apply certain aspects of the new lease standard, and ASU No. 2018-11, “Leases (Topic 842) – Targeted Improvements” (ASU 2018-11), which addresses implementation issues related to the new lease standard. The ~~new standard~~guidance is effective for ~~our~~ annual ~~period~~reporting periods beginning after December 15, 2018 and ~~can be~~interim periods within those fiscal years, and early ~~adopted by applying a modified retrospective approach for leases existing~~adoption is permitted. Under this standard, disclosures are required to enable users of financial statements in assessing the amount, timing, and uncertainty of cash flows arising from leases. The standard permits two transition methods, (1) to apply the new lease requirements at ~~and entered into after,~~ the beginning of the earliest ~~comparable~~ period presented, or (2) to apply the new lease requirements at the effective date. Under both transition methods there is a cumulative effect adjustment.

We adopted the standard on the effective date of January 1, 2019 by applying the new lease requirements at the effective date. Prior periods continue to be presented based on the accounting standards originally in effect for such periods. We also elected the ~~financial statements.~~ package of practical expedients permitted under the transition guidance within the new standard, which, among other things, allows us to carry forward the historical lease classification. We ~~are currently evaluating~~will also apply the practical expedient not to separate lease and non-lease components for new and modified leases commencing after adoption. The standard had an impact ~~that the adoption~~ of ~~this standard may have~~approximately $3.0 million on our ~~consolidated financial statements.~~

~~In September 2016, the FASB issued ASU 2016-15,~~ ~~Classification of Certain Cash Receipts~~assets and ~~Cash Payments, which amends ASC Topic 230,~~ ~~Statement of Cash Flows~~, and includes provisions intended to reduce diversity in practice and provides guidance on eight specific statements of cash flows classification issues. The new standard is effective for our annual period ending after December 15, 2017, and for annual and interim periods thereafter, with early adoption permitted. We are currently evaluating the impact that the adoption of this standard may have$3.4 million on our ~~consolidated financial statements.~~liabilities, as of January 1, 2019, for the recognition of right-of-use assets and lease liabilities, which are primarily related to the lease of our corporate headquarters in Hopkinton, Massachusetts. The standard did not have a material impact on our results of operations or liquidity.

In July 2017, the FASB issued ASU 2017-11, Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480), Derivatives and Hedging (Topic 815): I. Accounting for Certain Financial Instruments with Down Round Features and II. Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception. Part I applies to entities that issue financial instruments such as warrants, convertible debt or convertible preferred stock that contain down round features. Part II simply replaces the indefinite deferral for certain mandatorily redeemable noncontrolling interests and mandatorily redeemable financial instruments of nonpublic entities contained within Accounting Standards Codification ~~(ASC)~~(“ASC”) Topic 480 with a scope exception and does not impact the accounting for these mandatorily redeemable instruments. This ASU is effective for public companies for the annual reporting periods beginning after December 15, 2018, and interim periods within those annual periods. Early adoption is permitted. We ~~are currently evaluating the impact that~~adopted this standard as of January 1, 2019; however, the adoption of this standard ~~may have on~~did not impact our consolidated financial ~~statements~~statements.

Other accounting standards that have been issued or proposed by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on our consolidated financial statements upon adoption.

We are exposed to market risk related to changes in interest rates. Our cash, cash equivalents and marketable securities of ~~$52.2~~$57.5 million as of ~~September 30, 2017,~~March 31, 2019, consisted of cash, ~~money market accounts~~cash equivalents and ~~short-term~~ marketable ~~debt~~ securities. Our primary exposure to market risk is interest income sensitivity, which is affected by changes in the general level of U.S. interest rates. However, because a significant amount of the ~~short-term nature of the instruments~~marketable securities in our investment portfolio are short-term in nature , an immediate 10% change in market interest rates would not be expected to have a material impact on the fair market value of our investment portfolio or on our financial condition or results of operations.

Our management, with the participation of our principal executive officer and our principal financial officer, evaluated, as of the end of the period covered by this Quarterly Report on Form 10-Q, the effectiveness of our disclosure controls and procedures. Based on that evaluation of our disclosure controls and procedures as of ~~September 30, 2017,~~March 31, 2019, our principal executive officer and principal financial officer concluded that our disclosure controls and procedures as of such date are effective at the reasonable assurance level. The term “disclosure controls and procedures,” as defined in Rules 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934, as amended, or the Exchange Act, means controls and other procedures of a company that are designed to ensure that information required to be disclosed by a company in the reports that it files or submits under the Exchange Act are recorded, processed, summarized and reported within the time periods specified in the SEC’s rules and forms. Disclosure controls and procedures include, without limitation, controls and procedures designed to ensure that information required to be disclosed by us in the reports we file or submit under the Exchange Act is accumulated and communicated to our management, including our principal executive officer and principal financial and accounting officer, as appropriate to allow timely decisions regarding required disclosure. Management recognizes that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving their objectives and our management necessarily applies its judgment in evaluating the cost-benefit relationship of possible controls and procedures.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Therefore, even those systems determined to be effective can provide only reasonable assurance with respect to financial statement preparation and presentation. Projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

There were no changes in our internal control over financial reporting (as defined in Rules 13a-15(f) and 15d-15(f) under the Exchange Act) during the ~~quarter~~three months ended ~~September 30, 2017,~~March 31, 2019, that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

From time to time, we may become involved in legal proceedings arising in the ordinary course of our business. We are not presently a party to any material litigation.

There have been no material changes in or additions to the risk factors included in our Annual Report on Form 10-K for the year endedDecember 31, ~~2016 and our Quarterly Report on Form 10-Q for the quarter ended June 30, 2017.~~2018.

On ~~October 26, 2017,~~February 19, 2019, we issued an option grant to our ~~Board~~new vice president, head of ~~Directors, or Board, elected Christiana Bardon, M.D., to the Board~~oncology & immunology clinical development, as a ~~class II director with a term expiring at the 2020 annual meeting of stockholders. The Board also appointed Dr. Bardon~~new hire inducement option grant pursuant to ~~the Compensation Committee~~Nasdaq Listing Rule 5635(c)(4) and Section 4(a)(2) of the ~~Board.~~

~~In accordance with our current non-employee director compensation policy, Dr. Bardon will receive a $35,000 annual cash retainer~~Securities Act of 1933, as amended. The option grant is for ~~service on~~ the Board and a $5,000 annual cash retainer for service on the Compensation Committee. These cash retainers are payable quarterly in arrears. The non-employee director compensation policy includes a stock-for-fees policy, under which Dr. Bardon has elected to receivepurchase of an aggregate of 40,000 shares of our common stock. This stock ~~in lieu~~option award is exercisable at $10.39 per share and vests as to 25% on the one-year anniversary of ~~cash fees.~~

~~In addition, in accordance~~the employee’s date of hire, with the non-employee director compensation policy, Dr. Bardon received an option to purchase 11,000 shares of common stock upon her election to the Board, at an exercise price of $15.17, the closing share price of the common stock on the NASDAQ Capital Market on October 26, 2017. This option becomes exercisable on aremaining vesting monthly ~~basis over the course of three years,~~thereafter until February 2023, subject to ~~Dr. Bardon’s~~ continued service as a director and, in the event of a change in control of the company, the vesting schedule of the option will accelerate in full. Dr. Bardon is also entitled to receive an option to purchase 5,500 shares of common stock on the date of each annual meeting of stockholders with an exercise price equal to the closing share price of the common stock on the NASDAQ Stock Market on the date of grant. Such option shall vest in 12 equal monthly installments while Dr. Bardon is serving as a director and, in the event of a change in control of the company, the vesting schedule of the option will accelerate in full.

Also, in connection with her election to the Board, we and Dr. Bardon entered into an indemnification agreement. The indemnification agreement is substantially the same as the form of indemnification agreement that we have entered into with our other directors, a copy of which was filed as Exhibit 10.1 to our Registration Statement on Form S-1 (File No. 333-208875) filed with the SEC on January 5, 2016 and is hereby incorporated by reference. The indemnification agreement provides that we will indemnify Dr. Bardon for certain expenses, including attorneys’ fees, judgments, fines and settlement amounts incurred by her in any action or proceeding arising out of her service as a director.

In November 2016, we entered into a definitive agreement with respect to the private placement of 1,644,737 shares of common stock and warrants to purchase 1,644,737 shares of our common stock to a group of accredited investors. All investors paid $9.12 for each share of common stock and warrant to purchase one share of common stock. The warrants are currently exercisable at an exercise price of $10.79 per share. Burrage Capital Healthcare Fund I, L.P. (“Burrage Capital”), of which Dr. Bardon serves as the Portfolio Manager, purchased 54,824 shares of common stock and warrants to purchase 54,824 shares of common stock in the private placement. UBS Oncology Impact Fund L.P. (“Oncology Impact Fund”) purchased 603,070 shares of common stock and warrants to purchase 603,070 shares of common stock in the private placement. Dr. Bardon’s spouse, Ansbert Gadicke, M.D., serves as the Managing Member of MPM Oncology Impact Management GP LLC, an indirect General Partner of Oncology Impact Fund. Additionally, in June 2017, we completed a public offering of 3,269,219 shares of our common stock at $13.00 per share. Oncology Impact Fund purchased 230,769 shares of common stock at the public offering price in this public offering. Dr. Bardon may be deemed to have a beneficial ownership interest in the shares purchased by the entities identified above.

~~There are no arrangements or understandings between Dr. Bardon and any other person pursuant to which Dr. Bardon was elected as a director.~~employment.

The exhibits filed as part of this Quarterly Report on Form 10-Q are set forth on the Exhibit ~~Index immediately below.~~Index.

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

Delaware	52-2386345
(State or other jurisdiction of incorporation or organization)	(I.R.S. Employer Identification No.)

~~86 South Street~~35 Parkwood Drive, Suite 210 Hopkinton, MA	01748
(Address of principal executive offices)	(Zip Code)

Large accelerated filer	☐	Accelerated filer	☒

Non-accelerated filer	☐	Smaller reporting company	☒

~~Non-accelerated filer~~	☐ ~~(Do not check if a smaller reporting company)~~	~~Smaller reporting~~Emerging growth company	☒

		~~Emerging growth company~~	☒

		~~Page~~
	PART I. FINANCIAL INFORMATION	Page
Item 1.	Consolidated Financial Statements (Unaudited)
	~~Condensed~~ Consolidated Balance Sheets	3
	~~Condensed~~ Consolidated Statements of Operations and Comprehensive Loss	4
	~~Condensed~~ Consolidated Statements of ~~Cash Flows~~Stockholders’ Equity	5
	Consolidated Statements of Cash Flows	6
	Notes to Unaudited ~~Condensed~~ Consolidated Financial Statements	67
Item 2.	Management’s Discussion and Analysis of Financial Condition and Results of Operations	2021
Item 3.	Quantitative and Qualitative Disclosures About Market Risk	3332
Item 4.	Controls and Procedures	3332
	PART II. OTHER INFORMATION
Item 1.	Legal Proceedings	3433
Item 1A.	Risk Factors	3433
Item 5.2.	~~Other Information~~Unregistered Sales of Equity Securities and Use of Proceeds	3433
Item 6.	Exhibits	3433
Exhibit Index		3534
Signatures		3635

	Warrants
Outstanding at December 31, ~~2015~~2017		~~1,181,776~~1,787,124
Grants		~~1,798,084~~—
Exercises		~~(641,743~~—	)
Expirations/cancellations		(~~540,033~~125,000	)
Outstanding at December 31, ~~2016~~2018		~~1,798,084~~1,662,124
Grants		—
Exercises		—
Expirations/cancellations		—
Outstanding at ~~September 30, 2017~~March 31, 2019		~~1,798,084~~1,662,124

	Restricted Stock Units		Weighted-Average Grant Date Fair Value
Total Nonvested Units at December 31, 2018		—	$	��
Granted		203,700		8.49
Exercised		—		—
Vested		—		—
Total Nonvested Units at March 31, 2019		203,700	$	8.49

Asset Category		Useful Life
Equipment		5-7 years
Furniture and fixtures		5 years
Leasehold improvements		Lesser of 10 years or the remaining term of the respective lease

	November Private Placement Warrants
Balance at December 31, 2015	$	—
Issuance of warrants		8,275
Change in fair value		(1,942	)
Balance at December 31, 2016		6,333
Change in fair value		11,474
Balance at September 30, 2017	$	17,807

	November Private Placement Warrants
Balance at December 31, 2017	$	13,128
Change in fair value		(4,617	)
Balance at December 31, 2018		8,511
Change in fair value		(2,821	)
Balance at March 31, 2019	$	5,690

	March 31, 2019			December 31, 2018
Risk-free interest rate		2.2	%		2.5	%
Expected term (in years)		2.6			2.9
Expected volatility		51.1	%		78.1	%
Expected dividend yield		0	%		0	%

	September 30, 2017			December 31, 2016
Risk-free interest rate		1.8	%		1.9	%
Expected term (in years)		4.1			4.9
Expected volatility		70.0	%		65.5	%
Expected dividend yield		0	%		0	%

	Three Months Ended March 31,
Cash paid for amounts included in the measurement of lease liabilities:	2019
Operating cash flow from operating leases (in thousands)	$	39

Right-of-use assets obtained in exchange for lease obligations:
Operating leases (in thousands)	$	2,980

Weighted Average Remaining Lease Term
Operating leases	8.9 years

Weighted Average Discount Rate
Operating leases		8.0	%

Year
2017	$	59
2018		174
2019		157
2020		164
Thereafter		70
Total minimum lease payments	$	624

Year
2019 (excluding the three months ended March 31, 2019)	$	378
2020		588
2021		508
2022		450
2023		462
Thereafter		2,405
Total lease payments	$	4,791
Less: present value discount		(1,381	)
Total	$	3,410

	For the Three Months Ended September 30,						Increase			For the Nine Months Ended September 30,						Increase
	2017			2016			(Decrease)			2017			2016			(Decrease)
Grant revenue	$	—		$	—		$	—		$	—		$	352		$	(352	)
Operating expenses:
Research and development		3,221			2,723			498			9,152			11,247			(2,095	)
General and administrative		1,968			1,452			516			5,811			4,136			1,675
Total operating expenses		5,189			4,175			1,014			14,963			15,383			(420	)
Loss from operations		(5,189	)		(4,175	)		(1,014	)		(14,963	)		(15,031	)		68
Other income		141			27			114			220			65			155
Change in fair value of warrant liabilities		(5,780	)		—			(5,780	)		(11,474	)		—			(11,474	)
Net loss	$	(10,828	)	$	(4,148	)	$	(6,680	)	$	(26,217	)	$	(14,966	)	$	(11,251	)

	Payments Due by Period
	Total		Less Than 1 Year		1 – 3 Years		3 – 5 Years		More than 5 Years
Operating lease commitments	$	624	$	194	$	430	$	0	$	—
Total	$	624	$	194	$	430	$	0	$	—


Exhibit Number		Description

10.1		~~Controlled Equity Offering~~^SM ~~Sales~~Form of Performance-Based Restricted Stock Unit Agreement ~~dated as of August 18, 2017, by and between Spring Bank Pharmaceuticals, Inc. and Cantor Fitzgerald & Co.~~under 2015 Stock Incentive Plan (incorporated by reference to Exhibit ~~10.1~~10.8 to Spring Bank Pharmaceuticals, Inc.’s ~~Current~~Annual Report on Form ~~8-K~~10-K filed on ~~August 18, 2017)~~March 11, 2019).

10.2		Amended and Restated Non-Employee Director Compensation Policy, effective January 1, 2019 (incorporated by reference to Exhibit 10.18.1 to Spring Bank Pharmaceuticals, Inc.’s Annual Report on Form 10-K filed on March 11, 2019).

31.1		Certification of Principal Executive Officer Pursuant to Rules 13a-14(a) and 15d-14(a) under the Securities Exchange Act of 1934, as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.

31.2		Certification of Principal Financial Officer Pursuant to Rules 13a-14(a) and 15d-14(a) under the Securities Exchange Act of 1934, as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.

32.1		Certification of Principal Executive Officer and Principal Financial Officer Pursuant to 18 U.S.C. Section 1350, as Adopted Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.

101.INS		XBRL Instance Document

101.SCH		XBRL Taxonomy Extension Schema Document

101.CAL		XBRL Taxonomy Extension Calculation Linkbase Document

101.DEF		XBRL Taxonomy Extension Definition Linkbase Document

101.LAB		XBRL Taxonomy Extension Label Linkbase Document

101.PRE		XBRL Taxonomy Extension Presentation Linkbase Document

	Spring Bank Pharmaceuticals, Inc.

Date: ~~October 31, 2017~~April 29, 2019	By:	/s/ Jonathan Freve
		Jonathan Freve
		Chief Financial Officer and Treasurer (Principal Financial and Accounting Officer)