Exicure (XCUR) 10-Q 7 Nov 19 2019 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Nov. 05, 2019
Document And Entity Information [Abstract]
Entity Registrant Name	EXICURE, INC.
Entity Central Index Key	0001698530
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	true
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Ex Transition Period	true
Entity Small Business	true
Document Type	10-Q
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding (in shares)		75,994,790

UNAUDITED CONDENSED CONSOLIDATE

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 70,392	$ 26,268
Unbilled revenue receivable	0	3
Receivable from related party	16	10
Prepaid expenses and other assets	1,345	1,382
Total current assets	71,753	27,663
Property and equipment, net	1,597	1,061
Other noncurrent assets	456	32
Total assets	73,806	28,756
Current liabilities:
Current portion of long-term debt	4,912	0
Accounts payable	1,110	500
Accrued expenses and other current liabilities	2,237	1,543
Current portion of deferred revenue	14	0
Total current liabilities	8,273	2,043
Long-term debt, net	0	4,925
Common stock warrant liability	437	797
Other noncurrent liabilities	144	39
Total liabilities	8,854	7,804
Stockholders’ equity:
Common stock, $0.0001 par value per share; 200,000,000 shares authorized, 44,369,790 issued and outstanding, June 30, 2019; 44,358,000 issued and outstanding, December 31, 2018	8	4
Additional paid-in capital	136,260	75,942
Accumulated deficit	(71,316)	(54,994)
Total stockholders' equity	64,952	20,952
Total liabilities and stockholders’ equity	$ 73,806	$ 28,756

UNAUDITED CONDENSED CONSOLIDA_2

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	75,994,790	44,358,000
Common stock, shares outstanding (in shares)	75,994,790	44,358,000

UNAUDITED CONDENSED CONSOLIDA_3

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue:
Collaboration revenue	$ 527	$ 57	$ 986	$ 112
Total revenue	527	57	986	112
Operating expenses:
Research and development expense	4,245	4,001	11,073	11,111
General and administrative expense	2,228	1,919	6,421	5,952
Total operating expenses	6,473	5,920	17,494	17,063
Operating loss	(5,946)	(5,863)	(16,508)	(16,951)
Other income (expense), net:
Interest expense	(203)	(170)	(589)	(497)
Other income (loss), net	333	709	775	(210)
Total other income (loss), net	130	539	186	(707)
Net loss	$ (5,816)	$ (5,324)	$ (16,322)	$ (17,658)
Basic and diluted loss per common share (in dollars per share)	$ (0.09)	$ (0.13)	$ (0.32)	$ (0.44)
Basic and diluted weighted-average common shares outstanding (in shares)	64,651,040	41,527,922	51,200,072	40,121,295

UNAUDITED CONDENSED CONSOLIDA_4

UNAUDITED CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in- Capital	Accumulated Deficit
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of new accounting standard - ASC 606	$ 1,034			$ 1,034
Balance at January 1, 2018	21,009	$ 4	$ 53,586	(32,581)
Beginning balance (in shares) at Dec. 31, 2017		39,300,823
Beginning balance at Dec. 31, 2017	19,975	$ 4	53,586	(33,615)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of options (in shares)		8,532
Exercise of options	7		7
Equity-based compensation	365		365
Issuance of common stock (in shares)		145,466
Issuance of common stock	436		436
Net loss	(5,509)			(5,509)
Ending balance (in shares) at Mar. 31, 2018		39,454,821
Ending balance at Mar. 31, 2018	16,308	$ 4	54,394	(38,090)
Beginning balance (in shares) at Dec. 31, 2017		39,300,823
Beginning balance at Dec. 31, 2017	19,975	$ 4	53,586	(33,615)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(17,658)
Ending balance (in shares) at Sep. 30, 2018		44,358,000
Ending balance at Sep. 30, 2018	25,198	$ 4	75,433	(50,239)
Beginning balance (in shares) at Mar. 31, 2018		39,454,821
Beginning balance at Mar. 31, 2018	16,308	$ 4	54,394	(38,090)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-based compensation	419		419
Net loss	(6,825)			(6,825)
Ending balance (in shares) at Jun. 30, 2018		39,454,821
Ending balance at Jun. 30, 2018	9,902	$ 4	54,813	(44,915)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of options (in shares)		13,962
Exercise of options	34		34
Equity-based compensation	516		516
Issuance of common stock (in shares)		4,889,217
Issuance of common stock	20,070		20,070
Net loss	(5,324)			(5,324)
Ending balance (in shares) at Sep. 30, 2018		44,358,000
Ending balance at Sep. 30, 2018	25,198	$ 4	75,433	(50,239)
Beginning balance (in shares) at Dec. 31, 2018		44,358,000
Beginning balance at Dec. 31, 2018	20,952	$ 4	75,942	(54,994)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-based compensation	489		489
Net loss	(5,286)			(5,286)
Ending balance (in shares) at Mar. 31, 2019		44,358,000
Ending balance at Mar. 31, 2019	16,155	$ 4	76,431	(60,280)
Beginning balance (in shares) at Dec. 31, 2018		44,358,000
Beginning balance at Dec. 31, 2018	$ 20,952	$ 4	75,942	(54,994)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of options (in shares)	11,790
Net loss	$ (16,322)
Ending balance (in shares) at Sep. 30, 2019		75,994,790
Ending balance at Sep. 30, 2019	64,952	$ 8	136,260	(71,316)
Beginning balance (in shares) at Mar. 31, 2019		44,358,000
Beginning balance at Mar. 31, 2019	16,155	$ 4	76,431	(60,280)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of options (in shares)		11,790
Exercise of options	17		17
Equity-based compensation	439		439
Net loss	(5,220)			(5,220)
Ending balance (in shares) at Jun. 30, 2019		44,369,790
Ending balance at Jun. 30, 2019	11,391	$ 4	76,887	(65,500)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-based compensation	511		511
Issuance of common stock (in shares)		31,625,000
Issuance of common stock	58,866	$ 4	58,862
Net loss	(5,816)			(5,816)
Ending balance (in shares) at Sep. 30, 2019		75,994,790
Ending balance at Sep. 30, 2019	$ 64,952	$ 8	$ 136,260	$ (71,316)

UNAUDITED CONDENSED CONSOLIDA_5

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net loss	$ (16,322)	$ (17,658)
Adjustments to reconcile net loss to cash used in operating activities:
Depreciation and amortization	265	266
Amortization of operating lease asset	249	0
Equity-based compensation	1,439	1,300
Amortization of long-term debt issuance costs and fees	139	71
Other	36	291
Change in fair value of warrant liabilities	(360)	461
Changes in operating assets and liabilities:
Unbilled revenue receivable and accounts receivable	3	(46)
Receivable from related party	(6)	13
Prepaid expenses and other current assets	(28)	135
Accounts payable	618	278
Accrued expenses and other current liabilities	176	1,602
Deferred revenue	14	0
Other noncurrent liabilities	(236)	(237)
Net cash used in operating activities	(14,013)	(13,524)
Cash flows from investing activities:
Capital expenditures	(462)	(65)
Net cash used in investing activities	(462)	(65)
Cash flows from financing activities:
Proceeds from common stock offering	63,250	22,001
Proceeds from exercise of common stock options	17	41
Payment of long-term debt fees and issuance costs	(284)	0
Payment of common stock financing costs	(4,384)	(1,771)
Net cash (used in) provided by financing activities	58,599	20,271
Net decrease in cash and cash equivalents	44,124	6,682
Cash and cash equivalents - beginning of period	26,268	25,764
Cash and cash equivalents - end of period	70,392	32,446
Non-cash financing activities:
Issuance of common stock for professional services	0	436
Debt fees (accrued expenses)	100	0
Common stock issuance costs (accounts payable and accrued expenses)	0	160
Non-cash investing activities:
Capital expenditures (accounts payable and accrued expenses)	$ 339	$ 14

Description of Business and Bas

Description of Business and Basis of Presentation	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Description of Business and Basis of Presentation	Description of Business and Basis of Presentation Description of Business Exicure, Inc. (the “Company”) is a clinical-stage biotechnology company developing therapeutics for immuno-oncology, inflammatory diseases and genetic disorders based on the Company’s proprietary Spherical Nucleic Acid (“SNA”) technology. The Company believes that the design of its SNAs gives rise to distinct chemical and biological properties that may provide advantages over other nucleic acid therapeutics and enable therapeutic activity outside of the liver. The Company intends to build a leading nucleic acid therapeutics company focused on the discovery and development of therapeutics based on the Company’s proprietary SNA technology, either on its own or in collaboration with pharmaceutical partners. August 2019 Offering On August 2, 2019, we completed the sale of 31,625,000 shares of our common stock at a public offering price of $2.00 per share in an underwritten public offering, which included the exercise in full of the underwriters’ option to purchase an additional 4,125,000 shares at the public offering price (the “August 2019 Offering”). We received gross proceeds of $63,250 in the August 2019 Offering before deducting underwriting discounts and commissions and offering expenses of $4,384 . The shares sold in the August 2019 Offering were sold pursuant to a shelf-registration the Company filed on Form S-3 with the SEC which was declared effective by the SEC on July 24, 2019. In connection with the August 2019 Offering, the Company’s common stock was approved for listing on the Nasdaq Capital Market under the symbol “XCUR” and began trading on July 31, 2019. Throughout these consolidated financial statements, the terms “the Company” and “Exicure” refer to Exicure, Inc. and its 100% owned subsidiary, Exicure Operating Company. Exicure Operating Company holds all material assets, and conducts all business activities and operations, of the Company. Basis of Presentation The accompanying unaudited condensed consolidated financial statements as of September 30, 2019 and December 31, 2018, and for the three and nine months ended September 30, 2019 and 2018, have been presented in conformity with generally accepted accounting principles in the United States (“GAAP”). Principles of Consolidation The accompanying unaudited condensed consolidated financial statements include the accounts of Exicure, Inc. and its 100% owned subsidiary, Exicure Operating Company. All intercompany transactions and accounts are eliminated in consolidation. Liquidity Risk As of September 30, 2019, the Company has generated an accumulated deficit of $90,153 since inception and expects to incur significant expenses and negative cash flows for the foreseeable future. Based on the Company’s current operating plans, it believes that existing working capital at September 30, 2019 is sufficient to fund the Company for at least the next 12 months. Management believes that it will be able to obtain additional working capital through equity financings, partnerships and licensing, or other arrangements, to fund operations. However, there can be no assurance that such additional financing will be available and, if available, can be obtained on terms acceptable to the Company. Unaudited Interim Financial Information The accompanying interim condensed consolidated balance sheet as of September 30, 2019, the interim condensed consolidated statements of operations for the three and nine months ended September 30, 2019 and 2018, the interim condensed consolidated statements of changes in stockholders’ equity for the three and nine months ended September 30, 2019 and 2018, and the interim condensed consolidated statements of cash flows for the nine months ended September 30, 2019 and 2018, are unaudited. The interim unaudited condensed consolidated financial statements have been prepared on the same basis as the annual audited financial statements; and in the opinion of management, reflect all adjustments, which include only normal recurring adjustments necessary for the fair statement of the Company’s financial position as of September 30, 2019, the results of its operations for the three and nine months ended September 30, 2019 and 2018, and the results of its cash flows for the nine months ended September 30, 2019 and 2018. The financial data and other information disclosed in these notes related to the three and nine months ended September 30, 2019 and 2018 are unaudited. The results for the three and nine months ended September 30, 2019 are not necessarily indicative of results to be expected for the year ending December 31, 2019, or any other interim periods, or any future year or period. Use of Estimates The preparation of the financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Management bases its estimates on certain assumptions which it believes are reasonable in the circumstance and while actual results could differ from those estimates, management does not believe that any change in those assumptions in the near term would have a significant effect on the Company’s financial position, results of operations or cash flows. Actual results in future periods could differ from those estimates.

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies There have been no changes to the significant accounting policies disclosed in the Company’s most recent Annual Report on Form 10-K, except as required by recently adopted accounting pronouncements, as discussed below: Recently Adopted Accounting Pronouncements Equity-based compensation In June 2018, the FASB issued Accounting Standards Update (“ASU”) No. 2018-07, Compensation-Stock Compensation: Improvements to Nonemployee Share-Based Payment Accounting (“ASU 2018-07”), which aligns the measurement and classification guidance for share-based payment to non-employees with the guidance for share-based payments to employees. Under the new guidance, the measurement period for equity-classified non-employee awards will be fixed at the grant date. Prior to the adoption of ASU 2018-07, the Company remeasured fair value of stock option awards to nonemployees at each financial statement reporting date. The Company adopted the guidance of ASU 2018-07 in the first quarter of 2019 on a modified retrospective basis. The adoption of ASU 2018-07 did not have a material impact on our financial statements. Leases In February 2016, FASB issued ASU 2016-02, Leases (Topic 842) (or “ASC 842), which replaces the guidance in ASC 840, Leases (“ASC 840”) and requires lessees to recognize right-of-use assets and lease liabilities on the balance sheet. The Company adopted ASC 842 on the required effective date of January 1, 2019 utilizing the modified retrospective transition method with no restatement of prior periods or cumulative adjustment to accumulated deficit. The Company has elected the package of practical expedients, which allows the Company not to reassess (1) whether any expired or existing contracts as of the adoption date are or contain a lease, (2) lease classification for any expired or existing leases as of the adoption date and (3) initial direct costs for any existing leases as of the adoption date. The Company elected to combine lease and non-lease components, elected not to record leases with an initial term of twelve months or less on the balance sheet and will recognize the associated lease payments in the consolidated statements of operations on a straight-line basis over the lease term. The Company did not elect to apply the hindsight practical expedient when determining lease term and assessing impairment of right-of-use assets. The adoption of ASC 842 on January 1, 2019 resulted in the recognition of an operating lease asset of approximately $613 and operating lease liabilities of approximately $623 , with no impact to operating expense, net loss, or basic and diluted loss per common share for the three and nine months ended September 30, 2019. The impact to the consolidated balance sheet upon adoption of ASC 842 is as follows: As Previously Reported December 31, 2018 ASC 842 Adoption Adjustment As Reported Under ASC 842 January 1, 2019 Prepaid expenses and other current assets $ 1,382 $ (28 ) $ 1,354 Other noncurrent assets 32 613 645 Accrued expenses and other current liabilities 1,543 243 1,786 Other noncurrent liabilities 39 342 381 See Note 11, Leases , for more information on leases. Recent Accounting Pronouncements Not Yet Adopted None.

Collaborative Research and Lice

Collaborative Research and License Agreements	9 Months Ended
	Sep. 30, 2019
Research and Development [Abstract]
Collaborative Research and License Agreements	Collaborative Research and License Agreements Dermelix Collaboration On February 17, 2019, Exicure entered into a License and Development Agreement (the “Dermelix Collaboration”) with Dermelix, LLC d/b/a Dermelix Biotherapeutics (“Dermelix”). Pursuant to the Dermelix Collaboration, the Company granted to Dermelix exclusive, worldwide royalty-bearing license rights to, develop, manufacture, have manufactured, use and commercialize the Company’s spherical nucleic acid (“SNA”) technology for the treatment of Netherton Syndrome (“NS”) and, at Dermelix’s option, up to five additional specified orphan diseases that are within the dermatology field. Upon written notice to the Company, Dermelix may exercise its option at any time following the effective date of the Dermelix Collaboration until the date that is six (6) years from the date that the first collaboration SNA therapeutic achieves first dosing in humans in a Phase 1 clinical trial for NS. Dermelix will initially seek to develop a targeted therapy for the treatment of NS. Under the terms of the Dermelix Collaboration, the Company will be responsible for conducting the early stage development for each indication up to IND enabling toxicology studies. Dermelix will assume subsequent development, commercial activities and financial responsibility for such indications. Dermelix will pay the costs and expenses of development and commercialization of any licensed products under the Dermelix Collaboration, including the Company’s expenses incurred in connection with development activities and in accordance with the development budget. Under the terms of the Dermelix License Agreement, Exicure received an upfront payment of $1,000 , to be applied against the initial $1,000 of the Company’s development expenses. If Dermelix exercises any of its option rights for additional indications, Dermelix will pay an option exercise fee equal to $1,000 for each exercised option (each, an “Option Exercise Fee”). Any Option Exercise Fee will be applied against the Company’s development expenses with respect to the particular indication for which the option was exercised. Pursuant to the Dermelix Collaboration, the Company shall have the right to pursue the development and commercialization of SNA technology for the treatment of orphan diseases which are neither NS nor one of the additional specified orphan diseases selected by Dermelix pursuant to its option rights. If the Company commences development activities of SNA technology for the treatment of such an orphan disease, the Company will notify Dermelix in writing of such development and Dermelix will have thirty (30) days following receipt of such notice to use one of its remaining option rights on such orphan disease. If Dermelix does not use one of its remaining option rights on such orphan disease, or has no option rights remaining, then the Company will have no further obligations to Dermelix with respect to the development of SNA therapeutics for such orphan disease and shall be free to continue commercialization and development activities with respect thereto. For each of NS as well as any additional licensed product for which Dermelix exercises one of its options, the Company shall be eligible to receive additional cash payments totaling up to $13,500 upon achievement of certain development and regulatory milestones and up to $152,500 upon achievement of certain sales milestones. The regulatory milestones are payable upon the initiation or completion of clinical trials, and regulatory approval in the United States and outside the United States, per program. The commercial sales milestones are payable upon achievement of specified aggregate annual product sales thresholds. In the event a therapeutic candidate subject to the collaboration results in commercial sales, the Company will receive low double-digit royalties on annual net sales for such licensed products. Dermelix Collaboration — Revenue Recognition The Company concluded that Dermelix is a customer in this arrangement, and as such the arrangement falls within the scope of the revenue recognition guidance. The Company identified performance obligations under the Dermelix Collaboration for the license of intellectual property for the NS therapeutic candidate and associated research and development services for the NS therapeutic candidate. The Company determined that the performance obligations were not separately identifiable and were not distinct or distinct within the context of the contract due to the specialized nature of the services to be provided by Exicure, specifically with respect to the Company’s expertise related to SNA technology, and the interdependent relationship between the performance obligations. As such, the Company concluded that there is a single identified performance obligation. The Company used the most likely amount method to estimate variable consideration and estimated that the most likely amount for each potential development and regulatory milestone, which is considered variable consideration, was zero, as the achievement of those milestones is uncertain and highly susceptible to factors outside of the Company’s control. Accordingly, all such milestones were excluded from the transaction price. Management will re-evaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur and adjust the transaction price as necessary. Sales-based royalties, including commercial sales milestone payments based on the level of sales, were also excluded from the transaction price, as the license is deemed to be the predominant item to which the royalties relate. The Company will recognize such revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). Revenue associated with the performance obligation will be recognized as services are provided using a cost-to-cost measure of progress method. The transfer of control occurs over time and, in management’s judgment, this input method is the best measure of progress towards satisfying the performance obligation and reflects a faithful depiction of the transfer of goods and services. The Company initially recorded the upfront payment of $1,000 as deferred revenue related to its wholly unsatisfied performance obligation and reduces this balance by recognizing revenue as services are provided. The Company recognized $527 and $986 of revenue under the Dermelix Collaboration during the three and nine months ended September 30, 2019, respectively. The amount remaining as deferred revenue is $14 at September 30, 2019. As of September 30, 2019, the Company expects to recognize this amount as revenue in the fourth quarter of 2019 based on the related level of performance during that period. The Company expects to incur additional early stage development costs beyond the initial $1,000 upfront payment and expects to be reimbursed by Dermelix for such costs under the terms of the Dermelix Collaboration. The Company will recognize both revenue and research and development expense for such costs on a gross basis during the period in which those costs are incurred. Purdue Collaboration During the three and nine months ended September 30, 2018, the Company recognized collaboration revenue of $57 and $112 , respectively, which consisted entirely of research and development activities that were reimbursed by Purdue Pharma L.P. (“Purdue”) and is presented on a gross basis in the accompanying unaudited condensed consolidated statement of operations. In April 2019, Purdue notified the Company that it will not be selecting any collaboration targets pursuant to the Company’s December 2016 research collaboration, option and license agreement with Purdue (the “Purdue Collaboration.”) As a result, the Company will not receive any research, regulatory and commercial sales milestones contingent upon successful development of such collaboration targets. Purdue re-asserted its right to develop new anti-TNF therapeutic candidates. At this time, there are no active development activities underway for a new anti-TNF therapeutic candidate. As a consequence, the Company also believes that it is highly unlikely that it will receive any research, regulatory and commercial sales milestones for any anti-TNF therapeutic candidates.

Supplemental Balance Sheet Info

Supplemental Balance Sheet Information	9 Months Ended
	Sep. 30, 2019
Supplemental Balance Sheet Information [Abstract]
Supplemental Balance Sheet Information	Supplemental Balance Sheet Information Prepaid expenses and other current assets September 30, December 31, Prepaid clinical, contract research and manufacturing costs $ 683 $ 293 Prepaid insurance 24 353 Other 638 736 Prepaid expenses and other current assets $ 1,345 $ 1,382 Property and equipment, net September 30, December 31, Scientific equipment $ 2,062 $ 1,979 Leasehold improvements 192 192 Furniture and fixtures 41 41 Computers and software 26 26 Construction in process 730 12 Property and equipment, gross 3,051 2,250 Less: accumulated depreciation (1,454 ) (1,189 ) Property and equipment, net $ 1,597 $ 1,061 Depreciation and amortization expense was $91 and $90 for the three months ended September 30, 2019 and 2018 , respectively, and $265 and $266 , for the nine months ended September 30, 2019 and 2018, respectively. Other noncurrent assets September 30, December 31, Operating lease asset $ 424 $ — Other 32 32 Other noncurrent assets $ 456 $ 32 Accrued expenses and other current liabilities September 30, December 31, Accrued payroll-related expenses $ 781 $ 899 Accrued loan fees 100 231 Accrued legal expenses 255 189 Operating lease liability 279 — Accrued clinical, contract research and manufacturing costs 244 102 Accrued other expenses 578 122 Accrued expenses and other current liabilities $ 2,237 $ 1,543 Other noncurrent liabilities September 30, December 31, Operating lease liability $ 144 $ — Other — 39 Other noncurrent liabilities $ 144 $ 39

Debt

Debt	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Debt	Debt On March 8, 2019, the Company and Hercules Technology Growth Capital (“Hercules”) amended its loan agreement so that the maturity date of its loan agreement is extended to March 1, 2020 and amortization payments are deferred to, and payable at, the new maturity date of March 1, 2020 (“Loan Amendment No. 4”). Fees of $52 paid to Hercules in connection with Loan Amendment No. 4, as well as a fee of $100 that is payable to Hercules at the new maturity date, are recorded as a reduction in the carrying amount of long-term debt on our balance sheet and will be amortized to interest expense through the new maturity date of March 1, 2020 using the effective interest method. At September 30, 2019 and December 31, 2018, the carrying value of the current and noncurrent portion of long-term debt is $4,912 and $4,925 , respectively. At September 30, 2019, the principal maturities of the long-term debt were as follows: September 30, 2019 2019 $ — 2020 4,999 Principal balance outstanding 4,999 less: unamortized discount and debt issuance costs (87 ) Long-term debt 4,912 Current portion 4,912 Noncurrent portion $ — The Company paid interest on debt of $152 and $146 during the three months ended September 30, 2019 and 2018, respectively, and $453 and $425 during the nine months ended September 30, 2019 and 2018, respectively.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2019
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity Preferred Stock As of September 30, 2019 and December 31, 2018, the Company had 10,000,000 shares of preferred stock, par value $0.0001 authorized and no shares issued and outstanding. Common Stock As of September 30, 2019 and December 31, 2018, the Company had authorized 200,000,000 shares of common stock, par value $0.0001 . As of September 30, 2019, the Company had 75,994,790 shares issued and outstanding. As of December 31, 2018, the Company had 44,358,000 shares issued and outstanding. The holders of shares of the Company’s common stock are entitled to one vote per share on all matters to be voted upon by Exicure stockholders and there are no cumulative rights. Subject to preferences that may be applicable to any outstanding preferred stock, the holders of shares of the Company’s common stock are entitled to receive ratably any dividends that may be declared from time to time by Exicure’s board of directors (the “Board”) out of funds legally available for that purpose. In the event of the Company’s liquidation, dissolution or winding up, the holders of shares of Exicure common stock are entitled to share ratably in all assets remaining after payment of liabilities, subject to prior distribution rights of preferred stock then outstanding. Exicure common stock has no preemptive or conversion rights or other subscription rights. There are no redemption or sinking fund provisions applicable to Exicure common stock. The outstanding shares of Exicure common stock are fully paid and non-assessable. Common Stock Warrants In connection with the private placement transactions that occurred in several closings on September 26, 2017, October 27, 2017 and November 2, 2017 in which we sold to accredited investors approximately $31,513 worth of shares of common stock (before deducting placement agent fees and expenses which are approximately $3,966 ), or 10,504,196 shares, at a price of $3.00 per share (the “2017 Private Placement”), placement agents received warrants to purchase an aggregate of 413,320 shares of Exicure common stock (the “Warrants”) in connection with all closings of the 2017 Private Placement. The Warrants expire on March 27, 2021, have an exercise price of $3.00 per share, and have been issued on the same terms in all closings of the 2017 Private Placement. The Warrants are classified as a liability. The common stock warrant liability is remeasured each period at fair value. As of September 30, 2019, Warrants to purchase 413,320 shares of common stock remain outstanding. See Note 10, Fair Value Measurements for more information on the fair value of the common stock warrant liability.

Equity-Based Compensation

Equity-Based Compensation	9 Months Ended
	Sep. 30, 2019
Share-based Payment Arrangement [Abstract]
Equity-Based Compensation	Equity-Based Compensation As of September 30, 2019, the aggregate number of common stock options available for grant under the 2017 Equity Incentive Plan was 650,822 . Equity-based compensation expense is classified in the statements of operations as follows: Three Months Ended Nine Months Ended September 30, 2019 2018 2019 2018 Research and development expense $ 199 $ 133 $ 423 $ 353 General and administrative expense 312 383 1,016 947 $ 511 $ 516 $ 1,439 $ 1,300 Unamortized equity-based compensation expense at September 30, 2019 was $2,574 , which is expected to be amortized over a weighted-average period of 2.3 years. The Company utilizes the Black-Scholes option-pricing model to determine the fair value of common stock option grants. The Black-Scholes option-pricing model was developed for use in estimating the fair value of traded options that have no vesting restrictions and are fully transferable. The model also requires the input of highly subjective assumptions. In addition to an assumption on the expected term of the option grants as discussed below, application of the Black-Scholes model requires additional inputs for which we have assumed the values described in the table below: Nine Months Ended September 30, 2019 2018 Expected term 5.3 to 6.1 years 5.3 to 6.0 years Risk-free interest rate 1.69% to 2.56%; weighted avg. 2.16% 2.72% to 2.87%; weighted avg. 2.78% Expected volatility 83.2% to 86.7%; weighted avg. 84.9% 78.1% to 82.4%; weighted avg. 80.6% Forfeiture rate 5 % 5 % Expected dividend yield — % — % The expected term is based upon the “simplified method” as described in Staff Accounting Bulletin Topic 14.D.2. Currently, the Company does not have sufficient experience to provide a reasonable estimate of an expected term of its common stock options. The Company will continue to use the “simplified method” until there is sufficient experience to provide a more reasonable estimate in conformance with ASC 718-10-30-25 through 30-26. The risk-free interest rate assumptions were based on the U.S. Treasury bond rate appropriate for the expected term in effect at the time of grant. The expected volatility is based on calculated enterprise value volatilities for publicly traded companies in the same industry and general stage of development. The estimated forfeiture rates were based on historical experience for similar classes of employees. The dividend yield was based on expected dividends at the time of grant. The fair value of the underlying common stock and the exercise price for the common stock options granted during the nine months ended September 30, 2019 and 2018 are summarized in the table below: Common Stock Options Granted During Period Ended: Fair Value of Underlying Common Stock Exercise Price of Common Stock Option Nine months ended September 30, 2019 $2.32 to $2.95; weighted avg. $2.75 $2.32 to $2.95; weighted avg. $2.75 Nine months ended September 30, 2018 $3.00 to $5.82; weighted avg. $3.45 $3.00 to $5.82; weighted avg. $3.45 The weighted-average grant date fair value of common stock options granted in the nine months ended September 30, 2019 and 2018 was $1.96 and $2.40 per common stock option, respectively. A summary of common stock option activity as of the periods indicated is as follows: Options Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term (years) Aggregate Intrinsic Value (thousands) Outstanding - December 31, 2018 4,891,588 $ 2.22 7.3 $ 7,330 Granted 617,009 2.75 Exercised (11,790 ) 1.45 Forfeited (339,388 ) 2.89 Outstanding - September 30, 2019 5,157,419 $ 2.24 6.5 $ 3,754 Exercisable - September 30, 2019 3,884,020 $ 1.94 5.7 $ 3,718 Vested and Expected to Vest - September 30, 2019 5,082,248 $ 2.23 6.4 $ 3,753 The aggregate intrinsic value of common stock options exercised during the nine months ended September 30, 2019 and 2018 was $13 and $51 , respectively.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company incurred a pretax loss in each of the three and nine months ended September 30, 2019 and 2018, which consists entirely of loss in the U.S. and resulted in no provision for income tax expense during the periods then ended. The effective tax rate is 0% in each of the three and nine months ended September 30, 2019 and 2018 because the Company has generated tax losses and has provided a full valuation allowance against its deferred tax assets.

Loss Per Common Share

Loss Per Common Share	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Loss Per Common Share	Loss Per Common Share Basic loss per common share is calculated by dividing net loss by the weighted-average number of shares of common stock outstanding during the period. Diluted loss per common share is calculated using the treasury share method by giving effect to all potentially dilutive securities that were outstanding. Potentially dilutive options and warrants to purchase common stock that were outstanding during the periods presented were excluded from the diluted loss per share calculation because such shares had an anti-dilutive effect due to the net loss reported in those periods. Therefore, basic and diluted loss per common share is the same for each of the three and nine months ended September 30, 2019 and 2018. The following is the computation of loss per common share for the three and nine months ended September 30, 2019 and 2018: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Net loss $ (5,816 ) $ (5,324 ) $ (16,322 ) $ (17,658 ) Weighted-average basic and diluted common shares outstanding 64,651,040 41,527,922 51,200,072 40,121,295 Loss per share - basic and diluted $ (0.09 ) $ (0.13 ) $ (0.32 ) $ (0.44 ) The outstanding securities presented below were excluded from the calculation of net loss per common share, because such securities would have been anti-dilutive due to the Company’s net loss per share during the periods ending on the dates presented: September 30, 2019 2018 Options to purchase common stock 5,157,419 4,891,588 Warrants to purchase common stock 413,320 413,320

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements ASC Topic 820, Fair Value Measurement, establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value, as follows: Level 1 Inputs - unadjusted quoted prices in active markets for identical assets or liabilities accessible to the reporting entity at the measurement date; Level 2 Inputs - other than quoted prices included in Level 1 inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the asset or liability; and Level 3 Inputs - unobservable inputs for the asset or liability used to measure fair value to the extent that observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at measurement date. The Company uses the market approach and Level 1 inputs to value its cash equivalents. The Company’s long-term debt bore interest at the prevailing market rates for instruments with similar characteristics and, accordingly, the carrying value for this instrument also approximates its fair value and the financial measurement is also classified within Level 2 of the fair value hierarchy. The Company’s common stock warrant liability (refer to Note 6, Stockholders’ Equity for more information) is classified within Level 3 of the fair value hierarchy. The fair value of the common stock warrant liability was determined using the Black-Scholes option-pricing model. The following weighted-average assumptions were used to estimate the fair value of the common stock warrant liability at September 30, 2019: September 30, 2019 Expected term 1.5 years Risk-free interest rate 1.67 % Expected volatility 97.94 % Expected dividend yield — % A 10% change in the estimate of expected volatility at September 30, 2019 would increase or decrease the fair value of the common stock warrant liability in the amount of $44 . A 10% change in the estimate of fair value of the common stock at September 30, 2019 would increase or decrease the fair value of the common stock warrant liability in the amount of $73 . The following is a reconciliation of the Company’s liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3) for the nine months ended September 30, 2019: Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Common Stock Warrant Liability Balance at January 1, 2019 $ 797 Gain included in other income (expense), net (360 ) Balance at September 30, 2019 $ 437

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases	Leases The Company determines if an arrangement is a lease at contract inception. Operating lease assets represent the Company’s right to use an underlying asset for the lease term and operating lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease assets and liabilities are recognized on the balance sheet at the commencement date of the lease based upon the present value of lease payments over the lease term. When determining the lease term, the Company includes options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. The Company uses the implicit interest rate when readily determinable and uses the Company’s incremental borrowing rate when the implicit rate is not readily determinable based upon the information available at the commencement date in determining the present value of the lease payments. The lease payments used to determine the Company’s operating lease assets may include lease incentives, stated rent increases and escalation clauses linked to rates of inflation when determinable. In addition, the Company’s lease arrangements may contain lease and non-lease components. The Company combines lease and non-lease components, which are accounted for together as a single lease component. Variable lease payments, such as real estate taxes and facility maintenance costs that are allocated by the lessor to the lessee and are not based on an index or a rate, are excluded from the measurement of the lease liability. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. Short-term leases, defined as leases that have a lease term of twelve months or less at the commencement date, are excluded from this treatment and are recognized on a straight-line basis over the term of the lease. Costs for variable lease payments that are not included in the lease liability are recognized as expense as incurred. The Company’s lease arrangements consist of (i) a lease for office and laboratory space at its headquarters in Skokie, IL that commenced in March 2012 and is scheduled to end in February 2021 (the “Skokie Lease”), (ii) a lease for office space at a multi-tenant facility in Cambridge, MA that commenced in March 2019 and is cancelable at any time (the “Cambridge Lease”), and (iii) leases for office equipment (the “Office Equipment Leases”). Each of these leases are classified as operating leases. The Skokie Lease includes a renewal option which the Company concluded that it is not reasonably certain that the renewal option would be exercised. Lease payments for the Skokie Lease include a fixed payment amount as well as variable payments related to a proportionate share of operating and real estate expenses. Due to the nature of the Cambridge Lease, the Company determined that this lease represented a short-term lease with an initial term of less than twelve months and, as such, the Cambridge Lease is not recorded on the balance sheet and related lease costs are recognized in the statement of operations as they are incurred. The Company has also elected to not record the Office Equipment Leases on the balance sheet since related payment amounts and lease costs are insignificant. Lease costs for the Office Equipment Leases are recognized in the statement of operations on a straight-line basis over the lease term. The following table summarizes the presentation in the Company’s unaudited condensed consolidated balance sheets of its operating leases: September 30, Assets: Operating lease asset $ 424 Liabilities: Operating lease liability $ 279 Operating lease liability, noncurrent 144 Total operating lease liability $ 423 Because the rate implicit in each lease is not readily determinable, the Company uses its incremental borrowing rate to determine the present value of the lease payments. Information related to the Company's operating lease asset and related operating lease liabilities were as follows: September 30, 2019 Remaining lease term (1) 1.4 years Discount rate 16.1 % (1) Does not include a renewal term beyond February 28, 2021. Renewal terms are included in the lease term when it is reasonably certain that the Company will exercise the option. The following table summarizes lease costs in the Company’s unaudited condensed consolidated statement of operations: Three Months Ended Nine Months Ended September 30, 2019 2019 Operating lease costs $ 84 $ 252 Short term lease costs 42 79 Variable lease costs 84 259 Total lease costs $ 210 $ 590 During the three and nine months ended September 30, 2019, the Company made cash payments of $207 and $634 for operating leases, respectively. Maturities of the Company’s lease liability as of September 30, 2019 were as follows: Years Ending December 31, Operating Leases 2019 (remaining three months) $ 58 2020 353 2021 59 Total $ 470 Less: imputed interest (47 ) Total lease liability $ 423 Current operating lease liability 279 Noncurrent operating lease liability 144 Total lease liability $ 423 Leases - ASC 840 Disclosures Lease expense consisted of the following during the three and nine months ended September 30, 2018: Three Months Ended September 30, Nine Months Ended September 30, 2018 2018 Straight-line rent expense $ 83 $ 249 Contingent rent expense 67 231 Total rent expense $ 150 $ 480 The future minimum lease payments under the Company’s operating leases as of December 31, 2018, were as follows: Years Ending December 31, Operating Leases 2019 $ 347 2020 353 2021 59 Total $ 759

Commitment and Contingencies (N

Commitment and Contingencies (Notes)	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Leases Refer to Note 11, Leases , for a discussion of the commitments associated with the Company’s lease agreements. Northwestern University License Agreements On December 12, 2011, (1) AuraSense, LLC assigned to the Company all of its worldwide rights and interests under AuraSense, LLC’s 2009 license agreement with Northwestern University (“NU”) in the field of the use of nanoparticles, nanotechnology, microtechnology or nanomaterial-based constructs as therapeutics or accompanying therapeutics as a means of delivery, but expressly excluding diagnostics (the “assigned field”); (2) in accordance with the terms and conditions of this assignment, the Company assumed all liabilities and obligations of AuraSense, LLC as set forth in its license agreement in the assigned field; and (3) in order to secure this assignment and the patent rights from NU, the Company agreed (i) to pay NU an annual license fee, which may be credited against any royalties due to NU in the same year, (ii) to reimburse NU for expenses associated with the prosecution and maintenance of the license patent rights, (iii) to pay NU royalties based on any net revenue generated by the Company’s sale or transfer of any licensed product, and (iv) to pay NU, in the event the Company grants a sublicense under the licensed patent rights, the greater of a percentage of all sublicensee royalties or a percentage of any net revenue generated by a sublicensee’s sale or transfer of any licensed product. In August 2015, we entered into a restated license agreement with NU (the “restated license agreement”). In February 2016, we obtained exclusive license as to NU’s rights in certain SNA technology we jointly own with NU. Our license to NU’s rights is limited to the assigned field, however we have no such limitation as to our own rights in this jointly owned technology. In June 2016, we entered into an exclusive license with NU to obtain worldwide rights to certain inhibitors of glucosylceramide synthase and their use in wound healing in diabetes. Our rights and obligations in these 2016 agreements are substantially the same as in the restated license agreement from August 2015 (collectively referred to as “the Northwestern University License Agreements”). As of September 30, 2019, the Company has paid to NU an aggregate of $4,143 in consideration of each of the obligations described above.

Related-Party Transactions

Related-Party Transactions	9 Months Ended
	Sep. 30, 2019
Related Party Transactions [Abstract]
Related-Party Transactions	Related-Party Transactions Since its inception in 2011, the Company has shared facilities, certain staff members and certain operating expenses with AuraSense, LLC, our former parent and largest stockholder. On an infrequent basis, the Company also pays certain expenses directly on behalf of AuraSense, LLC which are related to AuraSense, LLC’s grants, and AuraSense, LLC sometimes pays expenses directly on behalf of the Company. These costs are summarized and directly billed between the Company and AuraSense, LLC on a quarterly basis. In addition, certain expense and administrative activities are shared between the Company and AuraSense, LLC. Effective January 1, 2016, the Company and AuraSense, LLC amended its shared services agreement to simplify the billing arrangement. Under the amended shared services agreement, the Company bills AuraSense, LLC $8 per quarter for indirect costs incurred by the Company plus a specified rate for hours worked by Company scientists on projects directly related to AuraSense, LLC. The amended shared services arrangement continues to require direct non-labor expenses incurred by the Company to be billed to AuraSense, LLC. Effective January 1, 2017, the Company and AuraSense, LLC further amended its shared services agreement so that the quarterly fee related to administrative activities billed by the Company to AuraSense, LLC be reduced to $3 per quarter. This decrease is to reflect the current and expected future reduction in administrative activities to be provided by the Company to AuraSense, LLC. The amounts due from AuraSense, LLC in connection with the above-mentioned activities were $16 and $10 at September 30, 2019 and December 31, 2018, respectively. The following is a summary of amounts billed to AuraSense, LLC and recognized in the accompanying unaudited condensed consolidated statement of operations in connection with the above-mentioned activities: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Quarterly fee for indirect costs 3 3 $ 9 $ 9 Direct costs of AuraSense LLC paid by the Company 2 2 7 24 $ 5 $ 5 $ 16 $ 33 The Company received consulting services from, and paid fees to, one of its co-founders who is not an employee but serves as a member of the Board. The Company paid $75 in each of the nine months ended September 30, 2019 and 2018 in connection with these consulting services and these amounts are recognized as an expense in the accompanying unaudited condensed consolidated statement of operations.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The Company has evaluated subsequent events which may require adjustment to or disclosure in the accompanying unaudited condensed consolidated financial statements and has concluded that there are no subsequent events or transactions that occurred subsequent to the balance sheet date that would require recognition or disclosure in the accompanying unaudited condensed consolidated financial statements.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Basis of presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements as of September 30, 2019 and December 31, 2018, and for the three and nine months ended September 30, 2019 and 2018, have been presented in conformity with generally accepted accounting principles in the United States (“GAAP”).
Principles of consolidation	Principles of Consolidation The accompanying unaudited condensed consolidated financial statements include the accounts of Exicure, Inc. and its 100% owned subsidiary, Exicure Operating Company. All intercompany transactions and accounts are eliminated in consolidation.
Use of estimates	Use of Estimates The preparation of the financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Management bases its estimates on certain assumptions which it believes are reasonable in the circumstance and while actual results could differ from those estimates, management does not believe that any change in those assumptions in the near term would have a significant effect on the Company’s financial position, results of operations or cash flows. Actual results in future periods could differ from those estimates.
Recent accounting pronouncements	Recently Adopted Accounting Pronouncements Equity-based compensation In June 2018, the FASB issued Accounting Standards Update (“ASU”) No. 2018-07, Compensation-Stock Compensation: Improvements to Nonemployee Share-Based Payment Accounting (“ASU 2018-07”), which aligns the measurement and classification guidance for share-based payment to non-employees with the guidance for share-based payments to employees. Under the new guidance, the measurement period for equity-classified non-employee awards will be fixed at the grant date. Prior to the adoption of ASU 2018-07, the Company remeasured fair value of stock option awards to nonemployees at each financial statement reporting date. The Company adopted the guidance of ASU 2018-07 in the first quarter of 2019 on a modified retrospective basis. The adoption of ASU 2018-07 did not have a material impact on our financial statements. Leases In February 2016, FASB issued ASU 2016-02, Leases (Topic 842) (or “ASC 842), which replaces the guidance in ASC 840, Leases (“ASC 840”) and requires lessees to recognize right-of-use assets and lease liabilities on the balance sheet. The Company adopted ASC 842 on the required effective date of January 1, 2019 utilizing the modified retrospective transition method with no restatement of prior periods or cumulative adjustment to accumulated deficit. The Company has elected the package of practical expedients, which allows the Company not to reassess (1) whether any expired or existing contracts as of the adoption date are or contain a lease, (2) lease classification for any expired or existing leases as of the adoption date and (3) initial direct costs for any existing leases as of the adoption date. The Company elected to combine lease and non-lease components, elected not to record leases with an initial term of twelve months or less on the balance sheet and will recognize the associated lease payments in the consolidated statements of operations on a straight-line basis over the lease term. The Company did not elect to apply the hindsight practical expedient when determining lease term and assessing impairment of right-of-use assets. The adoption of ASC 842 on January 1, 2019 resulted in the recognition of an operating lease asset of approximately $613 and operating lease liabilities of approximately $623 , with no impact to operating expense, net loss, or basic and diluted loss per common share for the three and nine months ended September 30, 2019. The impact to the consolidated balance sheet upon adoption of ASC 842 is as follows: As Previously Reported December 31, 2018 ASC 842 Adoption Adjustment As Reported Under ASC 842 January 1, 2019 Prepaid expenses and other current assets $ 1,382 $ (28 ) $ 1,354 Other noncurrent assets 32 613 645 Accrued expenses and other current liabilities 1,543 243 1,786 Other noncurrent liabilities 39 342 381 See Note 11, Leases , for more information on leases. Recent Accounting Pronouncements Not Yet Adopted None.
Loss per common share	Basic loss per common share is calculated by dividing net loss by the weighted-average number of shares of common stock outstanding during the period. Diluted loss per common share is calculated using the treasury share method by giving effect to all potentially dilutive securities that were outstanding. Potentially dilutive options and warrants to purchase common stock that were outstanding during the periods presented were excluded from the diluted loss per share calculation because such shares had an anti-dilutive effect due to the net loss reported in those periods.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Impact of Adoption of ASC 842	The impact to the consolidated balance sheet upon adoption of ASC 842 is as follows: As Previously Reported December 31, 2018 ASC 842 Adoption Adjustment As Reported Under ASC 842 January 1, 2019 Prepaid expenses and other current assets $ 1,382 $ (28 ) $ 1,354 Other noncurrent assets 32 613 645 Accrued expenses and other current liabilities 1,543 243 1,786 Other noncurrent liabilities 39 342 381

Supplemental Balance Sheet In_2

Supplemental Balance Sheet Information (Tables)	9 Months Ended
	Sep. 30, 2019
Supplemental Balance Sheet Information [Abstract]
Prepaid Expense and Other Current Assets	Prepaid expenses and other current assets September 30, December 31, Prepaid clinical, contract research and manufacturing costs $ 683 $ 293 Prepaid insurance 24 353 Other 638 736 Prepaid expenses and other current assets $ 1,345 $ 1,382
Property and Equipment, Net	Property and equipment, net September 30, December 31, Scientific equipment $ 2,062 $ 1,979 Leasehold improvements 192 192 Furniture and fixtures 41 41 Computers and software 26 26 Construction in process 730 12 Property and equipment, gross 3,051 2,250 Less: accumulated depreciation (1,454 ) (1,189 ) Property and equipment, net $ 1,597 $ 1,061
Other Noncurrent Assets	Other noncurrent assets September 30, December 31, Operating lease asset $ 424 $ — Other 32 32 Other noncurrent assets $ 456 $ 32
Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities September 30, December 31, Accrued payroll-related expenses $ 781 $ 899 Accrued loan fees 100 231 Accrued legal expenses 255 189 Operating lease liability 279 — Accrued clinical, contract research and manufacturing costs 244 102 Accrued other expenses 578 122 Accrued expenses and other current liabilities $ 2,237 $ 1,543
Other Noncurrent Liabilities	Other noncurrent liabilities September 30, December 31, Operating lease liability $ 144 $ — Other — 39 Other noncurrent liabilities $ 144 $ 39

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Principal Maturities of Long-term Debt	At September 30, 2019, the principal maturities of the long-term debt were as follows: September 30, 2019 2019 $ — 2020 4,999 Principal balance outstanding 4,999 less: unamortized discount and debt issuance costs (87 ) Long-term debt 4,912 Current portion 4,912 Noncurrent portion $ —

Equity-Based Compensation (Tabl

Equity-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2019
Share-based Payment Arrangement [Abstract]
Equity-Based Compensation Expense Classification in Statement of Operations	Equity-based compensation expense is classified in the statements of operations as follows: Three Months Ended Nine Months Ended September 30, 2019 2018 2019 2018 Research and development expense $ 199 $ 133 $ 423 $ 353 General and administrative expense 312 383 1,016 947 $ 511 $ 516 $ 1,439 $ 1,300
Assumptions Used to Determine Fair Value of Common Stock Option Grants	The fair value of the underlying common stock and the exercise price for the common stock options granted during the nine months ended September 30, 2019 and 2018 are summarized in the table below: Common Stock Options Granted During Period Ended: Fair Value of Underlying Common Stock Exercise Price of Common Stock Option Nine months ended September 30, 2019 $2.32 to $2.95; weighted avg. $2.75 $2.32 to $2.95; weighted avg. $2.75 Nine months ended September 30, 2018 $3.00 to $5.82; weighted avg. $3.45 $3.00 to $5.82; weighted avg. $3.45 In addition to an assumption on the expected term of the option grants as discussed below, application of the Black-Scholes model requires additional inputs for which we have assumed the values described in the table below: Nine Months Ended September 30, 2019 2018 Expected term 5.3 to 6.1 years 5.3 to 6.0 years Risk-free interest rate 1.69% to 2.56%; weighted avg. 2.16% 2.72% to 2.87%; weighted avg. 2.78% Expected volatility 83.2% to 86.7%; weighted avg. 84.9% 78.1% to 82.4%; weighted avg. 80.6% Forfeiture rate 5 % 5 % Expected dividend yield — % — %
Common Stock Option Activity	A summary of common stock option activity as of the periods indicated is as follows: Options Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term (years) Aggregate Intrinsic Value (thousands) Outstanding - December 31, 2018 4,891,588 $ 2.22 7.3 $ 7,330 Granted 617,009 2.75 Exercised (11,790 ) 1.45 Forfeited (339,388 ) 2.89 Outstanding - September 30, 2019 5,157,419 $ 2.24 6.5 $ 3,754 Exercisable - September 30, 2019 3,884,020 $ 1.94 5.7 $ 3,718 Vested and Expected to Vest - September 30, 2019 5,082,248 $ 2.23 6.4 $ 3,753

Loss Per Common Share (Tables)

Loss Per Common Share (Tables)	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Computation of Loss Per Common Share	The following is the computation of loss per common share for the three and nine months ended September 30, 2019 and 2018: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Net loss $ (5,816 ) $ (5,324 ) $ (16,322 ) $ (17,658 ) Weighted-average basic and diluted common shares outstanding 64,651,040 41,527,922 51,200,072 40,121,295 Loss per share - basic and diluted $ (0.09 ) $ (0.13 ) $ (0.32 ) $ (0.44 )
Antidilutive Securities	The outstanding securities presented below were excluded from the calculation of net loss per common share, because such securities would have been anti-dilutive due to the Company’s net loss per share during the periods ending on the dates presented: September 30, 2019 2018 Options to purchase common stock 5,157,419 4,891,588 Warrants to purchase common stock 413,320 413,320

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Schedule of Assumptions used to Estimate Fair Value of Warrant Liability	The following weighted-average assumptions were used to estimate the fair value of the common stock warrant liability at September 30, 2019: September 30, 2019 Expected term 1.5 years Risk-free interest rate 1.67 % Expected volatility 97.94 % Expected dividend yield — %
Reconciliation of Liabilities Measured at Fair Value on a Recurring Basis	The following is a reconciliation of the Company’s liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3) for the nine months ended September 30, 2019: Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Common Stock Warrant Liability Balance at January 1, 2019 $ 797 Gain included in other income (expense), net (360 ) Balance at September 30, 2019 $ 437

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Operating Lease Balance Sheet Presentation	The following table summarizes the presentation in the Company’s unaudited condensed consolidated balance sheets of its operating leases: September 30, Assets: Operating lease asset $ 424 Liabilities: Operating lease liability $ 279 Operating lease liability, noncurrent 144 Total operating lease liability $ 423
Lease Costs	Information related to the Company's operating lease asset and related operating lease liabilities were as follows: September 30, 2019 Remaining lease term (1) 1.4 years Discount rate 16.1 % (1) Does not include a renewal term beyond February 28, 2021. Renewal terms are included in the lease term when it is reasonably certain that the Company will exercise the option. The following table summarizes lease costs in the Company’s unaudited condensed consolidated statement of operations: Three Months Ended Nine Months Ended September 30, 2019 2019 Operating lease costs $ 84 $ 252 Short term lease costs 42 79 Variable lease costs 84 259 Total lease costs $ 210 $ 590
Schedule of Future Minimum Rental Payments	Maturities of the Company’s lease liability as of September 30, 2019 were as follows: Years Ending December 31, Operating Leases 2019 (remaining three months) $ 58 2020 353 2021 59 Total $ 470 Less: imputed interest (47 ) Total lease liability $ 423 Current operating lease liability 279 Noncurrent operating lease liability 144 Total lease liability $ 423
Schedule of Lease Expense - ASC 840	Lease expense consisted of the following during the three and nine months ended September 30, 2018: Three Months Ended September 30, Nine Months Ended September 30, 2018 2018 Straight-line rent expense $ 83 $ 249 Contingent rent expense 67 231 Total rent expense $ 150 $ 480
Future Minimum Lease Payments - ASC 840	The future minimum lease payments under the Company’s operating leases as of December 31, 2018, were as follows: Years Ending December 31, Operating Leases 2019 $ 347 2020 353 2021 59 Total $ 759

Related-Party Transactions (Tab

Related-Party Transactions (Tables)	9 Months Ended
	Sep. 30, 2019
Related Party Transactions [Abstract]
Schedule of Revenue from Related Party	The following is a summary of amounts billed to AuraSense, LLC and recognized in the accompanying unaudited condensed consolidated statement of operations in connection with the above-mentioned activities: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Quarterly fee for indirect costs 3 3 $ 9 $ 9 Direct costs of AuraSense LLC paid by the Company 2 2 7 24 $ 5 $ 5 $ 16 $ 33

Description of Business and B_2

Description of Business and Basis of Presentation (Details) - USD ($) $ / shares in Units, $ in Thousands	Aug. 02, 2019	Sep. 30, 2019	Sep. 30, 2018
Subsidiary, Sale of Stock [Line Items]
Gross proceeds		$ 63,250	$ 22,001
Accumulated deficit generated, since inception		$ 90,153
Underwritten Public Offering
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction (in shares)	31,625,000
Sale of stock (in usd per share)	$ 2
Additional shares issued (in shares)	4,125,000
Gross proceeds	$ 63,250
Stock issuance costs	$ 4,384

Significant Accounting Polici_4

Significant Accounting Policies - Narrative (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease asset	$ 424
Liability - operating lease	423
Prepaid expenses and other assets	1,345	$ 1,354	$ 1,382
Other noncurrent assets	456	645	32
Accrued expenses and other current liabilities	2,237	1,786	1,543
Other noncurrent liabilities	$ 144	381	$ 39
ASC 842
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease asset		613
Liability - operating lease		623
Prepaid expenses and other assets		(28)
Other noncurrent assets		613
Accrued expenses and other current liabilities		243
Other noncurrent liabilities		$ 342

Collaborative Research and Li_2

Collaborative Research and License Agreements (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)target	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue	$ 527	$ 57	$ 986	$ 112
Current portion of deferred revenue	$ 14		14		$ 0
Dermelix License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Aggregate regulatory milestone revenue			13,500
Potential milestone revenue			$ 152,500
Dermelix License Agreement | Collaboration Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of additional collaboration targets | target			5
Collaboration agreement term			6 years
Non-refundable upfront payment received for research agreement			$ 1,000
Collaboration development expenses			1,000
Collaboration option exercise fee			$ 1,000
Collaboration option rights usage term			30 days
Purdue Collaboration
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue		$ 57		$ 112

Supplemental Balance Sheet In_3

Supplemental Balance Sheet Information - Prepaid expenses and other current assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Supplemental Balance Sheet Information [Abstract]
Prepaid clinical, contract research and manufacturing costs	$ 683		$ 293
Prepaid insurance	24		353
Other	638		736
Prepaid expenses and other current assets	$ 1,345	$ 1,354	$ 1,382

Supplemental Balance Sheet In_4

Supplemental Balance Sheet Information - Property and Equipment, Net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 3,051		$ 3,051		$ 2,250
Less: accumulated depreciation	(1,454)		(1,454)		(1,189)
Property and equipment, net	1,597		1,597		1,061
Depreciation and amortization	91	$ 90	265	$ 266
Scientific equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	2,062		2,062		1,979
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	192		192		192
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	41		41		41
Computers and software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	26		26		26
Construction in process
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 730		$ 730		$ 12

Supplemental Balance Sheet In_5

Supplemental Balance Sheet Information - Other noncurrent assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Supplemental Balance Sheet Information [Abstract]
Operating lease asset	$ 424
Other	32		$ 32
Other noncurrent assets	$ 456	$ 645	$ 32

Supplemental Balance Sheet In_6

Supplemental Balance Sheet Information - Accrued Expense and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Supplemental Balance Sheet Information [Abstract]
Accrued payroll-related expenses	$ 781		$ 899
Accrued loan fees	100		231
Accrued legal expenses	255		189
Operating lease liability	279
Accrued clinical, contract research and manufacturing costs	244		102
Accrued other expenses	578		122
Accrued expenses and other current liabilities	$ 2,237	$ 1,786	$ 1,543

Supplemental Balance Sheet In_7

Supplemental Balance Sheet Information - Other noncurrent liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Supplemental Balance Sheet Information [Abstract]
Operating lease liability	$ 144
Other	0		$ 39
Other noncurrent liabilities	$ 144	$ 381	$ 39

Debt - Narrative (Details)

Debt - Narrative (Details) - USD ($) $ in Thousands	Mar. 08, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Debt Disclosure [Abstract]
Payment of long-term debt fees and issuance costs	$ 52			$ 284	$ 0
Debt fees (accrued expenses)	$ 100			100	0
Long-term debt		$ 4,912		4,912		$ 4,925
Interest paid on debt		$ 152	$ 146	$ 453	$ 425

Debt - Principal Maturities of

Debt - Principal Maturities of Long-Term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
2019	$ 0
2020	4,999
Principal balance outstanding	4,999
less: unamortized discount and debt issuance costs	(87)
Long-term debt	4,912	$ 4,925
Current portion	4,912	0
Noncurrent portion	$ 0	$ 4,925

Stockholders' Equity - Current

Stockholders' Equity - Current Capitalization (Details)	Sep. 30, 2019vote_per_share$ / sharesshares	Dec. 31, 2018$ / sharesshares
Equity [Abstract]
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, par value (in dollars per share) | $ / shares	$ 0.0001	$ 0.0001
Preferred stock, shares issued (in shares)	0	0
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, par value (in dollars per share) | $ / shares	$ 0.0001	$ 0.0001
Common stock, shares issued (in shares)	75,994,790	44,358,000
Common stock, voting rights for each share | vote_per_share	1
Common stock, shares outstanding (in shares)	75,994,790	44,358,000
Preferred stock, shares outstanding (in shares)	0	0

Stockholders' Equity - Common S

Stockholders' Equity - Common Stock Warrants (Details) - Private Placement - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended
	Nov. 02, 2017	Sep. 30, 2019
Class of Stock [Line Items]
Consideration received on transaction	$ 31,513
Payments of stock issuance costs	$ 3,966
Number of shares issued in transaction (in shares)	10,504,196
Exercise price (in dollars per share)	$ 3
Number of shares called by warrants (in shares)	413,320	413,320

Equity-Based Compensation - Nar

Equity-Based Compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost not yet recognized	$ 2,574
Compensation expense recognition period	2 years 3 months 18 days
Weighted-average grant date fair value (in dollars per share)	$ 1.96	$ 2.40
Intrinsic value of options exercised	$ 13	$ 51
Exicure, Inc. 2017 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant (in shares)	650,822

Equity-Based Compensation - Sch

Equity-Based Compensation - Schedule of Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 511	$ 516	$ 1,439	$ 1,300
Research and development expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	199	133	423	353
General and administrative expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 312	$ 383	$ 1,016	$ 947

Equity-Based Compensation - Ass

Equity-Based Compensation - Assumptions Used for Fair Value Measurement (Details)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate, minimum	1.69%	2.72%
Risk-free interest rate, maximum	2.56%	2.87%
Expected volatility, minimum	83.20%	78.10%
Expected volatility, maximum	86.70%	82.40%
Expected volatility, weighted average	84.90%	80.60%
Forfeiture rate	5.00%	5.00%
Expected dividend yield	0.00%	0.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term	5 years 3 months 18 days	5 years 3 months 18 days
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term	6 years 1 month 6 days	6 years
Weighted Average
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	2.16%	2.78%

Equity-Based Compensation - Fai

Equity-Based Compensation - Fair Value of Underlying Common Stock and Exercise Price of Stock Options (Details) - $ / shares	Sep. 30, 2019	Sep. 30, 2018
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair Value of Underlying Common Stock (dollars per share)	$ 2.32	$ 3
Exercise Price of Common Stock Option (dollars per share)	2.32	3
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair Value of Underlying Common Stock (dollars per share)	2.95	5.82
Exercise Price of Common Stock Option (dollars per share)	2.95	5.82
Weighted Average
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair Value of Underlying Common Stock (dollars per share)	2.75	3.45
Exercise Price of Common Stock Option (dollars per share)	$ 2.75	$ 3.45

Equity-Based Compensation - S_2

Equity-Based Compensation - Schedule of Stock Options Rollforward (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Options
Outstanding beginning balance (in shares)	4,891,588
Granted (in shares)	617,009
Exercised (in shares)	(11,790)
Forfeited (in shares)	(339,388)
Outstanding ending balance (in shares)	5,157,419	4,891,588
Weighted-Average Exercise Price
Outstanding beginning balance (in dollars per share)	$ 2.22
Granted (in dollars per share)	2.75
Exercised (in dollars per share)	1.45
Forfeited (in dollars per share)	2.89
Outstanding ending balance (in dollars per share)	$ 2.24	$ 2.22
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted-Average Remaining Contractual Term	6 years 6 months	7 years 3 months
Aggregate Intrinsic Value	$ 3,754	$ 7,330
Exercisable (in shares)	3,884,020
Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 1.94
Exercisable, Weighted-Average Remaining Contractual Term	5 years 8 months
Exercisable, Aggregate Intrinsic Value	$ 3,718
Vested and Expected to Vest (in shares)	5,082,248
Vested and Expected to Vest, Weighted-Average Exercise Price (in dollars per share)	$ 2.23
Vested and Expected to Vest, Weighted-Average Remaining Contractual Term	6 years 5 months
Vested and Expected to Vest, Aggregate Intrinsic Value (dollars per share)	$ 3,753

Income Taxes (Details)

Income Taxes (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Provision for income tax expense	$ 0	$ 0	$ 0	$ 0
Effective tax rate	0.00%	0.00%	0.00%	0.00%

Loss Per Common Share - Computa

Loss Per Common Share - Computation of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net loss	$ (5,816)	$ (5,220)	$ (5,286)	$ (5,324)	$ (6,825)	$ (5,509)	$ (16,322)	$ (17,658)
Weighted-average basic and diluted common shares outstanding (in shares)	64,651,040			41,527,922			51,200,072	40,121,295
Loss per share - basic and diluted (in dollars per share)	$ (0.09)			$ (0.13)			$ (0.32)	$ (0.44)

Loss Per Common Share - Antidil

Loss Per Common Share - Antidilutive Securities (Details) - shares	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares excluded from computation of weighted-average diluted common shares outstanding (in shares)	5,157,419	4,891,588
Warrants to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares excluded from computation of weighted-average diluted common shares outstanding (in shares)	413,320	413,320

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)
Fair Value Disclosures [Abstract]
Impact of 10% change in estimate of expected volatility of the fair value of the common stock	$ 44
Impact of 10% change in the estimate of fair value of the common stock	$ 73

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Assumptions used to Estimate Fair Value of Warrant Liability (Details) - Warrant Liability - Common Stock	Sep. 30, 2019
Expected term
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Common stock warrant liability, measurement input	1.5
Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Common stock warrant liability, measurement input	0.0167
Expected volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Common stock warrant liability, measurement input	0.9794
Expected dividend yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Common stock warrant liability, measurement input	0

Fair Value Measurements - Recon

Fair Value Measurements - Reconciliation of Liabilities Measured at Fair Value on a Recurring Basis (Details) - Fair Value Measurements Using Significant Unobservable Inputs (Level 3) - Common Stock - Warrant Liability $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1, 2019	$ 797
Gain included in other income (expense), net	(360)
Balance at September 30, 2019	$ 437

Leases - Balance Sheet Presenta

Leases - Balance Sheet Presentation (Details) $ in Thousands	Sep. 30, 2019USD ($)
Leases [Abstract]
Operating lease asset	$ 424
Operating lease liability	279
Operating lease liability	144
Total operating lease liability	$ 423

Leases - Right of Use Asset Inf

Leases - Right of Use Asset Information (Details)	Sep. 30, 2019
Leases [Abstract]
Remaining lease term	1 year 5 months
Discount rate	16.10%

Leases - Lease Costs (Details)

Leases - Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Leases [Abstract]
Operating lease costs	$ 84	$ 252
Short term lease costs	42	79
Variable lease costs	84	259
Total lease costs	210	590
Operating lease, cash payments	$ 207	$ 634

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum Rental Payments (Details) $ in Thousands	Sep. 30, 2019USD ($)
Leases [Abstract]
2019 (remaining three months)	$ 58
2020	353
2021	59
Total	470
Less: imputed interest	(47)
Total lease liability	423
Current operating lease liability	279
Noncurrent operating lease liability	$ 144

Leases - Rent Expense (Details)

Leases - Rent Expense (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018
Leases [Abstract]
Straight-line rent expense	$ 83	$ 249
Contingent rent expense	67	231
Total rent expense	$ 150	$ 480

Leases - Schedule of Future M_2

Leases - Schedule of Future Minimum Rental Payments-2018 (Details) $ in Thousands	Dec. 31, 2018USD ($)
Leases [Abstract]
2019	$ 347
2020	353
2021	59
Total	$ 759

Commitment and Contingencies (D

Commitment and Contingencies (Details) $ in Thousands	94 Months Ended
	Sep. 30, 2019USD ($)
Commitments and Contingencies Disclosure [Abstract]
Payment for license agreements	$ 4,143

Related-Party Transactions - Na

Related-Party Transactions - Narrative (Details) - USD ($) $ in Thousands	Jan. 01, 2017	Jan. 01, 2016	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Related Party Transaction [Line Items]
Receivable from related party			$ 16		$ 10
Board of Directors | Consulting services
Related Party Transaction [Line Items]
Expenses from transactions with related party			75	$ 75
AuraSense
Related Party Transaction [Line Items]
Quarterly revenue from related party for indirect costs	$ 3	$ 8
Receivable from related party			$ 16		$ 10

Related-Party Transactions - Sc

Related-Party Transactions - Schedule of Revenue from Related Party (Details) - AuraSense - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Related Party Transaction [Line Items]
Revenue from related parties	$ 5	$ 5	$ 16	$ 33
Quarterly fee for indirect costs
Related Party Transaction [Line Items]
Revenue from related parties	3	3	9	9
Direct costs of AuraSense LLC paid by the Company
Related Party Transaction [Line Items]
Revenue from related parties	$ 2	$ 2	$ 7	$ 24