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Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2019	Apr. 30, 2019
Document and Entity Information
Entity Registrant Name	CATABASIS PHARMACEUTICALS INC
Entity Central Index Key	0001454789
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Common Stock, Shares Outstanding		11,498,742
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 11,652	$ 15,294
Short-term investments	40,012	22,276
Prepaid expenses and other current assets	985	1,345
Total current assets	52,649	38,915
Property and equipment, net	48	56
Restricted cash	113	113
Right-of-use asset	1,577
Other assets	110	85
Total assets	54,497	39,169
Current liabilities:
Accounts payable	1,588	1,408
Accrued expenses	1,451	2,763
Current portion of operating lease liabilities	1,259
Total current liabilities	4,298	4,171
Long-term portion of operating lease liabilities	330
Other long-term liabilities		56
Total liabilities	4,628	4,227
Commitments (Note 6)
Stockholders' equity:
Preferred stock, $0.001 par value per share, 5,000,000 shares authorized and no shares issued and outstanding
Common stock, $0.001 par value per share, 150,000,000 shares authorized; 11,496,242 and 7,141,996 shares issued and outstanding at March 31, 2019 and December 31, 2018, respectively	11	7
Additional paid-in capital	253,200	232,243
Accumulated other comprehensive loss		(4)
Accumulated deficit	(203,342)	(197,304)
Total stockholders' equity	49,869	34,942
Total liabilities and stockholders' equity	$ 54,497	$ 39,169

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
Condensed Consolidated Balance Sheets
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, authorized (in shares)	5,000,000	5,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	150,000,000	150,000,000
Common stock, issued (in shares)	11,496,242	7,141,996
Common stock, outstanding (in shares)	11,496,242	7,141,996

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating expenses:
Research and development	$ 4,197	$ 5,247
General and administrative	2,137	2,392
Total operating expenses	6,334	7,639
Loss from operations	(6,334)	(7,639)
Other income (expense):
Interest expense		(57)
Interest and investment income	226	32
Other income, net	70	12
Total other income (expense), net	296	(13)
Net loss	$ (6,038)	$ (7,652)
Net loss per share - basic and diluted (in dollars per share)	$ (0.62)	$ (2.88)
Weighted-average common shares outstanding used in net loss per share - basic and diluted (in shares)	9,686,224	2,655,584

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Condensed Consolidated Statements of Comprehensive Loss
Net loss	$ (6,038)	$ (7,652)
Other comprehensive income:
Gain on short-term investments	4
Total other comprehensive income:	4
Comprehensive loss	$ (6,034)	$ (7,652)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss	Total
Balance at Dec. 31, 2017	$ 2	$ 183,223	$ (171,434)		$ 11,791
Balance (in shares) at Dec. 31, 2017	2,364,526
Increase (Decrease) in Shareholders' Equity
Issuance of common stock for at-the-market offerings, net of issuance costs of $0.1 million and $0.3 million for the years 2019 and 2018 respectively	$ 1	8,312			8,313
Issuance of common stock for at-the-market offerings, net of issuance costs of $0.1 million and $0.3 million for the years 2019 and 2018 respectively (in shares)	539,026
Stock-based compensation expense		479			479
Net loss			(7,652)		(7,652)
Balance at Mar. 31, 2018	$ 3	192,014	(179,086)		12,931
Balance (in shares) at Mar. 31, 2018	2,903,552
Balance at Dec. 31, 2018	$ 7	232,243	(197,304)	$ (4)	$ 34,942
Balance (in shares) at Dec. 31, 2018	7,141,996				7,141,996
Increase (Decrease) in Shareholders' Equity
Issuance of common stock for at-the-market offerings, net of issuance costs of $0.1 million and $0.3 million for the years 2019 and 2018 respectively		2,045			$ 2,045
Issuance of common stock for at-the-market offerings, net of issuance costs of $0.1 million and $0.3 million for the years 2019 and 2018 respectively (in shares)	353,746
Issuance of common stock and warrants in public offering, net of issuance costs of $1.5 million	$ 4	18,501			18,505
Issuance of common stock and warrants in public offering, net of issuance costs of $1.5 million (in shares)	4,000,000
Issuance of common stock upon exercise of warrants		3			3
Issuance of common stock upon exercise of warrants (in shares)	500
Stock-based compensation expense		408			408
Realized gain on short-term investments				$ 4	4
Net loss			(6,038)		(6,038)
Balance at Mar. 31, 2019	$ 11	$ 253,200	$ (203,342)		$ 49,869
Balance (in shares) at Mar. 31, 2019	11,496,242				11,496,242

Condensed Consolidated Statements of Shareholders' Equity (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Initial public offering
Stock issuance costs	$ 0.1	$ 0.3
Common stock warrants
Stock issuance costs	$ 1.5

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating activities
Net loss	$ (6,038)	$ (7,652)
Reconciliation of net loss to net cash used in operating activities:
Depreciation and amortization	8	62
Stock-based compensation expense	408	479
Accretion of discount/premium on investment securities	7
Non-cash interest expense		20
Services received in non-monetary exchange	6
Changes in assets and liabilities:
Prepaid expenses and other current assets	354	205
Other assets	(25)
Right-of-use asset-operating	12
Accounts payable	48	342
Accrued expenses	(1,313)	(277)
Other liabilities	(54)	2
Net cash used in operating activities	(6,587)	(6,819)
Investing activities
Purchases of short-term investments	(47,015)
Sales and maturities of short-term investments	29,277
Net cash used in investing activities	(17,738)
Financing activities
Proceeds from public offerings, net of issuance costs	18,635
Proceeds from at-the-market offering, net of issuance costs	2,045	8,313
Proceeds from exercise of common stock options and warrants	3
Payments on borrowing		(833)
Net cash provided by financing activities	20,683	7,480
Net (decrease) increase in cash, cash equivalents and restricted cash	(3,642)	661
Cash, cash equivalents and restricted cash, beginning of period	15,407	16,482
Cash, cash equivalents and restricted cash, end of period	11,765	17,143
Supplemental disclosure of cash flow information
Cash paid for interest		$ 42
Non-cash financing activities
Public offering issuance costs included in accounts payable	$ 130

Organization and Operations	3 Months Ended
Organization and Operations	Mar. 31, 2019
Organization and Operations
Organization and Operations	1. Organization and Operations The Company Catabasis Pharmaceuticals, Inc. (the "Company") is a clinical-stage biopharmaceutical company. The Company’s lead program is edasalonexent, formerly known as CAT-1004, an oral small molecule designed to inhibit NF-B, or nuclear factor kappa-light-chain-enhancer of activated B cells, in development for the treatment of Duchenne muscular dystrophy (“DMD”). The Company believes edasalonexent has the potential to be a foundational therapy for all patients affected by DMD, regardless of the underlying dystrophin mutation. DMD is an ultimately fatal genetic disorder involving progressive muscle degeneration. The United States Food and Drug Administration has granted orphan drug, fast track and rare pediatric disease designations to edasalonexent for the treatment of DMD. The European Commission has granted orphan medicinal product designation to edasalonexent for the treatment of DMD. The Company was incorporated in the State of Delaware on June 26, 2008. Liquidity The Company has entered into various sales agreements with Cowen and Company LLC, (“Cowen”), pursuant to which the Company could issue and sell shares of common stock under at-the-market offering programs (the “ATM Programs”). Shares sold pursuant to these sales agreements were sold pursuant to a shelf registration statement, which became effective on July 19, 2016. The Company pays Cowen 3% of the gross proceeds from any common stock sold through these sales agreements. The Company has $22.6 million remaining available under its current sales agreement. During the three months ended March 31, 2019, the Company sold an aggregate of 353,746 shares of common stock pursuant to the ATM Programs, at an average price of $5.96 per share, for gross proceeds of $2.1 million, resulting in net proceeds of $2.0 million after deducting sales commissions and offering expenses. On February 6, 2019, the Company entered into an underwriting agreement with Oppenheimer & Co. Inc. relating to an underwritten public offering (the “February 2019 Financing”) of 4,000,000 shares of the Company’s common stock, par value $0.001 per share, and accompanying warrants to purchase up to 2,000,000 shares of common stock, at a combined price to the public of $5.00 per unit, for gross proceeds of $20.0 million, and net proceeds of $18.5 million. As of March 31, 2019, the Company had an accumulated deficit of $203.3 million. The Company has been primarily involved with research and development activities and has incurred operating losses and negative cash flows from operations since its inception. The Company is subject to a number of risks similar to other life science companies, including, but not limited to, successful discovery and development of its drug candidates, raising additional capital, development by its competitors of new technological innovations, protection of proprietary technology and regulatory approval and market acceptance of the Company's products. The Company anticipates that it will continue to incur significant operating losses for the next several years as it continues to develop its product candidates. As of March 31, 2019, the Company had available cash, cash equivalents and short-term investments of $51.7 million. Based on the Company’s current operating plan, the Company believes it has sufficient cash, cash equivalents and short-term investments to fund operations into the fourth quarter of 2020. The Company will require substantial additional capital to fund operations. The Company has not generated any product revenues and has financed its operations primarily through public offerings and private placements of its equity securities. There can be no assurance that the Company will be able to obtain additional debt or equity financing or generate product revenue or revenues from collaborative partners, on terms acceptable to the Company, on a timely basis or at all. The failure of the Company to obtain sufficient funds on acceptable terms when needed could have a material adverse effect on the Company's business, results of operations, and financial condition.

Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2019

Summary of Significant Accounting Policies

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation and Principles of Consolidation

The accompanying financial statements and the related disclosures are unaudited and have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”). Additionally, certain information and footnote disclosures normally included in the Company’s annual financial statements have been condensed or omitted from this report. Accordingly, these condensed financial statements should be read in conjunction with the financial statements as of and for the year ended December 31, 2018 and notes thereto included in the 2018 Annual Report on Form 10-K.

The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited financial statements except for the adoption of the new lease accounting standard discussed below. In the opinion of the Company’s management, the accompanying unaudited interim condensed consolidated financial statements contain all adjustments which are necessary to fairly present the Company’s financial position as of March 31, 2019, the results of its operations for the three months ended March 31, 2019 and 2018, the statement of stockholders’ equity as of March 31, 2019 and 2018 and its cash flows for the three months ended March 31, 2019 and 2018. Such adjustments are of a normal and recurring nature. The results for the three months ended March 31, 2019 are not necessarily indicative of the results for the year ending December 31, 2019, or for any future period.

The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary, Catabasis Securities Corporation. All intercompany balances and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of the Company’s condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Actual results could differ from such estimates.

The Company utilizes certain estimates to record expenses relating to research and development contracts. These contract estimates, which are primarily related to the length of service of each contract and the amount of service provided as of each measurement date, are determined by the Company based on input from internal project management, as well as from third-party service providers.

Stock-Based Compensation

The Company accounts for its stock-based compensation awards in accordance with Accounting Standards Codification (“ASC”) Topic 718, Compensation—Stock Compensation (“ASC 718”). ASC 718 requires all share-based payments to employees, including grants of employee stock options, to be recognized in the statements of operations based on their grant date fair values. For stock options granted to employees and to members of the board of directors for their services on the board of directors, the Company estimates the grant date fair value of each option award using the Black-Scholes option-pricing model. The use of the Black-Scholes option-pricing model requires management to make assumptions with respect to the expected term of the option, the expected volatility of the Common Stock consistent with the expected term of the option, risk-free interest rates and expected dividend yields of the Common Stock.

For awards subject to service-based vesting conditions, the Company recognizes stock-based compensation expense equal to the grant date fair value of stock options on a straight-line basis over the requisite service period.

The Company expenses restricted stock awards based on the fair value of the award on a straight-line basis over the associated service period of the award.

For equity instruments granted to non-employees, the Company recognizes stock-based compensation expense equal to the grant date fair value of stock options on a straight-line basis.

During the three months ended March 31, 2019 and 2018, the Company recorded stock-based compensation expense for employee and non-employee stock options, which was allocated as follows in the condensed consolidated statements of operations (in thousands):


	Three Months Ended March 31,
	2019		2018
Research and development	$	135	$	173
General and administrative		273		306
Total	$	408	$	479

Net Loss Per Share

Basic net loss per share is calculated by dividing net loss by the weighted average shares outstanding during the period, without consideration for Common Stock equivalents. Diluted net loss per share is calculated by adjusting weighted average shares outstanding for the dilutive effect of Common Stock equivalents outstanding for the period, determined using the treasury-stock method. For purposes of the Company’s dilutive net loss per share calculation, stock options and warrants to purchase Common Stock were considered to be Common Stock equivalents but were excluded from the calculation of diluted net loss per share, as their effect would be anti-dilutive; therefore, basic and diluted net loss per share were the same for all periods presented.

The following Common Stock equivalents were excluded from the calculation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect:


	Three Months Ended March 31,
	2019	2018
Stock options	758,304	377,563
Common stock warrants	6,201,949	2,454
	6,960,253	380,017

Cash, Cash Equivalents and Restricted Cash

The reconciliation of cash, cash equivalents and restricted cash reported within the applicable balance sheet that sum to the total of the same such amount shown in the statement of cash flows is as follows:


	March 31,
	2019		2018
Cash and cash equivalents	$	11,652	$	17,030
Restricted cash		113		113
Total	$	11,765	$	17,143

Leases

Effective January 1, 2019, the Company determines if an arrangement is a lease at inception. Operating leases are included in right-of-use (“ROU”) lease assets, current portion of lease obligations, and long-term lease obligations on the Company’s balance sheets. The Company does not currently hold any financing leases.

ROU lease assets represent the Company’s right to use an underlying asset for the lease term and lease obligations represent the Company’s obligation to make lease payments arising from the lease. Operating ROU lease assets and obligations are recognized at the commencement date based on the present value of lease payments over the lease term. As the Company’s lease does not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The ROU lease asset also includes any lease payments made and excludes lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term.

Recent Accounting Pronouncements - Adopted

In February 2016, the Financial Accounting Standards Board, ("FASB”) issued Accounting Standards Update ("ASU”) 2016-02, Leases. This standard amends the existing guidance to require lessees to present most leases on their balance sheets but recognize corresponding expenses on their statements of operations. The FASB also provided practical expedients that give lessors an option to combine non-lease and associated lease components when certain criteria are met and requires a lessor to account for the combined component in accordance with the new revenue standard if the associated non-lease components are the predominant component. The Company adopted this standard effective January 1, 2019 by recording the cumulative effect on the date of the adoption. The Company has elected the package of practical expedients permitted under the transition guidance in ASC Topic 842 ("ASC Topic 842"). Accordingly, the Company accounted for its existing operating leases as operating leases under the new guidance, without reassessing (a) whether the contracts contain a lease under ASC Topic 842, (b) whether classification of the operating leases would be different in accordance with ASC Topic 842, or (c) whether the unamortized initial direct costs before transition adjustments would have met the definition of initial direct costs in ASC Topic 842 at lease commencement. As a result of the adoption of the new lease accounting guidance, the Company recognized on January 1, 2019 a lease liability and right-of-use asset of approximately $1.9 million. The lease liability represents the present value of the remaining lease payments, discounted using the Company’s incremental borrowing rate of 7.49%. The ROU asset represents the lease liability adjusted for any prepaid and accrued rent payments as well as any remaining liability associated with the sublease. This standard did not have a material impact on the Company’s cash flows from operations and had no impact on the Company’s operating results. The most significant impact was the recognition of ROU assets and lease obligations for operating leases.

Recent Accounting Pronouncements - Not Yet Adopted

From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its financial position or results of operations upon adoption.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326). This standard requires a financial asset to be presented at amortized cost basis at the net amount expected to be collected. It also requires that credit losses relating to available-for-sale debt securities should be recorded through an allowance for credit losses. This amendment is effective for annual reporting periods beginning after December 15, 2019. The Company is currently evaluating the impact that this standard will have on its consolidated financial statements.

In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820). This standard includes amendments regarding changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and disclosure requirements of measurement uncertainty. This amendment is effective for annual reporting periods beginning after December 15, 2019. The Company is currently evaluating the impact that this standard will have on its consolidated financial statements.

Summary of Significant Accounting Policies

The Company’s significant accounting policies are described in Note 2, “Summary of Significant Accounting Policies,” in the 2018 Annual Report on Form 10-K, and there were no significant changes to such policies in the three months ended March 31, 2019 that had a material impact on the Company’s results of operations or financial position.

Financial Instruments

3 Months Ended

Mar. 31, 2019

Financial Instruments

Financial Instruments

3. Financial Instruments

The tables below present information about the Company’s assets and liabilities that are measured at fair value on a recurring basis as of March 31, 2019 and December 31, 2018 and indicate the fair value hierarchy of the valuation techniques the Company utilized to determine such fair value. In general, fair values determined by Level 1 inputs utilize observable inputs such as quoted prices in active markets for identical assets or liabilities. Fair values determined by Level 2 inputs utilize data points that are either directly or indirectly observable, such as quoted prices, interest rates and yield curves. Fair values determined by Level 3 inputs utilize unobservable data points for which there is little or no market data, which require the Company to develop its own assumptions for the asset or liability. There were no transfers between fair value measurement levels during the three months ended March 31, 2019 or 2018.

The Company’s investment portfolio may include fixed income securities that do not always trade on a daily basis. As a result, the pricing services used by the Company apply other available information as applicable through processes such as benchmark yields, benchmarking of like securities, sector groupings and matrix pricing to prepare valuations.

The Company validates the prices provided by its third party pricing services by obtaining market values from other pricing sources and analyzing pricing data in certain instances. The Company also invests in certain reverse repurchase agreements which are collateralized by deposits in the form of U.S. Government Securities and Obligations for an amount no less than 102% of their value. The Company does not record an asset or liability for the collateral as the Company is not permitted to sell or re-pledge the collateral. The collateral has at least the prevailing credit rating of U.S. Government Treasuries and Agencies. The Company utilizes a third party custodian to manage the exchange of funds and ensure that collateral received is maintained at 102% of the value of the reverse repurchase agreements on a daily basis.

Below is a summary of assets measured at fair value on a recurring basis (in thousands):


	As of March 31, 2019
	Quoted Prices		Significant		Significant
	in Active		Observable		Unobservable
	Markets		Inputs		Inputs
	(Level 1)		(Level 2)		(Level 3)		Total
Assets:
Cash and cash equivalents:
Money market funds	$	3,481	$	—	$	—	$	3,481
Corporate debt securities		—		2,589		—		2,589
Reverse repurchase agreements		—		2,000		—		2,000
Short-term investments:
Corporate debt securities		—		2,012		—		2,012
Reverse repurchase agreements		—		38,000		—		38,000
Total assets	$	3,481	$	44,601	$	—	$	48,082


	As of December 31, 2018
	Quoted Prices		Significant		Significant
	in Active		Observable		Unobservable
	Markets		Inputs		Inputs
	(Level 1)		(Level 2)		(Level 3)		Total
Assets:
Cash and cash equivalents:
Money market funds	$	5,956	$	—	$	—	$	5,956
Corporate debt securities		—		1,948		—		1,948
Reverse repurchase agreements		—		3,000		—		3,000
Short-term investments:
Corporate debt securities		—		7,276		—		7,276
Reverse repurchase agreements		—		15,000		—		15,000
Total assets	$	5,956	$	27,224	$	—	$	33,180

At March 31, 2019 and December 31, 2018 the Company’s cash equivalents consisted of money market funds, U.S. reverse repurchase agreements, and corporate debt securities. At March 31, 2019, and December 31, 2018, cash equivalents approximated their fair value due to their short-term nature.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Short-Term Investments

3 Months Ended

Mar. 31, 2019

Short-Term Investments

Short-Term Investments

4. Short-Term Investments

The following table summarizes the short-term investments securities held at March 31, 2019 and December 31, 2018 (in thousands):


			Gross Unrealized		Gross Unrealized
	Amortized Cost		Gains		Losses		Fair Value
March 31, 2019
Corporate debt securities	$	2,012	$	—	$	—	$	2,012
Reverse repurchase agreements		38,000		—		—		38,000
Total	$	40,012	$	—	$	—	$	40,012


			Gross Unrealized		Gross Unrealized
	Amortized Cost		Gains		Losses		Fair Value
December 31, 2018
Corporate debt securities	$	7,280	$	—	$	(4)	$	7,276
Reverse repurchase agreements		15,000		—		—		15,000
Total	$	22,280	$	—	$	(4)	$	22,276

The contractual maturities of all short-term investments held at March 31, 2019 and December 31, 2018 were one year or less. There was one short-term investment in an unrealized loss position at March 31, 2019 and seven short-term investments in an unrealized loss position at December 31, 2018, none of which had been in an unrealized loss position for more than 12 months. The aggregate fair value of these investments was approximately $2.0 million and $7.3 million at March 31, 2019 and December 31, 2018, respectively. The Company did not hold any investments with other-than-temporary impairments at March 31, 2019 and December 31, 2018.

Gross realized gains and losses on the sales of short-term investments are included in other income, net. Unrealized holding gains or losses for the period that have been included in accumulated other comprehensive income, as well as gains and losses reclassified out of accumulated other comprehensive income into other income, net were not material to the Company’s condensed consolidated results of operations. The cost of investments sold or the amount reclassified out of the accumulated other comprehensive income into other income, net is based on the specific identification method for purposes of recording realized gains and losses. There were no proceeds from sales of short-term investments in the three-month periods ended March 31, 2019 and 2018. All proceeds in the three-month periods ended March 31, 2019 and March 31, 2018 related to maturities of underlying investments. The gains on proceeds from maturities of short-term investments were not material to the Company’s condensed consolidated results of operations for the three months ended March 31, 2019 and 2018.

Accrued Expenses

3 Months Ended

Mar. 31, 2019

Accrued Expenses

Accrued Expenses

5. Accrued Expenses

Accrued expenses consisted of the following (in thousands):


	March 31,		December 31,
	2019		2018
Accrued compensation	$	436	$	1,241
Accrued contracted research costs		511		680
Accrued professional fees		346		393
Accrued severence		21		109
Accrued franchise tax		50		168
Accrued other		87		172
Total	$	1,451	$	2,763

Commitments

3 Months Ended

Mar. 31, 2019

Commitments

Commitments

6. Commitments

Operating Leases

In November 2010, the Company entered into an operating lease for office and laboratory space, which has been amended multiple times. Based on the latest amendment, the lease agreement includes escalating rent payments and is effective through June 30, 2020. The Company is recognizing rent expense on a straight-line basis over the lease term.

The following is a maturity analysis of the annual undiscounted cash flows of the operating lease liabilities as of March 31, 2019 (in thousands):


Period Ending December 31,	Amount
2019		1,071
2020		721
Total minimum lease payments	$	1,792

Rent expense was $0.1 million and $0.3 million for the three months ended March 31, 2019 and 2018, respectively. During the three months ended March 31, 2019, the Company paid $0.3 million in lease payments. During the three months ended March 31, 2019, the Company paid $0.3 million in lease payments.

On October 15, 2018, the Company entered into a short-term lease with Inzen Therapeutics (“Inzen”), to sublease a portion of the Company’s facility (the “Sublease”). The sublease term is from October 15, 2018 through June 30, 2020. Inzen is obligated to pay the Company approximately $0.8 million in base rent during the remainder of the year ended December 31, 2019 and $0.5 million in base rent during the year ended December 31, 2020. The Company is still obligated to all payment terms pursuant to the lease agreement, as amended. During the three months ended March 31, 2019, the Company received $0.3 million in payments from Inzen which was recorded as a deduction to rent expense in the accompanying condensed consolidated statement of operations.

Stockholders' Equity	3 Months Ended
Stockholders' Equity	Mar. 31, 2019
Stockholders' Equity
Stockholders' Equity	7. Stockholders’ Equity Preferred Stock As of March 31, 2019, the Company had 5,000,000 shares of preferred stock authorized for issuance, $0.001 par value per share, with none issued or outstanding. Preferred stock may be issued from time to time in one or more series, each series to have such terms as stated or expressed in the resolutions providing for the issue of such series adopted by the board of directors of the Company. Preferred stock which may be redeemed, purchased or acquired by the Company may be reissued except as otherwise provided by law. Common Stock Warrants February 2019 Warrants In the February 2019 Financing, the Company issued warrants to purchase 2,000,000 shares of common stock with an exercise price of $6.25 per share, which were immediately exercisable upon issuance and will expire five years from the date of issuance. The terms of the warrants include certain provisions related to fundamental transactions, a cashless exercise provision in the event registered shares are not available and do not include any mandatory redemption provisions. Therefore, the warrants have been classified in stockholders’ equity. Any changes to the fair value of the warrants will not be recognized so long as the warrants continue to be equity classified. As of March 31, 2019, 1,999,500 warrants related to the February 2019 Financing were outstanding with a remaining contractual life of 4.86 years. June 2018 Warrants On June 19, 2018, the Company entered into an underwriting agreement with Oppenheimer & Co. Inc. relating to an underwritten public offering (the "June 2018 Financing") of 4,200,000 shares of the Company's common stock , par value $0.001 per share, and accompanying warrants to purchase up to 4,200,000 shares of common stock. The warrants were issued at an exercise price of $12.00 per share, and were immediately exercisable upon issuance expiring five years from the date of issuance. The terms of the warrants include certain provisions related to fundamental transactions, a cashless exercise provision in the event registered shares are not available and do not include any mandatory redemption provisions. Therefore, the warrants have been classified in stockholders’ equity. Any changes to the fair value of the warrants will not be recognized so long as the warrants continue to be equity classified. As of March 31, 2019, all warrants related to the June 2018 Financing were outstanding with a remaining contractual life of 4.23 years.

Common Stock Reserved for Future Issuance

3 Months Ended

Mar. 31, 2019

Common Stock Reserved for Future Issuance

Common Stock Reserved for Future Issuance

8. Common Stock Reserved for Future Issuance

The Company has reserved for future issuance the following shares of Common Stock:


	March 31,	December 31,
	2019	2018
Warrants for the purchase of Common Stock	6,201,949	4,202,449
Options outstanding to purchase Common Stock	758,304	433,389
Options reserved to purchase Common Stock	553,014	877,917
Shares reserved for the employee stock purchase plan	112,481	76,011
Total	7,625,748	5,589,766

Stock Incentive Plans

3 Months Ended

Mar. 31, 2019

Stock Incentive Plans

Stock Incentive Plans

9. Stock Incentive Plans

Prior to the Company's initial public offering in June 2015, the Company granted awards to eligible participants under its 2008 Equity Incentive Plan (“2008 Plan”). In May 2015, the Company’s board of directors adopted and, in June 2015, the Company’s stockholders approved the 2015 Stock Incentive Plan (“2015 Plan”), which became effective immediately prior to the effectiveness of the IPO. Subsequent to the IPO, option grants are awarded to eligible participants only under the 2015 Plan.

The 2015 Plan provides for the grant of incentive stock options, non-statutory stock options, restricted stock awards, restricted stock units, stock appreciation rights and other stock-based awards. The Company’s employees, officers, directors and consultants and advisors are eligible to receive awards under the 2015 Plan.

Terms of stock option agreements, including vesting requirements, are determined by the Company's board of directors, subject to the provisions of the applicable stock incentive plan. Options granted by the Company generally vest ratably over four years, with a one-year cliff, and options are exercisable from the date of grant for a period of ten years. For options granted through March 31, 2019, the exercise price or purchase price, as applicable, equaled the estimated fair value of the Common Stock as determined by the Company's board of directors on the date of grant.

A summary of the Company’s stock option activity and related information follows:


				Weighted
				Average
		Weighted-		Remaining	Aggregate
		Average		Contractual	Intrinsic Value
	Shares	Exercise Price		Term (years)	(in thousands)
Outstanding at December 31, 2018	433,389	$	29.05	7.97	$	—
Granted	349,500	$	4.39
Cancelled or forfeited	(24,585)	$	14.35
Outstanding at March 31, 2019	758,304	$	18.16	8.68	$	1,318
Vested and Exercisable at March 31, 2019	197,643	$	46.85	6.41	$	2

There were no options exercised in the three months ended March 31, 2019 and 2018. The total fair value of employee and non-employee options vested for the three months ended March 31, 2019 and 2018 was $0.5 million and $0.6 million, respectively. The weighted-average grant date fair value of options granted to employees and non-employees for the three months ended March 31, 2019 and 2018 was $3.00 and $8.80, respectively.

At March 31, 2019, the total unrecognized compensation expense related to unvested stock option awards was $2.7 million. The Company expects to recognize that cost over a weighted-average period of approximately 2.2 years.

Subsequent Events	3 Months Ended
Subsequent Events	Mar. 31, 2019
Subsequent Events
Subsequent Events	10. Subsequent Events The Company considers events or transactions that occur after the balance sheet date but prior to the issuance of the financial statements to provide additional evidence for certain estimates and to identify matters that require additional disclosure. Subsequent events have been evaluated as required.

Summary of Significant Accounting Polices (Polices)

3 Months Ended

Mar. 31, 2019

Summary of Significant Accounting Policies

Basis of Presentation and Principles of Consolidation

Use of Estimates

Stock-Based Compensation

The Company expenses restricted stock awards based on the fair value of the award on a straight-line basis over the associated service period of the award.

For equity instruments granted to non-employees, the Company recognizes stock-based compensation expense equal to the grant date fair value of stock options on a straight-line basis.


	Three Months Ended March 31,
	2019		2018
Research and development	$	135	$	173
General and administrative		273		306
Total	$	408	$	479

Net Loss Per Share

The following Common Stock equivalents were excluded from the calculation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect:


	Three Months Ended March 31,
	2019	2018
Stock options	758,304	377,563
Common stock warrants	6,201,949	2,454
	6,960,253	380,017

Cash, Cash Equivalents and Restricted Cash


	March 31,
	2019		2018
Cash and cash equivalents	$	11,652	$	17,030
Restricted cash		113		113
Total	$	11,765	$	17,143

Leases

Recent Accounting Pronouncements

Recent Accounting Pronouncements - Adopted

Recent Accounting Pronouncements - Not Yet Adopted

Summary of Significant Accounting Policies

Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2019

Summary of Significant Accounting Policies

Schedule of stock-based compensation expense


	Three Months Ended March 31,
	2019		2018
Research and development	$	135	$	173
General and administrative		273		306
Total	$	408	$	479

Schedule of anti-dilutive common stock equivalents excluded from calculation of diluted net loss per share


	Three Months Ended March 31,
	2019	2018
Stock options	758,304	377,563
Common stock warrants	6,201,949	2,454
	6,960,253	380,017

Schedule of reconciliation of cash, cash equivalents and restricted cash


	March 31,
	2019		2018
Cash and cash equivalents	$	11,652	$	17,030
Restricted cash		113		113
Total	$	11,765	$	17,143

Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2019

Financial Instruments

Summary of assets measured at fair value on a recurring basis

Below is a summary of assets measured at fair value on a recurring basis (in thousands):


	As of March 31, 2019
	Quoted Prices		Significant		Significant
	in Active		Observable		Unobservable
	Markets		Inputs		Inputs
	(Level 1)		(Level 2)		(Level 3)		Total
Assets:
Cash and cash equivalents:
Money market funds	$	3,481	$	—	$	—	$	3,481
Corporate debt securities		—		2,589		—		2,589
Reverse repurchase agreements		—		2,000		—		2,000
Short-term investments:
Corporate debt securities		—		2,012		—		2,012
Reverse repurchase agreements		—		38,000		—		38,000
Total assets	$	3,481	$	44,601	$	—	$	48,082


	As of December 31, 2018
	Quoted Prices		Significant		Significant
	in Active		Observable		Unobservable
	Markets		Inputs		Inputs
	(Level 1)		(Level 2)		(Level 3)		Total
Assets:
Cash and cash equivalents:
Money market funds	$	5,956	$	—	$	—	$	5,956
Corporate debt securities		—		1,948		—		1,948
Reverse repurchase agreements		—		3,000		—		3,000
Short-term investments:
Corporate debt securities		—		7,276		—		7,276
Reverse repurchase agreements		—		15,000		—		15,000
Total assets	$	5,956	$	27,224	$	—	$	33,180

- Definition

Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.

+ References + Details

Short-Term Investments (Tables)

3 Months Ended

Mar. 31, 2019

Short-Term Investments

Summary of short-term investments securities

The following table summarizes the short-term investments securities held at March 31, 2019 and December 31, 2018 (in thousands):


			Gross Unrealized		Gross Unrealized
	Amortized Cost		Gains		Losses		Fair Value
March 31, 2019
Corporate debt securities	$	2,012	$	—	$	—	$	2,012
Reverse repurchase agreements		38,000		—		—		38,000
Total	$	40,012	$	—	$	—	$	40,012


			Gross Unrealized		Gross Unrealized
	Amortized Cost		Gains		Losses		Fair Value
December 31, 2018
Corporate debt securities	$	7,280	$	—	$	(4)	$	7,276
Reverse repurchase agreements		15,000		—		—		15,000
Total	$	22,280	$	—	$	(4)	$	22,276

Accrued Expenses (Tables)

3 Months Ended

Mar. 31, 2019

Accrued Expenses

Schedule of components of accrued expenses

Accrued expenses consisted of the following (in thousands):


	March 31,		December 31,
	2019		2018
Accrued compensation	$	436	$	1,241
Accrued contracted research costs		511		680
Accrued professional fees		346		393
Accrued severence		21		109
Accrued franchise tax		50		168
Accrued other		87		172
Total	$	1,451	$	2,763

Commitments (Tables)

3 Months Ended

Mar. 31, 2019

Commitments

Schedule of maturity analysis of the annual undiscounted cash flows of the operating lease liabilities

The following is a maturity analysis of the annual undiscounted cash flows of the operating lease liabilities as of March 31, 2019 (in thousands):


Period Ending December 31,	Amount
2019		1,071
2020		721
Total minimum lease payments	$	1,792

Common Stock Reserved For Future Issuance (Tables)

3 Months Ended

Mar. 31, 2019

Common Stock Reserved for Future Issuance

Schedule of Common Stock reserved for future issuance


	March 31,	December 31,
	2019	2018
Warrants for the purchase of Common Stock	6,201,949	4,202,449
Options outstanding to purchase Common Stock	758,304	433,389
Options reserved to purchase Common Stock	553,014	877,917
Shares reserved for the employee stock purchase plan	112,481	76,011
Total	7,625,748	5,589,766

Stock Incentive Plans (Tables)

3 Months Ended

Mar. 31, 2019

Stock Incentive Plans

Summary of stock option activity


				Weighted
				Average
		Weighted-		Remaining	Aggregate
		Average		Contractual	Intrinsic Value
	Shares	Exercise Price		Term (years)	(in thousands)
Outstanding at December 31, 2018	433,389	$	29.05	7.97	$	—
Granted	349,500	$	4.39
Cancelled or forfeited	(24,585)	$	14.35
Outstanding at March 31, 2019	758,304	$	18.16	8.68	$	1,318
Vested and Exercisable at March 31, 2019	197,643	$	46.85	6.41	$	2

Organization and Operations - Liquidity (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended
	Feb. 06, 2019	Jul. 19, 2016	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Common Stock
Additional common stock issued			$ 2,045	$ 8,313
Accumulated deficit			(203,342)		$ (197,304)
Cash, cash equivalents and short-term investments			$ 51,700
Common Stock
Common Stock
Number of shares issued			353,746	539,026
Additional common stock issued				$ 1
Common Stock \| Cowen
Common Stock
Percentage of commission paid to underwriter based on proceeds from common stock		3.00%
Common Stock \| ATM
Common Stock
Number of shares issued			353,746
Share price (in dollars per share)			$ 5.96
Additional common stock issued			$ 2,100
Net proceeds			$ 2,000
Common Stock \| First ATM Program \| Cowen
Common Stock
Remaining current sales agreement		$ 22,600
Common Stock \| February 2019 Financing \| Oppenheimer & Co. Inc
Common Stock
Number of shares issued	4,000,000
Share price (in dollars per share)	$ 0.001
Additional common stock issued	$ 20,000
Number of warrants issued	2,000,000
Warrants price (in dollars per unit)	$ 5.00
Proceeds from public offering, net of issuance costs	$ 18,500

Summary of Significant Accounting Policies - Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Stock-Based Compensation
Stock-based compensation expense	$ 408	$ 479
Research and development
Stock-Based Compensation
Stock-based compensation expense	135	173
General and administrative
Stock-Based Compensation
Stock-based compensation expense	$ 273	$ 306

Summary of Significant Accounting Policies - Net Loss Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Antidilutive common stock equivalents excluded from computation of diluted net loss per share
Anti-dilutive securities excluded from the calculation of diluted net loss per share (in shares)	6,960,253	380,017
Stock options
Antidilutive common stock equivalents excluded from computation of diluted net loss per share
Anti-dilutive securities excluded from the calculation of diluted net loss per share (in shares)	758,304	377,563
Common stock warrants
Antidilutive common stock equivalents excluded from computation of diluted net loss per share
Anti-dilutive securities excluded from the calculation of diluted net loss per share (in shares)	6,201,949	2,454

Summary of Significant Accounting Policies - Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Summary of Significant Accounting Policies
Cash and cash equivalents	$ 11,652	$ 15,294	$ 17,030
Restricted cash	113	113	113
Total	$ 11,765	$ 15,407	$ 17,143	$ 16,482

Summary of Significant Accounting Policies - Recent Accounting Pronouncements (Details) - ASU 2016-02 - USD ($) $ in Millions	Jan. 01, 2019	Mar. 31, 2019
New Accounting Pronouncements
Package of practical expedients	true
Lessee, Operating Lease, Discount Rate		7.49%
Incremental borrowing rate		7.49%
Restatement Adjustment
New Accounting Pronouncements
Lease liability	$ 1.9
Right-of-use asset	$ 1.9

Financial Instruments (Details) $ in Thousands	3 Months Ended
Financial Instruments (Details) $ in Thousands	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Mar. 31, 2018 USD ($)
Financial Instruments
Transfers between fair value measurement levels	$ 0		$ 0
Cash and cash equivalents:
Cash and cash equivalents	11,652	$ 15,294	$ 17,030
Short-term investments:
Short-term investments	40,012	22,276
Corporate debt securities
Short-term investments:
Short-term investments	2,012	7,276
Reverse repurchase agreements
Short-term investments:
Short-term investments	$ 38,000	15,000
Government Securities and Obligations \| Reverse Repurchase Agreement \| Minimum
Financial Instruments
Percentage of investment amount to collateralized deposits value	102
Recurring
Assets:
Total assets	$ 48,082	33,180
Recurring \| Money market funds
Cash and cash equivalents:
Cash and cash equivalents	3,481	5,956
Recurring \| Corporate debt securities
Cash and cash equivalents:
Cash and cash equivalents	2,589	1,948
Short-term investments:
Short-term investments	2,012	7,276
Recurring \| Reverse repurchase agreements
Cash and cash equivalents:
Cash and cash equivalents	2,000	3,000
Short-term investments:
Short-term investments	38,000	15,000
Recurring \| Level 1
Assets:
Total assets	3,481	5,956
Recurring \| Level 1 \| Money market funds
Cash and cash equivalents:
Cash and cash equivalents	3,481	5,956
Recurring \| Level 2
Assets:
Total assets	44,601	27,224
Recurring \| Level 2 \| Corporate debt securities
Cash and cash equivalents:
Cash and cash equivalents	2,589	1,948
Short-term investments:
Short-term investments	2,012	7,276
Recurring \| Level 2 \| Reverse repurchase agreements
Cash and cash equivalents:
Cash and cash equivalents	2,000	3,000
Short-term investments:
Short-term investments	$ 38,000	$ 15,000

Short-Term Investments (Details) $ in Thousands	3 Months Ended		12 Months Ended
Short-Term Investments (Details) $ in Thousands	Mar. 31, 2019 USD ($) instrument	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($) instrument
Short-Term Investments
Amortized Cost	$ 40,012		$ 22,280
Gross Unrealized Losses			(4)
Fair Value	$ 40,012		$ 22,276
Number of short term investments in unrealized loss position \| instrument	1		7
Number of short term investments in an unrealized loss position more than 12 months \| instrument	0
Aggregate fair value of the investments in an unrealized loss position	$ 2,000		$ 7,300
Proceeds from Sale of Short-term Investments	0	$ 0
Corporate debt securities
Short-Term Investments
Amortized Cost	2,012		7,280
Gross Unrealized Losses			(4)
Fair Value	2,012		7,276
Reverse repurchase agreements
Short-Term Investments
Amortized Cost	38,000		15,000
Fair Value	$ 38,000		$ 15,000

Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Accrued Expenses
Accrued compensation	$ 436	$ 1,241
Accrued contracted research costs	511	680
Accrued professional fees	346	393
Accrued severance	21	109
Accrued franchise tax	50	168
Accrued other	87	172
Total	$ 1,451	$ 2,763

Commitments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended	12 Months Ended
Commitments (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2020
Maturity analysis of the annual undiscounted cash flows of the operating lease liabilities
2019	$ 1,071
2020	721
Total minimum lease payments	1,792
Rent expense	100	$ 300
Lease payment	300
Amount of base rent from sub-lease			$ 800	$ 500
Sublease income	$ 300

Stockholders' Equity - Preferred Stock (Details)	3 Months Ended
Stockholders' Equity - Preferred Stock (Details)	Mar. 31, 2019 series $ / shares shares	Dec. 31, 2018 $ / shares shares
Preferred Stock
Preferred stock, authorized (in shares)	5,000,000	5,000,000
Preferred stock, par value (in dollars per share) \| $ / shares	$ 0.001	$ 0.001
Preferred stock, shares issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Minimum number of series used to issue preferred stock \| series	1

Stockholders' Equity - Common Stock Warrants (Details) - $ / shares		1 Months Ended	3 Months Ended
	Jun. 19, 2018	Feb. 28, 2019	Mar. 31, 2019	Mar. 31, 2018
February 2019 common stock warrants
Convertible Preferred Stock
Number of warrants issued		2,000,000
Exercise price of warrants (in dollars per share)		$ 6.25
Warrants term		5 years
Warrants outstanding			1,999,500
Weighted average remaining contractual life			4 years 10 months 10 days
June 2018 common stock warrants
Convertible Preferred Stock
Number of warrants issued	4,200,000
Exercise price of warrants (in dollars per share)	$ 12.00
Warrants term	5 years
Weighted average remaining contractual life			4 years 2 months 23 days
Common Stock
Convertible Preferred Stock
Number of shares issued			353,746	539,026
Oppenheimer & Co. Inc \| Common Stock \| June 2018 common stock warrants
Convertible Preferred Stock
Number of shares issued	4,200,000
Share price (in dollars per share)	$ 0.001

Common Stock Reserved for Future Issuance (Details) - shares	Mar. 31, 2019	Mar. 31, 2018
Stockholders' equity
Shares reserved for future issuance (in shares)	7,625,748	5,589,766
Common stock warrants
Stockholders' equity
Shares reserved for future issuance (in shares)	6,201,949	4,202,449
Common stock options outstanding
Stockholders' equity
Shares reserved for future issuance (in shares)	758,304	433,389
Common stock options reserved
Stockholders' equity
Shares reserved for future issuance (in shares)	553,014	877,917
Employee stock purchase plan reserved
Stockholders' equity
Shares reserved for future issuance (in shares)	112,481	76,011

Stock Incentive Plans - Plan Information and Valuation Assumptions (Details) - Stock options	3 Months Ended
	Mar. 31, 2019
Stock-Based Compensation
Vesting period	4 years
Cliff period for vesting	1 year
Exercisable period	10 years

Stock Incentive Plans - Stock Option Plan Activity (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Stock options
Outstanding at beginning of year (in shares)	433,389
Granted (in shares)	349,500
Cancelled or forfeited (in shares)	(24,585)
Outstanding at end of year (in shares)	758,304		433,389
Vested and Exercisable to vest at end of year (in shares)	197,643
Weighted-Average Exercise Price
Outstanding at beginning of year (in dollars per share)	$ 29.05
Granted (in dollars per share)	4.39
Cancelled or forfeited (in dollars per share)	14.35
Outstanding at end of year (in dollars per share)	18.16		$ 29.05
Vested and Exercisable at end of year (in dollars per share)	$ 46.85
Weighted Average Remaining Contractual Term (years)
Outstanding at end of year	8 years 8 months 5 days		7 years 11 months 19 days
Vested and Exercisable at end of year	6 years 4 months 28 days
Aggregate Intrinsic Value
Outstanding at the end of the year	$ 1,318,000
Vested and Exercisable at end of year	2,000
Stock options
Unrecognized stock-based compensation expense
Intrinsic value of options exercised	0	$ 0
Adjusted fair value of options vested	$ 500,000	$ 600,000
Weighted average grant date fair value of options granted (in dollars per share)	$ 3.00	$ 8.80
Unrecognized compensation expense related to unvested stock option awards	$ 2,700,000
Weighted-average amortization period over which cost is expected to be recognized	2 years 2 months 12 days