Altimmune (ALT) 10-Q 11 Aug 22 2022 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2022	Aug. 05, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q2
Trading Symbol	ALT
Entity Registrant Name	ALTIMMUNE, INC.
Entity Central Index Key	0001326190
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	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		48,535,230
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Entity File Number	001-32587
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-2726770
Entity Address, Address Line One	910 Clopper Road
Entity Address, Address Line Two	Suite 201S
Entity Address, City or Town	Gaithersburg
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	20878
City Area Code	240
Local Phone Number	654-1450
Document Transition Report	false

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 135,858	$ 190,301
Restricted cash	34	34
Total cash, cash equivalents and restricted cash	135,892	190,335
Short-term investments	48,898
Accounts receivable	195	429
Income tax and R&D incentive receivables	5,900	5,410
Prepaid expenses and other current assets	4,619	7,952
Total current assets	195,504	204,126
Property and equipment, net	1,236	1,448
Intangible assets, net	12,419	12,419
Other assets	747	872
Total assets	209,906	218,865
Current liabilities:
Accounts payable	2,872	2,034
Contingent consideration		6,090
Accrued expenses and other current liabilities	10,973	10,152
Total current liabilities	13,845	18,276
Other long-term liabilities	1,526	1,454
Total liabilities	15,371	19,730
Commitments and contingencies (Note 14)
Stockholders' equity:
Common stock, $0.0001 par value; 200,000,000 shares authorized; 46,372,105 and 40,993,768 shares issued and outstanding as of June 30, 2022 and December 31, 2021, respectively	5	4
Additional paid-in capital	532,398	497,342
Accumulated deficit	(332,708)	(293,171)
Accumulated other comprehensive loss, net	(5,160)	(5,040)
Total stockholders' equity	194,535	199,135
Total liabilities and stockholders' equity	$ 209,906	$ 218,865

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2022	Dec. 31, 2021
CONSOLIDATED BALANCE SHEETS
Common stock, par or stated value per share	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	46,372,105	40,993,768
Common stock, shares outstanding	46,372,105	40,993,768

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS
Revenues	$ 8	$ 137	$ 40	$ 975
Operating expenses:
Research and development	15,993	13,272	31,097	25,150
General and administrative	4,410	3,659	8,837	7,480
Impairment loss on construction-in-progress		8,070		8,070
Total operating expenses	20,403	25,001	39,934	40,700
Loss from operations	(20,395)	(24,864)	(39,894)	(39,725)
Other income (expense):
Interest expense	(65)	(22)	(127)	(34)
Interest income	328	33	349	75
Other income (expense), net	25	26	135	(7)
Total other income (expense), net	288	37	357	34
Income tax benefit			0	0
Net loss	(20,107)	(24,827)	(39,537)	(39,691)
Other comprehensive income - unrealized (loss) gain on short-term investments	(120)	1	(120)	6
Comprehensive loss	$ (20,227)	$ (24,826)	$ (39,657)	$ (39,685)
Net loss per share, basic	$ (0.42)	$ (0.60)	$ (0.90)	$ (0.99)
Net loss per share, diluted	$ (0.42)	$ (0.60)	$ (0.90)	$ (0.99)
Weighted-average common shares outstanding, basic	47,502,599	41,356,643	44,150,835	40,142,561
Weighted-average common shares outstanding, diluted	47,502,599	41,356,643	44,150,835	40,142,561

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Total
Beginning Balance at Dec. 31, 2020	$ 4	$ 417,337	$ (186,421)	$ (5,044)	$ 225,876
Beginning Balance (in shares) at Dec. 31, 2020	37,142,946
Stock-based compensation		1,218			1,218
Vesting of restricted stock awards including withholding, net		(92)			(92)
Vesting of restricted stock awards including withholding, net (in shares)	(6,349)
Issuance of common stock from Employee Stock Purchase Plan		106			106
Issuance of common stock from Employee Stock Purchase Plan (in shares)	8,733
Issuance of common stock in at the market offerings, net		34,178			34,178
Issuance of common stock in at the market offerings, net (in shares)	2,110,800
Retirement of common stock in exchange for common stock warrant		(7,540)	(9,660)		(17,200)
Retirement of common stock in exchange for common stock warrant (in Shares)	(1,000,000)
Issuance of common stock warrant in exchange for retirement of common stock		17,200			17,200
Issuance of common stock upon cashless exercise of warrants		10			10
Issuance of common stock upon cashless exercise of warrants (in shares)	1,050
Other comprehensive income - unrealized (loss) gain on short-term investments				5	5
Net loss			(14,864)		(14,864)
Ending Balance at Mar. 31, 2021	$ 4	462,417	(210,945)	(5,039)	246,437
Ending Balance (in shares) at Mar. 31, 2021	38,257,180
Beginning Balance at Dec. 31, 2020	$ 4	417,337	(186,421)	(5,044)	225,876
Beginning Balance (in shares) at Dec. 31, 2020	37,142,946
Other comprehensive income - unrealized (loss) gain on short-term investments					6
Net loss					(39,691)
Ending Balance at Jun. 30, 2021	$ 4	482,084	(235,772)	(5,038)	241,278
Ending Balance (in shares) at Jun. 30, 2021	39,693,524
Beginning Balance at Mar. 31, 2021	$ 4	462,417	(210,945)	(5,039)	246,437
Beginning Balance (in shares) at Mar. 31, 2021	38,257,180
Stock-based compensation		1,485			1,485
Exercise of stock options		94			94
Exercise of stock options (in shares)	38,217
Vesting of restricted stock awards including withholding, net		(90)			(90)
Vesting of restricted stock awards including withholding, net (in shares)	(7,583)
Issuance of common stock in at the market offerings, net		18,178			18,178
Issuance of common stock in at the market offerings, net (in shares)	1,405,710
Other comprehensive income - unrealized (loss) gain on short-term investments				1	1
Net loss			(24,827)		(24,827)
Ending Balance at Jun. 30, 2021	$ 4	482,084	(235,772)	(5,038)	241,278
Ending Balance (in shares) at Jun. 30, 2021	39,693,524
Beginning Balance at Dec. 31, 2021	$ 4	497,342	(293,171)	(5,040)	199,135
Beginning Balance (in shares) at Dec. 31, 2021	40,993,768
Stock-based compensation		2,033			2,033
Exercise of stock options		197			197
Exercise of stock options (in shares)	95,771
Vesting of restricted stock awards including withholding, net		(170)			(170)
Vesting of restricted stock awards including withholding, net (in shares)	17,568
Issuance of common stock from Employee Stock Purchase Plan		113			113
Issuance of common stock from Employee Stock Purchase Plan (in shares)	16,450
Issuance of common stock in at the market offerings, net		2,990			2,990
Issuance of common stock in at the market offerings, net (in shares)	335,485
Issuance of common stock upon cashless exercise of warrants (in shares)	1,760,854
Net loss			(19,430)		(19,430)
Ending Balance at Mar. 31, 2022	$ 4	502,505	(312,601)	(5,040)	184,868
Ending Balance (in shares) at Mar. 31, 2022	43,219,896
Beginning Balance at Dec. 31, 2021	$ 4	497,342	(293,171)	(5,040)	199,135
Beginning Balance (in shares) at Dec. 31, 2021	40,993,768
Other comprehensive income - unrealized (loss) gain on short-term investments					(120)
Net loss					(39,537)
Ending Balance at Jun. 30, 2022	$ 5	532,398	(332,708)	(5,160)	194,535
Ending Balance (in shares) at Jun. 30, 2022	46,372,105
Beginning Balance at Mar. 31, 2022	$ 4	502,505	(312,601)	(5,040)	184,868
Beginning Balance (in shares) at Mar. 31, 2022	43,219,896
Stock-based compensation		2,048			2,048
Exercise of stock options		403			403
Exercise of stock options (in shares)	152,913
Vesting of restricted stock awards including withholding, net		(80)			(80)
Vesting of restricted stock awards including withholding, net (in shares)	(5,865)
Issuance of common stock in at the market offerings, net	$ 1	21,346			21,347
Issuance of common stock in at the market offerings, net (in shares)	2,157,717
Issuance of common stock related to contingent consideration liability		6,176			6,176
Issuance of common stock related to contingent consideration liability (in shares)	847,444
Other comprehensive income - unrealized (loss) gain on short-term investments				(120)	(120)
Net loss			(20,107)		(20,107)
Ending Balance at Jun. 30, 2022	$ 5	$ 532,398	$ (332,708)	$ (5,160)	$ 194,535
Ending Balance (in shares) at Jun. 30, 2022	46,372,105

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (39,537)	$ (39,691)
Adjustments to reconcile net loss to net cash used in operating activities:
Change in fair value of contingent consideration liability	86	(120)
Impairment loss on construction-in-progress		8,070
Stock-based compensation expense	4,081	2,703
Depreciation and amortization	172	149
Unrealized (gains) losses on foreign currency exchange	(134)	10
Changes in operating assets and liabilities:
Accounts receivable	233	(94)
Prepaid expenses and other current assets	3,397	(7,156)
Accounts payable	838	809
Accrued expenses and other liabilities	1,124	(4,051)
Income tax and R&D incentive receivables	(490)	875
Net cash used in operating activities	(30,230)	(38,496)
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from sales and maturities of short-term investments		63,712
Purchases of short-term investments	(48,949)	(7,424)
Purchases of property and equipment, net	(28)	(11,900)
Cash paid for internally developed patents		(145)
Net cash (used in) provided by investing activities	(48,977)	44,243
CASH FLOWS FROM FINANCING ACTIVITIES:
Payments of deferred offering costs	(36)	(118)
Proceeds from issuance of common stock in at-the-market offerings, net	24,337	52,356
Proceeds from issuance of common stock from Employee Stock Purchase Plan	113	106
Proceeds from exercises of stock options, net	350	94
Net cash provided by financing activities	24,764	52,438
Net (decrease) increase in cash and cash equivalents and restricted cash	(54,443)	58,185
Cash, cash equivalents and restricted cash at beginning of period	190,335	115,952
Cash, cash equivalents and restricted cash at end of period	135,892	$ 174,137
SUPPLEMENTAL NON-CASH ACTIVITIES:
Common stock issued related to contingent consideration liability	$ 6,176

Nature of Business and Basis of

Nature of Business and Basis of Presentation	6 Months Ended
	Jun. 30, 2022
Nature of Business and Basis of Presentation
Nature of Business and Basis of Presentation	1. Nature of Business and Basis of Presentation Nature of Business Altimmune, Inc., headquartered in Gaithersburg, Maryland, United States, together with its subsidiaries (collectively, the “Company” or “Altimmune”) is a clinical stage biopharmaceutical company incorporated under the laws of the State of Delaware. The Company is focused on developing treatments for obesity and liver diseases. The Company’s pipeline includes next generation peptide therapeutics for obesity and non-alcoholic steatohepatitis (“NASH”) (for both, pemvidutide [proposed INN], formerly known as ALT-801), and for chronic hepatitis B (HepTcell). Since its inception, the Company has devoted substantially all of its efforts to business planning, research and development, recruiting management and technical staff and raising capital, and has financed its operations through the issuance of common and preferred stock, long-term debt and proceeds from research grants and government contracts. The Company has not generated any revenues from the sale of any products to date, and there is no assurance of any future revenues from product sales. Basis of Presentation The accompanying unaudited consolidated financial statements are prepared pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Accordingly, they do not include all of the information and disclosures required by accounting principles generally accepted in the United States (“U.S. GAAP”) for complete consolidated financial statements and should be read in conjunction with the audited consolidated financial statements for the year ended December 31, 2021 included in the Annual Report on Form 10-K which was filed with the SEC on March 15, 2022. In the opinion of management, the Company has prepared the accompanying unaudited consolidated financial statements on the same basis as the audited consolidated financial statements, and these consolidated financial statements include all adjustments, consisting only of normal recurring adjustments, necessary for a fair presentation of the results of the interim periods presented. The operating results for the interim periods presented are not necessarily indicative of the results expected for the full year 2022 or any future years or periods. The accompanying unaudited consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All significant intercompany accounts and transactions have been eliminated in consolidation. The accompanying unaudited consolidated financial statements have been prepared on the basis of continuity of operations, realization of assets, and the satisfaction of liabilities in the ordinary course of business. The financial statements do not include any adjustments relating to the recoverability and classification of recorded assets and liabilities that might be necessary should we be unable to continue as a going concern.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2022
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies During the six months ended June 30, 2022, there have been no significant changes to the Company’s summary of significant accounting policies contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021 as filed with the SEC. Use of Estimates The preparation of these financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. The extent to which the COVID-19 pandemic, including any resurgences or the emergence of new variants, may directly or indirectly impact the Company’s business, financial condition, and results of operations is highly uncertain and subject to change. The Company considered the potential impact of the COVID-19 pandemic on the Company’s estimates and assumptions and determined that there was not a material impact to the Company’s unaudited consolidated financial statements as of and for the three and six months ended June 30, 2022. However, actual results could differ from those estimates and there may be changes to the Company’s estimates in future periods.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2022
Fair Value Measurements
Fair Value Measurements	3. Fair Value Measurements The Company’s assets measured at fair value on a recurring basis as of June 30, 2022 consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement at June 30, 2022 ​ Total Level 1 Level 2 Level 3 Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents - money market funds ​ $ 91,807 ​ $ 91,807 ​ $ — ​ $ — Short-term investments ​ 48,898 ​ — ​ 48,898 ​ — Total ​ $ 140,705 ​ $ 91,807 ​ $ 48,898 ​ $ — ​ The Company’s assets and liabilities measured at fair value on a recurring basis as of December 31, 2021 consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement at December 31, 2021 ​ Total Level 1 Level 2 Level 3 Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents - money market funds ​ $ 65,634 $ 65,634 $ — $ — Total ​ ​ 65,634 ​ ​ 65,634 ​ ​ — ​ ​ — Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration liability (see Note 6) ​ 6,090 ​ — ​ — ​ 6,090 Total ​ $ 6,090 ​ $ — ​ $ — ​ $ 6,090 ​ ​ As described in Note 6, the remaining milestone payment underlying the contingent consideration liability was fully settled in shares of the Company’s common stock. As of June 30, 2022, the Company had no contingent consideration liability. Short-term investments have been initially valued at the transaction price and subsequently valued, at the end of each reporting period, utilizing third party pricing services or other market observable data (Level 2). The pricing services utilize industry standard valuation models, including both income and market-based approaches and observable market inputs to determine value. Short-term investments had quoted prices as of June 30, 2022 as shown below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2022 ​ ​ Amortized Cost ​ Unrealized Loss ​ Market Value United States treasury securities $ 9,937 $ (52) $ 9,885 Commercial paper and corporate debt securities ​ ​ 34,072 ​ ​ (64) ​ ​ 34,008 Asset backed securities ​ 5,009 ​ (4) ​ 5,005 Total ​ $ 49,018 ​ $ (120) ​ $ 48,898 ​ Separate disclosure is required for assets and liabilities measured at fair value on a recurring basis from those measured at fair value on a non-recurring basis. Assets recorded at fair value on a non-recurring basis, such as property and equipment and intangible assets are recognized at fair value when they are impaired. During the six months ended June 30, 2022, the Company had no significant assets or liabilities that were measured at fair value on a non-recurring basis. During the year ended December 31, 2021, the Company recorded non-cash impairment charges to property and equipment, net on a non-recurring basis (see below). Lonza Manufacturing Agreement ​ In March 2021, the Company expanded its manufacturing collaboration with Lonza Houston, Inc. (“Lonza”) for the manufacture of AdCOVID or other adenovirus-based vaccines. Under the expanded agreement, the Company had committed approximately $23.0 million to Lonza to procure long-lead equipment and construct a dedicated manufacturing suite for clinical and commercial production of adenovirus-based vaccines. This work was completed during the fourth quarter of 2021. The Company capitalized a total of $11.4 million as construction-in-progress (“CIP”) during the six months ended June 30, 2021 under this expanded agreement. In connection with the discontinuation of further development of AdCOVID, the Company recorded a non-cash impairment charge of $8.1 million in the unaudited consolidated statements of operations and comprehensive loss for the three and six months ended June 30, 2021 to write-down the CIP associated with the construction of the Lonza facility to its fair value of $3.3 million as of June 30, 2021. As of June 30, 2021, the fair value of the CIP related assets was primarily determined utilizing the cost approach, which reflects the current replacement cost of the asset being appraised, adjusted for contractual restrictions on the assets, the probability of satisfying the contractual restrictions, physical deterioration, functional obsolescence and economic obsolescence. The fair value measurement was considered a Level 3 measurement within the valuation hierarchy. Furthermore, the remaining $3.3 million CIP was fully charged to impairment during the three months ended December 31, 2021 upon termination of the agreement.

Operating Leases

Operating Leases	6 Months Ended
	Jun. 30, 2022
Operating Leases
Operating Leases	4. Operating Leases The Company rents office and laboratory space in the United States. The Company also leases office equipment under non-cancellable equipment leases through June 2026. Rent expense during the three and six months ended June 30, 2022 under all of the Company’s operating leases was $0.1 million and $0.2 million, respectively. Rent expense during the three and six months ended June 30, 2021 under all of the Company’s operating leases was $0.1 million and $0.3 million, respectively. Rent expense includes short-term leases and variable lease costs that are not included in the lease obligation. Short-term leases are leases having a term of twelve months or less. The Company recognizes short-term leases on a straight-line basis and does not record a related lease asset or liability for such leases. The office space leases provide for increases in future minimum annual rental payments as defined in the lease agreements. The office space lease also includes an option to renew the lease as of the end of the term. The Company has determined that the lease renewal option is not reasonably certain of being exercised. The cash paid for operating lease liabilities for the six months ended June 30, 2022 and 2021 was $0.3 million and $0.2 million, respectively. Supplemental other information related to the operating leases balance sheet information is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2022 ​ December 31, 2021 Operating lease obligations (see Note 5 and 7) $ 1,335 $ 1,535 ​ Operating lease right-of-use assets (included in "Other assets" in Balance Sheet) ​ $ 701 ​ $ 798 ​ Weighted-average remaining lease term (years) ​ 2.8 ​ 3.3 ​ Weighted-average discount rate ​ 7.2 % 7.2 % ​

Accrued Expenses

Accrued Expenses	6 Months Ended
	Jun. 30, 2022
Accrued Expenses
Accrued Expenses	5. Accrued Expenses Accrued expenses and other current liabilities consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2022 ​ December 31, 2021 Accrued professional services $ 705 $ 396 Accrued payroll and employee benefits ​ 1,493 ​ 2,313 Accrued research and development ​ 8,295 ​ 6,988 Lease obligation, current portion (see Note 4) ​ 431 ​ 411 Accrued interest and other ​ 49 ​ 44 Total accrued expenses and other current liabilities ​ $ 10,973 ​ $ 10,152 ​

Contingent Consideration

Contingent Consideration	6 Months Ended
	Jun. 30, 2022
Contingent Consideration
Contingent consideration	6. Contingent Consideration The Company entered into an Agreement and Plan of Merger and Reorganization, dated July 8, 2019, by and among the Company, Springfield Merger Sub, Inc., Springfield Merger Sub, LLC, Spitfire Pharma, Inc. and David Collier, as the Stockholder Representative (the “Spitfire Merger Agreement”) to acquire all of the equity interests of Spitfire Pharma, Inc. (“Spitfire”). Spitfire was a privately held, preclinical pharmaceutical company developing a novel dual GLP-1/glucagon receptor agonist for the treatment of non-alcoholic steatohepatitis. The transaction closed on July 12, 2019. The Company issued 1,887,250 unregistered shares of its common stock as upfront consideration to certain former securityholders of Spitfire (collectively, the “Spitfire Equityholders”), representing an amount equal to $5.0 million less working capital and transaction expense adjustment amounts as defined in the agreement. The acquisition of Spitfire was accounted for as an asset acquisition instead of a business combination because substantially all of the fair value of the gross assets acquired was concentrated in a single identifiable asset or group of similar identifiable assets, and therefore, the asset was not considered a business. The Company expensed the acquired intellectual property as of the acquisition date as in-process research and development with no alternative future uses. The Spitfire Merger Agreement also includes future contingent payments up to $88.0 million in cash and shares of the Company’s common stock as follows (each, a “Milestone Event”): ● a one-time payment of $5.0 million (the “IND Milestone Consideration Amount”) within sixty days of the submission of an Investigational New Drug Application (“IND”) to the United States Food and Drug Administration (the “FDA”) or other applicable governmental authority in a foreign jurisdiction, which IND has not been rejected or placed on clinical hold by the FDA or such applicable foreign governmental authority within time specified in the Merger Agreement; ● a one-time payment of $3.0 million (the “Phase 2 Milestone Consideration Amount” and together with the IND Milestone Consideration Amount, the “Regulatory Milestones”) within sixty days of the initiation (first patient, first dosing) of a Phase 2 clinical trial of a product candidate anywhere in the world; and ● payments of up to $80.0 million upon the achievement of specified worldwide net sales (the “Sales Milestones”) of all products developed using the technology acquired in the License Agreement within ten years following the approval of a new drug application filed with the FDA. The Regulatory Milestones were payable in shares of the Company’s common stock, with the number of shares of the Company’s common stock issued in connection with each milestone amount, if any, dependent on the share price at the time of achievement. The number of shares issued in consideration for the IND Milestone Consideration Amount was determined based on the lower of (A) the average of the closing prices of the Company’s common stock as reported on the Nasdaq Global Market for the twenty Global Market for the twenty The contingent payments related to the Regulatory Milestones were stock-based payments accounted for under FASB Accounting Standards Codification Topic 480, Distinguishing Liabilities From Equity Contingencies On November 3, 2020, the Company received acknowledgement from the Australian Government Department of Health on the Company’s submitted clinical trial notification (“CTN”) which triggered the obligation to settle the IND Milestone payment to the former owners. As a result, on November 19, 2020, the Company issued 1,694,906 shares of its common stock valued at $9.57 per share for the amount value of $13.6 million to the former Spitfire stockholders. Pursuant to the Spitfire Merger Agreement, the Company issued the shares within sixty days of the submission of the CTN, which was October 29, 2020. From September 30, 2020 through November 19, 2020, the date of issuance, the Company recognized a decrease in the fair value of the IND Milestone payment of $5.4 million to research and development expense and reclassified the balance in the contingent consideration liability associated with the fair value of the IND Milestone payment to equity in the Company’s consolidated balance sheet. On April 26, 2022, the Company dosed the first patient in the Phase 2 MOMENTUM trial of pemvidutide in obesity, which triggered the obligation to pay the Phase 2 Milestone Consideration Amount to the former owners. As a result, on June 10, 2022, the Company issued 847,444 shares of its common stock valued at $8.55 per share for the amount value of $7.2 million to the former Spitfire stockholders. From the last valuation date on March 31, 2022 through June 10, 2022, the date of issuance, the Company recognized an increase in the fair value of the Phase 2 Milestone Consideration Amount of $1.9 million to research and development expense and reclassified the balance in the contingent consideration liability to equity in the Company’s consolidated balance sheet. As of June 30, 2022, the Company had no contingent consideration liability. Below is a summary of the contingent consideration activity (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Six Months Ended June 30, ​ ​ 2022 ​ 2021 Beginning balance $ 6,090 $ 5,390 Change in fair value ​ 86 ​ (120) Fair value of payments settled in common stock (Phase II Milestone) ​ (6,176) ​ — Ending balance ​ $ — ​ $ 5,270 ​

Other Long-Term Liabilities

Other Long-Term Liabilities	6 Months Ended
	Jun. 30, 2022
Other Long-Term Liabilities
Other Long-Term Liabilities	7. Other Long-Term Liabilities The Company’s other long-term liabilities are summarized as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2022 ​ December 31, 2021 Lease obligation, long-term portion (see Note 4) $ 904 $ 1,124 Conditional economic incentive grants ​ 250 ​ 250 Other ​ 372 ​ 80 Total other long-term liabilities ​ $ 1,526 ​ $ 1,454 ​

Common Stock

Common Stock	6 Months Ended
	Jun. 30, 2022
Common Stock
Common Stock	8. Common Stock Public Offering On July 16, 2020, the Company offered and sold (i) 3,369,564 shares of common stock, at a price to the public of $23.00 per share, and (ii) pre-funded warrants of the Company to purchase 1,630,436 shares of common stock at an exercise price equal to $0.0001 per share (the “Pre-Funded Warrants”), at a price to the public of $22.9999 per share of common stock underlying the Pre-Funded Warrants (equal to the public offering price per share of Common Stock, minus the exercise price of each Pre-Funded Warrant). The Pre-Funded Warrants are exercisable at any time, provided that each Pre-Funded Warrant holder will be prohibited from exercising such Pre-Funded Warrants into shares of the Company’s common stock if, as a result of such exercise, the holder, together with its affiliates, would own more than 4.99% of the total number of shares of the Company’s common stock then issued and outstanding, which percentage may change at the holders’ election to any other number less than or equal to 19.99% upon 61 days’ notice to the Company. The gross proceeds of this offering were approximately $132.2 million, which includes the exercise in full of the underwriters’ option to purchase an additional 750,000 shares of common stock, before deducting underwriting discounts and commissions and offering expenses during the third quarter of 2020. The net proceeds of this offering were approximately $124.0 million, after deducting underwriting discounts and commissions and offering expenses payable by the Company. The Company has assessed the Pre-Funded Warrants for appropriate equity or liability classification and determined that the Pre-Funded Warrants are freestanding instruments that do not meet the definition of a liability pursuant to ASC 480 and do not meet the definition of a derivative pursuant to FASB Accounting Standards Codification Topic 815, Derivatives and Hedging At-the-Market Offerings On February 25, 2021, the Company entered into an Equity Distribution Agreement (the “2021 Agreement”) with Piper Sandler & Co., Evercore Group L.L.C. and B. Riley Securities, Inc., serving as sales agents (the “Sales Agents”) with respect to an at-the-market offerings program under which the Company may offer and sell, from time to time at its sole discretion, shares of its common stock, par value $0.0001 per share (the “Common Stock”), having an aggregate offering price of up to $125.0 million (the “Shares”) through the Sales Agents (the “2021 Offering”). Any Shares offered and sold in the 2021 Offering will be issued pursuant to the Company’s Registration Statement on Form S-3 filed with the Securities and Exchange Commission (the “SEC”) on December 31, 2020, which was declared effective on January 11, 2021 (“2021 Shelf”), the prospectus supplement relating to the 2021 Offering filed with the SEC on February 25, 2021 and any applicable additional prospectus supplements related to the 2021 Offering that form a part of the Registration Statement. During the six months ended June 30, 2022, the Company sold 2,493,202 shares of Common Stock under the 2021 Agreement resulting in approximately $24.3 million in net proceeds. As of June 30, 2022, the Company has sold in aggregate 7,293,656 shares of Common Stock under the 2021 Agreement resulting in approximately $89.2 million in net proceeds, with $32.9 million remaining available to be sold under the 2021 Agreement. As of June 30, 2022, the Company recorded approximately $0.2 million of offering costs which offset the proceeds received from the shares sold through June 30, 2022. The Company capitalized approximately $0.1 million of deferred offering costs which will offset future proceeds received under the 2021 Agreement. Exchange Agreement On February 25, 2021, the Company entered into an exchange agreement (the “Exchange Agreement”) with an investor and its affiliates (the “Exchanging Stockholders”), pursuant to which the Company exchanged an aggregate of 1,000,000 shares of the Company’s common stock, par value $0.0001 per share, owned by the Exchanging Stockholders for pre-funded warrants (the “Exchange Warrants”) to purchase an aggregate of 1,000,000 shares of common stock (subject to adjustment in the event of any stock dividends and splits, reverse stock split, recapitalization, reorganization or similar transaction, as described in the Exchange Warrants), with an exercise price of $0.0001 per share. The Exchange Warrants did not have an expiration date and were exercisable at any time except that the Exchange Warrants could not be exercised by the Exchanging Stockholders if, after giving effect thereto, the Exchanging Stockholders would beneficially own more than 9.99% of the Company’s common stock, subject to certain exceptions. In accordance with FASB Accounting Standards Codification Topic 505, Equity

Warrants

Warrants	6 Months Ended
	Jun. 30, 2022
Warrants
Warrants	9. Warrants A summary of warrant activity during the six months ended June 30, 2022 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ ​ ​ Weighted ​ Remaining ​ ​ Number of ​ ​ Average ​ Contractual Term ​ ​ Warrants ​ ​ Exercise Price ​ (Years) Warrants outstanding, December 31, 2021 2,776,191 ​ ​ ​ ​ Expired ​ (155) ​ ​ ​ ​ ​ Exercises (see Note 8) (1,760,870) ​ ​ ​ ​ Warrants outstanding, June 30, 2022 1,015,166 $ 0.66 ​ 1.4 ​ The warrants outstanding as of June 30, 2022 included 869,566 Pre-Funded Warrants with an exercise price of $0.0001 per-share and no expiration date.

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2022
Stock-Based Compensation
Stock-Based Compensation	10. Stock-Based Compensation Stock Options The Company’s stock option awards generally vest over four years and typically have a contractual life of ten years. As of June 30, 2022, there was $12.6 million of unrecognized compensation cost related to stock options, which is expected to be recognized over a weighted-average period of 2.8 years. During the six months ended June 30, 2022, the Company granted 1,158,927 stock options with a weighted average exercise price of $7.13 and per share weighted average grant date fair value of $5.93. Information related to stock options outstanding as of June 30, 2022 is as follows (in thousands, except share and per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ ​ ​ ​ ​ ​ Weighted- ​ Remaining ​ ​ ​ ​ ​ Number of ​ Average ​ Contractual Term ​ Aggregate Intrinsic ​ ​ Stock Options ​ Exercise Price ​ (Years) ​ Value Outstanding 3,360,313 ​ $ 8.57 6.0 ​ $ 3,642 Exercisable 1,300,590 ​ $ 8.33 5.8 ​ $ 2,466 Unvested 2,059,723 ​ $ 8.73 6.1 ​ $ 1,176 ​ Restricted Stock As of June 30, 2022, the Company had unvested restricted stock of 33,636 shares with total unrecognized compensation expense of $0.1 million, which the Company expects to recognize over a weighted average period of approximately 0.4 years. During the six months ended June 30, 2022, the Company issued 22,972 of unrestricted common stock as a result of the vesting of 40,364 restricted stock net of 17,392 shares of common stock withheld to satisfy tax withholding obligations. Restricted Stock Units (RSUs) During the six months ended June 30, 2022, the Company granted 285,000 shares of RSUs with a weighted average grant date fair value of $7.11 which vest over four years. As of June 30, 2022, the Company had unvested RSUs of 472,150 shares with total unrecognized compensation expense of $3.7 million, which the Company expects to recognize over a weighted average period of approximately 3.3 years. During the six months ended June 30, 2022, the Company issued 29,095 shares of unrestricted common stock as a result of the vesting of 44,778 RSUs net of 15,683 shares of common stock withheld to satisfy tax withholding obligations. 2019 Employee Stock Purchase Plan (ESPP) Under the ESPP, employees purchased 16,450 shares for $0.1 million during the six months ended June 30, 2022. During the three and six months ended June 30, 2022, the Company recognized compensation expense of $47,000 and $0.1 million respectively. During the three and six months ended June 30, 2021, the Company recognized compensation expense of $0.1 million and $0.2 million, respectively. Stock-based Compensation Expense Stock-based compensation expense is classified in the unaudited consolidated statements of operations and comprehensive loss for the three and six months ended June 30, 2022 and 2021 as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Three Months Ended For the Six Months Ended ​ ​ June 30, ​ June 30, ​ ​ 2022 2021 ​ 2022 2021 Research and development ​ $ 663 ​ $ 441 ​ $ 1,281 ​ $ 762 General and administrative ​ 1,385 ​ 1,044 ​ 2,800 ​ 1,941 Total ​ $ 2,048 ​ $ 1,485 ​ $ 4,081 ​ $ 2,703 ​

U.S. Government Contracts and G

U.S. Government Contracts and Grants	6 Months Ended
	Jun. 30, 2022
U.S. Government Contracts and Grants
U.S. Government Contracts and Grants	11. U.S. Government Contracts and Grants In June 2020, the Company was awarded $4.7 million from the U.S. Army Medical Research & Development Command (“USAMRDC”) to fund its Phase 1/2 clinical trial of T-COVID. The competitive award was granted by USAMRDC in collaboration with the Medical Technology Enterprise Consortium (“MTEC”), a 501(c)(3) biomedical technology consortium working in partnership with the Department of Defense (“DoD”). Under the contract, MTEC paid the Company a firm fixed fee based upon the achievement of certain milestones for conduct and completion of a Phase 1/2 study and research and development work on the replication-deficient adenovirus 5 (“RD-Ad5”) vector vaccine platform. For the six months ended June 30, 2021, the Company recognized approximately $0.5 million of grant revenue under the contract, which completed the full recognition of this award. No revenue was recognized for this contract for the three and six months ended June 30, 2022. In July 2016, the Company signed a five-year contract with Biomedical Advanced Research and Development Authority (“BARDA”). The contract, as amended, had a total value of up to $136.8 million to be used to fund clinical development of NasoShield. Under the contract, BARDA paid the Company a fixed fee and reimbursed certain costs for the research and development of an Ad5-vectored, protective antigen-based intranasal anthrax vaccine through cGMP manufacture and conduct of a Phase 1 clinical trial dose ranging assessment of safety and immunogenicity. The contract consisted of an initial base performance period providing approximately $30.9 million in funding for the period July 2016 through December 2021. BARDA had seven options to extend the contract to fund certain continued development and manufacturing activities for the anthrax vaccine, including Phase 2 clinical studies. Each option, if exercised by BARDA, would have provided additional funding ranging from approximately $1.1 million to $34.4 million for a three-year period beginning in 2021. For the three and six months ended June 30, 2021, the Company recognized approximately $0.1 million and $0.3 million, respectively, of grant revenue under the BARDA contract. For the three and six months ended June 30, 2022, the Company has recognized de minimis grant revenue related to the close-out of the BARDA contract. BARDA did not extend the contract beyond the end of December 2021.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2022
Income Taxes
Income Taxes	12. Income Taxes Due to a full valuation allowance, the Company did not record an income tax benefit in either the six months ended June 30, 2022 or 2021.

Net Loss Per Share

Net Loss Per Share	6 Months Ended
	Jun. 30, 2022
Net Loss Per Share
Net Loss Per Share	13. Net Loss Per Share Because the Company has reported a net loss attributable to common stockholders for all periods presented, basic and diluted net loss per share attributable to common stockholders are the same for all periods presented. Basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average numbers of shares of common stock outstanding for the period. Basic shares outstanding includes the weighted average effect of the Company’s outstanding pre-funded warrants, the exercise of which requires little or no consideration for the delivery of shares of common stock. 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. As such, all unvested restricted stock, restricted stock units, common stock warrants and stock options have been excluded from the computation of diluted weighted average shares outstanding because such securities would have an anti-dilutive impact for all periods presented. Potential common shares issuable upon conversion, vesting or exercise of unvested restricted stock, restricted stock units, common stock warrants and stock options that are excluded from the computation of diluted weighted-average shares outstanding, as they are anti-dilutive, are as follows: ​ ​ ​ ​ ​ ​ ​ ​ For the Three and Six Months Ended ​ ​ ​ June 30, ​ ​ ​ 2022 ​ 2021 ​ Common stock warrants 145,600 145,755 Common stock options 3,372,768 2,506,846 Restricted stock units 472,150 114,363 ​ Restricted stock 33,636 211,279 ​

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2022
Commitments And Contingencies.
Commitments and Contingencies	14. Commitments and Contingencies Spitfire Acquisition As disclosed in Note 6, the Company is obligated to make payments of up to $80.0 million upon the achievement of specified worldwide net sales of all products developed using the technology acquired from Spitfire Pharma Inc. within ten years following the approval of a new drug application filed with the FDA. Litigation In December 2019, a complaint was filed by Dr. De-Chu Christopher Tang (“Plaintiff”) against the Company, which was removed to the United States District Court for the Eastern District of Texas. The Plaintiff amended the complaint in February 2020 to include Vipin K. Garg and David J. Drutz as defendants, in addition to the Company (Dr. Garg, Dr. Drutz, and the Company are collectively referred to as “Defendants”). In March 2020 the Defendants filed a motion to dismiss the complaint. The Court denied the motion without prejudice and allowed Plaintiff an opportunity to file an amended complaint. Plaintiff’s second amended complaint was filed on April 17, 2020, and Defendants filed a motion to dismiss that complaint on May 1, 2020. A hearing on Defendants’ motion to dismiss was held on May 20, 2020. Plaintiff, who is representing himself, alleges five causes of action as follows: (1) Defendants’ alleged retention of Plaintiff’s lab notebooks after the termination of his employment in 2012; (2) alleged plagiarism based on publishing an article without naming Plaintiff as an author; (3) use of the Adhigh System, which Plaintiff alleges he developed; (4) allegations that Defendants manipulated the Company’s stock and caused a decrease in value; and (5) allegations that the Defendants “wast[ed] government grant money and poison[ed] science by leaving data to rot.” On September 30, 2020, Plaintiff filed a motion titled “Motion to Proscribe Defendants’ Allegedly Illegal Use of Plaintiff’s AdHigh System in Altimmune’s Human Clinical Trials,” to which Defendants filed an opposition on October 13, 2020. The court has not yet ruled on that motion, which also remains pending. On November 6, 2020, Defendants filed a motion for summary judgment on the basis of lack of personal jurisdiction, insufficient service of process, and failure to state a claim. The court ruled on that motion on March 25, 2021, which dismissed the case on the basis of lack of personal jurisdiction. On December 1, 2020, the magistrate judge assigned to the case issued a report and recommendation that Defendants’ motion to dismiss of May 1, 2020 be granted and that this action be dismissed for lack of personal jurisdiction. Plaintiff filed objections to the report and recommendation on December 14, 2020, and the resolution of those objections by the district court remains pending. In December 2021, the Plaintiff refiled the complaint in the United States District Court for the District of Maryland. On February 24, 2022, Defendants filed a memorandum containing a brief description of the planned motion and a concise summary of the factual and legal support for it. On the basis of that memorandum, the Court granted Defendants’ request to file a motion to dismiss and allowed Plaintiff an opportunity to file an amended complaint. Plaintiff’s amended complaint was filed on March 3, 2022, and Defendants filed a motion to dismiss that complaint on April 4, 2022. The Company believes the allegations in the complaint are without merit and intends to vigorously defend the litigation. The Company is a party in various contracts and subject to disputes, litigation and potential claims arising in the ordinary course of business, none of which are currently reasonably possible or probable of material loss.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2022
Summary of Significant Accounting Policies
Use of Estimates	Use of Estimates The preparation of these financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. The extent to which the COVID-19 pandemic, including any resurgences or the emergence of new variants, may directly or indirectly impact the Company’s business, financial condition, and results of operations is highly uncertain and subject to change. The Company considered the potential impact of the COVID-19 pandemic on the Company’s estimates and assumptions and determined that there was not a material impact to the Company’s unaudited consolidated financial statements as of and for the three and six months ended June 30, 2022. However, actual results could differ from those estimates and there may be changes to the Company’s estimates in future periods.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2022
Fair Value Measurements
Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis	The Company’s assets measured at fair value on a recurring basis as of June 30, 2022 consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement at June 30, 2022 ​ Total Level 1 Level 2 Level 3 Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents - money market funds ​ $ 91,807 ​ $ 91,807 ​ $ — ​ $ — Short-term investments ​ 48,898 ​ — ​ 48,898 ​ — Total ​ $ 140,705 ​ $ 91,807 ​ $ 48,898 ​ $ — ​ The Company’s assets and liabilities measured at fair value on a recurring basis as of December 31, 2021 consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement at December 31, 2021 ​ Total Level 1 Level 2 Level 3 Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents - money market funds ​ $ 65,634 $ 65,634 $ — $ — Total ​ ​ 65,634 ​ ​ 65,634 ​ ​ — ​ ​ — Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration liability (see Note 6) ​ 6,090 ​ — ​ — ​ 6,090 Total ​ $ 6,090 ​ $ — ​ $ — ​ $ 6,090
Schedule of Short Term Investments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2022 ​ ​ Amortized Cost ​ Unrealized Loss ​ Market Value United States treasury securities $ 9,937 $ (52) $ 9,885 Commercial paper and corporate debt securities ​ ​ 34,072 ​ ​ (64) ​ ​ 34,008 Asset backed securities ​ 5,009 ​ (4) ​ 5,005 Total ​ $ 49,018 ​ $ (120) ​ $ 48,898

Operating Leases (Tables)

Operating Leases (Tables)	6 Months Ended
	Jun. 30, 2022
Operating Leases
Summary of Supplemental other Information Related to Operating Leases Balance Sheet	Supplemental other information related to the operating leases balance sheet information is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2022 ​ December 31, 2021 Operating lease obligations (see Note 5 and 7) $ 1,335 $ 1,535 ​ Operating lease right-of-use assets (included in "Other assets" in Balance Sheet) ​ $ 701 ​ $ 798 ​ Weighted-average remaining lease term (years) ​ 2.8 ​ 3.3 ​ Weighted-average discount rate ​ 7.2 % 7.2 %

Accrued Expenses (Tables)

Accrued Expenses (Tables)	6 Months Ended
	Jun. 30, 2022
Accrued Expenses
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2022 ​ December 31, 2021 Accrued professional services $ 705 $ 396 Accrued payroll and employee benefits ​ 1,493 ​ 2,313 Accrued research and development ​ 8,295 ​ 6,988 Lease obligation, current portion (see Note 4) ​ 431 ​ 411 Accrued interest and other ​ 49 ​ 44 Total accrued expenses and other current liabilities ​ $ 10,973 ​ $ 10,152

Contingent Consideration (Table

Contingent Consideration (Tables)	6 Months Ended
	Jun. 30, 2022
Contingent Consideration
Summary of Fair Value of Contingent Consideration	Below is a summary of the contingent consideration activity (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Six Months Ended June 30, ​ ​ 2022 ​ 2021 Beginning balance $ 6,090 $ 5,390 Change in fair value ​ 86 ​ (120) Fair value of payments settled in common stock (Phase II Milestone) ​ (6,176) ​ — Ending balance ​ $ — ​ $ 5,270

Other Long-Term Liabilities (Ta

Other Long-Term Liabilities (Tables)	6 Months Ended
	Jun. 30, 2022
Other Long-Term Liabilities
Summary of Other Long-Term Liabilities	The Company’s other long-term liabilities are summarized as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2022 ​ December 31, 2021 Lease obligation, long-term portion (see Note 4) $ 904 $ 1,124 Conditional economic incentive grants ​ 250 ​ 250 Other ​ 372 ​ 80 Total other long-term liabilities ​ $ 1,526 ​ $ 1,454

Warrants (Tables)

Warrants (Tables)	6 Months Ended
	Jun. 30, 2022
Warrants
Summary of Warrant Activity	A summary of warrant activity during the six months ended June 30, 2022 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ ​ ​ Weighted ​ Remaining ​ ​ Number of ​ ​ Average ​ Contractual Term ​ ​ Warrants ​ ​ Exercise Price ​ (Years) Warrants outstanding, December 31, 2021 2,776,191 ​ ​ ​ ​ Expired ​ (155) ​ ​ ​ ​ ​ Exercises (see Note 8) (1,760,870) ​ ​ ​ ​ Warrants outstanding, June 30, 2022 1,015,166 $ 0.66 ​ 1.4

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2022
Stock-Based Compensation
Schedule of Information Related to Stock Options Outstanding	Information related to stock options outstanding as of June 30, 2022 is as follows (in thousands, except share and per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ ​ ​ ​ ​ ​ Weighted- ​ Remaining ​ ​ ​ ​ ​ Number of ​ Average ​ Contractual Term ​ Aggregate Intrinsic ​ ​ Stock Options ​ Exercise Price ​ (Years) ​ Value Outstanding 3,360,313 ​ $ 8.57 6.0 ​ $ 3,642 Exercisable 1,300,590 ​ $ 8.33 5.8 ​ $ 2,466 Unvested 2,059,723 ​ $ 8.73 6.1 ​ $ 1,176
Schedule of Stock-based Compensation Expense	Stock-based compensation expense is classified in the unaudited consolidated statements of operations and comprehensive loss for the three and six months ended June 30, 2022 and 2021 as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Three Months Ended For the Six Months Ended ​ ​ June 30, ​ June 30, ​ ​ 2022 2021 ​ 2022 2021 Research and development ​ $ 663 ​ $ 441 ​ $ 1,281 ​ $ 762 General and administrative ​ 1,385 ​ 1,044 ​ 2,800 ​ 1,941 Total ​ $ 2,048 ​ $ 1,485 ​ $ 4,081 ​ $ 2,703

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	6 Months Ended
	Jun. 30, 2022
Net Loss Per Share
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	Potential common shares issuable upon conversion, vesting or exercise of unvested restricted stock, restricted stock units, common stock warrants and stock options that are excluded from the computation of diluted weighted-average shares outstanding, as they are anti-dilutive, are as follows: ​ ​ ​ ​ ​ ​ ​ ​ For the Three and Six Months Ended ​ ​ ​ June 30, ​ ​ ​ 2022 ​ 2021 ​ Common stock warrants 145,600 145,755 Common stock options 3,372,768 2,506,846 Restricted stock units 472,150 114,363 ​ Restricted stock 33,636 211,279

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	$ 48,898
Contingent consideration liability (see Note 6)		$ 6,090	$ 5,270	$ 5,390
Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	48,898
Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total	140,705	65,634
Contingent consideration liability (see Note 6)		6,090
Total		6,090
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total	91,807	65,634
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total	48,898
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Contingent consideration liability (see Note 6)		6,090
Total		6,090
Money Market Funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	91,807	65,634
Money Market Funds [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	$ 91,807	$ 65,634

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Short Term Investments (Detail) $ in Thousands	Jun. 30, 2022 USD ($)
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 49,018
Unrealized Gain Loss	(120)
Market Value	48,898
United States Treasury Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	9,937
Unrealized Gain Loss	(52)
Market Value	9,885
Commercial Paper and Corporate Debt Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	34,072
Unrealized Gain Loss	(64)
Market Value	34,008
Asset Backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	5,009
Unrealized Gain Loss	(4)
Market Value	$ 5,005

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Dec. 31, 2021	Jun. 30, 2021	Jun. 30, 2021	Jun. 30, 2022
Assets or liabilities measured at fair value on a non-recurring basis.					$ 0
Non-cash impairment charge			$ 8,070	$ 8,070
Lonza Manufacturing Agreement [Member]
Non-cash impairment charge			8,100	8,100
Commitment to procure equipment and construction	$ 23,000
Lonza Manufacturing Agreement [Member] | Construction-In-Progress
Non-cash impairment charge		$ 3,300
Capitalized costs				11,400
Lonza Manufacturing Agreement [Member] | Construction-In-Progress | Fair Value, Nonrecurring [Member] | Level 3 [Member]
Fair value of impaired assets			$ 3,300	$ 3,300

Operating Leases - Additional I

Operating Leases - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Operating Leases
Non-cancellable lease maturity period			2026-06
Cash paid for operating lease liabilities			$ 0.3	$ 0.2
Operating lease rent expense	$ 0.1	$ 0.1	$ 0.2	$ 0.3

Operating Leases - Summary of S

Operating Leases - Summary of Supplemental other Information Related to Operating Leases Balance Sheet (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Operating Leases
Operating lease obligations (see Note 5 and 7)	$ 1,335	$ 1,535
Operating lease right-of-use assets (included in "Other assets" in Balance Sheet)	$ 701	$ 798
Weighted-average remaining lease term (years)	2 years 9 months 18 days	3 years 3 months 18 days
Weighted-average discount rate	7.20%	7.20%

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Accrued Liabilities And Other Liabilities [Abstract]
Accrued professional services	$ 705	$ 396
Accrued payroll and employee benefits	1,493	2,313
Accrued research and development	8,295	6,988
Lease obligation, current portion (see Note 4)	431	411
Accrued interest and other	49	44
Total accrued expenses and other current liabilities	$ 10,973	$ 10,152

Contingent Consideration - Addi

Contingent Consideration - Additional Information (Detail) - USD ($)				2 Months Ended	6 Months Ended
	Apr. 26, 2022	Nov. 19, 2020	Jul. 12, 2019	Nov. 19, 2020	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Common stock issued related to contingent consideration liability					$ 6,176,000
Estimated future contingent consideration						$ 5,270,000	$ 6,090,000	$ 5,390,000
Change in value of contingent consideration for acquired in-process research and development					$ 86,000	$ (120,000)
Clinical Trial Notification [Member]
Business Acquisition [Line Items]
Common stock issued related to contingent consideration liability		$ 13,600,000
Shares issued for contingent milestone payment		1,694,906
Period for submission of clinical trial notification		60 days
Submission date of clinical trial notification		Oct. 29, 2020
Clinical Trial Notification [Member] | Regulatory Milestones [Member]
Business Acquisition [Line Items]
Change in value of contingent consideration for acquired in-process research and development				$ 5,400,000
Spitfire Pharma, Inc. [Member]
Business Acquisition [Line Items]
Agreement date			Jul. 08, 2019
Unregistered shares of common stock			1,887,250
Up-front consideration			$ 5,000,000
Spitfire Pharma, Inc. [Member] | Investigational New Drug Application Milestone [Member]
Business Acquisition [Line Items]
Estimated future contingent consideration			$ 5,000,000
Estimated future contingent consideration term			60 days
Number of consecutive trading days			20 days
Consideration amount			$ 2.95
Spitfire Pharma, Inc. [Member] | Investigational New Drug Application and Regulatory Milestones [Member]
Business Acquisition [Line Items]
Estimated future contingent consideration			$ 3,000,000
Estimated future contingent consideration term			60 days
Number of consecutive trading days			20 days
Consideration amount			$ 3.54
Spitfire Pharma, Inc. [Member] | Sales Milestones [Member]
Business Acquisition [Line Items]
Estimated future contingent consideration			$ 80,000,000
License agreement term			10 years
Spitfire Pharma, Inc. [Member] | Regulatory Milestones [Member]
Business Acquisition [Line Items]
Contingent consideration, percentage of shares released after three months			50%
Contingent consideration, percentage of shares released after six months			50%
Spitfire Pharma, Inc. [Member] | Phase Two Milestone [Member]
Business Acquisition [Line Items]
Common stock issued related to contingent consideration liability	$ 7,200,000
Estimated future contingent consideration	$ 0
Consideration amount	$ 8.55
Shares issued for contingent milestone payment	847,444
Change in value of contingent consideration for acquired in-process research and development	$ 1,900,000
Spitfire Pharma, Inc. [Member] | Clinical Trial Notification [Member]
Business Acquisition [Line Items]
Consideration amount		$ 9.57		$ 9.57
Spitfire Pharma, Inc. [Member] | Common Stock [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated future contingent consideration			$ 88,000,000

Contingent Consideration - Summ

Contingent Consideration - Summary of Fair Value of Contingent Consideration (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Contingent Consideration
Beginning balance	$ 6,090	$ 5,390
Change in fair value of contingent consideration liability	86	(120)
Fair value of payments settled in common stock (IND Milestone)	$ (6,176)
Ending balance		$ 5,270

Other Long-Term Liabilities - S

Other Long-Term Liabilities - Summary of Other Long-Term Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Other Long-Term Liabilities
Lease obligation, long-term portion (see Note 6)	$ 904	$ 1,124
Conditional economic incentive grants	250	250
Other	372	80
Total other long-term liabilities	$ 1,526	$ 1,454

Common Stock - Additional Infor

Common Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands				3 Months Ended				6 Months Ended
	Jan. 24, 2022	Feb. 25, 2021	Jul. 16, 2020	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Changes In Equity And Comprehensive Income Line Items [Line Items]
Warrants outstanding				1,015,166				1,015,166		2,776,191
Exercise price of warrants or rights				$ 0.66				$ 0.66
Proceeds from issuance of common stock in public offering, net								$ 24,337	$ 52,356
Common stock, par or stated value per share				$ 0.0001				$ 0.0001		$ 0.0001
Issuance costs								$ 36	$ 118
Pre-Funded Warrants [Member]
Changes In Equity And Comprehensive Income Line Items [Line Items]
Number of securities called by warrants or rights				760,870				760,870
Warrants outstanding				869,566				869,566
Exercise price of warrants or rights				$ 0.0001				$ 0.0001
Common Stock [Member]
Changes In Equity And Comprehensive Income Line Items [Line Items]
Shares of common stock sold				2,157,717	335,485	1,405,710	2,110,800
Exchange Warrants [Member]
Changes In Equity And Comprehensive Income Line Items [Line Items]
Shares of common stock sold	999,984
Number of securities called by warrants or rights		1,000,000
Exercise price of warrants or rights		$ 0.0001
Common stock, par or stated value per share		$ 0.0001
Common stock exchanged for pre-funded warrants		1,000,000
Number of warrants exercised	1,000,000
Exchange Warrants [Member] | Exchanging Stockholders [Member]
Changes In Equity And Comprehensive Income Line Items [Line Items]
Ownership percentage		9.99%
Public Offering [Member]
Changes In Equity And Comprehensive Income Line Items [Line Items]
Gross proceeds from offering including exercise of underwriter's option			$ 132,200
Public Offering [Member] | Pre-Funded Warrants [Member]
Changes In Equity And Comprehensive Income Line Items [Line Items]
Exercise price of warrants or rights			$ 0.0001
Purchase price of warrants issued			$ 22.9999
Ownership percentage on exercise of warrants without notice, minimum			4.99%
Ownership percentage on exercise of warrants with notice, maximum			19.99%
Notice period to increase ownership percentage on exercise of warrants			61 days
Public Offering [Member] | Common Stock [Member]
Changes In Equity And Comprehensive Income Line Items [Line Items]
Shares of common stock sold			3,369,564
Public offering price, per share			$ 23
Public Offering [Member] | Common Stock [Member] | Pre-Funded Warrants [Member]
Changes In Equity And Comprehensive Income Line Items [Line Items]
Number of securities called by warrants or rights			1,630,436
Over-Allotment Option [Member] | Common Stock [Member]
Changes In Equity And Comprehensive Income Line Items [Line Items]
Shares of common stock sold			750,000
Proceeds from issuance of common stock in public offering, net			$ 124,000
At-The-Market Offering [Member]
Changes In Equity And Comprehensive Income Line Items [Line Items]
Shares of common stock sold								2,493,202
Proceeds from issuance of common stock in public offering, net								$ 24,300
At-The-Market Offering [Member] | Equity Distribution Agreement [Member] | Piper Sandler company and evercore group limited liability company and B Riley Securities inc [Member]
Changes In Equity And Comprehensive Income Line Items [Line Items]
Shares of common stock sold								7,293,656
Proceeds from issuance of common stock in public offering, net								$ 89,200
Common stock, par or stated value per share		$ 0.0001
Aggregate offering price		$ 125,000
Common stock available to be sold				$ 32,900				32,900
Deferred offering costs				$ 100				$ 100
Deferred offering costs applied to the proceeds					$ 200

Warrants - Summary of Warrant A

Warrants - Summary of Warrant Activity (Detail)	6 Months Ended
	Jun. 30, 2022 $ / shares shares
Warrants
Warrants outstanding, December 31, 2021	2,776,191
Expired	(155)
Exercises (see Note 10)	(1,760,870)
Warrants outstanding, June 30, 2022	1,015,166
Weighted Average Exercise Price | $ / shares	$ 0.66
Weighted-Average Remaining Contractual Term (Years)	1 year 4 months 24 days

Warrants - Additional Informati

Warrants - Additional Information (Detail) - $ / shares	Jun. 30, 2022	Dec. 31, 2021
Class Of Warrant Or Right [Line Items]
Warrants outstanding	1,015,166	2,776,191
Exercise price of warrants or rights	$ 0.66
Pre-Funded Warrants [Member]
Class Of Warrant Or Right [Line Items]
Warrants outstanding	869,566
Exercise price of warrants or rights	$ 0.0001

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($)	3 Months Ended				6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Employees purchased, value		$ 113,000		$ 106,000
Stock-based compensation expense					$ 4,081,000	$ 2,703,000
2019 Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Employees purchased, shares					16,450
Employees purchased, value					$ 100,000
Stock-based compensation expense	$ 47,000		$ 100,000		$ 100,000	$ 200,000
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting Period					4 years
Stock option expiration Period					10 years
Unrecognized compensation cost, stock options	$ 12,600,000				$ 12,600,000
Number of Stock Options, Granted					1,158,927
Stock options granted, weighted-average exercise price					$ 7.13
Weighted-average grant date fair value of stock options granted					$ 5.93
Unrecognized stock-based compensation expense, period for recognition					2 years 9 months 18 days
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested restricted stock, shares	33,636				33,636
Unrecognized compensation expense	$ 100,000				$ 100,000
Unrecognized stock-based compensation expense, period for recognition					4 months 24 days
Unrestricted common stock					22,972
Number of share vested					40,364
Common stock withheld to satisfy tax withholding obligations.					17,392
Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares granted					285,000
Weighted average grant date fair value					$ 7.11
Vesting Period					4 years
Unvested restricted stock, shares	472,150				472,150
Unrecognized compensation expense	$ 3,700,000				$ 3,700,000
Unrecognized stock-based compensation expense, period for recognition					3 years 3 months 18 days
Unrestricted common stock					29,095
Number of share vested					44,778
Common stock withheld to satisfy tax withholding obligations.					15,683

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Information Related to Stock Options Outstanding (Detail)	6 Months Ended
	Jun. 30, 2022 USD ($) $ / shares shares
Stock-Based Compensation
Number of Stock Options, Outstanding | shares	3,360,313
Number of Stock Options, Exercisable | shares	1,300,590
Number of Stock Options, Unvested | shares	2,059,723
Weighted-average Exercise Price, Outstanding | $ / shares	$ 8.57
Weighted-average Exercise Price, Exercisable | $ / shares	8.33
Weighted-average Exercise Price, Unvested | $ / shares	$ 8.73
Weighted-average Remaining Contractual Term, Outstanding	6 years
Weighted-average Remaining Contractual Term, Exercisable	5 years 9 months 18 days
Weighted-average Remaining Contractual Term, Unvested	6 years 1 month 6 days
Aggregate Intrinsic Value, Outstanding | $	$ 3,642
Aggregate Intrinsic Value, Exercisable | $	2,466
Aggregate Intrinsic Value, Unvested | $	$ 1,176

Stock-Based Compensation - Sc_2

Stock-Based Compensation - Schedule of Stock-based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock based compensation expense	$ 2,048	$ 1,485	$ 4,081	$ 2,703
Research and Development [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock based compensation expense	663	441	1,281	762
General and Administrative [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock based compensation expense	$ 1,385	$ 1,044	$ 2,800	$ 1,941

U.S. Government Contracts and_2

U.S. Government Contracts and Grants - Additional Information (Detail) - USD ($) $ in Thousands		1 Months Ended		3 Months Ended		6 Months Ended
	Jan. 01, 2021	Jun. 30, 2020	Jul. 31, 2016	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Revenues				$ 8	$ 137	$ 40	$ 975
BARDA Contract [Member]
Duration of contract	3 years		5 years
Amount used to fund clinical development			$ 136,800
BARDA Contract [Member] | Minimum [Member]
Additional funding for development and manufacturing activities	$ 1,100
BARDA Contract [Member] | Maximum [Member]
Additional funding for development and manufacturing activities	$ 34,400
MTEC Collaborative Arrangement [Member]
Revenues		$ 4,700
Grant [Member] | BARDA Contract [Member]
Revenues					$ 100		300
Grant [Member] | MTEC Collaborative Arrangement [Member]
Revenues				$ 0		$ 0	$ 500
Investment Performance [Member] | BARDA Contract [Member]
Revenues			$ 30,900

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Income Taxes
Income tax benefit	$ 0	$ 0

Net Loss Per Share - Schedule o

Net Loss Per Share - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Detail) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Common Stock Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	145,600	145,755	145,600	145,755
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	3,372,768	2,506,846	3,372,768	2,506,846
Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	472,150	114,363	472,150	114,363
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	33,636	211,279	33,636	211,279

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	Jul. 12, 2019	Dec. 31, 2021	Jun. 30, 2021	Dec. 31, 2020
Commitments And Contingencies [Line Items]
Estimated future contingent consideration		$ 6,090	$ 5,270	$ 5,390
Spitfire Pharma, Inc. [Member] | Sales Milestones [Member]
Commitments And Contingencies [Line Items]
Estimated future contingent consideration	$ 80,000
License agreement term	10 years