Aceragen (ACGN) 10-Q 30 Apr 20 2020 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2020	Apr. 30, 2020
Document and Entity Information
Document Type	10-Q
Document Period End Date	Mar. 31, 2020
Entity Registrant Name	IDERA PHARMACEUTICALS, INC.
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		33,702,854
Entity Central Index Key	0000861838
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Amendment Flag	false

CONDENSED BALANCE SHEETS

CONDENSED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 27,909	$ 40,019
Short-term investments	5,578	2,774
Prepaid expenses and other current assets	2,422	3,475
Total current assets	35,909	46,268
Property and equipment, net	80	97
Operating lease right-of-use asset	1,007	1,054
Other assets	70	70
Total assets	37,066	47,489
Current liabilities:
Accounts payable	941	457
Accrued expenses	7,385	7,461
Operating lease liability	162	163
Future tranche right liability	25,725	46,436
Total current liabilities	34,213	54,517
Warrant liability, long-term	2,140	3,241
Operating lease liability, net of current portion	857	899
Total liabilities	37,210	58,657
Commitments and contingencies
Stockholders’ equity (deficit)
Common stock, $0.001 par value, Authorized — 70,000 shares; Issued and outstanding — 30,607 and 29,672 at March 31, 2020 and December 31, 2019, respectively	31	30
Additional paid-in capital	711,898	709,692
Accumulated deficit	(712,073)	(720,890)
Total stockholders’ deficit	(144)	(11,168)
Total liabilities and stockholders’ deficit	37,066	47,489
Series B1 redeemable convertible preferred stock (Note 7); Designated — 278 shares, Issued and outstanding — 24 shares at March 31, 2020 and December 31, 2019
Stockholders’ equity (deficit)
Preferred stock
Series A convertible preferred stock; Designated — 1,500 shares, Issued and outstanding — 1 share
Stockholders’ equity (deficit)
Preferred stock

CONDENSED BALANCE SHEETS (Paren

CONDENSED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2020	Dec. 31, 2019
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	70,000,000	70,000,000
Common stock, shares issued	30,607,000	29,672,000
Common stock, shares outstanding	30,607,000	29,672,000
Series A convertible preferred stock; Designated — 1,500 shares, Issued and outstanding — 1 share
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares designated	1,500,000	1,500,000
Preferred stock, shares issued	1,000	1,000
Preferred stock, shares outstanding	1,000	1,000
Series B1 redeemable convertible preferred stock (Note 7); Designated — 278 shares, Issued and outstanding — 24 shares at March 31, 2020 and December 31, 2019
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares designated	278,000	278,000
Preferred stock, shares issued	24,000	24,000
Preferred stock, shares outstanding	24,000	24,000
Common stock, shares outstanding	24,000	24,000

CONDENSED STATEMENTS OF OPERATI

CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Operating expenses:
Research and development	$ 9,510	$ 8,102
General and administrative	3,642	3,143
Restructuring costs		131
Total operating expenses	13,152	11,376
Loss from operations	(13,152)	(11,376)
Other income (expense):
Interest income	125	404
Warrant revaluation income	1,101
Future tranche right revaluation income	20,711
Foreign currency exchange gain (loss)	32	(2)
Net income (loss)	$ 8,817	$ (10,974)
Net income (loss) per share applicable to common stockholders (Note 12)
Basic	$ 0.27	$ (0.40)
Diluted	$ 0.22	$ (0.40)
Weighted-average number of common shares used in computing net income (loss) per share applicable to common stockholders
Basic	30,300	27,676
Diluted	33,010	27,676
Comprehensive income (loss):
Net income (loss)	$ 8,817	$ (10,974)
Unrealized gain on available-for-sale securities		2
Total other comprehensive income		2
Comprehensive income (loss):	$ 8,817	$ (10,972)

CONDENSED STATEMENTS OF CASH FL

CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash Flows from Operating Activities:
Net income (loss)	$ 8,817	$ (10,974)
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Stock-based compensation	750	1,016
Warrant liability revaluation income	(1,101)
Future tranche right liability revaluation income	(20,711)
Issuance of common stock for services rendered	26	23
Accretion of discounts on short-term investments	(18)	(181)
Unrealized gain on available-for-sale securities		2
Depreciation and amortization expense	24	35
Gain on disposal of property and equipment		(8)
Changes in operating assets and liabilities:
Prepaid expenses and other assets	1,313	(576)
Accounts payable, accrued expenses, and other liabilities	148	(2,694)
Other	4
Net cash used in operating activities	(10,748)	(13,357)
Cash Flows from Investing Activities:
Purchases of available-for-sale securities	(5,535)	(35,485)
Proceeds from maturity of available-for-sale securities	2,749
Proceeds from the sale of property and equipment		8
Purchases of property and equipment	(7)	(4)
Net cash used in investing activities	(2,793)	(35,481)
Cash Flows from Financing Activities:
Proceeds from common stock financings, net	1,406	1,585
Proceeds from employee stock purchases	25	26
Other		(6)
Net cash provided by financing activities	1,431	1,605
Net decrease in cash and cash equivalents	(12,110)	(47,233)
Cash and cash equivalent, beginning of period	40,019	71,431
Cash and cash equivalents, end of period	27,909	24,198
Supplemental disclosure of cash flow information:
Increase to right-of-use asset upon adoption of ASC 842		261
Increase to lease liability upon adoption of ASC 842		$ 261
Supplemental disclosure of non-cash financing and investing activities:
Capitalized offering costs in accounts payable and accrued expenses	$ 260

CONDENSED STATEMENTS OF STOCKHO

CONDENSED STATEMENTS OF STOCKHOLDER’S EQUITY (DEFICIT) - USD ($) shares in Thousands, $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income	Series B1 redeemable convertible preferred stock (Note 7); Designated — 278 shares, Issued and outstanding — 24 shares at March 31, 2020 and December 31, 2019	Total
Beginning balance at Dec. 31, 2018	$ 27	$ 728,342	$ (664,375)			$ 63,994
Beginning balance (in shares) at Dec. 31, 2018	27,188
Sale of common stock, net of issuance costs	$ 1	1,584				1,585
Sale of common stock, net of issuance costs (in shares)	533
Issuance of commitment shares (in shares)	270
Issuance of common stock under employee stock purchase plan		26				26
Issuance of common stock under employee stock purchase plan (in shares)	11
Issuance of common stock for services rendered		23				23
Issuance of common stock for services rendered (in shares)	6
Stock-based compensation expense		1,016				1,016
Unrealized gain on marketable securities				$ 2		2
Net income (loss)			(10,974)			(10,974)
Ending balance at Mar. 31, 2019	$ 28	730,991	(675,349)	$ 2		55,672
Ending balance (in shares) at Mar. 31, 2019	28,008
Beginning balance at Dec. 31, 2018	$ 27	728,342	(664,375)			63,994
Beginning balance (in shares) at Dec. 31, 2018	27,188
Net income (loss)						(10,974)
Ending balance at Dec. 31, 2019	$ 30	709,692	(720,890)			$ (11,168)
Ending balance (in shares) at Dec. 31, 2019	29,672				24	29,672
Sale of common stock, net of issuance costs	$ 1	1,405				$ 1,406
Sale of common stock, net of issuance costs (in shares)	854
Issuance of common stock under employee stock purchase plan		25				25
Issuance of common stock under employee stock purchase plan (in shares)	19
Issuance of common stock under equity incentive plan (vesting of restricted stock units)	48
Issuance of common stock for services rendered		26				26
Issuance of common stock for services rendered (in shares)	14
Stock-based compensation expense		750				750
Net income (loss)			8,817			8,817
Ending balance at Mar. 31, 2020	$ 31	$ 711,898	$ (712,073)			$ (144)
Ending balance (in shares) at Mar. 31, 2020	30,607				24	30,607

Business and Organization

Business and Organization	3 Months Ended
	Mar. 31, 2020
Business and Organization
Business and Organization	Note 1. Business and Organization Business Overview Idera Pharmaceuticals, Inc. (“Idera” or the “Company”), a Delaware corporation, is a clinical-stage biopharmaceutical company with a business strategy focused on the clinical development, and ultimately the commercialization, of drug candidates for both oncology and rare disease indications characterized by small, well-defined patient populations with serious unmet medical needs. The Company’s current focus is on its Toll-like receptor, or TLR, agonist, tilsotolimod (IMO-2125), for oncology. The Company believes it can develop and commercialize targeted therapies on its own. To the extent the Company seeks to develop drug candidates for broader disease indications, it has entered into and may explore additional collaborative alliances to support development and commercialization. Liquidity and Financial Condition As of March 31, 2020, the Company had an accumulated deficit of $712.1 million and a cash, cash equivalents, and short-term investments balance of $33.5 million, which includes the $6.2 million contingently refundable option fee received in connection with the 2019 Private Placement, as defined and more fully described in Note 7. The Company expects to incur substantial operating losses in future periods and will require additional capital as it seeks to advance tilsotolimod and any future drug candidates through development to commercialization. The Company does not expect to generate product revenue, sales-based milestones or royalties until the Company successfully completes development of and obtains marketing approval for The Company follows the provisions of Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 205-40, Presentation of Financial Statements—Going Concern , which requires management to assess the Company’s ability to continue as a going concern within one year after the date the financial statements are issued. The Company’s balance of cash, cash equivalents, and short-term investments on hand as of March 31, 2020, excluding the $6.2 million contingently refundable Option Fee (Note 7), plus the $5.0 million gross proceeds received in April 2020 pursuant to the April 2020 Securities Purchase Agreement (Note 13) , is sufficient to fund operations into the first quarter of 2021, but is not sufficient to fund operations for the one-year period after the date the financial statements are issued. As a result, there is substantial doubt about the Company’s ability to continue as a going concern through the one-year period from the date these financial statements are issued. However, the Company estimates that it is probable that the $6.2 million contingently refundable Option Fee will not need to be refunded and, in this scenario, the Company’s cash, cash equivalents, and short term-investments as of March 31, 2020, plus the $5.0 million gross proceeds received in April 2020 pursuant to the April 2020 Securities Purchase Agreement (Note 13), will be sufficient to fund operations into the second quarter of 2021. Management’s plans that are intended to mitigate the risk of going concern include raising additional capital through the Company’s December 2019 Securities Purchase Agreement (Note 7), Common Stock Purchase Agreement (Note 8), “At-The-Market” Equity Program (Note 8) The Company has and will continue to evaluate available alternatives to extend its operations beyond the one-year period after the date the financial statements are issued. Management’s operating plan which underlies the analysis of the Company’s ability to continue as a going concern involves the estimation of the amount and timing of future cash inflows and outflows. Actual results could vary from the operating plan.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2020
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	Note 2. Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited financial statements included herein have been prepared by the Company in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Accordingly, certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. In the opinion of management, all adjustments, consisting of normal recurring adjustments, and disclosures considered necessary for a fair presentation of interim period results have been included. Interim results for the three months ended March 31, 2020 are not necessarily indicative of results that may be expected for the year ending December 31, 2020. For further information, refer to the financial statements and footnotes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2019 (“2019 Form 10-K”), which was filed with the SEC on March 12, 2020. Cash and Cash Equivalents The Company considers all highly liquid investments with maturities of 90 days or less when purchased to be “cash equivalents.” Cash and cash equivalents at March 31, 2020 and December 31, 2019 consisted of cash, money market funds, and commercial paper. Financial Instruments The fair value of the Company’s financial instruments is determined and disclosed in accordance with the three-tier fair value hierarchy specified in Note 3. The Company is required to disclose the estimated fair values of its financial instruments. As of March 31, 2020 and December 31, 2019, the Company’s financial instruments consisted of cash, cash equivalents, short-term investments, receivables and warrant and future tranche right liabilities. The estimated fair values of these financial instruments approximate their carrying values. As of March 31, 2020, the Company did not have any derivatives, hedging instruments, or other similar financial instruments. Concentration of Credit Risk Financial instruments that subject the Company to credit risk primarily consist of cash, cash equivalents, and investments. The Company’s credit risk is managed by investing in highly rated money market instruments, certificates of deposit, corporate bonds, commercial paper and debt securities. Due to these factors, no significant additional credit risk is believed by management to be inherent in the Company’s assets. As of March 31, 2020, all of the Company’s cash and cash equivalents were held at two financial institutions. Operating Lease Right-of-use Asset and Lease Liability The Company accounts for leases under ASC Topic 842, Leases . The Company determines if an arrangement is a lease at inception. Operating leases are included in long-term right-of-use assets and current and long-term lease liabilities within the Company’s condensed balance sheets. Right-of-use (“ROU”) assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease right-of-use assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. As most of the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rates, which are the rates incurred to borrow on a collateralized basis over a similar term, an amount equal to the lease payments in a similar economic environment. Lease expense for lease payments is recognized on a straight-line basis over the lease term. The right-of-use assets are tested for impairment according to ASC 360. Leases with an initial term of 12 months or less are not recorded on the balance sheet and are recognized as lease expense on a straight-line basis over the lease term. As of March 31, 2020 and December 31, 2019, the Company’s operating lease ROU asset and corresponding short-term and long-term lease liabilities relate to its existing Exton, PA facility operating lease which expires on May 31, 2025 as a result of the Company’s election to exercise its five-year renewal option in January 2020. Note 2. Summary of Significant Accounting Policies (Continued) Warrant Liability The Company accounts for stock warrants as either equity instruments, liabilities or derivative liabilities in accordance with ASC 480, Distinguishing Liabilities from Equity (ASC 480) and/or ASC 815, Derivatives and Hedging (ASC 815), depending on the specific terms of the warrant agreement. Freestanding warrants for shares that are potentially redeemable, whereby the Company may be required to transfer assets (e.g. cash or other assets) outside of its control, are classified as liabilities. Liability-classified warrants are recorded at their estimated fair values at each reporting period until they are exercised, terminated, reclassified or otherwise settled. Changes in the estimated fair value of liability-classified warrants are recorded in Warrant Revaluation Income in the Company’s condensed statements of operations and comprehensive income (loss). Equity classified warrants are recorded within additional paid-in capital at the time of issuance and not subject to remeasurement. For additional discussion on warrants, see Note 7. Future Tranche Right Liability In connection with the Company’s 2019 Private Placement, as more fully described in Note 7, the Company entered into the December 2019 Securities Purchase Agreement, which contains call options on redeemable preferred shares with warrants (conditionally exercisable for shares that are puttable). The Company determined that these call options represent freestanding financial instruments and accounts for the options as a liabilities (“Future Tranche Right Liability”) under ASC 480, which requires the measurement of the fair value of the liability at the time of issuance and recording changes as a charge to current earnings at each reporting period, which is included in Future Tranche Right Liability Revaluation Income in the Company’s condensed statements of operations and comprehensive income (loss). Preferred Stock The Company applies ASC 480 when determining the classification and measurement of its preferred stock. Preferred shares subject to mandatory redemption are classified as liability instruments and are measured at fair value. Conditionally redeemable preferred shares (including preferred shares that feature redemption rights that are either within the control of the holder or subject to redemption upon the occurrence of uncertain events not solely within the Company’s control) are classified as temporary equity. At all other times, preferred shares are classified as stockholders’ equity. Accretion of redeemable convertible preferred stock includes the accretion of the Company's Series B redeemable convertible preferred stock to its stated value. The carrying value of the Series B redeemable convertible preferred stock is being accreted to redemption value using the effective interest method, from the date of issuance to the earliest date the holders can demand redemption. Income Taxes In accordance with ASC 270, Interim Reporting , and ASC 740, Income Taxes , the Company is required at the end of each interim period to determine the best estimate of its annual effective tax rate and then apply that rate in providing for income taxes on a current year-to-date (interim period) basis. For the three months ended March 31, 2020 and 2019, the Company recorded no tax expense or benefit due to the expected current year loss and its historical losses. The Company has not recorded its net deferred tax asset as of either March 31, 2020 or December 31, 2019 because it maintained a full valuation allowance against all deferred tax assets as of these dates as management has determined that it is not more likely than not that the Company will realize these future tax benefits. As of March 31, 2020 and December 31, 2019, the Company had no uncertain tax positions. Note 2. Summary of Significant Accounting Policies (Continued) New Accounting Pronouncements From time to time, new accounting pronouncements are issued by the FASB and rules are issued by the SEC that the Company has or will adopt as of a specified date. Unless otherwise noted, management does not believe that any other recently issued accounting pronouncements issued by the FASB or guidance issued by the SEC had, or is expected to have, a material impact on the Company’s present or future financial statements. Recently Adopted Accounting Pronouncements In June 2016, the FASB issued Accounting Standard Update (“ASU’) No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). This standard requires that credit losses be reported using an expected losses model rather than the incurred losses model that is currently used, and establishes additional disclosures related to credit risks. For available-for-sale debt securities with unrealized losses, this standard now requires allowances to be recorded instead of reducing the amortized cost of the investment. The Company adopted ASU 2016-13 in the first quarter of 2020. The adoption of this ASU did not have a material effect on the Company’s financial statements. In August 2018, the FASB issued ASU No. 2018-13, Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”), which amends ASC 820, Fair Value Measurement . ASU 2018-13 modifies the disclosure requirements for fair value measurements by removing, modifying, or adding certain disclosures. The Company adopted ASU 2018-13 in the first quarter of 2020. The adoption of this ASU did not have a material effect on the Company’s financial statements.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2020
Fair Value Measurements
Fair Value Measurements	Note 3. Fair Value Measurements Assets and Liabilities Measured at Fair Value on a Recurring Basis The Company applies the guidance in ASC 820, Fair Value Measurement , to account for financial assets and liabilities measured on a recurring basis. Fair value is measured at the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. As such, fair value is a market-based measurement that is determined based on assumptions that market participants would use in pricing an asset or liability. The Company uses a fair value hierarchy, which distinguishes between assumptions based on market data (observable inputs) and an entity's own assumptions (unobservable inputs). The guidance requires that fair value measurements be classified and disclosed in one of the following three categories: · Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities; · Level 2: Quoted prices in markets that are not active or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability · Level 3: Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity). Determining which category an asset or liability falls within the hierarchy requires significant judgment. The Company evaluates its hierarchy disclosures each reporting period. There were no transfers between Level 1, 2 and 3 during the three months ended March 31, 2020. Note 3. Fair Value Measurements (Continued) The table below presents the assets and liabilities measured and recorded in the financial statements at fair value on a recurring basis at March 31, 2020 and December 31, 2019 categorized by the level of inputs used in the valuation of each asset and liability. March 31, 2020 (In thousands) Total Level 1 Level 2 Level 3 Assets Cash $ 250 $ 250 $ — $ — Cash equivalents – money market funds 26,860 26,860 — — Cash equivalents – commercial paper 799 — 799 — Short-term investments – commercial paper 5,578 — 5,578 — Total assets $ 33,487 $ 27,110 $ 6,377 $ — Liabilities Warrant liability $ 2,140 $ — $ — $ 2,140 Future tranche right liability 25,725 — — 25,725 Total liabilities $ 27,865 $ — $ — $ 27,865 December 31, 2019 (In thousands) Total Level 1 Level 2 Level 3 Assets Cash $ 250 $ 250 $ — $ — Cash equivalents – money market funds 39,769 39,769 — — Short-term investments – commercial paper 2,774 — 2,774 — Total assets $ 42,793 $ 40,019 $ 2,774 $ — Liabilities Warrant liability $ 3,241 $ — $ — $ 3,241 Future tranche right liability 46,436 — — 46,436 Total liabilities $ 49,677 $ — $ — $ 49,677 The Level 1 assets consist of money market funds, which are actively traded daily. The Level 2 assets consist of commercial paper whose fair value may not represent actual transactions of identical securities. The fair value of commercial paper is generally determined based on the relationship between the investment’s discount rate and the discount rates of the same issuer’s commercial paper available in the market which may not be actively traded daily. Since these fair values may not be based upon actual transactions of identical securities, they are classified as Level 2. Changes in Level 3 Liabilities Measured at Fair Value on a Recurring Basis Warrant Liability and Future Tranche Right Liability The reconciliation of the Company's warrant and future tranche right liability measured at fair value on a recurring basis using unobservable inputs (Level 3) is as follows: Future Warrant Tranche Right (In thousands) Liability Liability Balance, December 31, 2019 $ 3,241 $ 46,436 Change in the fair value of liability (1,101) (20,711) Balance, March 31, 2020 $ 2,140 $ 25,725 Note 3. Fair Value Measurements (Continued) Assumptions Used in Determining Fair Value of Liability-Classified Warrants The Company utilizes an option pricing model to value its liability-classified warrants. Inherent in the valuation model are assumptions related to volatility, risk-free interest rate, expected term, dividend rate, and other scenarios (i.e. probability of complex features of the warrants being triggered). The fair value of the warrants has been estimated with the following weighted-average assumptions: March 31, December 31, 2020 2019 Risk-free interest rate Expected dividend yield — — Expected term (years) 6.73 6.98 Expected volatility Exercise price (per share) $ 1.52 $ 1.52 Assumptions Used in Determining Fair Value of Future Tranche Rights The Company utilizes a binomial lattice model to value the Series B2 (tranche 2) and B3 (tranche 3) tranches and a Monte Carlo simulation to value the Series B4 (tranche 4) future tranche rights. The Company selected these models as it believes they are reflective of all significant assumptions that market participants would likely consider in negotiating the transfer of the Future Tranche Rights. Such assumptions include, among other inputs, stock price volatility, risk-free rates, redemption and early exercise assumptions, cancellation and conversion assumptions, and the potential for future adjustment of the conversion price due to a future dilutive financing. The estimated fair value of the Future Tranche Rights is determined using Level 2 and Level 3 inputs. Significant inputs and assumptions used in the valuation models are as follows: March 31, December 31, 2020 2019 Risk-free interest rate for warrants Risk-free interest rate for preferred stock 0.59% - 0.65% 1.84% - 1.88% Expected dividend yield — — Expected term (years) of call option on preferred stock 0.91 - 1.91 1.16 - 2.16 Expected term (years) of warrants 7.91 - 8.91 8.16 - 9.16 Expected volatility Exercise price (per share) for common stock equivalent for preferred stock and warrant $ 1.52 - 1.82 $ 1.52 - 1.82 As of March 31, 2020 and December 31, 2019, the Company deemed it probable that shareholder approval would be obtained, on or prior to December 31, 2020, with respect to increasing the Company’s authorized shares of common stock in an amount sufficient to cover the conversion of all potential convertible securities issuable upon exercise of the Future Tranche Rights. See Note 7 for further details on the such required shareholder approval.

Investments

Investments	3 Months Ended
	Mar. 31, 2020
Investments
Investments	Note 4. Investments The Company ’s available-for-sale investments at fair value consisted of the following as of March 31, 2020 and December 31, 2019: March 31, 2020 Gross Gross Estimated Unrealized Unrealized Fair (In thousands) Cost (Losses) Gains Value Short-term investments – commercial paper $ 5,578 $ — $ — $ 5,578 Total short-term investments 5,578 — — 5,578 Total investments $ 5,578 $ — $ — $ 5,578 December 31, 2019 Gross Gross Estimated Unrealized Unrealized Fair (In thousands) Cost (Losses) Gains Value Short-term investments – commercial paper $ 2,774 $ — $ — $ 2,774 Total short-term investments 2,774 — — 2,774 Total investments $ 2,774 $ — $ — $ 2,774 The Company had no realized gains or losses from the sale of investments in available-for-sale securities in each of the three months ended March 31, 2020 and 2019. In accordance with ASU 2016-13, if the fair value of the Company’s investments in available-for-sale debt securities is less than the amortized cost, the Company records (i) an allowance for credit losses with a corresponding charge to net income (loss) for any credit-related impairment, with subsequent improvements in expected credit losses recognized as a reversal of the allowance, and/or (ii) any non-credit impairment loss to other comprehensive income (loss). As of March 31, 2020 and December 31, 2019, the Company had no allowance for credit losses pertaining to the Company’s investments in available-for-sale debt securities. Additionally, there were no impairment charges or recoveries recorded during each of the three months ended March 31, 2020 and 2019.

Property and Equipment

Property and Equipment	3 Months Ended
	Mar. 31, 2020
Property and Equipment
Property and Equipment	Note 5. Property and Equipment At March 31, 2020 and December 31, 2019, property and equipment, net, consisted of the following: March 31, December 31, (In thousands) 2020 2019 Leasehold improvements $ 107 $ 107 Equipment and other 770 764 Total property and equipment, at cost 877 871 Less: Accumulated depreciation and amortization 797 774 Property and equipment, net $ 80 $ 97 Depreciation and amortization expense on property and equipment was less than $0.1 million for each of the three months ended March 31, 2020 and 2019 . Additionally, there were no non-cash property additions or impairment-related charges recognized during each of the respective time periods.

Accrued Expenses

Accrued Expenses	3 Months Ended
	Mar. 31, 2020
Accrued Expenses
Accrued Expenses	Note 6. Accrued Expenses At March 31, 2020 and December 31, 2019, accrued expenses consisted of the following: March 31, December 31, (In thousands) 2020 2019 Payroll and related costs $ 1,260 $ 2,179 Clinical and nonclinical trial expenses 5,247 4,199 Professional and consulting fees 701 859 Restructuring expenses 64 113 Other 113 111 Total accrued expenses $ 7,385 $ 7,461

Redeemable Convertible Preferre

Redeemable Convertible Preferred Stock	3 Months Ended
	Mar. 31, 2020
Redeemable Convertible Preferred Stock
Redeemable Convertible Preferred Stock	Note 7. Redeemable Convertible Preferred Stock December 2019 Private Placement On December 23, 2019, the Company entered into a Securities Purchase Agreement (the “December 2019 Securities Purchase Agreement”) with institutional investors affiliated with Baker Brothers (the “Purchasers”), an existing shareholder and related party as more fully described in Note 11, under which the Company sold 23,684 shares of Series B1 convertible preferred stock (“Series B1 Preferred Stock”) and warrants to purchase 2,368,400 shares of the Company’s common stock at an exercise price of $1.52 per share (or, if the holder elects to exercise the warrants for shares of Series B1 Preferred Stock, 23,684 shares of Series B1 Preferred Stock at an exercise price of $152 per share) for aggregate gross proceeds of $3.9 million (the “Initial Closing”). In addition, the Company has agreed to sell to the Purchasers, at their option and subject to certain conditions including stockholder approval to increase the Company’s authorized shares of common stock, shares of Series B2 convertible preferred stock (“Series B2 Preferred Stock”), Series B3 convertible preferred stock (“Series B3 Preferred Stock”) and Series B4 convertible preferred stock (“Series B4 Preferred Stock) and accompanying warrants to purchase common stock (or preferred stock at the election of the holder) over a 21-month period after stockholder approval is received (the “Future Tranche Rights”). As of March 31, 2020, the Company’s outstanding Future Tranche Rights are as follows: Price Per Aggregate Future Tranche Rights Preferred Shares Share Purchase Price Tranche 2 (Series B2) (1) 98,685 $ $ 15,000,120 Tranche 3 (Series B3) (2) 82,418 $ 15,000,076 Tranche 4 (Series B4) (2) 82,418 $ 15,000,076 Total 263,521 $ 45,000,272 (1) Accompanied by related warrants to purchase up to 9,868,500 shares of the Company’s common stock (or, if the holder elects to exercise the warrants for shares of Series B1 Preferred Stock, 98,685 shares of Series B1 Preferred Stock), at an exercise price of $1.52 per share (or, if the holder elects to exercise the warrants for Series B1 Preferred Stock, $152 per share of Series B1 Preferred Stock). (2) Accompanied by related warrants to purchase up to 6,593,440 shares of the Company’s common stock (or, if the holder elects to exercise the warrants for shares of Series B1 Preferred Stock, 65,934 shares of Series B1 Preferred Stock), at an exercise price of $1.82 per share (or, if the holder elects to exercise the warrants for Series B1 Preferred Stock, $182 per share of Series B1 Preferred Stock). As consideration for the Future Tranche Rights, the Company received aggregate gross proceeds of $6.2 million (the “Option Fee”). In the event the Company does not receive the required shareholder approval to increase the Company’s authorized shares of common stock in an amount sufficient to cover the conversion of all potential convertible securities issuable under the December 2019 Securities Purchase Agreement on or prior to December 31, 2020, the Option Fee shall be returned to the Purchasers. The Board recommends the stockholders support the proposal to increase the authorized shares. Note 7. Redeemable Convertible Preferred Stock (Continued) The purchase and sale of the securities issuable under tranches 2, 3 and 4 may occur in two or more separate closings, each to be conducted at the Purchasers’ discretion. The right of the Purchasers to purchase Series B2, Series B3 and Series B4 Preferred Stock will expire 9 months (or on the 10 th business day following the Company’s ORR Data Announcement, as defined in the December 2019 Securities Purchase Agreement, for its ILLUMINATE-301 study, if later) , 15 months, and 21 months following shareholder approval, respectively. However, the Purchasers’ right to purchase securities under tranches 3 and 4 is contingent on the purchase of all of the securities in each preceding tranche right. In the event the Purchaser’s do not purchase all of the securities in a given tranche, their right to purchase shares in future tranches terminates and any outstanding warrants issued under the December 2019 Securities Purchase Agreement would terminate. Additionally, the Company has the right to decline the Series B4 Preferred Stock investment if its common stock trades at $7.60 for 20 days out of 30 days subsequent to the closing of the Series B3 Preferred Stock investment. In addition to the aggregate gross proceeds received from the Initial Closing and the Option Fee, the Company is eligible, at the discretion of the Purchasers, to receive aggregate gross proceeds of up to an additional $87.6 million under the December 2019 Securities Purchase Agreement. Accounting Considerations The Company determined that the Series B1 Preferred Stock, the accompanying Series B1 warrants, and each of the Future Tranche Rights represented a freestanding financial instrument. The warrants and the Future Tranche Rights are liability classified as the underlying shares are potentially redeemable and such redemption is deemed to be outside of the Company’s control. Due to the redeemable nature of the Series B1 Preferred Stock, the Series B1 Preferred Stock is currently classified as temporary equity. While the Series B1 Preferred Stock is not currently redeemable, it will become redeemable either on (i) the fifth anniversary of the initial issue date, or December 23, 2024, provided that certain events (the “Redemption Loss Events”) do not occur first or (ii) upon a liquidation or deemed liquidation event, provided that certain events (the “Liquidation Loss Events”) do not occur first. The Company cannot assess the probability of whether the Redemption Loss Events will occur prior to the fifth anniversary of the initial issue date, if ever, as certain factors triggering such events are outside the control of the Company. Accordingly, the carrying value of the Series B1 Preferred Stock is being accreted to its redemption value as of March 31, 2020. In the event the holders of the Series B1 Preferred Stock lose their right to request redemption, the Series B Preferred Stock will no longer be accreted to its redemption value until redemption upon a liquidation event is deemed probable. For the three months ended March 31, 2020, accretion was de minimis.

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2020
Stockholders' Equity
Stockholders' Equity	Note 8. Stockholders’ Equity Equity Financings Common Stock Purchase Agreement On March 4, 2019, the Company entered into a Purchase Agreement with Lincoln Park Capital Fund, LLC (“Lincoln Park”), pursuant to which, upon the terms and subject to the conditions and limitations set forth therein, Lincoln Park has committed to purchase an aggregate of $35.0 million of shares of Company common stock from time to time at the Company’s sole discretion (the “LPC Purchase Agreement”). As consideration for entering into the LPC Purchase Agreement, the Company issued 269,749 shares of Company common stock to Lincoln Park as a commitment fee (the “Commitment Shares”). The closing price of the Company’s common stock on March 4, 2019 was $2.84 and the Company did not receive any cash proceeds from the issuance of the Commitment Shares. During the three months ended March 31, 2020, the Company sold 450,000 shares pursuant to the LPC Purchase Agreement, resulting in net proceeds of $0.8 million. No shares were sold during the three months ended March 31, 2019. Note 8. Stockholders’ Equity (Continued) "At-The-Market" Equity Program In November 2018, the Company entered into an Equity Distribution Agreement (the “ATM Agreement”) with JMP Securities LLC (“JMP”) pursuant to which the Company may issue and sell shares of its common stock having an aggregate offering price of up to $50.0 million (the “Shares”) through JMP as its agent. Subject to the terms and conditions of the ATM Agreement, JMP will use its commercially reasonable efforts to sell the Shares from time to time, based upon the Company’s instructions, by methods deemed to be an “at the market offering” as defined in Rule 415(a)(4) promulgated under the Securities Act of 1933, as amended, or if specified by the Company, by any other method permitted by law, including but not limited to in negotiated transactions. The Company has no obligation to sell any of the Shares, and the Company or JMP may at any time suspend sales under the ATM Agreement or terminate the ATM Agreement. JMP is entitled to a fixed commission of 3.0% of the gross proceeds from Shares sold. During the three months ended March 31, 2020 and 2019, the Company sold 403,983 and 532,700 Shares, respectively, pursuant to the ATM Agreement, resulting in net proceeds, after deduction of commissions and other offering expenses, of $0.6 million and $1.6 million, respectively. Common Stock Warrants In connection with various financing transactions, the Company has issued warrants to purchase shares of the Company’s common and preferred stock. The Company accounts for common and preferred stock warrants as equity instruments or liabilities, depending on the specific terms of the warrant agreement. The following table summarizes outstanding warrants to purchase shares of the Company’s common and preferred stock as of March 31, 2020 and December 31, 2019: Number of Shares March 31, December 31, Weighted-Average Description 2020 2019 Exercise Price Expiration Date Liability-classified Warrants December 2019 Series B1 warrants (1) 2,368,400 2,368,400 $ 1.52 Dec 2026 2,368,400 2,368,400 Equity-classified Warrants May 2013 warrants 1,949,754 1,949,754 $ 0.08 None September 2013 warrants 514,756 514,756 $ 0.08 None February 2014 warrants 266,006 266,006 $ 0.08 None 2,730,516 2,730,516 Total outstanding 5,098,916 5,098,916 (1) The Series B1 warrants are exercisable for either common stock (exercise price of $1.52) or Series B1 Convertible Preferred Stock (exercise price of $152) at the discretion of the warrant holder.

Collaboration and License Agree

Collaboration and License Agreements	3 Months Ended
	Mar. 31, 2020
Collaboration and License Agreements
Collaboration and License Agreements	Note 9. Collaboration and License Agreements Option and License Agreement with Licensee In April 2019, the Company entered into an amended and restated option and license agreement with a Note 9. Collaboration and License Agreements (Continued) Under the terms of the Licensee Agreement, the Company received upfront, non-refundable fees totaling approximately $1.4 million and ownership of 10% of Licensee’s outstanding common stock, subject to future adjustment, for granting Licensee the IMO-8400 License, the IMO-9200 Option Period License and transfer of related drug materials. In addition, the Company is eligible to receive a $1 million non-refundable fee upon Licensee exercising the IMO-9200 Option (“Option Fee”) and is entitled to certain sub-licensing payments on sublicense revenue received by Licensee, if any. The Company may also be eligible for certain development and sales-based milestone payments and royalties on global net sales for any future products. The Company does not anticipate the receipt of any of the future milestones or royalties in the short term, if ever. The Company accounts for the Licensee Agreement in accordance with ASC 606. As of March 31, 2020, the Option Fee and all potential future development/sales milestone payments were fully constrained, and there were no remaining performance obligations under the Licensee Agreement. The Company re-evaluates its performance obligations and the transaction price in each reporting period and as uncertain events are resolved or other changes in circumstances occur. As disclosed above, in connection with the Licensee Agreement, the Company owns 10% of Licensee’s outstanding common stock, subject to future adjustment. The Company accounts for the investment using the measurement alternative provided for in ASC Topic 321, Investments-Equity Securities , as the equity securities are without a readily determinable fair value, and the arrangement does not result in Idera having control or significant influence over Licensee. Accordingly, the securities are measured at cost, less any impairment, plus or minus changes resulting from observable price changes and are recorded in Other assets at a value of less than $0.1 million in the accompanying balance sheets. As of March 31, 2020, the Company considered the cost of the investment to not exceed the fair value of the investment and did not identify any observable price changes.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2020
Stock-Based Compensation
Stock-Based Compensation	Note 10. Stock-Based Compensation As of March 31, 2020, the only equity compensation plans from which the Company may currently issue new awards are the Company’s 2013 Stock Incentive Plan Equity Incentive and Employee Stock Purchase Plans 2013 Stock Incentive Plan T he 2013 Plan allows for the issuance of incentive stock options intended to qualify under Section 422 of the Internal Revenue Code, non-statutory stock options, stock appreciation rights, restricted stock awards, restricted stock units, other stock-based awards and performance awards. The total number of shares of common stock authorized for issuance under the 2013 Plan is 5,653,057 shares of As of March 31, 2020, options to purchase a total of 3,977,830 shares of common stock and 376,210 restricted stock units were outstanding and up to 1,571,751 shares of common stock remained available for grant under the 2013 Plan. Note 10. Stock-Based Compensation (Continued) Other Awards and Inducement Grants The Company has not made any awards pursuant to other equity incentive plans, including the 2008 Plan, since the Company’s stockholders approved the 2013 Plan. As of March 31, 2020, options to purchase a total of 333,512 shares of common stock were outstanding under the 2008 Plan. In addition, as of March 31, 2020, non-statutory stock options to purchase an aggregate of 393,750 shares of common stock were outstanding. These options were issued outside of the 2013 Plan to certain newly-hired employees in 2017, 2015 and 2014 pursuant to the Nasdaq inducement grant exception as a material component of such new hires’ employment compensation. 2017 Employee Stock Purchase Plan The 2017 ESPP is intended to qualify as an "employee stock purchase plan" as defined in Section 423 of the Internal Revenue Code. The total number of shares of common stock authorized for issuance under the 2017 ESPP is 412,500 shares of common stock, subject to adjustment as described in the 2017 ESPP. As of March 31, 2020, 302,493 shares remained available for issuance under the 2017 ESPP. For the three months ended March 31, 2020 and 2019, the Company issued 18,848 and 11,096 shares of common stock, respectively, under the 2017 ESPP and received proceeds of less than $0.1 million during each period, as a result of employee stock purchases. Accounting for Stock-based Compensation The Company recognizes non-cash compensation expense for stock-based awards under the Company’s equity incentive plans over an award’s requisite service period, or vesting period, using the straight-line attribution method, based on their grant date fair value determined using the Black-Scholes option-pricing model. The Company also recognizes non-cash compensation for stock purchases made under the 2017 ESPP. The fair value of the discounted purchases made under the Company’s 2017 ESPP is calculated using the Black-Scholes option-pricing model. The fair value of the look-back provisio n plus the 15% discount is recognized as compensation expense over each plan period. Total stock-based compensation expense attributable to stock-based payments made to employees and directors and employee stock purchases included in operating expenses in the Company's condensed statements of operations for the three months ended March 31, 2020 and 2019 were as follows: Three Months Ended March 31, (in thousands) 2020 2019 Stock-based compensation: Research and development Employee Stock Purchase Plans $ 11 $ 6 Equity Incentive Plans 193 330 $ 204 $ 336 General and administrative Employee Stock Purchase Plans $ 1 $ 6 Equity Incentive Plans 545 674 $ 546 $ 680 Total stock-based compensation expense $ 750 $ 1,016 During the three months ended March 31, 2020 and 2019, the weighted average fair market value of stock options granted was $1.07 and $1.83, respectively. Note 10. Stock-Based Compensation (Continued) The following weighted average assumptions apply to the options to purchase 643,629 and 480,502 shares of common stock granted to employees and directors during the three months ended March 31, 2020 and 2019, respectively: Three Months Ended March 31, 2020 2019 Average risk-free interest rate Expected dividend yield — — Expected lives (years) 3.8 3.6 Expected volatility Weighted average exercise price (per share) $ 1.80 $ 3.14 All options granted during the three months ended March 31, 2020 and 2019 were granted at exercise prices equal to the fair market value of the common stock on the dates of grant . Stock Option Activity The following table summarizes stock option activity for the three months ended March 31, 2020: ($ in thousands, except per share data) Stock Weighted-Average Weighted-Average Aggregate Outstanding at December 31, 2019 4,220,417 $ 13.08 6.6 $ Granted 643,629 1.80 Exercised — — Forfeited (38,874) 5.67 Expired (120,080) 19.73 Outstanding at March 31, 2020 (1) 4,705,092 $ 11.43 7.0 $ — Exercisable at March 31, 2020 2,373,804 $ 18.16 4.9 $ — (1) Includes both vested stock options as well as unvested stock options for which the requisite service period has not been rendered but that are expected to vest based on achievement of a service condition. The fair value of options that vested during the three months ended March 31, 2020 was $0.8 million. As of March 31, 2020, there was $5.1 million of unrecognized compensation cost related to unvested options, which the Company expects to recognize over a weighted average period of 2.5 years. Restricted Stock Activity The following table summarizes restricted stock activity for the three months ended March 31, 2020: ($ in thousands, except per share data) Number of Shares Weighted-Average Nonvested shares at December 31, 2019 193,625 $ 3.14 Granted 237,675 1.79 Cancelled (6,688) 2.34 Vested (48,402) 3.14 Nonvested shares at March 31, 2020 376,210 $ 2.30 As of March 31, 2020, there was $0.8 million of unrecognized compensation expense related to the restricted stock units, which is expected to be recognized over a weighted-average period of 3.3 years.

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2020
Related Party Transactions
Related Party Transactions	Note 11. Related Party Transactions Baker Brothers Julian C. Baker, a member of the Company’s Board until his resignation in September 2018, is a principal of Baker Bros. Advisors, LP. Additionally, Kelvin M. Neu, a member of Company’s Board until his resignation in June 2019, is an employee of Baker Bros. Advisors, LP. As of March 31, 2020, Baker Bros. Advisors, LP and certain of its affiliated funds (collectively, “Baker Brothers”) held sole voting power with respect to an aggregate of 4,608,786 shares of the Company’s common stock, representing approximately 15% of the Company's outstanding common stock. As of March 31, 2020, Baker Brothers held warrants to purchase up to 2,708,812 shares of the Company’s common stock at an exercise price of $0.08 per share, warrants to purchase up to 2,368,400 shares of the Company’s common stock (or, if Baker Brothers elects to exercise the warrants for shares of Series B1 Preferred Stock, 23,684 shares of Series B1 Preferred Stock), at an exercise price of $1.52 per share (or, if Baker Brothers elects to exercise the warrants for shares of Series B1 Preferred Stock, $152 per Series B1 Preferred Warrant Share). Pillar Investment Entities Youssef El Zein, a member of the Company’s board of directors until his resignation in October 2017, is a director and controlling stockholder of Pillar Invest Corporation, which is the general partner of Pillar Pharmaceuticals I, L.P. (“Pillar I”), Pillar Pharmaceuticals II, L.P. (“Pillar II”), Pillar Pharmaceuticals III, L.P. (“Pillar III”), Pillar Pharmaceuticals IV, L.P. (“Pillar IV”), Pillar Pharmaceuticals V, L.P. (“Pillar V”), Pillar Pharmaceuticals 6 L.P. (“Pillar 6”), and Pillar Partners Foundation, L.P. (“Pillar Partners”) (collectively, “Pillar”). As of March 31, 2020, Pillar owned approximately 11% of the Company's common stock. Subsequent to March 31, 2020, in April 2020, the Company sold shares of common stock and common stock warrants to Pillar Partners in a private placement transaction as more fully described in Note 13. Immediately following the private placement transaction, Pillar owned approximately 19% of the Company’s common stock. Board Fees Paid in Stock Pursuant to the Company’s director compensation program, in lieu of director board and committee fees of less than $0.1 million during each of the three months ended March 31, 2020 and 2019, the Company issued 56,014 and 13,719 shares of common stock, respectively, to certain of its directors. Director board and committee fees are paid in arrears and the number of shares issued was calculated based on the market closing price of the Company’s common stock on the issuance date.

Net Income (Loss) per Common Sh

Net Income (Loss) per Common Share	3 Months Ended
	Mar. 31, 2020
Net Income (Loss) per Common Share
Net Income (Loss) per Common Share	Note 12. Net Income (Loss) per Common Share The Company used the two-class method to compute net income (loss) per common share for the three months ended March 31, 2020 as the Company realized net income and has securities outstanding (redeemable convertible preferred stock) that entitle the holder to participate in dividends and earnings of the Company. Under this method, net income is reduced by the amount of any dividends earned and the accretion of redeemable convertible preferred stock to its redemption value, if any, during the period. The remaining earnings (undistributed earnings) are allocated to common stock and each series of redeemable convertible preferred stock to the extent that each preferred security may share in earnings as if all of the earnings for the period had been distributed. The total earnings allocated to common stock is then divided by the number of outstanding shares to which the earnings are allocated to determine the earnings per share. The two-class method is not applicable during periods with a net loss, as the holders of the redeemable convertible preferred stock have no obligation to fund losses. Details in the computation of basic and diluted net income (loss) per common share were as follows: Three Months Ended March 31, ($ in thousands except per share data) 2020 2019 Net income (loss) per share — Basic: Net income (loss) $ 8,817 $ (10,974) Less: Undistributed earnings to preferred stockholders (639) — Net income (loss) attributable to common stockholders - basic $ 8,178 $ (10,974) Numerator for basic net income (loss) per share $ 8,178 $ (10,974) Denominator for basic net income (loss) per share 30,300 27,676 Basic net income (loss) per common share $ 0.27 $ (0.40) Net income (loss) per share — Diluted: Net income (loss) $ 8,817 $ (10,974) Less: Warrant revaluation income for dilutive warrants (1,101) — Less: Undistributed earnings to preferred stockholders (517) — Numerator for diluted net income (loss) per share $ 7,199 (10,974) Denominator for basic net income (loss) per share 30,300 27,676 Plus: Incremental shares underlying “in the money” warrants outstanding 2,710 — Denominator for diluted net income (loss) per share 33,010 27,676 Diluted net income (loss) per common share $ 0.22 $ (0.40) Diluted net income (loss) per common share for the periods presented do not reflect the following potential common shares, as the effect would be antidilutive: Three Months Ended March 31, (in thousands) 2020 2019 Stock options 4,705 3,738 Restricted stock units 376 194 Common stock warrants — 2,769 Future tranche rights 49,407 — Total 54,488 6,701

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2020
Subsequent Events
Subsequent Events	Note 13. Subsequent Events April 2020 Private Placement On April 7, 2020, the Company entered into a Securities Purchase Agreement (the “April 2020 Securities Purchase Agreement”) with Pillar Partners, an existing shareholder and related party as more fully described in Note 11, under which the Company sold 3,039,514 shares of common stock and accompanying warrants to purchase 3,039,514 shares of the Company’s common stock with an exercise price of $2.28 per share, for aggregate gross proceeds of $5.0 million. Each share and the accompanying common warrant had a combined purchase price of $1.645, which included $0.125 for each share of common stock underlying each warrant. In addition, we have agreed to sell to Pillar Partners, at its option, 2,747,252 shares of the Company’s common stock (or pre-funded warrants to purchase shares of the Company’s common stock in lieu of certain shares to the extent that purchasing such shares will cause Pillar Investment Entities to beneficially own in excess of 19.99% of the total number of shares of common stock outstanding post transaction) and warrants to purchase up to 1,373,626 shares of the Company’s common stock (with an exercise price of $2.71), for aggregate gross proceeds of $5.0 million (the “Second Closing”). Each share and the accompanying 0.5 common warrant will have a combined purchase price of $1.82 and each pre-funded warrant and the accompanying 0.5 common warrant will have a combined purchase price of $1.81, each combined price includes $0.125 for each share of common stock underlying each common warrant. The pre-funded warrants issued in the Second Closing will have an exercise price of $0.01 per share of common stock. The Second Closing will occur on or before December 30, 2020 and will be held on or before the fifth day following delivery of written notice by Pillar Partners to the Company; provided that, if at any time after June 30, 2020, the Company’s common stock has achieved a closing price on the Nasdaq Capital Market of at least $3.01 per share for twenty (20) consecutive trading days, the Company may elect, in its sole discretion, to cancel the Second Closing. Subject to certain beneficial ownership limitation, the pre-funded warrants will be immediately exercisable upon issuance and do not have an expiration date. The common warrants are exercisable at any time or times on or after the next business day after the date on which the Company publicly announces through the filing of a Current Report on Form 8-K that an amendment to the Company Restated Certificate of Incorporation, as amended, to sufficiently increase the Company’s authorized shares of common stock to cover the exercise of the common warrants into common stock has been filed with the Secretary of St ate of the State of Delaware, subject to certain beneficial ownership limitation.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2020
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation The accompanying unaudited financial statements included herein have been prepared by the Company in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Accordingly, certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. In the opinion of management, all adjustments, consisting of normal recurring adjustments, and disclosures considered necessary for a fair presentation of interim period results have been included. Interim results for the three months ended March 31, 2020 are not necessarily indicative of results that may be expected for the year ending December 31, 2020. For further information, refer to the financial statements and footnotes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2019 (“2019 Form 10-K”), which was filed with the SEC on March 12, 2020.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with maturities of 90 days or less when purchased to be “cash equivalents.” Cash and cash equivalents at March 31, 2020 and December 31, 2019 consisted of cash, money market funds, and commercial paper.
Financial Instruments	Financial Instruments The fair value of the Company’s financial instruments is determined and disclosed in accordance with the three-tier fair value hierarchy specified in Note 3. The Company is required to disclose the estimated fair values of its financial instruments. As of March 31, 2020 and December 31, 2019, the Company’s financial instruments consisted of cash, cash equivalents, short-term investments, receivables and warrant and future tranche right liabilities. The estimated fair values of these financial instruments approximate their carrying values. As of March 31, 2020, the Company did not have any derivatives, hedging instruments, or other similar financial instruments.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that subject the Company to credit risk primarily consist of cash, cash equivalents, and investments. The Company’s credit risk is managed by investing in highly rated money market instruments, certificates of deposit, corporate bonds, commercial paper and debt securities. Due to these factors, no significant additional credit risk is believed by management to be inherent in the Company’s assets. As of March 31, 2020, all of the Company’s cash and cash equivalents were held at two financial institutions.
Operating Lease Right-of-use Asset and Lease Liability	Operating Lease Right-of-use Asset and Lease Liability The Company accounts for leases under ASC Topic 842, Leases . The Company determines if an arrangement is a lease at inception. Operating leases are included in long-term right-of-use assets and current and long-term lease liabilities within the Company’s condensed balance sheets. Right-of-use (“ROU”) assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease right-of-use assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. As most of the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rates, which are the rates incurred to borrow on a collateralized basis over a similar term, an amount equal to the lease payments in a similar economic environment. Lease expense for lease payments is recognized on a straight-line basis over the lease term. The right-of-use assets are tested for impairment according to ASC 360. Leases with an initial term of 12 months or less are not recorded on the balance sheet and are recognized as lease expense on a straight-line basis over the lease term. As of March 31, 2020 and December 31, 2019, the Company’s operating lease ROU asset and corresponding short-term and long-term lease liabilities relate to its existing Exton, PA facility operating lease which expires on May 31, 2025 as a result of the Company’s election to exercise its five-year renewal option in January 2020.
Warrant Liability	Warrant Liability The Company accounts for stock warrants as either equity instruments, liabilities or derivative liabilities in accordance with ASC 480, Distinguishing Liabilities from Equity (ASC 480) and/or ASC 815, Derivatives and Hedging (ASC 815), depending on the specific terms of the warrant agreement. Freestanding warrants for shares that are potentially redeemable, whereby the Company may be required to transfer assets (e.g. cash or other assets) outside of its control, are classified as liabilities. Liability-classified warrants are recorded at their estimated fair values at each reporting period until they are exercised, terminated, reclassified or otherwise settled. Changes in the estimated fair value of liability-classified warrants are recorded in Warrant Revaluation Income in the Company’s condensed statements of operations and comprehensive income (loss). Equity classified warrants are recorded within additional paid-in capital at the time of issuance and not subject to remeasurement. For additional discussion on warrants, see Note 7.
Future Tranche Right Liability	Future Tranche Right Liability In connection with the Company’s 2019 Private Placement, as more fully described in Note 7, the Company entered into the December 2019 Securities Purchase Agreement, which contains call options on redeemable preferred shares with warrants (conditionally exercisable for shares that are puttable). The Company determined that these call options represent freestanding financial instruments and accounts for the options as a liabilities (“Future Tranche Right Liability”) under ASC 480, which requires the measurement of the fair value of the liability at the time of issuance and recording changes as a charge to current earnings at each reporting period, which is included in Future Tranche Right Liability Revaluation Income in the Company’s condensed statements of operations and comprehensive income (loss).
Preferred Stock	Preferred Stock The Company applies ASC 480 when determining the classification and measurement of its preferred stock. Preferred shares subject to mandatory redemption are classified as liability instruments and are measured at fair value. Conditionally redeemable preferred shares (including preferred shares that feature redemption rights that are either within the control of the holder or subject to redemption upon the occurrence of uncertain events not solely within the Company’s control) are classified as temporary equity. At all other times, preferred shares are classified as stockholders’ equity. Accretion of redeemable convertible preferred stock includes the accretion of the Company's Series B redeemable convertible preferred stock to its stated value. The carrying value of the Series B redeemable convertible preferred stock is being accreted to redemption value using the effective interest method, from the date of issuance to the earliest date the holders can demand redemption.
Income Taxes	Income Taxes In accordance with ASC 270, Interim Reporting , and ASC 740, Income Taxes , the Company is required at the end of each interim period to determine the best estimate of its annual effective tax rate and then apply that rate in providing for income taxes on a current year-to-date (interim period) basis. For the three months ended March 31, 2020 and 2019, the Company recorded no tax expense or benefit due to the expected current year loss and its historical losses. The Company has not recorded its net deferred tax asset as of either March 31, 2020 or December 31, 2019 because it maintained a full valuation allowance against all deferred tax assets as of these dates as management has determined that it is not more likely than not that the Company will realize these future tax benefits. As of March 31, 2020 and December 31, 2019, the Company had no uncertain tax positions.
New Accounting Pronouncements	New Accounting Pronouncements From time to time, new accounting pronouncements are issued by the FASB and rules are issued by the SEC that the Company has or will adopt as of a specified date. Unless otherwise noted, management does not believe that any other recently issued accounting pronouncements issued by the FASB or guidance issued by the SEC had, or is expected to have, a material impact on the Company’s present or future financial statements. Recently Adopted Accounting Pronouncements In June 2016, the FASB issued Accounting Standard Update (“ASU’) No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). This standard requires that credit losses be reported using an expected losses model rather than the incurred losses model that is currently used, and establishes additional disclosures related to credit risks. For available-for-sale debt securities with unrealized losses, this standard now requires allowances to be recorded instead of reducing the amortized cost of the investment. The Company adopted ASU 2016-13 in the first quarter of 2020. The adoption of this ASU did not have a material effect on the Company’s financial statements. In August 2018, the FASB issued ASU No. 2018-13, Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”), which amends ASC 820, Fair Value Measurement . ASU 2018-13 modifies the disclosure requirements for fair value measurements by removing, modifying, or adding certain disclosures. The Company adopted ASU 2018-13 in the first quarter of 2020. The adoption of this ASU did not have a material effect on the Company’s financial statements.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2020
Schedule of assets and liabilities measured and recorded in financial statements at fair value on a recurring basis	March 31, 2020 (In thousands) Total Level 1 Level 2 Level 3 Assets Cash $ 250 $ 250 $ — $ — Cash equivalents – money market funds 26,860 26,860 — — Cash equivalents – commercial paper 799 — 799 — Short-term investments – commercial paper 5,578 — 5,578 — Total assets $ 33,487 $ 27,110 $ 6,377 $ — Liabilities Warrant liability $ 2,140 $ — $ — $ 2,140 Future tranche right liability 25,725 — — 25,725 Total liabilities $ 27,865 $ — $ — $ 27,865 December 31, 2019 (In thousands) Total Level 1 Level 2 Level 3 Assets Cash $ 250 $ 250 $ — $ — Cash equivalents – money market funds 39,769 39,769 — — Short-term investments – commercial paper 2,774 — 2,774 — Total assets $ 42,793 $ 40,019 $ 2,774 $ — Liabilities Warrant liability $ 3,241 $ — $ — $ 3,241 Future tranche right liability 46,436 — — 46,436 Total liabilities $ 49,677 $ — $ — $ 49,677
Schedule of reconciliation measured at fair value on a recurring basis using unobservable inputs	Future Warrant Tranche Right (In thousands) Liability Liability Balance, December 31, 2019 $ 3,241 $ 46,436 Change in the fair value of liability (1,101) (20,711) Balance, March 31, 2020 $ 2,140 $ 25,725
Warrant liability
Schedule of assumptions used in determining fair value	March 31, December 31, 2020 2019 Risk-free interest rate Expected dividend yield — — Expected term (years) 6.73 6.98 Expected volatility Exercise price (per share) $ 1.52 $ 1.52
Future tranche right liability
Schedule of assumptions used in determining fair value	March 31, December 31, 2020 2019 Risk-free interest rate for warrants Risk-free interest rate for preferred stock 0.59% - 0.65% 1.84% - 1.88% Expected dividend yield — — Expected term (years) of call option on preferred stock 0.91 - 1.91 1.16 - 2.16 Expected term (years) of warrants 7.91 - 8.91 8.16 - 9.16 Expected volatility Exercise price (per share) for common stock equivalent for preferred stock and warrant $ 1.52 - 1.82 $ 1.52 - 1.82

Investments (Tables)

Investments (Tables)	3 Months Ended
	Mar. 31, 2020
Investments
Schedule of available-for-sale investments at fair value	March 31, 2020 Gross Gross Estimated Unrealized Unrealized Fair (In thousands) Cost (Losses) Gains Value Short-term investments – commercial paper $ 5,578 $ — $ — $ 5,578 Total short-term investments 5,578 — — 5,578 Total investments $ 5,578 $ — $ — $ 5,578 December 31, 2019 Gross Gross Estimated Unrealized Unrealized Fair (In thousands) Cost (Losses) Gains Value Short-term investments – commercial paper $ 2,774 $ — $ — $ 2,774 Total short-term investments 2,774 — — 2,774 Total investments $ 2,774 $ — $ — $ 2,774

Property and Equipment (Tables)

Property and Equipment (Tables)	3 Months Ended
	Mar. 31, 2020
Property and Equipment
Schedule of net property and equipment at cost	March 31, December 31, (In thousands) 2020 2019 Leasehold improvements $ 107 $ 107 Equipment and other 770 764 Total property and equipment, at cost 877 871 Less: Accumulated depreciation and amortization 797 774 Property and equipment, net $ 80 $ 97

Accrued Expenses (Tables)

Accrued Expenses (Tables)	3 Months Ended
	Mar. 31, 2020
Accrued Expenses
Schedule of accrued expenses	March 31, December 31, (In thousands) 2020 2019 Payroll and related costs $ 1,260 $ 2,179 Clinical and nonclinical trial expenses 5,247 4,199 Professional and consulting fees 701 859 Restructuring expenses 64 113 Other 113 111 Total accrued expenses $ 7,385 $ 7,461

Redeemable Convertible Prefer_2

Redeemable Convertible Preferred Stock (Tables)	3 Months Ended
	Mar. 31, 2020
Redeemable Convertible Preferred Stock
Schedule of Redeemable Convertible Preferred Stock	Price Per Aggregate Future Tranche Rights Preferred Shares Share Purchase Price Tranche 2 (Series B2) (1) 98,685 $ $ 15,000,120 Tranche 3 (Series B3) (2) 82,418 $ 15,000,076 Tranche 4 (Series B4) (2) 82,418 $ 15,000,076 Total 263,521 $ 45,000,272 (1) Accompanied by related warrants to purchase up to 9,868,500 shares of the Company’s common stock (or, if the holder elects to exercise the warrants for shares of Series B1 Preferred Stock, 98,685 shares of Series B1 Preferred Stock), at an exercise price of $1.52 per share (or, if the holder elects to exercise the warrants for Series B1 Preferred Stock, $152 per share of Series B1 Preferred Stock). (2) Accompanied by related warrants to purchase up to 6,593,440 shares of the Company’s common stock (or, if the holder elects to exercise the warrants for shares of Series B1 Preferred Stock, 65,934 shares of Series B1 Preferred Stock), at an exercise price of $1.82 per share (or, if the holder elects to exercise the warrants for Series B1 Preferred Stock, $182 per share of Series B1 Preferred Stock).

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2020
Stockholders' Equity
Schedule of warrants outstanding and exercisable for purchase of common stock	Number of Shares March 31, December 31, Weighted-Average Description 2020 2019 Exercise Price Expiration Date Liability-classified Warrants December 2019 Series B1 warrants (1) 2,368,400 2,368,400 $ 1.52 Dec 2026 2,368,400 2,368,400 Equity-classified Warrants May 2013 warrants 1,949,754 1,949,754 $ 0.08 None September 2013 warrants 514,756 514,756 $ 0.08 None February 2014 warrants 266,006 266,006 $ 0.08 None 2,730,516 2,730,516 Total outstanding 5,098,916 5,098,916 The Series B1 warrants are exercisable for either common stock (exercise price of $1.52) or Series B1 Convertible Preferred Stock (exercise price of $152) at the discretion of the warrant holder.

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2020
Stock-Based Compensation
Schedule of stock-based compensation expense attributable to share-based payments made to employees and directors and included in operating expenses	Three Months Ended March 31, (in thousands) 2020 2019 Stock-based compensation: Research and development Employee Stock Purchase Plans $ 11 $ 6 Equity Incentive Plans 193 330 $ 204 $ 336 General and administrative Employee Stock Purchase Plans $ 1 $ 6 Equity Incentive Plans 545 674 $ 546 $ 680 Total stock-based compensation expense $ 750 $ 1,016
Schedule of weighted average assumptions applied to options	Three Months Ended March 31, 2020 2019 Average risk-free interest rate Expected dividend yield — — Expected lives (years) 3.8 3.6 Expected volatility Weighted average exercise price (per share) $ 1.80 $ 3.14
Schedule of information related to outstanding and exercisable options	($ in thousands, except per share data) Stock Weighted-Average Weighted-Average Aggregate Outstanding at December 31, 2019 4,220,417 $ 13.08 6.6 $ Granted 643,629 1.80 Exercised — — Forfeited (38,874) 5.67 Expired (120,080) 19.73 Outstanding at March 31, 2020 (1) 4,705,092 $ 11.43 7.0 $ — Exercisable at March 31, 2020 2,373,804 $ 18.16 4.9 $ — (1) Includes both vested stock options as well as unvested stock options for which the requisite service period has not been rendered but that are expected to vest based on achievement of a service condition.
Schedule of summary of restricted stock activity	($ in thousands, except per share data) Number of Shares Weighted-Average Nonvested shares at December 31, 2019 193,625 $ 3.14 Granted 237,675 1.79 Cancelled (6,688) 2.34 Vested (48,402) 3.14 Nonvested shares at March 31, 2020 376,210 $ 2.30

Net Income (Loss) per Common _2

Net Income (Loss) per Common Share (Tables)	3 Months Ended
	Mar. 31, 2020
Net Income (Loss) per Common Share
Computation of basic and diluted net income (loss) per share	Three Months Ended March 31, ($ in thousands except per share data) 2020 2019 Net income (loss) per share — Basic: Net income (loss) $ 8,817 $ (10,974) Less: Undistributed earnings to preferred stockholders (639) — Net income (loss) attributable to common stockholders - basic $ 8,178 $ (10,974) Numerator for basic net income (loss) per share $ 8,178 $ (10,974) Denominator for basic net income (loss) per share 30,300 27,676 Basic net income (loss) per common share $ 0.27 $ (0.40) Net income (loss) per share — Diluted: Net income (loss) $ 8,817 $ (10,974) Less: Warrant revaluation income for dilutive warrants (1,101) — Less: Undistributed earnings to preferred stockholders (517) — Numerator for diluted net income (loss) per share $ 7,199 (10,974) Denominator for basic net income (loss) per share 30,300 27,676 Plus: Incremental shares underlying “in the money” warrants outstanding 2,710 — Denominator for diluted net income (loss) per share 33,010 27,676 Diluted net income (loss) per common share $ 0.22 $ (0.40)
Schedule of potentially dilutive securities excluded from diluted net income (loss) per common share	Three Months Ended March 31, (in thousands) 2020 2019 Stock options 4,705 3,738 Restricted stock units 376 194 Common stock warrants — 2,769 Future tranche rights 49,407 — Total 54,488 6,701

Business and Organization (Deta

Business and Organization (Details) - USD ($) $ in Thousands	1 Months Ended
	Apr. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Business and Organization
Accumulated deficit		$ 712,073	$ 720,890
Cash, cash equivalents and investments		33,500
Contingently refundable option fee received in connection with Private Placement		$ 6,200
Gross proceeds from sale of common stock and warrants excluding the proceeds from exercise of the warrants, if any	$ 5,000

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)Institution	Mar. 31, 2019USD ($)	Jan. 31, 2020	Dec. 31, 2019USD ($)
Summary of Significant Accounting Policies
Number of financial institutions | Institution	2
Tax expense (benefit)	$ 0	$ 0
Uncertain tax positions	$ 0			$ 0
Operating lease renewal term			5 years

Fair Value Measurements - Trans

Fair Value Measurements - Transfers Between Levels (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Fair Value Measurements
Fair value of assets transfers from level 1 to level 2	$ 0
Fair value of assets transfers from level 2 to level 1	0
Fair value of liabilities transfers from level 1 to level 2	0
Fair value of liabilities transfers from level 2 to level 1	0
Fair value of assets transfers into level 3	0
Fair value of assets transfers out of level 3	0
Fair value of liabilities transfers into level 3	0
Fair value of liabilities transfers out of level 3	$ 0

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis
Cash equivalents and Short-term investments	$ 5,578	$ 2,774
Fair value on a recurring basis
Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis
Total Assets	33,487	42,793
Total Liabilities	27,865	49,677
Fair value on a recurring basis | Warrant liability
Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis
Total Liabilities	2,140	3,241
Fair value on a recurring basis | Future tranche right liability
Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis
Total Liabilities	25,725	46,436
Fair value on a recurring basis | Cash
Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis
Cash and Money market funds	250	250
Fair value on a recurring basis | Money market funds
Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis
Cash and Money market funds	26,860	39,769
Fair value on a recurring basis | Cash equivalents – commercial paper
Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis
Cash equivalents and Short-term investments	799
Fair value on a recurring basis | Short-term investments – commercial paper
Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis
Cash equivalents and Short-term investments	5,578	2,774
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Fair value on a recurring basis
Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis
Total Assets	27,110	40,019
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Fair value on a recurring basis | Cash
Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis
Cash and Money market funds	250	250
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Fair value on a recurring basis | Money market funds
Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis
Cash and Money market funds	26,860	39,769
Significant Other Observable Inputs (Level 2) | Fair value on a recurring basis
Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis
Total Assets	6,377	2,774
Significant Other Observable Inputs (Level 2) | Fair value on a recurring basis | Cash equivalents – commercial paper
Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis
Cash equivalents and Short-term investments	799
Significant Other Observable Inputs (Level 2) | Fair value on a recurring basis | Short-term investments – commercial paper
Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis
Cash equivalents and Short-term investments	5,578	2,774
Significant Other Unobservable Inputs (Level 3) | Fair value on a recurring basis
Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis
Total Liabilities	27,865	49,677
Significant Other Unobservable Inputs (Level 3) | Fair value on a recurring basis | Warrant liability
Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis
Total Liabilities	2,140	3,241
Significant Other Unobservable Inputs (Level 3) | Fair value on a recurring basis | Future tranche right liability
Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis
Total Liabilities	$ 25,725	$ 46,436

Fair Value Measurements - Ass_2

Fair Value Measurements - Assets and Liabilities at Fair Value Changes in Level 3 Liabilities (Details) - Fair value on a recurring basis $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Warrant liability
Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis
Beginning balance	$ 3,241
Change in the fair value of liability	(1,101)
Ending balance	2,140
Future tranche right liability
Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis
Beginning balance	46,436
Change in the fair value of liability	(20,711)
Ending balance	$ 25,725

Fair Value Measurements - Weigh

Fair Value Measurements - Weighted-average assumptions (Details)	Mar. 31, 2020$ / sharesUSD ($)	Dec. 31, 2019$ / sharesUSD ($)
Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt instrument measurement input	0.53	1.79
Expected term
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt instrument measurement input	6.73	6.98
Expected volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt instrument measurement input	80	80
Exercise price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt instrument measurement input | $ / shares	1.52	1.52

Fair Value Measurements - Futur

Fair Value Measurements - Future Tranche Rights (Details)	Mar. 31, 2020$ / sharesUSD ($)	Dec. 31, 2019$ / sharesUSD ($)
Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt instrument measurement input	0.53	1.79
Risk-free interest rate | Warrants
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt instrument measurement input	0.53	1.79
Risk-free interest rate | Preferred stock | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt instrument measurement input	0.59	1.84
Risk-free interest rate | Preferred stock | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt instrument measurement input	0.65	1.88
Expected term
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt instrument measurement input	6.73	6.98
Expected term | Warrants | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt instrument measurement input	7.91	8.16
Expected term | Warrants | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt instrument measurement input	8.91	9.16
Expected term | Preferred stock | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt instrument measurement input	0.91	1.16
Expected term | Preferred stock | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt instrument measurement input	1.91	2.16
Expected volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt instrument measurement input	80	80
Expected volatility | Future tranche right liability
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt instrument measurement input	80	80
Exercise price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt instrument measurement input | $ / shares	1.52	1.52
Exercise price | Future tranche right liability | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt instrument measurement input	1.52	1.52
Exercise price | Future tranche right liability | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt instrument measurement input	1.82	1.82

Investments - Summary of Availa

Investments - Summary of Available-for-Sale Investments at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Schedule of Available-for-sale Securities
Cost	$ 5,578	$ 2,774
Estimated Fair Value	5,578	2,774
Short-term investments
Schedule of Available-for-sale Securities
Cost	5,578	2,774
Estimated Fair Value	5,578	2,774
Short-term investments – commercial paper
Schedule of Available-for-sale Securities
Cost	5,578	2,774
Estimated Fair Value	$ 5,578	$ 2,774

Investments - Additional Inform

Investments - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Investments
Realized gains or losses	$ 0	$ 0
Allowance for credit losses on available-for-sale debt securities	0		$ 0
Losses or other-than-temporary declines	$ 0	$ 0

Property and Equipment - Net Pr

Property and Equipment - Net Property and Equipment at Cost (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment
Total property and equipment, at cost	$ 877	$ 871
Less: accumulated depreciation and amortization	797	774
Property and equipment, net	80	97
Leasehold improvements
Property, Plant and Equipment
Total property and equipment, at cost	107	107
Laboratory equipment and other
Property, Plant and Equipment
Total property and equipment, at cost	$ 770	$ 764

Property and Equipment - Deprec

Property and Equipment - Depreciation and Amortization Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Non-cash property additions	$ 0	$ 0
Maximum
Depreciation and amortization expense on property and equipment	$ 100	$ 100

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Accrued Expenses
Payroll and related costs	$ 1,260	$ 2,179
Clinical and nonclinical trial expenses	5,247	4,199
Professional and consulting fees	701	859
Restructuring expenses	64	113
Other	113	111
Total accrued expenses	$ 7,385	$ 7,461

Redeemable Convertible Prefer_3

Redeemable Convertible Preferred Stock (Details) - USD ($)	Dec. 23, 2019	Mar. 31, 2020
Temporary Equity
Aggregate gross proceeds	$ 3,900,000
Preferred Shares		263,521
Aggregate Purchase Price		$ 45,000,272
Gross proceeds	$ 6,200,000
Common stock trading Price	$ 7.60
Common stock trading Price, Number of trading days	20 days
Common stock trading Price, Number of trading days Subsequent to closing	30 days
Aggregate gross proceeds	$ 87,600,000
Series B1 redeemable convertible preferred stock (Note 7); Designated — 278 shares, Issued and outstanding — 24 shares at March 31, 2020 and December 31, 2019
Temporary Equity
Sale of redeemable convertible preferred stock	23,684
Series B1 redeemable convertible preferred stock (Note 7); Designated — 278 shares, Issued and outstanding — 24 shares at March 31, 2020 and December 31, 2019 | Common stock warrants
Temporary Equity
Warrant to purchase common stock	2,368,400
Warrant exercise price (per share)	$ 1.52
Series B1 redeemable convertible preferred stock (Note 7); Designated — 278 shares, Issued and outstanding — 24 shares at March 31, 2020 and December 31, 2019 | Preferred Stock Warrant
Temporary Equity
Warrant to purchase common stock	23,684
Warrant exercise price (per share)	$ 152
Series B2 Redeemable Convertible Preferred Stock
Temporary Equity
Preferred Shares		98,685
Share Price		$ 152
Aggregate Purchase Price		$ 15,000,120
Expiration period	9 months
Series B2 Redeemable Convertible Preferred Stock | Common stock warrants
Temporary Equity
Sale of redeemable convertible preferred stock	9,868,500
Warrant exercise price (per share)	$ 1.52
Series B2 Redeemable Convertible Preferred Stock | Preferred Stock Warrant
Temporary Equity
Warrant to purchase common stock	98,685
Warrant exercise price (per share)	$ 152
Series B3 Redeemable Convertible Preferred Stock
Temporary Equity
Preferred Shares		82,418
Share Price		$ 182
Aggregate Purchase Price		$ 15,000,076
Expiration period	15 months
Series B3 Redeemable Convertible Preferred Stock | Common stock warrants
Temporary Equity
Warrant to purchase common stock	6,593,440
Warrant exercise price (per share)	$ 1.82
Series B3 Redeemable Convertible Preferred Stock | Preferred Stock Warrant
Temporary Equity
Warrant to purchase common stock	65,934
Warrant exercise price (per share)	$ 182
Series B4 Redeemable Convertible Preferred Stock
Temporary Equity
Preferred Shares		82,418
Share Price		$ 182
Aggregate Purchase Price		$ 15,000,076
Expiration period	21 months

Stockholders' Equity - Common S

Stockholders' Equity - Common Stock (Details) - USD ($) $ / shares in Units, $ in Millions	Mar. 04, 2019	Nov. 30, 2018	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Class of Stock
Common stock, par value			$ 0.001		$ 0.001
"At-The-Market" Equity Program
Class of Stock
Stock issued (in shares)			403,983	532,700
Net proceeds from offering of common stock			$ 0.6	$ 1.6
Percentage of fixed commission expense of gross proceeds of shares sold in ATM agreement		3.00%
Lincoln Park Capital Fund, LLC (“Investor”)
Class of Stock
Value of shares investor has committed to purchase from time to time at Company’s sole discretion	$ 35
Stock issued (in shares)	269,749		450,000	0
Stock issued (per share)	$ 2.84
Net proceeds from offering of common stock			$ 0.8
Common Stock | "At-The-Market" Equity Program
Class of Stock
Net proceeds from offering of common stock		$ 50

Stockholders' Equity - Common_2

Stockholders' Equity - Common Stock Warrants (Details) - $ / shares	Mar. 31, 2020	Dec. 31, 2019
Class of Warrant or Right
Number of Warrants	5,098,916	5,098,916
Warrants
Class of Warrant or Right
Warrant exercise price per share	$ 1.52
Preferred stock
Class of Warrant or Right
Warrant exercise price per share	$ 152
Liability Classified Warrants
Class of Warrant or Right
Number of Warrants	2,368,400	2,368,400
December 2019 Series B1 warrants
Class of Warrant or Right
Number of Warrants	2,368,400	2,368,400
Warrant exercise price per share	$ 1.52	$ 1.52
Equity Classified Warrants
Class of Warrant or Right
Number of Warrants	2,730,516	2,730,516
May 2013 Warrants
Class of Warrant or Right
Number of Warrants	1,949,754	1,949,754
Warrant exercise price per share	$ 0.08	$ 0.08
September 2013 Warrants
Class of Warrant or Right
Number of Warrants	514,756	514,756
Warrant exercise price per share	$ 0.08	$ 0.08
February 2014 Warrants
Class of Warrant or Right
Number of Warrants	266,006	266,006
Warrant exercise price per share	$ 0.08	$ 0.08

Collaboration and License Agr_2

Collaboration and License Agreements (Details) - USD ($)	1 Months Ended	3 Months Ended	12 Months Ended
	Apr. 30, 2019	Mar. 31, 2020	Dec. 31, 2019
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Operating expenses		$ 13,152,000	$ 11,376,000
Option and License Agreement with Licensee
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Performance obligation		$ 0
Percentage of shares acquired		10.00%
Option and License Agreement with Licensee | Other Assets
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Equity Securities without Readily Determinable Fair Value, Amount		$ 100,000
IMO-9200 License | Up-front Payment Arrangement
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Upfront payment received under collaboration agreement	$ 1,400,000
Non-refundable fee upon exercise of option	$ 1,000,000
IMO-9200 License | Option and License Agreement with Licensee
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Percentage of shares acquired	10.00%

Stock-Based Compensation - Equi

Stock-Based Compensation - Equity Incentive Plans (Details) - shares	1 Months Ended	3 Months Ended
	Jun. 30, 2019	Mar. 31, 2020	Dec. 31, 2019
Class of Stock
Common stock options outstanding		4,705,092	4,220,417
Options outstanding under earlier plans		333,512
Grant of inducement stock option		393,750
2013 Stock Incentive Plan
Class of Stock
Common stock, shares reserved for future issuance	5,653,057
Common shares available for grant		1,571,751
Maximum number of additional common shares	868,372
Common stock options outstanding		3,977,830
Restricted stock units outstanding		376,210

Stock-Based Compensation - Empl

Stock-Based Compensation - Employee Stock Purchase Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Jun. 07, 2017
Class of Stock
Proceeds from employee stock purchases	$ 25	$ 26
2017 Employee Stock Purchase Plan
Class of Stock
Common stock shares authorized for issuance under stock purchase plan			412,500
Proceeds from employee stock purchases	$ 100	$ 100
Common shares available for grant			302,493
Employee Stock Purchase Plans
Class of Stock
Common stock share issued	18,848	11,096

Stock-Based Compensation - Acco

Stock-Based Compensation - Accounting for Stock-based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award
Percentage of share-based compensation expense	15.00%
Weighted average grant date fair value of options granted during the period (per share)	$ 1.07	$ 1.83
Stock-based compensation	$ 750	$ 1,016
Research and development
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	204	336
Research and development | Employee Stock Purchase Plans
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	11	6
Research and development | Equity Incentive Plans
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	193	330
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	546	680
General and administrative | Employee Stock Purchase Plans
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	1	6
General and administrative | Equity Incentive Plans
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	$ 545	$ 674

Stock-Based Compensation - Assu

Stock-Based Compensation - Assumptions Used in Determining Fair Value of Stock Options (Details) - $ / shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Summary of Significant Accounting Policies
Options to purchase common stock granted to employees and directors	643,629	480,502
Average risk free interest rate	1.60%	2.40%
Dividend rate	0.00%	0.00%
Expected lives (years)	3 years 9 months 18 days	3 years 7 months 6 days
Expected volatility	82.70%	82.00%
Weighted average exercise price of options granted during the period (per share)	$ 1.80	$ 3.14

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Options, Outstanding, Beginning Balance	4,220,417
Granted	643,629
Forfeited	(38,874)
Expired	(120,080)
Options, Outstanding, Ending Balance	4,705,092		4,220,417
Exercisable, Ending Balance	2,373,804
Weighted Average Exercise Price, Beginning Balance	$ 13.08
Granted, Weighted Average Exercise Price	1.80	$ 3.14
Forfeited, Weighted Average Exercise Price	5.67
Expired, Weighted Average Exercise Price	19.73
Weighted Average Exercise Price, Ending Balance	11.43		$ 13.08
Exercisable, Weighted Average Exercise Price	$ 18.16
Outstanding, Ending balance, Weighted Average Remaining Contractual Term	7 years		6 years 7 months 6 days
Exercisable Ending Balance, Weighted Average Remaining Contractual Term	4 years 10 months 24 days
Fair value of options, vested	$ 0.8
Unrecognized compensation cost related to nonvested stock-based compensation	$ 5.1
Weighted average remaining period over which unrecognized compensation expense will be recognized	2 years 6 months
Restricted stock units
Unrecognized compensation cost related to nonvested stock-based compensation	$ 0.8
Weighted average remaining period over which unrecognized compensation expense will be recognized	3 years 3 months 18 days

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock Activity (Details) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)$ / sharesshares
Restricted Stock Activity, Weighted-Average Grant Date Fair Value
Unrecognized compensation expense | $	$ 5.1
Weighted average remaining period over which unrecognized compensation expense will be recognized	2 years 6 months
Restricted stock units
Restricted Stock Activity, Number of Shares
Nonvested shares, Beginning Balance | shares	193,625
Granted | shares	237,675
Cancelled | shares	(6,688)
Vested | shares	(48,402)
Nonvested shares, Ending Balance | shares	376,210
Restricted Stock Activity, Weighted-Average Grant Date Fair Value
Nonvested shares, Weighted Average Grant Date Fair Value, Beginning Balance | $ / shares	$ 3.14
Granted, Weighted-Average Grant Date Fair Value | $ / shares	1.79
Cancelled, Weighted-Average Grant Date Fair Value | $ / shares	2.34
Vested, Weighted-Average Grant Date Fair Value | $ / shares	3.14
Nonvested shares, Weighted Average Grant Date Fair Value, Ending Balance | $ / shares	$ 2.30
Unrecognized compensation expense | $	$ 0.8
Weighted average remaining period over which unrecognized compensation expense will be recognized	3 years 3 months 18 days

Related Party Transactions - Ov

Related Party Transactions - Overview of Related Parties (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Apr. 30, 2020	Dec. 31, 2019
Related Party Transactions
Number of Warrants	5,098,916			5,098,916
Common stock issued in lieu of board fees	56,014	13,719
Maximum
Related Party Transactions
Proceeds from issuance of common stock in lieu of director board and committee fees	$ 0.1	$ 0.1
Baker Bros. Advisors LP
Related Party Transactions
Ownership percentage	15.00%
Aggregate common shares	4,608,786
Baker Bros. Advisors LP | Series B1 Preferred Warrant | Scenario One
Related Party Transactions
Exercise price of warrants	$ 1.52
Number of Warrants	23,684
Baker Bros. Advisors LP | Series B1 Preferred Warrant | Scenario Two
Related Party Transactions
Exercise price of warrants	$ 152
Baker Bros. Advisors LP | Series B1 Preferred Warrant | Scenario Two | Maximum
Related Party Transactions
Number of Shares	2,368,400
Pillar Investment Entities
Related Party Transactions
Ownership percentage			19.00%
Pillar Investment Entities | Board of Director
Related Party Transactions
Ownership percentage	11.00%
Baker Bros. Advisors LP | Pre-funded Warrants | Scenario One
Related Party Transactions
Exercise price of warrants	$ 0.08
Baker Bros. Advisors LP | Pre-funded Warrants | Scenario One | Maximum
Related Party Transactions
Number of Shares	2,708,812

Net Income (Loss) per Common _3

Net Income (Loss) per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Net Income (loss) per share — Basic:
Net income (loss)	$ 8,817	$ (10,974)	$ (10,974)
Less: Undistributed earnings to preferred stockholders	(639)
Net income (loss) applicable to common stockholders	$ 8,178	$ (10,974)
Denominator for basic net income (loss) per share	30,300	27,676
Basic net income (loss) per common share	$ 0.27	$ (0.40)	$ (0.40)
Loss per share — Diluted:
Net income (loss)	$ 8,817	$ (10,974)	$ (10,974)
Less: Warrant revaluation income for dilutive warrants	(1,101)
Less: Undistributed earnings to preferred stockholders	(517)
Numerator for diluted net income (loss) per share	$ 7,199	$ (10,974)
Denominator for basic net income (loss) per share	30,300	27,676
Plus: Incremental shares underlying “in the money” warrants outstanding	2,710
Denominator for diluted net income (loss) per share	33,010	27,676	27,676
Diluted net income (loss) per common share	$ 0.22	$ (0.40)	$ (0.40)

Net Income (Loss) per Common _4

Net Income (Loss) per Common Share - Antidilutive securities (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Antidilutive securities
Total antidilutive securities	54,488	6,701
Stock options
Antidilutive securities
Total antidilutive securities	4,705	3,738
Restricted stock units
Antidilutive securities
Total antidilutive securities	376	194
Common stock warrants
Antidilutive securities
Total antidilutive securities		2,769
Future tranche right liability
Antidilutive securities
Total antidilutive securities	49,407

Subsequent Events - Proceeds fr

Subsequent Events - Proceeds from Sale of Common Stock (Details) - USD ($) $ / shares in Units, $ in Millions	Apr. 07, 2020	Apr. 30, 2020
Subsequent Events
Gross proceeds from sale of common stock and warrants excluding the proceeds from exercise of the warrants, if any		$ 5
Pillar Investment Entities
Subsequent Events
Ownership percentage		19.00%
Subsequent Events | Future plans | Pillar Investment Entities
Subsequent Events
Ownership percentage	19.99%
Subsequent Events | Pillar Investment Entities
Subsequent Events
Stock issued (in shares)	3,039,514
Shares of common stock that may be purchased upon exercise of warrants	3,039,514
Warrant exercise price (per share)	$ 2.28
Gross proceeds from sale of common stock and warrants excluding the proceeds from exercise of the warrants, if any	$ 5
Combined purchase price (per share)	$ 1.645
Stock price underlying warrants (per share)	$ 0.125
Subsequent Events | Pillar Investment Entities | Future plans
Subsequent Events
Stock issued (in shares)	2,747,252
Shares of common stock that may be purchased upon exercise of warrants	1,373,626
Warrant exercise price (per share)	$ 2.71
Gross proceeds from sale of common stock and warrants excluding the proceeds from exercise of the warrants, if any	$ 5
Number of common warrants	0.5
Stock price (in dollars per share)	$ 3.01
Number of consecutive trading days	20 days
Subsequent Events | Pillar Investment Entities | Future plans | Common stock warrants
Subsequent Events
Combined purchase price (per share)	$ 1.82
Subsequent Events | Pillar Investment Entities | Future plans | Pre-funded Warrants
Subsequent Events
Warrant exercise price (per share)	0.01
Combined purchase price (per share)	1.81
Stock price underlying warrants (per share)	$ 0.125