Oruka Therapeutics (ORKA) 10-Q 15 May 17 2017 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2017	May 11, 2017
Document And Entity Information [Abstract]
Entity Registrant Name	ARCA Biopharma, Inc.
Entity Central Index Key	907,654
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2017
Document Fiscal Period Focus	Q1
Trading Symbol	ABIO
Document Fiscal Year Focus	2,017
Current Fiscal Year End Date	--12-31
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		9,242,281

BALANCE SHEETS (Unaudited)

BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 6,170	$ 7,401
Marketable securities	13,041	13,762
Other current assets	643	282
Total current assets	19,854	21,445
Marketable securities		2,352
Property and equipment, net	59	66
Other assets	676	766
Total assets	20,589	24,629
Current liabilities:
Accounts payable	980	1,205
Accrued compensation and employee benefits	241	719
Accrued expenses and other liabilities	1,297	472
Total current liabilities	2,518	2,396
Deferred rent, net of current portion	35	39
Total liabilities	2,553	2,435
Commitments and contingencies
Stockholders’ equity:
Common stock, $0.001 par value; 100 million shares authorized at March 31, 2017 and December 31, 2016; 9,172,868 and 9,082,366 shares issued and outstanding at March 31, 2017 and December 31, 2016, respectively	9	9
Additional paid-in capital	134,885	134,715
Accumulated other comprehensive loss	(9)	(19)
Accumulated deficit	(116,849)	(112,511)
Total stockholders’ equity	18,036	22,194
Total liabilities and stockholders’ equity	$ 20,589	$ 24,629

BALANCE SHEETS (Unaudited) (Par

BALANCE SHEETS (Unaudited) (Parenthetical) - $ / shares	Mar. 31, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	9,172,868	9,082,366
Common stock, shares outstanding	9,172,868	9,082,366

STATEMENTS OF OPERATIONS AND CO

STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Costs and expenses:
Research and development	$ 3,246	$ 2,594
General and administrative	1,135	1,074
Total costs and expenses	4,381	3,668
Loss from operations	(4,381)	(3,668)
Interest and other income	45	21
Interest expense	(2)
Net loss	(4,338)	(3,647)
Change in unrealized loss on marketable securities	10	6
Comprehensive loss	$ (4,328)	$ (3,641)
Net loss per share:
Basic and diluted	$ (0.48)	$ (0.40)
Weighted average shares outstanding:
Basic and diluted	9,094,276	9,053,186

STATEMENTS OF STOCKHOLDERS' EQU

STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning Balance, shares at Dec. 31, 2015		9,051,217
Beginning Balance at Dec. 31, 2015	$ 38,070	$ 9	$ 134,128		$ (96,067)
Issuance of common stock upon vesting of Restricted Stock Units, shares		31,149
Issuance of common stock upon vesting of Restricted Stock Units, value	0	$ 0	0	$ 0	0
Share-based compensation	576		576
Change in unrealized loss on marketable securities	(19)			(19)
Other	11		11
Net loss	$ (16,444)				(16,444)
Ending Balance, shares at Dec. 31, 2016	9,082,366	9,082,366
Ending Balance at Dec. 31, 2016	$ 22,194	$ 9	134,715	(19)	(112,511)
Issuance of common stock for cash, net of offering costs, shares		85,068
Issuance of common stock for cash, net of offering costs	69		69
Issuance of common stock upon vesting of Restricted Stock Units, shares		5,434
Issuance of common stock upon vesting of Restricted Stock Units, value	0	$ 0	0	0	0
Share-based compensation	101		101
Change in unrealized loss on marketable securities	10			10
Net loss	$ (4,338)				(4,338)
Ending Balance, shares at Mar. 31, 2017	9,172,868	9,172,868
Ending Balance at Mar. 31, 2017	$ 18,036	$ 9	$ 134,885	$ (9)	$ (116,849)

STATEMENTS OF CASH FLOWS (Unaud

STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net loss	$ (4,338)	$ (3,647)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	7	5
Amortization of other assets	90	57
Amortization of premiums and discounts on marketable securities	55
Share-based compensation	101	155
Change in operating assets and liabilities:
Other current assets	(74)	(277)
Other assets		(7)
Accounts payable	(234)	380
Accrued compensation and employee benefits	(478)	(517)
Accrued expenses and other liabilities	527	(32)
Net cash used in operating activities	(4,344)	(3,883)
Cash flows from investing activities:
Purchases of property and equipment		(1)
Purchases of marketable securities	(1,542)	(5,201)
Proceeds from maturities of marketable securities	4,550
Net cash provided by (used in) investing activities	3,008	(5,202)
Cash flows from financing activities:
Proceeds from the issuance of common stock	210
Common stock offering costs	(105)
Net cash provided by financing activities	105
Net decrease in cash and cash equivalents	(1,231)	(9,085)
Cash and cash equivalents, beginning of period	7,401	38,802
Cash and cash equivalents, end of period	6,170	29,717
Supplemental disclosure of noncash investing and financing transactions:
Vendor finance agreement	256
Proceeds receivable from the issuance of common stock	11
Common stock offering costs accrued but not yet paid	47
Change in unrealized loss on marketable securities	$ 10	6
Payable for purchases of marketable securities		$ 1,009

The Company and Summary of Sign

The Company and Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
The Company and Summary of Significant Accounting Policies	(1) The Company and Summary of Significant Accounting Policies Description of Business ARCA biopharma, Inc. (the Company or ARCA) a Delaware corporation, is headquartered in Westminster, Colorado. The Company is a biopharmaceutical company applying a precision medicine approach to developing genetically-targeted therapies for cardiovascular diseases. The Company’s lead product candidate, Gencaro™ (bucindolol hydrochloride), is an investigational, pharmacologically unique beta-blocker and mild vasodilator that ARCA is developing for the potential treatment of patients with atrial fibrillation (AF) and chronic heart failure in patients with heart failure with reduced left ventricular ejection fraction (HFrEF). The Company is conducting a Phase 2B/Phase 3 clinical superiority trial, known as GENETIC-AF, in which the Company is evaluating Gencaro for the treatment of AF in HFrEF patients against TOPROL-XL (metoprolol succinate), a drug approved for treating HFrEF that is also prescribed, but not approved, for treating AF in patients with HFrEF. Enrollment in GENETIC-AF is limited to patients that possess the specific genotype that the Company believes enhances Gencaro’s potential therapeutic effects. The current development of Gencaro is, in part, based on a prospectively designed DNA substudy of adrenergic receptor polymorphisms in the BEST trial, a previous Phase 3 study of 2,708 HF patients. In the BEST trial, Gencaro showed evidence of potential efficacy in treating AF and in reducing mortality and hospitalizations in patients with this specific genotype. GENETIC-AF is an adaptive, seamless design Phase 2B/Phase 3, multi-center, randomized, double-blind, clinical superiority trial comparing the safety and efficacy of Gencaro against an active comparator, the beta-blocker TOPROL-XL (metoprolol succinate), that seeks to enroll a combined total of approximately 620 patients. Eligible patients will have HFrEF, a history of paroxysmal AF (episodes lasting 7 days or less) or persistent AF (episodes lasting more than 7 days and less than 1 year) in the past 6 months, and the beta-1 389 arginine homozygous genotype that the Company believes responds most favorably to Gencaro. The primary endpoint of the study is time to first event of symptomatic AF/atrial flutter (AFL), or all-cause mortality. The GENETIC-AF Data and Safety Monitoring Board (DSMB) will conduct a pre-specified interim analysis of study endpoints for efficacy, safety and futility to recommend whether or not the trial should proceed to Phase 3. The DSMB will make its recommendation based on a predictive probability analysis of certain trial data after a sufficient number of patients have evaluable endpoint data. A randomized patient has evaluable endpoint data either when they experience their first composite endpoint event, AF/AFL or all-cause mortality, or after completion of the 24-week primary endpoint follow up period. The DSMB interim analysis will focus on analyses of the AF/AFL endpoints in the trial using both clinical-based intermittent monitoring and device-based continuous monitoring techniques. Based on the results of the interim analysis, the DSMB may recommend that the trial proceed to Phase 3, the trial be completed as a Phase 2B study, or termination of the trial due to futility. ARCA, in collaboration with the GENETIC-AF Steering Committee, will determine the next steps for the trial based on the DSMB recommendation from this interim analysis and on the Company’s available financing. The Company randomized the 200th patient in the trial in April 2017. The Company projects that the outcome of the DSMB interim analysis and recommendation will be available in September 2017. Should the DSMB recommend that the study continue to Phase 3, the trial would continue enrolling to a total of approximately 620 patients, subject to the Company obtaining sufficient financing to fund the Phase 3 portion of the trial. If the Company continues with the Phase 3 portion of the GENETIC-AF, it will need to raise additional capital to complete the Phase 3 portion of the GENETIC-AF clinical trial and submit for approval by the U.S. Food and Drug Administration (FDA). If the Company is unable to obtain additional funding or is unable to complete a strategic transaction, it may have to discontinue development activities on Gencaro or discontinue its operations. Liquidity and Going Concern The Company devotes substantially all of its efforts towards obtaining regulatory approval and raising capital necessary to fund its operations and it is subject to a number of risks associated with clinical research and development, including dependence on key individuals, the development of and regulatory approval of commercially viable products, the need to raise adequate additional financing necessary to fund the development and commercialization of its products, and competition from larger companies. The Company has not generated revenue to date and has incurred substantial losses and negative cash flows from operations since its inception. The Company has historically funded its operations through issuances of common and preferred stock. The Company is enrolling patients in the Phase 2B portion of the GENETIC-AF trial, and the Company believes that its current cash, cash equivalents and marketable securities will be sufficient to fund its operations, at its projected cost structure, through the end of 2017. In January 2017, the Company entered into a sales agreement with an agent to sell, from time to time, its common stock having an aggregate offering price of up to $7.3 million, in an “at the market offering.” As of March 31, 2017, the Company has sold an aggregate of 85,068 shares of its common stock pursuant to the terms of such sales agreement for aggregate gross proceeds of approximately $221,000. Net proceeds received in the period were approximately $69,000, including initial expenses for executing the “at the market offering” and commissions to the placement agent. However, notwithstanding this sales agreement, in light of the significant uncertainties regarding clinical development timelines and costs for developing drugs such as Gencaro, the Company expects it will need to raise additional capital to finance the completion of GENETIC-AF and the Company’s future operations. If the Company is delayed in completing or is unable to complete additional funding and/or a strategic transaction, the Company may discontinue its development activities or operations. The Company’s liquidity, and its ability to raise additional capital or complete any strategic transaction, depends on a number of factors, including, but not limited to, the following: • progress of GENETIC-AF, including enrollment and any data that may become available; • the costs and timing for the potential additional clinical trials in order to gain possible regulatory approval for Gencaro; • the market price of the Company’s stock and the availability and cost of additional equity capital from existing and potential new investors; • the Company’s ability to retain the listing of its common stock on the Nasdaq Capital Market; • general economic and industry conditions affecting the availability and cost of capital; • the Company’s ability to control costs associated with its operations; • the costs of filing, prosecuting, defending and enforcing any patent claims and other intellectual property rights; and • the terms and conditions of the Company’s existing collaborative and licensing agreements. The sale of additional equity or convertible debt securities would likely result in substantial additional dilution to the Company’s stockholders. If the Company raises additional funds through the incurrence of indebtedness, the obligations related to such indebtedness would be senior to rights of holders of the Company’s capital stock and could contain covenants that would restrict the Company’s operations. The Company also cannot predict what consideration might be available, if any, to the Company or its stockholders, in connection with any strategic transaction. Should strategic alternatives or additional capital not be available to the Company, or not be available on acceptable terms, the Company may be unable to realize value from its assets and discharge its liabilities in the normal course of business which may, among other alternatives, cause the Company to further delay, substantially reduce or discontinue operational activities to conserve its cash resources. The significant uncertainties surrounding the clinical development timelines and costs and the need to raise a significant amount of capital raises substantial doubt about the Company’s ability to continue as a going concern from one year after the Company’s financial statements have been issued. The Company could delay or cancel certain significant planned expenditures related to the GENETIC-AF trial and/or implement cost reduction measures to conserve our cash balances; however, there is no assurance that those measures would be adequate to allow the Company to continue as a going concern for a period beyond one year from the issuance of these financial statements. These financial statements have been prepared with the assumption that the Company will continue as a going concern and will be able to realize its assets and discharge its liabilities in the normal course of business and do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classification of liabilities that may result from the inability of the Company to continue as a going concern. The Company may not be able to raise sufficient capital on acceptable terms, or at all, to continue development of Gencaro or to otherwise continue operations and may not be able to execute any strategic transaction. Basis of Presentation The accompanying unaudited financial statements of the Company were prepared in accordance with generally accepted accounting principles for interim financial information and instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, these financial statements do not include all of the information and footnotes required by accounting principles generally accepted in the United States of America (GAAP) for complete financial statements. In the opinion of management, these financial statements include all normal and recurring adjustments considered necessary for a fair presentation of these interim financial statements. The results of operations for the three months ended March 31, 2017 are not necessarily indicative of results expected for the full year ending December 31, 2017. The Company has generated no revenue to date and its activities have consisted of seeking regulatory approval, research and development, exploring strategic alternatives for further developing and commercializing Gencaro, and raising capital. These unaudited financial statements should be read in conjunction with the audited financial statements and footnotes thereto for the year ended December 31, 2016 included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission. Amounts presented are rounded to the nearest thousand, where indicated, except per share data and par values. Concentrations of Credit Risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents. The Company has no off-balance-sheet concentrations of credit risk, such as foreign exchange contracts, option contracts, or foreign currency hedging arrangements. The Company maintains cash and cash equivalent balances in the form of bank demand deposits and money market fund accounts with financial institutions that management believes are creditworthy. Such balances may at times exceed the insured amount. Accrued Expenses As part of the process of preparing its financial statements, the Company is required to estimate accrued expenses. This process involves identifying services that third parties have performed on the Company’s behalf and estimating the level of service performed and the associated cost incurred for these services as of the balance sheet date. Examples of estimated accrued expenses include contract service fees, such as fees payable to contract manufacturers in connection with the production of materials related to the Company’s drug product, and professional service fees, such as attorneys, consultants, and clinical research organizations. The Company develops estimates of liabilities using its judgment based upon the facts and circumstances known at the time. Recent Accounting Pronouncements In January 2016, Financial Accounting Standards Board (FASB) issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) In March 2016, the FASB issued ASU No. 2016-09, Compensation - Stock Compensation: Improvements to Employee Share-Based Payment Accounting

Net Loss Per Share

Net Loss Per Share	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Net Loss Per Share	(2) Net Loss Per Share The Company calculates basic earnings per share by dividing net loss by the weighted average common shares outstanding during the period. Diluted earnings per share is computed by dividing net loss by the weighted average number of common shares outstanding during the period increased to include, if dilutive, the number of additional common shares that would have been outstanding if the potential common shares had been issued. The Company’s potentially dilutive shares include stock options, restricted stock units and warrants for common stock . Because the Company reported a net loss for the three months ended March 31, 2017 and 2016, all potentially dilutive shares of common stock have been excluded from the computation of the dilutive net loss per share for all periods presented. March 31, 2017 2016 Potentially dilutive securities, excluded: Outstanding stock options 826,617 175,041 Unvested restricted stock units 24,905 56,458 Warrants to purchase common stock 3,686,894 3,739,948 4,538,416 3,971,447

Marketable Securities and Fair

Marketable Securities and Fair Value Disclosures	3 Months Ended
	Mar. 31, 2017
Marketable Securities And Fair Value Disclosures [Abstract]
Marketable Securities and Fair Value Disclosures	(3) Marketable Securities and Fair Value Disclosures Marketable securities consisted of the following as of March 31, 2017 and December 31, 2016 (in thousands): March 31, 2017 Gross Gross Amortized Unrealized Unrealized Fair Cost Gains Losses Value Short-term available-for-sale securities: Corporate bonds $ 13,050 $ 3 $ (12 ) $ 13,041 Total $ 13,050 $ 3 $ (12 ) $ 13,041 December 31, 2016 Gross Gross Amortized Unrealized Unrealized Fair Cost Gains Losses Value Short-term available-for-sale securities: Corporate bonds $ 13,778 $ — $ (16 ) $ 13,762 Total $ 13,778 $ — $ (16 ) $ 13,762 Long-term available-for-sale securities: Corporate bonds $ 2,355 $ 3 $ (6 ) $ 2,352 Total $ 2,355 $ 3 $ (6 ) $ 2,352 As of March 31, 2017, the amortized cost and estimated fair value of available-for-sale securities by contractual maturity were as follows (in thousands): Amortized Fair Cost Value Due in one year or less $ 13,050 $ 13,041 Total $ 13,050 $ 13,041 Fair value is defined as 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 (exit price). Inputs used to measure fair value are classified into the following hierarchy: • Level 1—Unadjusted quoted prices in active markets for identical assets or liabilities. The Company’s Level 1 assets consist of money market investments. The Company does not have any Level 1 liabilities. • Level 2—Unadjusted quoted prices in active markets for similar assets or liabilities; unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active; or inputs other than quoted prices that are observable for the asset or liability. The Company’s Level 2 assets consist of corporate bonds and commercial paper securities. The Company does not have any Level 2 liabilities. • Level 3—Unobservable inputs for the asset or liability. The Company does not have any Level 3 assets or liabilities. The following table identifies the Company’s assets that were measured at fair value on a recurring basis (in thousands): Balance Level 1 Level 2 Level 3 March 31, 2017 Money market $ 6,170 $ 6,170 $ — $ — Corporate bonds 13,041 — 13,041 — Total $ 19,211 $ 6,170 $ 13,041 $ — December 31, 2016 Money market $ 7,672 $ 7,672 $ — $ — Corporate bonds 16,114 — 16,114 — Total $ 23,786 $ 7,672 $ 16,114 $ — As of March 31, 2017 and December 31, 2016, the Company had $6.2 million and $7.7 million, respectively, of cash equivalents consisting of money market funds with maturities of 90 days or less. The Company has the ability to liquidate these investments without restriction. The Company determines fair value for these money market funds and equity securities with Level 1 inputs through quoted market prices. There were no transfers of assets between fair value hierarchy levels during the three month period ended March 31, 2017. Fair Value of Other Financial Instruments The carrying amount of other financial instruments, including accounts payable and short-term notes payable approximated fair value due to their short maturities.

Property and Equipment

Property and Equipment	3 Months Ended
	Mar. 31, 2017
Property Plant And Equipment [Abstract]
Property and Equipment	(4) Property and Equipment Property and equipment consist of the following (in thousands): Estimated Life March 31, 2017 December 31, 2016 Computer equipment 3 years $ 84 $ 84 Lab equipment 5 years 142 142 Furniture and fixtures 5 years 83 83 Computer software 3 years 85 85 Leasehold improvements Lesser of useful life or life of the lease 59 59 453 453 Accumulated depreciation and amortization (394 ) (387 ) Property and equipment, net $ 59 $ 66 For the three months ended March 31, 2017 and 2016, depreciation and amortization expense was $7,000 and $5,000, respectively.

Related Party Arrangements

Related Party Arrangements	3 Months Ended
	Mar. 31, 2017
Related Party Transactions [Abstract]
Related Party Arrangements	(5) Related Party Arrangements Transactions with the Company’s President and Chief Executive Officer The Company has entered into unrestricted research grants with its President and Chief Executive Officer’s academic research laboratory at the University of Colorado. Funding of any unrestricted research grants is contingent upon the Company’s financial condition, and can be deferred or terminated at the Company’s discretion. Total expense under these arrangements for the three months ended March 31, 2017 and 2016 was $103,000 and $117,000 respectively.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	(6) Commitments and Contingencies The Company has or is subject to the following commitments and contingencies: Employment Agreements The Company maintains employment agreements with several key executive employees. The agreements may be terminated at any time by the Company with or without cause upon written notice to the employee, and entitle the employee to wages in lieu of notice for periods not exceeding one calendar year from the date of termination without cause or by the employee for good reason. Certain of these agreements also provide for payments to be made under certain conditions related to a change in control of the Company. Operating Lease On August 1, 2013 the Company entered into a lease agreement for approximately 5,300 square feet of office facilities in Westminster, Colorado which has served as the Company’s primary business office since October 1, 2013. Effective March 2, 2016, the lease was renewed for an additional 38 month term beginning October 1, 2016 and expiring on November 30, 2019. Below is a summary of the future minimum lease payments committed for the Company’s facility in Westminster, Colorado as of March 31, 2017 (in thousands): Remainder of 2017 $ 62 2018 88 2019 83 Total future minimum lease payments $ 233 Rent expense for the three months ended March 31, 2017 and 2016 was $21,000 and $20,000, respectively. Duke University In November 2013, the Company entered into a clinical research agreement with Duke University (Duke) to serve as the clinical research organization for the Company’s GENETIC-AF clinical study. Under the agreement the Company is responsible to pay Duke for their work managing certain aspects of the clinical study. Upon completion of the clinical study, the agreement will terminate. The agreement can be terminated earlier by the Company for any reason with 90 . Cardiovascular Pharmacology and Engineering Consultants, LLC ARCA has licensed worldwide rights to Gencaro, including all preclinical and clinical data from Cardiovascular Pharmacology and Engineering Consultants, LLC (CPEC), who has licensed rights in Gencaro from Bristol Myers Squib (BMS). CPEC is a licensing subsidiary of Indevus Pharmaceuticals Inc. (a wholly owned subsidiary of Endo Pharmaceuticals), holding ownership rights to certain clinical trial data of Gencaro. Under the terms of its license agreement with CPEC, the Company will incur milestone and royalty obligations upon the occurrence of certain events. If the FDA grants marketing approval for Gencaro, the license agreement states that the Company will owe CPEC a milestone payment of $8.0 million within six months after FDA approval. The license agreement states that a milestone payment of up to $5.0 million in the aggregate shall be paid upon regulatory marketing approval in Europe and Japan. The license agreement also states that the Company’s royalty obligation ranges from 12.5% to 25% of revenue from the related product based on achievement of specified product sales levels, including a 5% royalty that CPEC is obligated to pay under its original license agreement for Gencaro. The agreement states that the Company has the right to buy down the royalties to a range of 12.5% to 17% by making a payment to CPEC within six months of regulatory approval.

Equity Financings and Warrants

Equity Financings and Warrants	3 Months Ended
	Mar. 31, 2017
Equity [Abstract]
Equity Financings and Warrants	(7) Equity Financings and Warrants 2017 Equity Financing On January 11, 2017, the Company entered into a Capital on Demand TM Under the Sales Agreement, JonesTrading may sell the Shares by any method permitted by law and deemed to be an “at the market offering” as defined in Rule 415 promulgated under the Securities Act of 1933, as amended, including sales made directly on or through The NASDAQ Capital Market, on any other existing trading market for the Common Stock or to or through a market maker. In addition, under the Sales Agreement, JonesTrading may sell the Shares by any other method permitted by law, including in negotiated transactions. The Company may instruct JonesTrading not to sell Shares if the sales cannot be effected at or above the price designated by the Company from time to time. The Company is not obligated to make any sales of the Shares under the Sales Agreement. The offering of Shares pursuant to the Sales Agreement will terminate upon the earlier of (a) the sale of all of the Shares subject to the Sales Agreement or (b) the termination of the Sales Agreement by JonesTrading or the Company, as permitted therein. The Company will pay JonesTrading a commission rate equal to 3.0% of the aggregate gross proceeds from each sale of Shares and have agreed to provide JonesTrading with customary indemnification and contribution rights. The Company will also reimburse JonesTrading for certain specified expenses in connection with entering into the Sales Agreement. As of March 31, 2017, the Company has sold an aggregate of 85,068 shares of Common Stock pursuant to the terms of such sales agreement for aggregate gross proceeds of approximately $221,000. Net proceeds received in the period were approximately $69,000, including initial expenses for executing the “at the market offering” and commissions to the placement agent. Subsequent to March 31, 2017, there have not been any significant sales through this facility. Warrants Warrants to purchase shares of common stock were previously granted as part of various financing and business agreements. All outstanding warrants were recorded in additional paid-in capital at their estimated fair market value at the date of grant using a Black-Scholes option-pricing model. As of March 31, 2017, these warrants, by year of expiration, are summarized below: Year of Expiration Number of Warrants Weighted Average Exercise Price 2017 53,886 42.46 2018 963,153 11.77 2019 224,323 15.73 2020 44,299 15.96 2022 2,401,233 6.10 3,686,894 $ 8.82

Share-based Compensation

Share-based Compensation	3 Months Ended
	Mar. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-based Compensation	(8) Share-based Compensation For the three month periods ended March 31, 2017 and 2016, the Company recognized the following non-cash, share-based compensation expense in the statements of operations (in thousands): Three Months Ended March 31, 2017 2016 Research and development $ 36 $ 42 General and administrative 65 113 Total $ 101 $ 155 Stock option transactions for the three month period ended March 31, 2017 under the Company’s stock incentive plans were as follows: Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Term (in years) Options outstanding at December 31, 2016 629,629 $ 6.30 8.86 Granted 469,600 2.54 Exercised — — Forfeited and cancelled (272,612 ) 3.34 Options outstanding at March 31, 2017 826,617 $ 5.14 9.14 Options exercisable at March 31, 2017 209,658 $ 11.83 7.46 Options vested and expected to vest 824,931 $ 5.15 9.14 Stock award transactions related to restricted stock units for the three month period ended March 31, 2017 under the Company’s stock incentive plans were as follows: Number of Shares Weighted Average Grant Date Fair Value Restricted stock units outstanding at December 31, 2016 30,739 $ 7.91 Granted — — Vested and released (5,434 ) 13.65 Forfeited and cancelled (400 ) 6.03 Restricted stock units outstanding at March 31, 2017 24,905 $ 6.69

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	(9) Income Taxes In accordance with GAAP, a valuation allowance should be provided if it is more likely than not that some or all of the Company’s deferred tax assets will not be realized. The Company’s ability to realize the benefit of its deferred tax assets will depend on the generation of future taxable income. Due to the uncertainty of future profitable operations and taxable income, the Company has recorded a full valuation allowance against its net deferred tax assets. The Company believes its tax filing positions and deductions related to tax periods subject to examination will be sustained upon audit and, therefore, has no reserve for uncertain tax positions.

The Company and Summary of Si16

The Company and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
Description of Business	Description of Business ARCA biopharma, Inc. (the Company or ARCA) a Delaware corporation, is headquartered in Westminster, Colorado. The Company is a biopharmaceutical company applying a precision medicine approach to developing genetically-targeted therapies for cardiovascular diseases. The Company’s lead product candidate, Gencaro™ (bucindolol hydrochloride), is an investigational, pharmacologically unique beta-blocker and mild vasodilator that ARCA is developing for the potential treatment of patients with atrial fibrillation (AF) and chronic heart failure in patients with heart failure with reduced left ventricular ejection fraction (HFrEF). The Company is conducting a Phase 2B/Phase 3 clinical superiority trial, known as GENETIC-AF, in which the Company is evaluating Gencaro for the treatment of AF in HFrEF patients against TOPROL-XL (metoprolol succinate), a drug approved for treating HFrEF that is also prescribed, but not approved, for treating AF in patients with HFrEF. Enrollment in GENETIC-AF is limited to patients that possess the specific genotype that the Company believes enhances Gencaro’s potential therapeutic effects. The current development of Gencaro is, in part, based on a prospectively designed DNA substudy of adrenergic receptor polymorphisms in the BEST trial, a previous Phase 3 study of 2,708 HF patients. In the BEST trial, Gencaro showed evidence of potential efficacy in treating AF and in reducing mortality and hospitalizations in patients with this specific genotype. GENETIC-AF is an adaptive, seamless design Phase 2B/Phase 3, multi-center, randomized, double-blind, clinical superiority trial comparing the safety and efficacy of Gencaro against an active comparator, the beta-blocker TOPROL-XL (metoprolol succinate), that seeks to enroll a combined total of approximately 620 patients. Eligible patients will have HFrEF, a history of paroxysmal AF (episodes lasting 7 days or less) or persistent AF (episodes lasting more than 7 days and less than 1 year) in the past 6 months, and the beta-1 389 arginine homozygous genotype that the Company believes responds most favorably to Gencaro. The primary endpoint of the study is time to first event of symptomatic AF/atrial flutter (AFL), or all-cause mortality. The GENETIC-AF Data and Safety Monitoring Board (DSMB) will conduct a pre-specified interim analysis of study endpoints for efficacy, safety and futility to recommend whether or not the trial should proceed to Phase 3. The DSMB will make its recommendation based on a predictive probability analysis of certain trial data after a sufficient number of patients have evaluable endpoint data. A randomized patient has evaluable endpoint data either when they experience their first composite endpoint event, AF/AFL or all-cause mortality, or after completion of the 24-week primary endpoint follow up period. The DSMB interim analysis will focus on analyses of the AF/AFL endpoints in the trial using both clinical-based intermittent monitoring and device-based continuous monitoring techniques. Based on the results of the interim analysis, the DSMB may recommend that the trial proceed to Phase 3, the trial be completed as a Phase 2B study, or termination of the trial due to futility. ARCA, in collaboration with the GENETIC-AF Steering Committee, will determine the next steps for the trial based on the DSMB recommendation from this interim analysis and on the Company’s available financing. The Company randomized the 200th patient in the trial in April 2017. The Company projects that the outcome of the DSMB interim analysis and recommendation will be available in September 2017. Should the DSMB recommend that the study continue to Phase 3, the trial would continue enrolling to a total of approximately 620 patients, subject to the Company obtaining sufficient financing to fund the Phase 3 portion of the trial. If the Company continues with the Phase 3 portion of the GENETIC-AF, it will need to raise additional capital to complete the Phase 3 portion of the GENETIC-AF clinical trial and submit for approval by the U.S. Food and Drug Administration (FDA). If the Company is unable to obtain additional funding or is unable to complete a strategic transaction, it may have to discontinue development activities on Gencaro or discontinue its operations.
Liquidity and Going Concern	Liquidity and Going Concern The Company devotes substantially all of its efforts towards obtaining regulatory approval and raising capital necessary to fund its operations and it is subject to a number of risks associated with clinical research and development, including dependence on key individuals, the development of and regulatory approval of commercially viable products, the need to raise adequate additional financing necessary to fund the development and commercialization of its products, and competition from larger companies. The Company has not generated revenue to date and has incurred substantial losses and negative cash flows from operations since its inception. The Company has historically funded its operations through issuances of common and preferred stock. The Company is enrolling patients in the Phase 2B portion of the GENETIC-AF trial, and the Company believes that its current cash, cash equivalents and marketable securities will be sufficient to fund its operations, at its projected cost structure, through the end of 2017. In January 2017, the Company entered into a sales agreement with an agent to sell, from time to time, its common stock having an aggregate offering price of up to $7.3 million, in an “at the market offering.” As of March 31, 2017, the Company has sold an aggregate of 85,068 shares of its common stock pursuant to the terms of such sales agreement for aggregate gross proceeds of approximately $221,000. Net proceeds received in the period were approximately $69,000, including initial expenses for executing the “at the market offering” and commissions to the placement agent. However, notwithstanding this sales agreement, in light of the significant uncertainties regarding clinical development timelines and costs for developing drugs such as Gencaro, the Company expects it will need to raise additional capital to finance the completion of GENETIC-AF and the Company’s future operations. If the Company is delayed in completing or is unable to complete additional funding and/or a strategic transaction, the Company may discontinue its development activities or operations. The Company’s liquidity, and its ability to raise additional capital or complete any strategic transaction, depends on a number of factors, including, but not limited to, the following: • progress of GENETIC-AF, including enrollment and any data that may become available; • the costs and timing for the potential additional clinical trials in order to gain possible regulatory approval for Gencaro; • the market price of the Company’s stock and the availability and cost of additional equity capital from existing and potential new investors; • the Company’s ability to retain the listing of its common stock on the Nasdaq Capital Market; • general economic and industry conditions affecting the availability and cost of capital; • the Company’s ability to control costs associated with its operations; • the costs of filing, prosecuting, defending and enforcing any patent claims and other intellectual property rights; and • the terms and conditions of the Company’s existing collaborative and licensing agreements. The sale of additional equity or convertible debt securities would likely result in substantial additional dilution to the Company’s stockholders. If the Company raises additional funds through the incurrence of indebtedness, the obligations related to such indebtedness would be senior to rights of holders of the Company’s capital stock and could contain covenants that would restrict the Company’s operations. The Company also cannot predict what consideration might be available, if any, to the Company or its stockholders, in connection with any strategic transaction. Should strategic alternatives or additional capital not be available to the Company, or not be available on acceptable terms, the Company may be unable to realize value from its assets and discharge its liabilities in the normal course of business which may, among other alternatives, cause the Company to further delay, substantially reduce or discontinue operational activities to conserve its cash resources. The significant uncertainties surrounding the clinical development timelines and costs and the need to raise a significant amount of capital raises substantial doubt about the Company’s ability to continue as a going concern from one year after the Company’s financial statements have been issued. The Company could delay or cancel certain significant planned expenditures related to the GENETIC-AF trial and/or implement cost reduction measures to conserve our cash balances; however, there is no assurance that those measures would be adequate to allow the Company to continue as a going concern for a period beyond one year from the issuance of these financial statements. These financial statements have been prepared with the assumption that the Company will continue as a going concern and will be able to realize its assets and discharge its liabilities in the normal course of business and do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classification of liabilities that may result from the inability of the Company to continue as a going concern. The Company may not be able to raise sufficient capital on acceptable terms, or at all, to continue development of Gencaro or to otherwise continue operations and may not be able to execute any strategic transaction.
Basis of Presentation	Basis of Presentation The accompanying unaudited financial statements of the Company were prepared in accordance with generally accepted accounting principles for interim financial information and instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, these financial statements do not include all of the information and footnotes required by accounting principles generally accepted in the United States of America (GAAP) for complete financial statements. In the opinion of management, these financial statements include all normal and recurring adjustments considered necessary for a fair presentation of these interim financial statements. The results of operations for the three months ended March 31, 2017 are not necessarily indicative of results expected for the full year ending December 31, 2017. The Company has generated no revenue to date and its activities have consisted of seeking regulatory approval, research and development, exploring strategic alternatives for further developing and commercializing Gencaro, and raising capital. These unaudited financial statements should be read in conjunction with the audited financial statements and footnotes thereto for the year ended December 31, 2016 included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission. Amounts presented are rounded to the nearest thousand, where indicated, except per share data and par values.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents. The Company has no off-balance-sheet concentrations of credit risk, such as foreign exchange contracts, option contracts, or foreign currency hedging arrangements. The Company maintains cash and cash equivalent balances in the form of bank demand deposits and money market fund accounts with financial institutions that management believes are creditworthy. Such balances may at times exceed the insured amount.
Accrued Expenses	Accrued Expenses As part of the process of preparing its financial statements, the Company is required to estimate accrued expenses. This process involves identifying services that third parties have performed on the Company’s behalf and estimating the level of service performed and the associated cost incurred for these services as of the balance sheet date. Examples of estimated accrued expenses include contract service fees, such as fees payable to contract manufacturers in connection with the production of materials related to the Company’s drug product, and professional service fees, such as attorneys, consultants, and clinical research organizations. The Company develops estimates of liabilities using its judgment based upon the facts and circumstances known at the time.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In January 2016, Financial Accounting Standards Board (FASB) issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) In March 2016, the FASB issued ASU No. 2016-09, Compensation - Stock Compensation: Improvements to Employee Share-Based Payment Accounting

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Summary of Potentially Dilutive Shares of Common Stock	Because the Company reported a net loss for the three months ended March 31, 2017 and 2016, all potentially dilutive shares of common stock have been excluded from the computation of the dilutive net loss per share for all periods presented. March 31, 2017 2016 Potentially dilutive securities, excluded: Outstanding stock options 826,617 175,041 Unvested restricted stock units 24,905 56,458 Warrants to purchase common stock 3,686,894 3,739,948 4,538,416 3,971,447

Marketable Securities and Fai18

Marketable Securities and Fair Value Disclosures (Tables)	3 Months Ended
	Mar. 31, 2017
Marketable Securities And Fair Value Disclosures [Abstract]
Summary of Marketable Securities	Marketable securities consisted of the following as of March 31, 2017 and December 31, 2016 (in thousands): March 31, 2017 Gross Gross Amortized Unrealized Unrealized Fair Cost Gains Losses Value Short-term available-for-sale securities: Corporate bonds $ 13,050 $ 3 $ (12 ) $ 13,041 Total $ 13,050 $ 3 $ (12 ) $ 13,041 December 31, 2016 Gross Gross Amortized Unrealized Unrealized Fair Cost Gains Losses Value Short-term available-for-sale securities: Corporate bonds $ 13,778 $ — $ (16 ) $ 13,762 Total $ 13,778 $ — $ (16 ) $ 13,762 Long-term available-for-sale securities: Corporate bonds $ 2,355 $ 3 $ (6 ) $ 2,352 Total $ 2,355 $ 3 $ (6 ) $ 2,352
Summary of Amortized Cost and Estimated Fair Value of Available-for-Sale Securities by Contractual Maturity	As of March 31, 2017, the amortized cost and estimated fair value of available-for-sale securities by contractual maturity were as follows (in thousands): Amortized Fair Cost Value Due in one year or less $ 13,050 $ 13,041 Total $ 13,050 $ 13,041
Summary of Assets Measured at Fair Value on Recurring Basis	The following table identifies the Company’s assets that were measured at fair value on a recurring basis (in thousands): Balance Level 1 Level 2 Level 3 March 31, 2017 Money market $ 6,170 $ 6,170 $ — $ — Corporate bonds 13,041 — 13,041 — Total $ 19,211 $ 6,170 $ 13,041 $ — December 31, 2016 Money market $ 7,672 $ 7,672 $ — $ — Corporate bonds 16,114 — 16,114 — Total $ 23,786 $ 7,672 $ 16,114 $ —

Property and Equipment (Tables)

Property and Equipment (Tables)	3 Months Ended
	Mar. 31, 2017
Property Plant And Equipment [Abstract]
Summary of Property and Equipment	Property and equipment consist of the following (in thousands): Estimated Life March 31, 2017 December 31, 2016 Computer equipment 3 years $ 84 $ 84 Lab equipment 5 years 142 142 Furniture and fixtures 5 years 83 83 Computer software 3 years 85 85 Leasehold improvements Lesser of useful life or life of the lease 59 59 453 453 Accumulated depreciation and amortization (394 ) (387 ) Property and equipment, net $ 59 $ 66

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
Future Minimum Lease Payments	Below is a summary of the future minimum lease payments committed for the Company’s facility in Westminster, Colorado as of March 31, 2017 (in thousands): Remainder of 2017 $ 62 2018 88 2019 83 Total future minimum lease payments $ 233

Equity Financings and Warrants

Equity Financings and Warrants (Tables)	3 Months Ended
	Mar. 31, 2017
Equity [Abstract]
Summary of Warrants by Year of Expiration	As of March 31, 2017, these warrants, by year of expiration, are summarized below: Year of Expiration Number of Warrants Weighted Average Exercise Price 2017 53,886 42.46 2018 963,153 11.77 2019 224,323 15.73 2020 44,299 15.96 2022 2,401,233 6.10 3,686,894 $ 8.82

Share-based Compensation (Table

Share-based Compensation (Tables)	3 Months Ended
	Mar. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Non-cash, Share-based Compensation Expense	For the three month periods ended March 31, 2017 and 2016, the Company recognized the following non-cash, share-based compensation expense in the statements of operations (in thousands): Three Months Ended March 31, 2017 2016 Research and development $ 36 $ 42 General and administrative 65 113 Total $ 101 $ 155
Summary of Stock Option Activities	Stock option transactions for the three month period ended March 31, 2017 under the Company’s stock incentive plans were as follows: Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Term (in years) Options outstanding at December 31, 2016 629,629 $ 6.30 8.86 Granted 469,600 2.54 Exercised — — Forfeited and cancelled (272,612 ) 3.34 Options outstanding at March 31, 2017 826,617 $ 5.14 9.14 Options exercisable at March 31, 2017 209,658 $ 11.83 7.46 Options vested and expected to vest 824,931 $ 5.15 9.14
Summary of RSU Activity	Stock award transactions related to restricted stock units for the three month period ended March 31, 2017 under the Company’s stock incentive plans were as follows: Number of Shares Weighted Average Grant Date Fair Value Restricted stock units outstanding at December 31, 2016 30,739 $ 7.91 Granted — — Vested and released (5,434 ) 13.65 Forfeited and cancelled (400 ) 6.03 Restricted stock units outstanding at March 31, 2017 24,905 $ 6.69

The Company and Summary of Si23

The Company and Summary of Significant Accounting Policies (Details Textual)	3 Months Ended	12 Months Ended
	Mar. 31, 2017USD ($)Patientsshares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)shares	Jan. 11, 2017USD ($)
Company And Summary Of Significant Accounting Policies Table [Line Items]
Revenues	$ 0
Common stock, shares issued | shares	9,172,868	9,082,366
Proceeds from sale of common stock	$ 210,000
Concentrations of credit risk	$ 0
Excess tax benefits from share-based payments		$ 0	$ 0
Number of shares withhold to satisfy statutory income tax withholding obligations | shares		0	0
At the Market Offering under Sales Agreement
Company And Summary Of Significant Accounting Policies Table [Line Items]
Aggregate offering price of common stock authorized				$ 7,300,000
Common stock, shares issued | shares	85,068
Proceeds from sale of common stock	$ 221,000
Net proceeds from issuance of common stock	$ 69,000
Phase 3 | BEST Trial
Company And Summary Of Significant Accounting Policies Table [Line Items]
Number of patients | Patients	2,708
Phase 2B/Phase 3 | GENETIC-AF Trial
Company And Summary Of Significant Accounting Policies Table [Line Items]
Number of patients company plans to enroll | Patients	620
Trial endpoint, term	168 days

Net Loss Per Share - Summary of

Net Loss Per Share - Summary of Potentially Dilutive Shares of Common Stock (Details) - shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	4,538,416	3,971,447
Outstanding stock options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	826,617	175,041
Unvested restricted stock units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	24,905	56,458
Warrants to purchase common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	3,686,894	3,739,948

Marketable Securities and Fai25

Marketable Securities and Fair Value Disclosures - Summary of Marketable securities (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 13,050
Fair Value	13,041
Short-term available-for-sale securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	13,050	$ 13,778
Gross Unrealized Gains	3
Gross Unrealized Losses	(12)	(16)
Fair Value	13,041	13,762
Short-term available-for-sale securities | Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	13,050	13,778
Gross Unrealized Gains	3
Gross Unrealized Losses	(12)	(16)
Fair Value	$ 13,041	13,762
Long-term available-for-sale securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		2,355
Gross Unrealized Gains		3
Gross Unrealized Losses		(6)
Fair Value		2,352
Long-term available-for-sale securities | Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		2,355
Gross Unrealized Gains		3
Gross Unrealized Losses		(6)
Fair Value		$ 2,352

Marketable Securities and Fai26

Marketable Securities and Fair Value Disclosures - Summary of Amortized Cost and Estimated Fair Value of Available-for-Sale Securities by Contractual Maturity (Details) $ in Thousands	Mar. 31, 2017USD ($)
Investments Debt And Equity Securities [Abstract]
Due in one year or less, Amortized Cost	$ 13,050
Amortized Cost	13,050
Due in one year or less, Fair Value	13,041
Fair Value	$ 13,041

Marketable Securities and Fai27

Marketable Securities and Fair Value Disclosures - Summary of Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	$ 19,211	$ 23,786
Corporate bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	13,041	16,114
Money market
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	6,170	7,672
Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	6,170	7,672
Level 1 | Money market
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	6,170	7,672
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	13,041	16,114
Level 2 | Corporate bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	$ 13,041	$ 16,114

Marketable Securities and Fai28

Marketable Securities and Fair Value Disclosures (Details Textual) - USD ($)	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Transfers of assets between fair value hierarchy levels	$ 0
Fair Value Measurements, Recurring | Level 1 | Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents consisting of money market funds	$ 6,200,000	$ 7,700,000

Property and Equipment - Summar

Property and Equipment - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Line Items]
Property and Equipment, Gross	$ 453	$ 453
Accumulated depreciation and amortization	(394)	(387)
Property and equipment, net	$ 59	66
Computer Equipment
Property Plant And Equipment [Line Items]
Estimated Life	3 years
Property and Equipment, Gross	$ 84	84
Lab Equipment
Property Plant And Equipment [Line Items]
Estimated Life	5 years
Property and Equipment, Gross	$ 142	142
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Estimated Life	5 years
Property and Equipment, Gross	$ 83	83
Computer Software
Property Plant And Equipment [Line Items]
Estimated Life	3 years
Property and Equipment, Gross	$ 85	85
Leasehold Improvements
Property Plant And Equipment [Line Items]
Estimated Life	Lesser of useful life or life of the lease
Property and Equipment, Gross	$ 59	$ 59

Property and Equipment (Details

Property and Equipment (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Property Plant And Equipment [Abstract]
Depreciation and amortization expense	$ 7	$ 5

Related Party Arrangements (Det

Related Party Arrangements (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Chief Executive Officer | Research Grants
Related Party Transaction [Line Items]
Total expense	$ 103	$ 117

Commitments and Contingencies32

Commitments and Contingencies (Details Textual) $ in Thousands	Mar. 02, 2016	Mar. 31, 2017USD ($)	Mar. 31, 2016USD ($)	Aug. 01, 2013ft²
Commitments And Contingencies [Line Items]
Area of office facilities taken on lease | ft²				5,300
Additional operating lease term	38 months
Lease renewal start date	Oct. 1, 2016
Lease expiration date	Nov. 30, 2019
Rent expense		$ 21	$ 20
Royalty buy down due period		6 months
Minimum
Commitments And Contingencies [Line Items]
Percentage of royalty obligation		12.50%
Percentage of range of royalties that can be bought down		12.50%
Maximum
Commitments And Contingencies [Line Items]
Percentage of royalty obligation		25.00%
Percentage of range of royalties that can be bought down		17.00%
Clinical Research Agreement with Duke University
Commitments And Contingencies [Line Items]
Agreement termination notice period		90 days
Upon Food and Drug Administration Approval
Commitments And Contingencies [Line Items]
Expected milestone payments due upon approval		$ 8,000
Upon Regulatory Marketing Approval
Commitments And Contingencies [Line Items]
Expected milestone payments due upon approval		$ 5,000
CPEC
Commitments And Contingencies [Line Items]
Percentage of royalty obligation		5.00%

Commitments and Contingencies -

Commitments and Contingencies - Future Minimum Lease Payments (Details) $ in Thousands	Mar. 31, 2017USD ($)
Commitments And Contingencies Disclosure [Abstract]
Remainder of 2017	$ 62
2,018	88
2,019	83
Total future minimum lease payments	$ 233

Equity Financings and Warrant34

Equity Financings and Warrants (Details Textual) - USD ($)	Apr. 02, 2017	Mar. 31, 2017	Jan. 11, 2017	Dec. 31, 2016
Equity Financing And Warrants [Line Items]
Common stock, par value		$ 0.001		$ 0.001
Common stock, shares issued		9,172,868		9,082,366
Proceeds from the issuance of common stock		$ 210,000
JonesTrading
Equity Financing And Warrants [Line Items]
Percentage of selling commission per share sold			3.00%
Sales Agreement
Equity Financing And Warrants [Line Items]
Common stock, shares issued		85,068
Proceeds from the issuance of common stock		$ 221,000
Net proceeds from issuance of common stock		$ 69,000
Sales Agreement | Subsequent Event
Equity Financing And Warrants [Line Items]
Proceeds from the issuance of common stock	$ 0
Sales Agreement | JonesTrading
Equity Financing And Warrants [Line Items]
Common stock, par value			$ 0.001
Sales Agreement | JonesTrading | Maximum
Equity Financing And Warrants [Line Items]
Aggregate offering price of common stock authorized			$ 7,300,000

Equity Financings and Warrant35

Equity Financings and Warrants - Summary of Warrants by Year of Expiration (Details)	3 Months Ended
	Mar. 31, 2017$ / sharesshares
Class Of Warrant Or Right [Line Items]
Number of Warrants | shares	3,686,894
Weighted Average Exercise Price | $ / shares	$ 8.82
2,017
Class Of Warrant Or Right [Line Items]
Year of Expiration	2,017
Number of Warrants | shares	53,886
Weighted Average Exercise Price | $ / shares	$ 42.46
2,018
Class Of Warrant Or Right [Line Items]
Year of Expiration	2,018
Number of Warrants | shares	963,153
Weighted Average Exercise Price | $ / shares	$ 11.77
2,019
Class Of Warrant Or Right [Line Items]
Year of Expiration	2,019
Number of Warrants | shares	224,323
Weighted Average Exercise Price | $ / shares	$ 15.73
2,020
Class Of Warrant Or Right [Line Items]
Year of Expiration	2,020
Number of Warrants | shares	44,299
Weighted Average Exercise Price | $ / shares	$ 15.96
2,022
Class Of Warrant Or Right [Line Items]
Year of Expiration	2,022
Number of Warrants | shares	2,401,233
Weighted Average Exercise Price | $ / shares	$ 6.10

Share-based Compensation - Summ

Share-based Compensation - Summary of Non-cash, Share-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total expenses	$ 101	$ 155
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total expenses	36	42
General and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total expenses	$ 65	$ 113

Share-based Compensation - Su37

Share-based Compensation - Summary of Stock Option Activities (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Number of Stock Options
Number of Options, Options outstanding, beginning of period	629,629
Number of Options, Granted	469,600
Number of Options, Forfeited and cancelled	(272,612)
Number of Options, Options outstanding, end of period	826,617	629,629
Number of Options, Options exercisable, end of period	209,658
Number of Options, Options vested and expected to vest	824,931
Stock Options, Weighted Average Exercise Price
Weighted Average Exercise Price, Options outstanding, beginning of period	$ 6.30
Weighted Average Exercise Price, Granted	2.54
Weighted Average Exercise Price, Forfeited and cancelled	3.34
Weighted Average Exercise Price, Options outstanding, end of period	5.14	$ 6.30
Weighted Average Exercise Price, Options exercisable, end of period	11.83
Weighted Average Exercise Price, Options vested and expected to vest, end of period	$ 5.15
Stock Options, Weighted Average Remaining Contractual Term
Weighted Average Remaining Contractual Term (in years), Options outstanding	9 years 7 days	8 years 10 months 10 days
Weighted Average Remaining Contractual Term (in years), Options exercisable	7 years 5 months 16 days
Weighted Average Remaining Contractual Term (in years), Options vested and expected to vest	9 years 1 month 21 days

Share-based Compensation - Su38

Share-based Compensation - Summary of RSU Activity (Details)	3 Months Ended
	Mar. 31, 2017$ / sharesshares
Restricted Stock Awards, Number of Shares
Restricted stock units outstanding, beginning of period | shares	30,739
Vested and released | shares	(5,434)
Forfeited and cancelled | shares	(400)
Restricted stock units outstanding, end of period | shares	24,905
Restricted Stock Awards, Weighted Average Grant Date Fair Value
Restricted stock units outstanding, beginning of period | $ / shares	$ 7.91
Vested and released | $ / shares	13.65
Forfeited and cancelled | $ / shares	6.03
Restricted stock units outstanding, end of period | $ / shares	$ 6.69

Income Taxes (Details Textual)

Income Taxes (Details Textual)	Mar. 31, 2017USD ($)
Income Tax Disclosure [Abstract]
Reserve for uncertain tax positions	$ 0