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ALT US Equity

Altimmune, Inc.Health Care · Pharmaceutical Preparations · CIK 1326190 · FY ends Dec 31
$3.12
+0.15 (+5.05%)
USD · as of 2026-08-19 · marketstack

ALT · 10-K · period ended 2021-12-31

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filed 2022-03-15 · EDGAR original ↗

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Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations

The following discussion and analysis of our financial condition and results of operations should be read together with our consolidated financial statements and related notes appearing elsewhere in this Annual Report. Some of the information contained in this discussion and analysis contains forward-looking statements that involve substantial risks and uncertainties. See “Forward-looking statements” in Part I of this Annual Report and the section entitled “Risk Factors” in Part I, Item 1A of this Annual Report for a discussion of certain factors that could cause actual results or events to differ materially from the forward-looking statements that we make.

Overview

Altimmune, Inc. is a clinical stage biopharmaceutical company focused on developing treatments for obesity and liver diseases. Our lead product candidate, pemvidutide (proposed INN, formerly known as ALT-801), is a GLP-1/glucagon dual receptor agonist that is being developed for the treatment of obesity and non-alcoholic steatohepatitis (“NASH”). In addition, we are developing HepTcell, an immunotherapeutic agent designed to achieve a functional cure for chronic hepatitis B. In June 2021, we announced the discontinuation of further development of our COVID-19 vaccine candidate, AdCOVID following our review of findings from the Phase 1 clinical trial, and in view of the highly competitive COVID-19 landscape. In the study, AdCOVID was generally well tolerated, but the immunogenicity data demonstrated lower than expected immune responses for each of the immune parameters tested.

Our business is the result of a merger between PharmAthene, Inc. (“PharmAthene”) and the business previously known as Altimmune, Inc. (“Private Altimmune”). On May 4, 2017, Private Altimmune merged with PharmAthene in a series of mergers and reorganizations (collectively, the “Mergers”) pursuant to an Agreement and Plan of Merger and Reorganization (the “PharmAthene Merger Agreement”) dated January 18, 2017, among Private Altimmune, PharmAthene, its wholly owned acquisition subsidiaries Mustang Merger Sub Corp I Inc. and Mustang Merger Sub II LLC. Upon closing of the Mergers, all equity instruments of Private Altimmune were exchanged for corresponding equity instruments of PharmAthene. Prior to the Mergers, PharmAthene was a publicly traded biodefense company engaged in Phase 2 clinical trials. Except where the context indicates otherwise, references to “we,” “us,” “our,” “Altimmune” or the “Company” refer, for periods prior to the completion of the Mergers, to Private Altimmune and its subsidiaries, and for periods following the completion of the Mergers to the combined company and its subsidiaries.

Pemvidutide

We completed an acquisition in July 2019 of all of the equity interests of Spitfire Pharma, Inc. (“Spitfire”). Spitfire was a privately held, preclinical pharmaceutical company with the primary asset being a novel peptide-based dual GLP-1/glucagon receptor agonist for the treatment of NASH. We refer to this product candidate as pemvidutide, and it is designed to treat obesity and the metabolic dysfunction that causes NASH.

Obesity is a significant burden to the global healthcare systems and is implicated in two-thirds of the leading causes of death from non-communicable diseases worldwide. Some of the leading co-morbidities of obesity include high blood pressure, high cholesterol, type 2 diabetes, coronary heart disease, stroke, gallbladder disease, osteoarthritis, sleep apnea and breathing problems, certain cancers and NASH. NASH involves multiple metabolic pathways leading to the abnormal accumulation of liver fat, toxic lipid metabolites, and inflammation, leading to fibrosis or eventually liver cancer. Non-alcoholic fatty liver disease (“NAFLD”), the fatty liver precursor to NASH, is present in up to 90% of obese patients, and approximately 20% of NAFLD patients progress to NASH. In addition, up to 40% of NASH patients develop NAFLD recurrence one year after liver transplant, which we believe indicates that the underlying metabolic disease is still present after transplant. We believe the treatment of obesity is the cornerstone of treating NASH and the principal morbidities of NASH.

Pemvidutide’s dual agonist mechanism of action is designed to combine the activity of GLP-1 for the reduction of appetite and inflammation, with the direct activity of glucagon on the liver, including increased energy expenditure, adipose browning, lipolysis and mobilization of the liver fat. Pemvidutide incorporates a proprietary side chain, referred to as the EuPort domain, which is designed to enhance pharmacokinetics for tolerability in the gastrointestinal tract and permit weekly dosing. As observed in a well-established preclinical model of the disease, pemvidutide is capable of inducing significant weight loss with concomitant decreases in liver fat, inflammation and fibrosis, with superior results

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compared to semaglutide. In addition, pemvidutide demonstrated improved metabolic function and exhibited pleiotropic effects in our preclinical testing across multiple metabolic pathways involved in NASH. We also observed in these studies that pemvidutide resulted in more profound suppression of genes associated with steatosis, inflammation and stellate cell fibrosis by RNA sequencing compared to semaglutide.

In September 2021, we announced the completion of a 12-week Phase 1 clinical trial of pemvidutide in Australia under a clinical trial application. The trial was a first-in-human, randomized, placebo-controlled, single-ascending and multiple-ascending dose (“MAD”) study in overweight and obese volunteers. The endpoints of the Phase 1 trial were to assess the safety, tolerability and pharmacokinetics of pemvidutide, with primary readouts on safety, pharmacokinetics and weight loss. Additional readouts included metabolic and lipid profile, cardiovascular measures and glucose homeostasis.

An Investigational New Drug application (“IND”) for obesity was submitted to the U.S. Food and Drug Administration (“FDA”) in December 2021 and we announced on January 31, 2022 that we had received FDA clearance for a Phase 2 trial in this indication. We expect to initiate this 48-week Phase 2 obesity trial in the first half of 2022. The readouts of that study will include safety, weight loss and other metabolic measures. The study will include a 24-week interim analysis of safety and weight loss that we expect will read out in the fourth quarter of 2022.

We are currently conducting a 12-week Phase 1b trial of pemvidutide in patients with NAFLD at multiple sites in the United States. This double-blind, randomized, placebo-controlled study will enroll approximately 72 diabetic and non-diabetic overweight and obese adult patients with a liver fat content greater than 10% as measured by MRI-PDFF. The primary efficacy endpoint is the change in liver fat content from baseline, with a secondary endpoint of weight loss. The study is expected to read out topline results in the third quarter of 2022. We expect to initiate a 12-week double-blind, placebo-controlled extension study which, combined with the 12-week Phase 1b NAFLD trial, will allow patients to receive up to a total of 24 weeks of continuous pemvidutide or placebo treatment and provide a read out on weight loss after 24 weeks of treatment, which is expected in the fourth quarter of 2022. Based on the findings of the NAFLD study and evaluation of other priorities, we intend to initiate a 52-week biopsy-driven Phase 2 NASH study in 2022.

HepTcell

HepTcell is an immunotherapeutic product candidate for patients chronically infected with the hepatitis B virus (“HBV”). Approximately 300 million people worldwide live with chronic HBV infection, including approximately 2.2 million in the United States. Chronic HBV infection can lead to serious complications, including cirrhosis and liver cancer. Approximately 780,000 people die per year worldwide due to cirrhosis and liver cancer. Current antivirals prevent disease progression but rarely clear chronic infection. HepTcell is designed to drive CD4+ and CD8+ T-cell responses against all HBV genotypes in patients of all ethnic backgrounds. Stimulating T-cell responses in chronically infected HBV patients has been challenging because chronic infection with HBV strongly suppresses T-cell immunity directed against the virus. HepTcell focuses the T cell response on discrete, highly conserved regions of the HBV proteome. We believe our approach allows HepTcell to break immune tolerance by activating T-cells against critical viral sequences with decreased probability of immune escape due to viral mutation. HepTcell is based on our synthetic peptide technology platform and is given by intramuscular injection. In 2018, we completed a Phase 1 trial in the United Kingdom and South Korea in adult patients with chronic HBV. The HepTcell Phase 1 trial was a double-blinded, placebo-controlled, randomized, dose-escalation study that enrolled 61 subjects with chronic HBV who were HBeAg-negative and well-controlled on licensed antivirals. A total of 41 patients received one of two dose levels of HepTcell, with and without IC31TM, a depot-forming TLR9 adjuvant developed by Valneva SE, while 20 control patients received either IC31 alone or placebo. Patients received three injections 28 days apart and were followed for six months after the final dose. All dose combinations were generally well-tolerated and met the primary endpoint of safety. In the two adjuvanted HepTcell arms, T-cell responses against HBV markedly increased over baseline compared to placebo.

We initiated a Phase 2 study during Q4 2020 in the United States, Canada and Europe that is a double-blind, randomized, placebo-controlled study of 80 adult patients with HBeAg-negative inactive CHB and HBsAg ≤ 100 IU/mL. Patients with HBsAg ≤ 100/mL are more likely to mount effective T cell responses against HBV than those with higher levels. The vision is that HepTcell could be used in combination with newer direct acting agents that may be more effective than nucleosides in reducing HBsAg to this level. HepTcell is being administered in 6 doses at the low dose level of HepTcell plus IC31TM at 4-week intervals for 24 weeks, and patients will be followed for one year to evaluate safety and

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durability of response. The primary efficacy endpoint is virological response, defined as a 1-log reduction in HBsAg levels from baseline or HBsAg clearance at 24 weeks. Secondary efficacy endpoints include reactivation of anti-HBV T cell responses, and other assessments of virologic response. We expect data from this study in the first half of 2023. A follow-up phase will assess the safety and durability of response one year after completion of treatment.

Discontinued Programs

AdCOVID

AdCOVID was an intranasal COVID-19 vaccine candidate designed to guard the respiratory tract from viral invasion and to provide protection against viral spread through stimulation of both mucosal and systemic antibodies (IgA and IgG) as well as cell-mediated immunity. By stimulating mucosal immunity in the nasal cavity, a key point of entry and replication for the SARS-CoV-2 virus, we believed that AdCOVID had the potential to defend against both the infection and spread of the virus to others. We submitted an IND to the FDA in the fourth quarter of 2020 and received clearance from the FDA in February 2021 to initiate a Phase 1 clinical trial of AdCOVID. The Phase 1 clinical trial evaluated the safety and immunogenicity of AdCOVID in 92 healthy adult volunteers between the ages of 18 and 55. In June 2021, we announced the discontinuation of the development program for AdCOVID following our review of findings from the Phase 1 clinical trial and in consideration of the highly competitive COVID-19 landscape. In the study, the tolerability of AdCOVID was similar to placebo, but the immunogenicity data demonstrated lower than expected immune responses for each of the immune parameters tested.

T-COVID

T-COVID was an intranasal immune modulating therapeutic candidate based on the same replication-deficient adenovirus 5 (“RD-Ad5”) vector technology behind our other intranasal vaccine candidates, but it acted through a different mechanism that may have involved the innate immune system. With the support of the U.S. Army Medical Research & Development Command in collaboration with the Medical Technology Enterprise Consortium, during 2020, we initiated a placebo-controlled Phase 1/2 double-blind clinical trial to evaluate the potential of T-COVID to prevent clinical worsening in patients with early COVID-19. The trial was expected to enroll 96 community-based patients who were 18 years and older that present with fever, cough, or shortness of breath, with onset of symptoms within 48 hours, and a diagnosis of COVID-19 within 72 hours. The primary endpoint of the trial was the proportion of patients with clinical worsening, defined as a 4% decrease in pulse oxygen saturation, or the need for hospitalization. Secondary endpoints measured the average decrease in resting pulse oxygen saturation, average increase in resting pulse rate and proportion of patients requiring oxygen supplementation and mechanical ventilation. However, the effective rollout in the U.S. of authorized COVID-19 vaccines and decreasing incidence of disease significantly reduced the number of patients meeting our enrollment criteria, and we had been unable to enroll subjects in the final cohort, the cohort most likely to benefit from T-COVID. As a result of enrollment challenges, we decided to terminate further enrollment and have terminated the development of T-COVID.

NasoShield

NasoShield was an anthrax vaccine product candidate designed to provide rapid and stable protection after a single intranasal administration. It was being developed with the support of the U.S. Biomedical Advanced Research and Development Authority (“BARDA”) for post-exposure prophylaxis against anthrax following exposure to aerosolized B. anthracis spores. We commenced a Phase 1b trial of NasoShield in adults in 2020 which builds on the Phase 1a trial completed in 2018 and evaluated the effect of modified methods of intranasal dosing on NasoShield safety and immunogenicity. The trial enrolled 42 healthy subjects who received intranasally administered NasoShield or saline placebo and were then monitored for 6 months post-dosing. The primary endpoint was the safety and tolerability of NasoShield. The primary immunogenicity readouts included the serum binding antibody to protective antigen and anthrax toxin blocking antibody responses at 28- and 56-days post-dose administration. Stimulation of the mucosal IgA immune response in the nasal cavity was also assessed. In April 2021, we received clinical data from the Phase 1b trial that showed positive immunogenicity results and a NasoShield tolerability profile similar to placebo. On December 31, 2021, the development support from BARDA ended and we have discontinued further development of the program.

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NasoVAX

NasoVAX was a recombinant intranasal vaccine product candidate that was being developed for both seasonal and pandemic use. We believed NasoVAX could simultaneously activate the humoral, mucosal and cellular immune arms which may enable a more comprehensive immune response. The data from our Phase 2a trial with a monovalent NasoVAX vaccine indicated that NasoVAX achieved 100% seroprotection based on serum antibody responses, which was comparable to published results of a licensed injected influenza vaccine. Statistically significant increases in mucosal antibody were noted as well as a robust T cell response directed against influenza. The tolerability profile of NasoVAX was similar to placebo. Approximately half of the subjects from the highest dose were evaluated between 12 and 14 months after initial dosing for additional immunogenicity assessment. The durability data show that the immune response elicited by NasoVAX was stable with no overall change in the antibody titer or level of seroprotection over an average of 13 months. After evaluating the development path of NasoVAX, we have discontinued further development of the program.

Impact of COVID-19

We are closely monitoring how the spread of COVID-19, including any resurgences or the emergence of new variants, is affecting our employees, business, preclinical studies and clinical trials. We have reopened our executive office to allow certain employees to return to the office based on a phased approach that is intended to comply with federal and state guidelines, with a focus on employee safety and optimal work environment. We are continuing our regular interactions with the FDA and other regulatory agencies and, based on current information, we do not anticipate COVID-19 to materially affect our regulatory timelines for our ongoing clinical trials. Furthermore, as a government contractor, we are subject to the federal government vaccination mandate, which requires federal contractor employees, except in certain limited circumstances, to be vaccinated against COVID-19 by December 8, 2021. While the vaccination mandate remains subject to the interpretation of various government agencies and other entities, and questions remain regarding the specific application of the vaccination mandate, we are continuing to develop and implement health, safety, employment and operational protocols in order to timely comply with the vaccination mandate. As of December 31, 2021, the vaccination mandate has not had a material impact on our employees or operations.

Although operations have not been materially affected by the ongoing COVID-19 pandemic at this time, there is significant uncertainty relating to the trajectory of the pandemic and the impact of related responses, and disruptions caused by the ongoing COVID-19 pandemic may result in difficulties or delays in initiating, enrolling, conducting or completing our planned and ongoing trials and the incurrence of unforeseen costs as a result of disruptions in clinical supply or preclinical study or clinical trial delays. The impact of the ongoing COVID-19 pandemic on our future results will largely depend on future developments, which are highly uncertain and cannot be predicted with confidence, such as the ultimate geographic spread of the disease, the duration of the pandemic, travel restrictions and social distancing in the United States and other countries, business closures or business disruptions, the ultimate impact on financial markets and the global economy, and the effectiveness of actions taken in the United States and other countries to contain and treat the disease. In addition, a recurrence of COVID-19 cases, or variants thereof, could cause other widespread or more severe impacts depending on where infection rates are highest. We continue to monitor developments as we deal with the disruptions and uncertainties relating to the ongoing COVID-19 pandemic. See “Risk Factors— A pandemic, epidemic or outbreak of an infectious disease in the United States such as the COVID-19 pandemic may adversely affect our business.” in Part I, Item 1A of this Annual Report on Form 10-K.

U.S. Government Contracts and Grants

In June 2020, we were awarded $4.7 million from the U.S. Army Medical Research & Development Command (“USAMRDC”) to fund our 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 us 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 year ended December 31, 2021 and 2020, we have recognized approximately $0.5 million and $4.2 million, respectively, of grant revenue under this contract.

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In July 2016, we signed a five-year contract with Biomedical Advanced Research and Development Authority (“BARDA”). The contract, as amended, has a total value of up to $136.8 million and is used to fund clinical development of NasoShield. Under the contract, BARDA paid us a fixed fee and reimburses 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 trials. 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 January 2021. For the year ended December 31, 2021 and 2020, we have recognized approximately $3.7 million and $3.1 million, respectively, of grant revenue under the current BARDA contract. At December 31, 2021, BARDA had not elected to extend the contract.

Financing

Public Offering

On July 16, 2020, we offered and sold (i) 3,369,564 shares of our common stock, at a price to the public of $23.00 per share, and (ii) pre-funded warrants to purchase 1,630,436 shares of our 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 our 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 our 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 us. 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 us.

At-the-Market Offering

On February 25, 2021, we 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 we may offer and sell, from time to time at its sole discretion, shares of our 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 Sale Agents (the “2021 Offering”). As of December 31, 2021, we sold 4,800,454 shares of Common Stock under the 2021 Agreement resulting in approximately $64.8 million in net proceeds, with $58.0 million remaining available to be sold under the 2021 Agreement.

On March 27, 2020, we entered into an Equity Distribution Agreement (the “2020 Agreement”) with JMP Securities LLC, serving as placement agent (the “Placement Agent”) with respect to an at-the-market offerings program under which we may offer and sell, from time to time at our sole discretion, shares of our common stock, par value $0.0001 per share (the “Common Stock”), having an aggregate offering price of up to $50.0 million (the “Shares”) through the Placement Agent (the “2020 Offering”). We offered Shares having an aggregate offering price of $18.9 million pursuant to the prospectus supplement filed with the SEC on March 27, 2020. On June 1, 2020, we filed an amendment to the 2020 Agreement which amended the prospectus supplement dated March 27, 2020 to increase the aggregate offering price to $50.0 million. The 2020 Agreement was fully utilized during the year ended December 31, 2020, and no Shares were sold under the 2020 Agreement during the year ended December 31, 2021.

Current Resources

We have financed our operations to date principally through our equity offerings and proceeds from issuances of our preferred stock, common stock and warrants. At December 31, 2021, we had $190.3 million of cash, cash equivalents

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and restricted cash. Accordingly, management believes that we have sufficient capital to fund our plan of operations for at least a twelve-month period from the issuance date of our December 31, 2021 consolidated financial statements. However, in order to address our capital needs in the long-term, including our planned clinical trials, we must continue to actively pursue additional equity or debt financing, government funding and monetization of our existing programs through partnership arrangements or sales to third parties.

Financial Operations Overview

The consolidated financial information presented below includes the accounts of Altimmune, Inc., Altimmune UK, Ltd, Spitfire Pharma, LLC. and Altimmune AU Pty, Ltd. All intercompany accounts and transactions have been eliminated in consolidation.

Revenue

We have not generated any revenues from the sale of any products to date. Our revenue consists primarily of government and foundation grants and contracts that support our efforts on specific research projects. These grants and contracts generally provide for reimbursement of approved costs as those costs are incurred by us. Research grants and contracts and the related accounts receivable are recognized as earned when reimbursable expenses are incurred and the performance obligation is complete. Payments received in advance of services being provided are recorded as deferred revenue. We anticipate that these government and foundation grants will decline in future periods.

Research and development expenses

Research and development expenses consist primarily of costs incurred for the development of our product candidates, which include:

Research and development costs are expensed as incurred. Costs for certain development activities are recognized based on an evaluation of the progress to completion of specific tasks using information and data provided to us by our vendors, CROs and clinical sites.

We cannot determine with certainty the duration and completion costs of the current or future clinical trials of our product candidates or if, when or to what extent we will generate sales from the commercialization of any of our product candidates if they receive regulatory approval. The successful development of our product candidates is highly uncertain and may never result in approved products. The duration, costs and timing of clinical trials and development of our product candidates will depend on a variety of factors, including:

● significant and potentially changing government regulation; and

● the timing and receipt of regulatory approvals, if any.

A change in the outcome of any of these variables with respect to the development of a product candidate could mean a significant change in the costs and timing associated with the development of that product candidate. For example, if the FDA, or another regulatory authority were to require us to conduct clinical trials beyond those that we currently

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anticipate will be required for the completion of clinical development of a product candidate, we could be required to expend significant additional financial resources and time on the completion of clinical development.

We plan to increase our research and development expenses for the foreseeable future as we continue the development of clinical and preclinical candidates. Our current planned research and development activities include the following:

● complete a Phase 1 clinical trial for pemvidutide in NASH;

● initiate a Phase 2 clinical trial for pemvidutide in obesity;

● conduct clinical and nonclinical safety studies for pemvidutide;

● complete a Phase 2 clinical trial for HepTcell; and

● manufacture clinical trial materials in support of our clinical trials.

To date, a significant portion of our research and development efforts have been related to the development of pemvidutide, HepTcell, as well as for NasoShield, NasoVAX, AdCOVID and T-COVID programs which were discontinued in 2021. We do not allocate personnel-related costs, costs associated with our general research platform improvements, depreciation or other indirect costs to specific programs.

General and Administrative Expenses

General and administrative expenses consist primarily of salaries and related costs for personnel, including stock-based compensation and travel expenses for our employees in executive, operational, finance and human resource functions. Other general and administrative expenses include facility-related costs and professional fees for directors, accounting and legal services, and expenses associated with obtaining and maintaining our intellectual property.

We anticipate that our general and administrative expenses will increase in the future as we increase our headcount to support our continued research and development activities. We also anticipate increased expenses related to audit, legal, regulatory and tax-related services associated with maintaining compliance with exchange listing and the SEC requirements, director and officer insurance, investor relations costs and other costs associated with being a public company. Additionally, if and when we believe a regulatory approval of the first product candidate appears likely, we anticipate an increase in staffing and related expenses as a result of our preparation for commercial operations, especially as it relates to the sales and marketing of our product candidates.

Critical Accounting Policies and Significant Judgment and Estimates

Our management’s discussion and analysis of our financial condition and results of operations is based on our consolidated financial statements, which have been prepared in accordance with U.S. generally accepted accounting principles. The preparation of our consolidated financial statements requires us to make judgments and estimates that affect the reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent liabilities in our consolidated financial statements. We base our estimates on historical experience, known trends and events, and various other factors that we believe to be reasonable under the circumstances. Actual results may differ from these estimates under different assumptions or conditions. On an ongoing basis, we evaluate our judgments and estimates in light of changes in circumstances, facts and experience. The effects of material revisions in estimates, if any, will be reflected in the consolidated financial statements prospectively from the date of change in estimates.

While our significant accounting policies are described in more detail in the notes to our consolidated financial statements appearing elsewhere in this Annual Report, we believe the following accounting policies used in the preparation of our consolidated financial statements require the most significant judgments and estimates.

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Impairment of long-lived assets

We evaluate our long-lived tangible and intangible assets for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Impairment of long-lived assets other than indefinite lived intangibles is assessed by comparing the undiscounted cash flows expected to be generated by the asset group to its carrying value.

As of December 31, 2021, we recorded non-cash impairment charges of $11.4 million for assets that were previously capitalized in connection with the construction of the Lonza facility and subsequent discontinuation of AdCOVID (see Note 3). In addition, the Company recorded an impairment loss of $0.6 million on intangible assets associated with the Company’s discontinued development programs (see Note 5).

We have indefinite lived intangible assets associated with in-process research and development (“IPR&D”). Our IPR&D assets are currently non-amortizing. Until such time as the projects are either completed or abandoned, we test those assets for impairment at least annually at year end, or more frequently at interim periods, by evaluating qualitative factors which could be indicative of impairment. Qualitative factors being considered include, but are not limited to, the current project status, forecasted changes in the timing or amounts required to complete the project, forecasted changes in timing or changes in the future cash flows to be generated by the completed products, a probability of success of the ultimate project and changes to other market-based assumptions, such as discount rates. If impairment indicators are present as a result of our qualitative assessment, we test those assets for impairment by comparing the fair value of the assets to their carrying value. Upon completion or abandonment, the value of the IPR&D assets will be amortized to expense over the anticipated useful life of the developed products, if completed, or charged to expense when abandoned if no alternative future use exists. Key assumptions used in our impairment analysis tests include projected cash flows, a probability of success of the ultimate project and the discount rate.

For the year ended December 31, 2021, we have one IPR&D asset, HepTcell, that was acquired in 2015. This candidate is a viral pathogen immunotherapy product for the treatment of chronic HBV. We performed a qualitative assessment for the IPR&D impairment testing for the years ended December 31, 2021 and 2020 and determined that no impairment indicators were present.

Fair Value Measurements

We follow the guidance in Financial Accounting Standards Board (“FASB”) Accounting Standard Codification Topic 820, Fair Value Measurements and Disclosures (“ASC 820”), which defines fair value and establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy are described below:

Level 1 — Quoted prices (unadjusted) in active markets for identical assets or liabilities that we can access at the measurement date.

Level 2 — Inputs other than quoted prices included within Level 1 that are either directly or indirectly observable. If the asset or liability has a specified (contractual) term, a Level 2 input must be observable for substantially the full term.

Level 3 — Unobservable inputs developed using estimates of assumptions developed by us, which reflect those that a market participant would use.

To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by us in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement.

Fair value is a market-based measure considered from the perspective of a market participant rather than an entity-specific measure. Therefore, even when market assumptions are not readily available, our own assumptions are set to

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reflect those that market participants would use in pricing the asset or liability at the measurement date. We use prices and inputs that are current as of the measurement date, including during periods of market dislocation. In periods of market dislocation, the observability of prices and inputs may change for many instruments. This condition could cause an instrument to be reclassified within levels in the fair value hierarchy. If applicable, we will recognize transfers into and out of Level 3 within the fair value hierarchy at the end of the reporting period in which the actual event or change in circumstance occurs. There were no transfers into or out of Level 3 of the fair value hierarchy during the years ended December 31, 2021 and 2020.

Contingent Consideration

We record contingent consideration associated with development and regulatory milestones that meets the definition of a liability under FASB Accounting Standards Codification Topic 480, Distinguishing Liabilities From Equity (“ASC 480”) at fair value. The fair value model used to calculate this obligation is based on the Monte Carlo simulation that has been risk adjusted based on the probability of achievement of the milestones. The inputs we use for determining the fair value of the contingent consideration associated with development and regulatory milestones are Level 3 fair value measurements. We re-evaluate the fair value on a quarterly basis. Changes in the fair value can result from adjustments to the probability of achievement of the milestones, stock price, volatility and the risk-free interest rate.

The change in our estimates associated with payments which will become due and payable for development and regulatory milestones will change the fair value of contingent consideration, resulting in a charge or contra expense to research and development expense in the period in which the increase or decrease is determined.

Research and Development

Research and development costs are expensed as incurred. Research and development costs consist of payroll and personnel expense, consulting costs, external contract research and development expenses, which includes fees paid to other entities that conduct certain research and development activities on our behalf, such as clinical research organizations (“CROs”) and contract manufacturing organizations (“CMOs”), raw materials, drug product manufacturing costs, laboratory supplies and allocated overhead, including depreciation and amortization, rent and utilities. Material research and development costs that are paid in advance of performance are capitalized as a prepaid expense and amortized over the service period as the services are provided.

Clinical trial costs are a significant component of research and development expenses, and we outsource a significant portion of these costs to third parties. Third party clinical trial expenses include investigator fees, site and patient costs, CRO costs, costs for central laboratory testing, data management and CMO costs. The accrual for site and patient costs includes inputs such as estimates of patient enrollment, patient cycles incurred, clinical site activations, and other pass-through costs. These inputs are required to be estimated due to a lag in receiving the actual clinical information from third parties. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected on the consolidated balance sheets as a prepaid asset or accrued expenses. These third-party agreements are generally cancelable, and related costs are recorded as research and development expenses as incurred. Material advance payments for goods or services that will be used or rendered for future research and development activities are recorded as a prepaid asset and recognized as expense as the related goods are delivered or the related services are performed. When evaluating the adequacy of the accrued expenses, we analyze progress of the studies, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates may be made in determining the accrued balances at the end of any reporting period.

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Results of Operations

Comparison of years ended December 31, 2021 and December 31, 2020:

​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

​ ​ For the Year Ended ​

​ ​ December 31, ​

(in thousands, except percentages) 2021 2020 Increase (Decrease)

Operating expenses: ​ ​ ​ ​ ​

Impairment loss on construction-in-progress ​ ​ 11,370 ​ ​ — ​ ​ 11,370 ​ 100 %

Other income (expense): ​ ​ ​ ​ ​

Interest expense ​ (6) ​ (9) ​ 3 33 %

Total other (expense) income, net ​ (177) ​ 337 ​ (514) (153) %

Revenue

Revenue from contracts and grants for the years ended December 31, 2021 and 2020 consisted primarily of research grants in the United States from MTEC for our T-COVID product candidate and BARDA for our NasoShield vaccine candidate. These grants consist of firm fixed fee contracts based on milestones and cost reimbursement contracts, with a fixed fee based on either costs incurred or milestones met.

​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

​ ​ Year Ended December 31,

(in thousands, except percentages) 2021 2020 Increase (Decrease)

Revenue decreased by $3.8 million, or 46% for the year ended December 31, 2021 as compared to the year ended December 31, 2020. The decrease was primarily the result of a decrease of $3.7 million in MTEC revenue attributable to the timing of clinical trial and the discontinuation of development work on the T-COVID program.

Research and development expenses

Research and development expenses for the years ended December 31, 2021 and 2020 consisted primarily of expenses related to product candidate development. Research and development expenses for the years ended December 31, 2021 and 2020 are summarized as follows:

​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

​ ​ Year Ended December 31,

(in thousands, except percentages) 2021 2020 Increase (Decrease)

Research and development expenses increased by $24.8 million, or 50%, during the year ended December 31, 2021 as compared to the year ended December 31, 2020. The increased expense was primarily due to:

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General and administrative expenses

The following is a summary of general and administrative expenses for the years ended December 31, 2021 and 2020:

​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

​ ​ Year Ended December 31,

(in thousands, except percentages) 2021 2020 Increase (Decrease)

General and administrative expenses increased by $2.2 million, or 17%, during the year ended December 31, 2021 as compared to the year ended December 31, 2020. The increased expense is primarily due to an increase of $1.9 million in labor-related and other costs, an increase of $1.4 million in stock compensation expense, partially offset by a decrease of $1.1 million in professional fees.

Impairment loss on construction-in-progress

Impairment loss on construction-in-progress of $11.4 million reported during the year ended December 31, 2021 represents non-cash impairment charges recorded for assets that were previously capitalized in connection with the construction of the Lonza facility and subsequent discontinuation of AdCOVID. There were no impairment charges reported during the year ended December 31, 2020.

Total other (expense) income, net

Total other (expense) income, net decreased by $0.5 million during the year ended December 31, 2021 as compared to the year ended December 31, 2020. The net decreases are primarily due to changes in foreign currency conversion and interest income.

Income tax benefit

​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

​ Year Ended December 31,

(in thousands, except percentages) ​ 2021 ​ 2020 ​ Increase (Decrease)

Income tax benefit decreased by $5.4 million during the year ended December 31, 2021 as compared to the year ended December 31, 2020. In both 2021 and 2020, we had a valuation allowance against all of our deferred tax assets, but in 2020 a benefit was recognized related to a net operating loss carryback refund claim pursuant to the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”) signed into law on March 27, 2020 which made temporary changes regarding the utilization and carry back of net operating losses.

Liquidity and Capital Resources

Overview

Our primary sources of cash for the year ended December 31, 2021 were from equity transactions, maturities of short-term investments, cash receipts of accounts receivables from research grants and cash receipts of income tax refunds. Our cash, cash equivalents, and restricted cash were $190.3 million at December 31, 2021. We believe, based on the operating cash requirements expected for 2022 and 2023, our cash on hand at December 31, 2021, together with expected cash receipts from our income tax refunds and R&D incentives, are sufficient to fund operations for at least a twelve-month period from issuance date of our December 31, 2021 consolidated financial statements.

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We have not generated any revenues from the sale of any products to date, and there is no assurance of any future revenues from product sales. Our sources of revenue have consisted of grant revenues under our arrangements with BARDA for the development of NasoShield, MTEC for a clinical trial and development work on T-COVID, and to a lesser degree from other licensing arrangements. We anticipate that these government and foundation grants will decline in future periods. We have incurred significant losses since we commenced operations. As of December 31, 2021, we had an accumulated deficit of $293.2 million. In addition, we have not generated positive cash flows from operations. We have had to rely on a variety of financing sources, including the issuance of debt and equity securities. As capital resources are consumed to fund our research and development activities, we may require additional capital beyond our currently anticipated amounts. In order to address our capital needs, including our planned clinical trials, we must continue to actively pursue additional equity or debt financing, government funding, and monetization of our existing programs through partnership arrangements or sales to third parties.

In June 2020, we were awarded $4.7 million from the U.S. Army Medical Research & Development Command (“USAMRDC”) to fund our 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 pays us 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. Through December 31, 2021, we have collected approximately $4.7 million in cash under the contract.

In July 2016, we signed a five-year contract with BARDA. The contract, as amended, has a total value of up to $136.8 million and is used to fund clinical development of NasoShield. Under the contract, BARDA pays us a fixed fee and reimburses 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 consists of an initial base performance period providing approximately $30.9 million in funding for the period July 2016 through December 2021. BARDA has 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 provide additional funding ranging from approximately $1.1 million to $34.4 million for a three-year period beginning in 2021. Through December 31, 2021, the end of the contract, we have collected approximately $29.2 million in cash under the current BARDA contract. At December 31, 2021, BARDA had not elected to extend the contract.

Indebtedness

Paycheck Protection Program

On April 7, 2020, we applied for a loan from ServisFirst Bank, as lender, pursuant to the Paycheck Protection Program of the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”) as administered by the U.S. Small Business Administration (the "SBA"). On April 13, 2020, the Loan was approved and we received the proceeds from a loan in the amount of $632,000 (the “PPP Loan”).

The PPP Loan, which took the form of a promissory note (the “Promissory Note”), was set to mature on April 7, 2022 and bore interest at a rate of 1% per annum. Monthly principal and interest payments, less the amount of any potential forgiveness, was to commence on November 7, 2020. All or a portion of the Loan may be forgiven by the SBA and lender upon application by us upon documentation of expenditures in accordance with the SBA requirements. In July 2020, we voluntarily extinguished the Promissory Note by paying the outstanding principal and accrued interest in cash. We had no indebtedness during the year ended and as of December 31, 2021.

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Cash Flows

The following table provides information regarding our cash flows for the years ended December 31, 2021 and 2020:

​ ​ ​ ​ ​ ​ ​ ​ ​ ​

​ ​ Year Ended December 31,

(in thousands) 2021 2020 Increase (Decrease)

Net cash (used in) provided by: ​ ​ ​

Operating Activities

Net cash used in operating activities was $78.2 million for the year ended December 31, 2021 compared to $34.3 million during the year ended December 31, 2020. Our sources of cash provided by operations during the year ended December 31, 2021 were primarily revenue generated by our BARDA and MTEC contracts and cash receipts of income tax refunds. The primary uses of cash from our operating activities include payments for labor and labor-related costs, professional fees, research and development costs associated with our clinical trials and Lonza, and other general corporate expenditures. The increase in cash used in operating activities of $43.9 million is due to an increase in net loss as adjusted for noncash items of $48.2 million and changes in working capital accounts of $4.3 million.

Investing Activities

Net cash provided by (used in) investing activities was $87.5 million for the year ended December 31, 2021 compared to $72.2 million during the year ended December 31, 2020. The net cash provided by investing activities during 2021 was primarily due to net proceeds from short-term investment activity, partially offset by purchases of property and equipment. The net cash used in investing activities during the year ended December 31, 2020 was primarily due to purchases of short-term investments, net of maturities.

Financing Activities

Net cash provided by financing activities was $65.1 million for the year ended December 31, 2021 compared to $213.5 million during the year ended December 31, 2020. The net cash provided by financing activities during 2021 was primarily the result of the receipt of $64.8 million in proceeds from the issuance of common stock from our at-the-market offerings program. The net cash provided by financing activities during 2020 was primarily the result of the receipt of $124.0 million in net proceeds from a public offering, $48.2 million in proceeds from the issuance of common stock from our at-the-market offerings program and $41.0 million in proceeds from the exercise of warrants.

Item 7A. Quantitative and Qualitative Disclosures about Market Risk

As a “smaller reporting company” as defined by Item 10 of Regulation S-K, we are not required to provide the information required by this Item.

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Item 8. Financial Statements and Supplementary Data

ALTIMMUNE, INC.

INDEX TO CONSOLIDATED FINANCIAL STATEMENTS

Consolidated Balance Sheets as of December 31, 2021 and 2020 97

Notes to Consolidated Financial Statements 101

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REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

The Shareholders and the Board of Directors of Altimmune, Inc.

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheets of Altimmune, Inc. (the Company) as of December 31, 2021 and 2020, the related consolidated statements of operations and comprehensive loss, changes in stockholders’ equity and cash flows for each of the two years in the period ended December 31, 2021, and the related notes (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company at December 31, 2021 and 2020, and the results of its operations and its cash flows for each of the two years in the period ended December 31, 2021, in conformity with U.S. generally accepted accounting principles.

Basis for opinion

These financial statements are the responsibility of the Company’s management. Our responsibility is to express an opinion on the Company’s financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company’s internal control over financial reporting. Accordingly, we express no such opinion.

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matters

The critical audit matter communicated below is a matter arising from the current period audit of the financial statements that was communicated or required to be communicated to the audit committee and that: (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective or complex judgments. The communication of the critical audit matter does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the account or disclosure to which it relates.

​ ​ ​

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/s/ Ernst & Young LLP

We have served as the Company’s auditor since 2017.

Tysons, Virginia

March 15, 2022

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ALTIMMUNE, INC.

CONSOLIDATED BALANCE SHEETS

​ ​ ​ ​ ​ ​ ​

​ December 31,

ASSETS ​ ​

Current assets: ​ ​

LIABILITIES AND STOCKHOLDERS’ EQUITY ​ ​

Current liabilities: ​ ​

Contingent consideration ​ ​ 6,090,000 ​ ​ —

Contingent consideration ​ — ​ 5,390,000

Commitments and contingencies (Note 17) ​ ​

Stockholders’ equity: ​ ​

The accompanying notes are an integral part of the consolidated financial statements.

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ALTIMMUNE, INC.

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS

​ ​ ​ ​ ​ ​ ​

​ ​ Year Ended December 31,

Operating expenses: ​ ​

Impairment loss on construction-in-progress ​ 11,370,000 ​ —

Other income (expense): ​ ​

Net loss per share, basic and diluted ​ $ (2.35) ​ $ (1.91)

The accompanying notes are an integral part of the consolidated financial statements

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ALTIMMUNE, INC.

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY

​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accumulated ​ ​ ​

​ ​ ​ ​ ​ ​ ​ Additional ​ ​ ​ ​ Other ​ Total

​ Common Stock Paid-In Accumulated Comprehensive Stockholders’

​ ​ Shares ​ Amount ​ Capital ​ Deficit ​ Loss ​ Equity

Unrealized gain on short-term investments — ​ — ​ — ​ — ​ 4,354 ​ 4,354

The accompanying notes are an integral part of the consolidated financial statement

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ALTIMMUNE, INC.

CONSOLIDATED STATEMENTS OF CASH FLOWS

​ ​ ​ ​ ​ ​ ​

​ Year Ended December 31,

CASH FLOWS FROM OPERATING ACTIVITIES: ​ ​

Adjustments to reconcile net loss to net cash used in operating activities: ​ ​

Impairment loss on construction-in-progress ​ 11,370,000 ​ —

Impairment loss on intangible assets ​ 579,497 ​ —

Unrealized losses (gains) on foreign currency exchange ​ 383,721 ​ (19,073)

Changes in operating assets and liabilities: ​ ​

CASH FLOWS FROM INVESTING ACTIVITIES: ​ ​

Cash paid for internally developed patents ​ (194,538) ​ (138,464)

CASH FLOWS FROM FINANCING ACTIVITIES: ​ ​

Payments of deferred offering costs ​ ​ (118,522) ​ ​ —

Proceeds from exercises of warrants ​ — ​ 41,038,458

Proceeds from issuance of notes payable ​ — ​ 632,000

Payments of notes payable ​ — ​ (632,000)

​ ​ ​ ​ ​ ​ ​

SUPPLEMENTAL CASH FLOW INFORMATION: ​ ​

Cash paid for interest ​ $ — ​ $ 1,791

SUPPLEMENTAL NON-CASH ACTIVITIES: ​ ​

Operating lease liability and right of use asset addition ​ $ 72,047 ​ $ 338,212

The accompanying notes are an integral part of the consolidated financial statements.

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ALTIMMUNE, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

1. Nature of Business and Organization

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.

2. Summary of Significant Accounting Policies

Basis of Presentation and Principles of Consolidation

The accompanying consolidated financial statements are prepared in conformity with generally accepted accounting principles in the United States (“U.S. GAAP”) and in accordance with the rules and regulations of the United States Securities and Exchange Commission (“SEC”). The accompanying 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.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenue and expenses, and the disclosure of contingent assets and liabilities as of and during the reporting period. The Company bases estimates and assumptions on historical experience when available and on various factors that it believes to be reasonable under the circumstances. Significant estimates relied upon in preparing the accompanying consolidated financial statements were related to revenue recognition, the fair value of common stock and other equity instruments, accounting for stock-based compensation, income taxes, useful lives of long-lived assets, fair value of contingent consideration, impairment of long-lived assets, and accounting for project development and certain accruals. The Company assesses the above estimates on an ongoing basis; however, actual results could differ materially from those estimates.

Segment Information

The Company is managed and operates as a single business focused on the research and development of treatments for various diseases and disorders, and vaccines. The Company is managed by a single management team, and consistent with its organizational structure, the Chief Executive Officer manages and allocates resources at a consolidated level. Accordingly, the Company views its business as one operating segment.

Cash Equivalents

The Company considers all highly liquid investments purchased with remaining maturities of 90 days or less on the purchase date to be cash equivalents, and include amounts held in money market funds which are actively traded (a Level 1 input).

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Restricted Cash

The Company had restricted cash of $34,174 at both December 31, 2021 and 2020, held in money market savings accounts as collateral. The restricted cash as of December 31, 2021 and 2020 is for the Company’s facility lease obligation. Restricted cash is classified as a component of cash, cash equivalents, and restricted cash in the accompanying consolidated balance sheets and consolidated statements of cash flows.

Short-term Investments

The Company’s short-term investments are comprised of U.S. Treasury, corporate debt securities and certificate of deposit that have original maturities less than or equal to one year and are classified as available-for-sale securities. Such securities are carried at estimated fair value, with any unrealized holding gains or losses reported as accumulated other comprehensive income or loss, which is a separate component of stockholders’ equity. Realized gains and losses and declines in value judged to be other-than-temporary, if any, are included in other income (expenses), net in the consolidated results of operations. The Company reviews its investment portfolio for impairment quarterly or more frequently if circumstances warrant. In determining whether a decline in the value of an investment is other-than-temporary, the Company evaluates currently available factors that may include, among others: (1) general market conditions; (2) the duration and extent to which fair value has been less than the carrying value; (3) the investment issuer’s financial condition and business outlook; and (4) its assessment as to whether it is more likely than not that the Company will be required to sell a security prior to recovery of its amortized cost basis. A decline in the market value of any available-for-sale security below cost that is deemed to be other-than-temporary results in a reduction in fair value charged to earnings in that period, and a new cost basis for the security is established. Dividend and interest income are recognized in other income when earned. The cost of securities sold is calculated using the specific identification method. The Company places all investments with government agencies, or corporate institutions whose debt is rated as investment grade.

Fair Value Measurements

The Company records certain financial assets and liabilities at fair value in accordance with the guidance in Financial Accounting Standards Board (“FASB”) Accounting Standard Codification Topic 820, Fair Value Measurements and Disclosures (“ASC 820”), which defines fair value and establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy are described below:

Level 1 — Quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company can access at the measurement date.

Level 2 — Inputs other than quoted prices included within Level 1 that are either directly or indirectly observable. If the asset or liability has a specified (contractual) term, a Level 2 input must be observable for substantially the full term.

Level 3 — Unobservable inputs developed using estimates of assumptions developed by the Company, which reflect those that a market participant would use.

To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement.

Fair value is a market-based measure considered from the perspective of a market participant rather than an entity-specific measure. Therefore, even when market assumptions are not readily available, the Company’s own assumptions are set to reflect those that market participants would use in pricing the asset or liability at the measurement date. The Company uses prices and inputs that are current as of the measurement date, including during periods of market dislocation. In periods of market dislocation, the observability of prices and inputs may change for many instruments. This condition could cause an instrument to be reclassified within levels in the fair value hierarchy. If applicable, the Company will recognize transfers into and out of Level 3 within the fair value hierarchy at the end of the reporting period in which the

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actual event or change in circumstance occurs. There were no transfers into or out of Level 3 of the fair value hierarchy during the years ended December 31, 2021 and 2020.

Financial Instruments

The Company’s financial instruments consist of cash, cash equivalents, restricted cash, accounts receivable, short-term investments, notes payable, accounts payable, accrued expenses, contingent consideration, common stock warrants classified as a liability, and common stock warrants classified as equity. The carrying amounts of cash, cash equivalents, restricted cash, accounts receivable, accounts payable, and accrued expenses approximate their fair value due to the short-term nature of those financial instruments. Short-term investments are recorded at fair value, with any unrealized holding gains or losses reported as accumulated other comprehensive income or loss. Notes payable, prior to their redemption or cancellation, are recorded at their repayment value which approximates fair value. Contingent payments classified as a liability are recorded at fair value estimated using the Monte Carlo simulation valuation model. Common stock warrants classified as equity are initially recorded at their grant date fair value. For those warrants with a down round feature, if the down round feature is triggered, the Company would remeasure those instruments at that time with changes recorded as a deemed dividend all within equity. Common stock warrants classified as a liability are recorded at fair value and are remeasured every reporting period with the changes in fair value recorded as a component of other income (expenses), net until their settlement or exercise.

Accounts Receivable

Accounts receivable includes both billed and unbilled amounts. The Company makes judgments as to its ability to collect outstanding receivables and provides an allowance for receivables when collection becomes doubtful. Provisions are made based upon a specific review of all significant outstanding invoices and the overall quality and age of those invoices not specifically reviewed. The Company’s receivables represent amounts reimbursed under its government grants and contracts. The Company believes that credit risks associated with these government grants and contracts is not significant. To date, the Company has not experienced any losses associated with accounts receivable and does not maintain an allowance for doubtful accounts.

Concentrations of Credit Risk

Financial instruments that potentially subject the Company to significant concentration of credit risk consist primarily of cash, cash equivalents, restricted cash, and accounts receivable. Periodically, the Company maintains deposits in financial institutions in excess of government insured limits. Management believes that the Company is not exposed to significant credit risk as the Company’s deposits are held at financial institutions that management believes to be of high credit quality. The Company has not experienced any losses in these deposits. The Company recognizes research grants and contracts earned in connection with the services provided on research and development projects. The Company provides credit in the normal course of providing such services based on evaluations of the grantors’ financial condition and generally does not require collateral. To manage accounts receivable credit risk, the Company monitors the creditworthiness of its grantors. The U.S. government accounts for 97% of revenue for both of the years ended December 31, 2021 and 2020. The U.S. government accounts for 100% of accounts receivable for both of the years ended December 31, 2021 and 2020.

Property and Equipment, Net

The Company records property and equipment at cost less accumulated depreciation and amortization. Expenditures for maintenance and repairs are charged to operations as incurred, whereas major improvements are capitalized as additions to property and equipment. Costs of assets under construction are capitalized but are not depreciated until the construction is substantially complete and the assets being constructed are ready for their intended use.

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Depreciation and amortization are recorded using the straight-line method over the estimated useful lives of the assets, as follows:

​ ​ ​

Asset Category Estimated Useful Life

Computer and telecommunications 3 – 5 years

Software 3 years

Furniture, fixtures and equipment 5 years

Laboratory equipment 7 years

Leasehold improvements Lesser of lease term or estimated useful lives

Intangible Assets

Intangible assets acquired in a business combination consist primarily of in-process research and development (“IPR&D”) assets. The value attributable to IPR&D projects at the time of acquisition is capitalized as an indefinite-lived intangible asset and tested for impairment until the project is completed or abandoned. Upon completion of the project, the indefinite-lived intangible asset will be accounted for as a finite-lived intangible asset and amortized on a straight-line basis over its estimated useful life. If the project is abandoned, the indefinite-lived intangible asset will be charged to expense. Intangible assets, including patents and licenses, acquired in other transactions are recorded at cost. Intangible assets with finite useful lives consist of legal and patent costs incurred in the course of obtaining patents and license issuance fees for the use of proprietary technologies. Costs incurred for obtaining patents are amortized on a straight-line basis over the estimated useful lives of the assets from the time of approval of the patent. Prior to approval, these costs are carried on the balance sheets and not amortized. In the event approval is denied, the cost of the denied application is expensed. License issuance fees are amortized on a straight-line basis over the estimated useful lives of the underlying licensed technology. Intangible assets with finite useful lives are being amortized over 6 to 20 years. These amortization costs are classified as research and development expenses in the accompanying statements of operations and comprehensive loss.

Impairment of Long-lived Assets

The Company evaluates its long-lived tangible and intangible assets for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Impairment of long-lived assets other than goodwill and indefinite lived intangibles is assessed by comparing the undiscounted cash flows expected to be generated by the asset group to its carrying value.

During the year ended December 31, 2021, the Company recorded non-cash impairment charges for assets that were previously capitalized in connection with the discontinuation of AdCOVID (see Note 3). In addition, the Company recorded an impairment loss of $0.6 million on intangible assets associated with the Company’s discontinued development programs (see Note 5).

The Company has indefinite lived intangible assets associated with in-process research and development (“IPR&D”). The Company’s IPR&D assets are currently non-amortizing. Until such time as the projects are either completed or abandoned, the Company test those assets for impairment at least annually at year end, or more frequently at interim periods, by evaluating qualitative factors which could be indicative of impairment. Qualitative factors being considered include, but are not limited to, the current project status, forecasted changes in the timing or amounts required to complete the project, forecasted changes in timing or changes in the future cash flows to be generated by the completed products, a probability of success of the ultimate project and changes to other market-based assumptions, such as discount rates. If impairment indicators are present as a result of the Company’s qualitative assessment, the Company will test those assets for impairment by comparing the fair value of the assets to their carrying value. Upon completion or abandonment, the value of the IPR&D assets will be amortized to expense over the anticipated useful life of the developed products, if completed, or charged to expense when abandoned if no alternative future use exists. Key assumptions used in the Company’s impairment analysis tests include projected cash flows, a probability of success of the ultimate project, and the discount rate.

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The Company has one IPR&D asset, HepTcell, that was acquired in 2015. This candidate is a viral pathogen immunotherapy product for the treatment of chronic HBV. The Company performed a qualitative assessment for the IPR&D impairment testing for 2021 and 2020 and determined that no impairment indicators were present.

Leases

The Company’s headquarters lease is the primary lease, accounted for as an operating lease under FASB Accounting Standards Codification Topic 842, Leases (“ASC 842”), utilizing the prospective optional transition method. The Company elected the package of practical expedients permitted. Accordingly, the Company accounted for its existing operating leases as operating leases under ASC 842, without reassessing (a) whether the contracts contain a lease, (b) whether classification of the operating leases would be different in accordance with ASC 842, or (c) whether the unamortized initial direct costs before transition adjustments would have met the definition of initial direct costs at lease commencement. In addition, the Company does not allocate the consideration between lease and non-lease components.

The Company determines if an arrangement is a lease at inception. Operating leases are recorded as a current and long-term lease obligation, with a corresponding right of use lease assets.

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

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.

Lease incentives and allowance provided by our landlord for the construction of leasehold improvements are recorded as lease incentive obligations as the related construction costs are incurred, up to the maximum allowance.

Contingent Consideration

The Company records contingent consideration associated with development and regulatory milestones that meets the definition of a liability under FASB Accounting Standards Codification Topic 480, Distinguishing Liabilities From Equity (“ASC 480”) at fair value. The fair value model used to calculate this obligation is based on the Monte Carlo simulation that has been risk adjusted based on the probability of achievement of the milestones. The inputs the Company uses for determining the fair value of the contingent consideration associated with development and regulatory milestones are Level 3 fair value measurements. The Company re-evaluates the fair value on a quarterly basis. Changes in the fair value can result from adjustments to the probability of achievement of the milestones, stock price, volatility and the risk-free interest rate.

The change in Company’s estimates associated with the timing of payments which will become due and payable for development and regulatory milestones will change the fair value of contingent consideration, resulting in a charge or contra expense to research and development expense in the period in which the increase or decrease is determined.

Warrants

Common stock warrants issued in connection with the 2018 Unit Offering, the 2018 and 2019 Registered Direct Offerings, and the 2020 Public Offering (all terms defined in Note 10 and Note 11), were classified as a component of permanent equity because they are freestanding financial instruments that were legally detachable and separately exercisable from other debt and equity instruments, are contingently exercisable, do not embody an obligation for the Company to repurchase its shares, and permits the holders to receive a fixed number of common shares upon exercise. In addition, such warrants did not provide any guarantee of value or return. The 2018 Registered Direct Offering and 2019 Registered Direct Offering triggered down round adjustments to the exercise price of warrants issued in connection with

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the 2018 Unit Offering. In 2019, the Company treated the value of the effect of the reduction in exercise price as a deemed dividend, resulting in a reduction to income available to common shareholders (see Note 11). There was a reduction in exercise price in 2020 due to the At-the-Market Offering which triggered an anti-dilution provision under the warrant agreement with the Company’s holders of redeemable preferred stock (see Note 11).

Stock-based Compensation

The Company accounts for all stock-based compensation granted to employees and non-employees using a fair value method. Stock-based compensation awarded to employees is measured at the grant date fair value of stock option grants and is recognized over the requisite service period of the awards, usually the vesting period, on a straight-line basis, net of estimated forfeitures.

If awards are modified, the Company compares the fair value of the affected award measured immediately prior to modification to its value after modification. To the extent that the fair value of the modified award exceeds the original award, the incremental fair value of the modified award is recognized as compensation expense on the date of modification for vested awards, and over the remaining vesting period for unvested awards.

Revenue

The Company’s revenue consists primarily of government and foundation grants and contracts that support the Company’s efforts on specific research projects. The Company has determined that the government agencies and foundations providing grants and contracts to the Company are not customers. These grants and contracts generally provide for reimbursement of approved costs as those costs are incurred by the Company. Research grants and contracts and the related accounts receivable are recognized as earned in proportion to when reimbursable expenses are incurred in performance of the contract. Payments received in advance of services being provided are recorded as deferred revenue. The Company anticipates that these government and foundation grants will decline in future periods.

Research and Development

Research and development costs are expensed as incurred. Research and development costs consist of payroll and personnel expense, consulting costs, external contract research and development expenses, which includes fees paid to other entities that conduct certain research and development activities on the Company’s behalf, such as clinical research organizations (“CROs”) and contract manufacturing organizations (“CMOs”), raw materials, drug product manufacturing costs, laboratory supplies and allocated overhead, including depreciation and amortization, rent and utilities. Material research and development costs that are paid in advance of performance are capitalized as a prepaid expense and amortized over the service period as the services are provided.

Clinical trial costs are a significant component of research and development expenses, and the Company outsources a significant portion of these costs to third parties. Third party clinical trial expenses include investigator fees, site and patient costs, CRO costs, costs for central laboratory testing, data management and CMO costs. The accrual for site and patient costs includes inputs such as estimates of patient enrollment, patient cycles incurred, clinical site activations and other pass-through costs. These inputs are required to be estimated due to a lag in receiving the actual clinical information from third parties. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected on the consolidated balance sheets as a prepaid asset or accrued expenses. These third-party agreements are generally cancelable, and related costs are recorded as research and development expenses as incurred. Material advance payments for goods or services that will be used or rendered for future research and development activities are recorded as a prepaid asset and recognized as expense as the related goods are delivered or the related services are performed. When evaluating the adequacy of the accrued expenses, the Company analyzes progress of the studies, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates may be made in determining the accrued balances at the end of any reporting period.

Research and Development Incentive Credits

The Company is eligible to obtain certain research and development (“R&D”) incentive credits, through the participation in the U.K. R&D Small and Medium Enterprise tax relief program (“U.K. R&D credit”) and the Australian

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research and development incentive credit (the “Australia R&D credit”) program administered through the Australian Tax Office (the “ATO”).

The U.K. R&D credits are calculated as a percentage of qualifying R&D expenses and are payable in cash by the U.K. government to the Company. Qualifying R&D expenses consist of employment costs for research staff, consumables, a proportion of relevant, permitted sub-contract costs and certain internal overhead costs incurred as part of research projects for which the Company does not receive income. The Australia R&D credits provide for a cash refund based on a percentage of certain research and development activities undertaken in Australia by the Company’s wholly owned subsidiary, Altimmune AU Pty, Limited. Qualifying R&D expenses must be incurred within the country. The Company will record a reduction to R&D expense in the consolidated statement of operations and comprehensive loss when there is reasonable assurance that the Company will comply with the conditions attached to the incentive credits and that the incentive credits will be received.

The U.K. and Australian incentive credits are available on the basis of specific criteria with which the Company must comply. The incentive credits are subject to future audits by the government authorities and a four-year statute of limitations. Although the incentive credits may be administered through the local tax authority, the Company has accounted for the incentives outside of the scope of FASB Accounting Standards Codification Topic 740, Income Taxes (“ASC 740”), since the incentives are not linked to the Company’s taxable income and can be realized regardless of whether the Company has generated taxable income in the respective jurisdictions. The Company accounts for these incentive credits as a government grant which analogizes with International Accounting Standards 20 (“IAS 20”), Accounting for Government Grants and Disclosure of Government Assistance. As of and for the year ended December 31, 2021 and 2020, the Company recognized $1.8 million and $2.3 million, respectively, of R&D credits included in “Income tax and R&D incentive receivables” on the accompanying consolidated balance sheets and a corresponding reduction to R&D expense in the consolidated statement of operations and comprehensive loss.

Income Taxes

The Company accounts for income taxes in accordance with ASC 740. ASC 740 uses the asset and liability approach, which requires the recognition of future tax benefits or liabilities on the temporary differences between the financial reporting and tax bases of our assets and liabilities. Deferred tax assets and liabilities represent future tax consequences of temporary differences between the financial statement carrying amounts and the tax basis of assets and liabilities and for loss carryforwards using enacted tax rates expected to be in effect in the years in which the differences reverse. A valuation allowance is established when necessary to reduce deferred tax assets to the amounts expected to be realized. The Company also recognizes a tax benefit from uncertain tax positions only if it is “more likely than not” that the position is sustainable based on its technical merits. The Company accounts for interest and penalties related to uncertain tax positions as part of its provision for income taxes. To date, the Company has not incurred interest and penalties related to uncertain tax positions. Should such costs be incurred, they would be classified as a component of provision for income taxes.

The Company conducts R&D activities potentially qualified to claim research tax credits for U.S. federal and state purposes under Internal Revenue Code Section 41. The Company has not performed a formal study claiming these credits in the tax returns because the Company does not yet have taxable profits. Once the Company becomes profitable, it will likely have a study prepared, and the amount of R&D tax credits available could generate income tax benefit, subject to an annual Section 383 limitation and valuation allowance for realizability of the deferred tax asset.

As of December 31, 2021 and 2020, the Company recognized $3.6 million and $5.4 million of income tax receivables included in “Income tax and R&D incentive receivables” on the accompanying consolidated balance sheets.

Comprehensive Loss

For the years presented, the total comprehensive loss includes net loss and other comprehensive income (loss) which represents unrealized gains or losses on investments.

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Net Loss per Share

Basic net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding for the period without consideration for potentially dilutive securities.

The Company computes diluted net loss per common share after giving consideration to all potentially dilutive common equivalents, including all unvested restricted stock, common stock warrants, and common stock options outstanding during the period except where the effect of such non-participating securities would be anti-dilutive.

Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares and dilutive common stock equivalents outstanding for the period determined using the treasury-stock and if-converted methods.

Recently Issued Accounting Pronouncements

Recently Adopted:

In December 2019, the FASB issued Accounting Standards Update (“ASU”) No. 2019-12, Income Taxes (Topic 740), Simplifying the Accounting for Income Taxes (“ASU No. 2019-12”). ASU No. 2019-12 amends the approaches and methodologies in accounting for income taxes during interim periods and makes changes to certain income tax classifications. The new standard allows exceptions to the use of the incremental approach for intra-period tax allocation, when there is a loss from continuing operations and income or a gain from other items, and to the general methodology for calculating income taxes in an interim period, when a year-to-date loss exceeds the anticipated loss for the year. The standard also requires franchise or similar taxes partially based on income to be reported as income tax and the effects of enacted changes in tax laws or rates to be included in the annual effective tax rate computation from the date of enactment. Lastly, in any future acquisition, the Company would be required to evaluate when the step-up in the tax basis of goodwill is part of the business combination and when it should be considered a separate transaction. The Company adopted the standard as of January 1, 2021 and determined that the adoption did not have a material impact on the Company’s consolidated financial statements.

In November 2021, the FASB issued ASU No. 2021-10, Government Assistance (Topic 832): Disclosures by Business Entities about Government Assistance (“ASU No. 2021-10”). ASU No. 2021-10 has an effective and transition date of January 1, 2022. This standard increases the transparency of transactions with the government that are accounted for by applying a grant or contribution accounting model and aims to reduce diversity that currently exists in the recognition, measurement, presentation, and disclosure of government assistance received by business entities due to the lack of specific authoritative guidance in GAAP. This standard requires an entity to provide information regarding the nature of the transaction with a government and the related accounting policy used to account for this transaction, the line item on the consolidated balance sheets and consolidated statement of operations and comprehensive loss that are affected by the transaction and the amounts applicable to each financial statement line item, and the significant terms and conditions of the transaction, including commitments and contingencies. The Company early adopted the standard as of December 31, 2021 and determined that the adoption of this standard did not have a material impact on the Company's consolidated financial statements.

Not Yet Adopted:

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU No. 2016-13”). ASU No. 2016-13 requires entities to measure all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions and reasonable and supportable forecasts. This update also required enhanced disclosures to help financial statement users better understand significant estimates and judgments used in estimating credit losses, as well as the credit quality and underwriting standards of an entity’s portfolio. This standard is effective for the Company as a smaller reporting company beginning January 1, 2023. Adoption is not expected to have a material impact on the Company’s consolidated financial statements.

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3. Fair Value Measurement

The Company records cash equivalents, short-term investments, contingent consideration and warrant liability at fair value on a recurring basis. Fair value is an exit price, representing the amount that would be received from the sale of an asset or paid to transfer a liability in an orderly transaction between market participants based on assumptions that market participants would use in pricing an asset or liability.

The Company’s assets and liabilities measured at fair value on a recurring basis at December 31, 2021 consisted of the following:

​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

​ ​ Fair Value Measurement at December 31, 2021

​ Total Level 1 Level 2 Level 3

Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Contingent consideration liability (see Note 8) ​ 6,090,000 ​ — ​ — ​ 6,090,000

The Company’s assets and liabilities measured at fair value on a recurring basis at December 31, 2020 consisted of the following:

​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

​ ​ Fair Value Measurement at December 31, 2020

​ Total Level 1 Level 2 Level 3

Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Contingent consideration liability (see Note 8) ​ 5,390,000 ​ — ​ — ​ 5,390,000

There was no warrant liability at December 31, 2021. The warranty liability is included in Other long-term liabilities in the consolidated balance sheet at December 31, 2020. The warrant liability was valued using the Monte Carlo simulation valuation model with Level 3 inputs.

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. There were no short-term investments at December 31, 2021.

Short-term investments with quoted prices at December 31, 2020 as shown below:

​ ​ ​ ​ ​ ​ ​ ​ ​ ​

​ ​ ​ ​ Unrealized Gain ​ ​ ​

​ ​ Amortized Cost ​ (Loss) ​ Market Value

The fair value of contingent payments classified as a liability is based on the regulatory milestones described in Note 8 and estimated using the Monte Carlo simulation valuation model with Level 3 inputs.

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The assumptions used to estimate the fair value of contingent payments that were classified as a liability at December 31, 2021 include the following significant unobservable inputs:

​ ​ ​ ​ ​

Unobservable input ​ Value or Range Weighted-Average

Expected volatility 80.1% ​ 80.1%

Risk-free interest rate 0.26% ​ 0.26%

Cost of capital 30% ​ 30%

Discount for lack of marketability 8%‐13% ​ 11%

Probability of payment 88% ​ 88%

The assumptions used to estimate the fair value of contingent payments that were classified as a liability at December 31, 2020 include the following significant unobservable inputs:

​ ​ ​ ​ ​

Unobservable input ​ Value or Range Weighted-Average

Risk-free interest rate 0.11% ​ 0.11%

Cost of capital 30% ​ 30%

Discount for lack of marketability 9%‐15% ​ 12%

Probability of payment 63% ​ 63%

If applicable, the Company will recognize transfers into and out of Level 3 within the fair value hierarchy at the end of the reporting period in which the actual event or change in circumstance occurs. There were no transfers into and out of Level 3 of the fair value hierarchy during the years ended December 31, 2021 or 2020.

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 year ended December 31, 2021, the Company recorded non-cash impairment charges to property and equipment, net on a non-recurring basis (see below). During the year ended December 31, 2020, the Company had no significant assets or liabilities that were measured at fair value on a non-recurring basis.

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 has 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 year ended December 31, 2021 under this expanded agreement.

In June 2021, the Company announced the discontinuation of further development of AdCOVID following the Company’s review of findings from the Phase 1 clinical trial. Construction continued at Lonza, and the Company assessed its strategic options with respect to the suite. Should Lonza contract a replacement project with another customer for the suite within 12 months of termination, Lonza shall reimburse the Company for 75% of the price paid for any equipment that can be utilized for the other customer. The Company’s expectation was that, more likely than not, the suite would be disposed of significantly before the end of its previously estimated useful life.

During the nine months ended September 30, 2021, the Company recorded a non-cash impairment charge of $8.1 million to property and equipment, net associated with the construction of the Lonza facility. The fair value of the CIP related assets was $3.3 million at September 30, 2021. At September 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

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deterioration, functional obsolescence and economic obsolescence. The fair value measurement was considered a Level 3 measurement within the valuation hierarchy.

During the fourth quarter of 2021, due to the failure of negotiations with the lead potential replacement customer for the CIP related assets and potential negotiations with other prospective customers failing to materialize, and due to other specific competitive and market conditions, as well as the termination of the manufacturing agreement with Lonza in December 2021, along with the remote probability of recovering cost after termination, the Company considered these triggering events and reassessed the CIP related assets for impairment and determined that the assets had no potential value and recorded an additional impairment charge of $3.3 million for the full remaining value of the CIP related assets.

For the year ended December 31, 2021, the Company recorded a total of $11.4 million in non-cash impairment charges associated with CIP in the accompanying audited consolidated statements of operations and comprehensive loss. Following the discontinuation of AdCOVID, incremental costs incurred under the construction contract have been recorded to research and development expenses in the accompanying audited consolidated statements of operations and comprehensive loss. Research and development expenses related to the Lonza manufacturing agreement was approximately $11.6 million, less $1.0 million of credit issued by Lonza, for the year ended December 31, 2021.

4. Property and Equipment, Net

Property and equipment, net consists of the following:

​ ​ ​ ​ ​ ​ ​

​ ​ December 31,

Less: accumulated depreciation and amortization ​ ​ (2,046,880) ​ ​ (1,598,811)

Depreciation expense related to property and equipment for the years ended December 31, 2021 and 2020 was $0.4 million and $0.3 million, respectively.

5. Intangible Assets

The Company’s intangible assets consist of the following:

​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

​ ​ ​ ​ Gross ​ ​ ​ ​ ​ ​ ​ ​ ​

​ ​ Estimated ​ Carrying ​ Accumulated ​ ​ ​ ​ Net Book

​ ​ Useful Lives ​ Value ​ Amortization ​ Impairment ​ Value

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​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

​ ​ ​ ​ Gross ​ ​ ​ ​ ​ ​ ​ ​ ​

​ ​ Estimated ​ Carrying ​ Accumulated ​ ​ ​ ​ Net Book

​ Useful Lives Value Amortization Impairment Value

Amortization expense of intangible assets subject to amortization totaled $19,920 and $46,813 for the years ended December 31, 2021 and 2020, respectively. Amortization expense was classified as research and development expenses in the accompanying consolidated statements of operations and comprehensive loss.

Intangible assets subject to amortization, which represent incomplete technologies, was amortized to expense over their estimated useful lives once the underlying technologies were substantially complete. In the event that in the future the Company ceases the development of these assets, the remaining carrying value would be written off at that time. IPR&D assets are periodically assessed for impairment by considering the state of completion of the projects, the remaining activities required to complete development, the anticipated market for the completed products and anticipated future cash required to complete development.

As of December 31, 2021, the Company recorded an impairment loss of $0.6 million for the remaining net book value of the internally developed patents that are associated with the Company's discontinued development programs. The impairment loss has been recorded to research and development expenses in the accompanying audited consolidated statements of operations and comprehensive loss. There was no IPR&D impairment loss during the year ended December 31, 2021 and 2020.

6. 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 years ended December 31, 2021 and 2020 under all of the Company’s operating leases was $0.5 million and $0.4 million, respectively, which includes short-term leases and variable lease costs that are not included in the lease obligation.

The office space lease provides 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 year ended December 31, 2021 and 2020 was $0.5 million and $0.4 million, respectively.

Supplemental balance sheet information related to the operating leases is as follows:

​ ​ ​ ​ ​ ​ ​ ​

​ ​ December 31,

Weighted-average remaining lease term (years) ​ 3.3 ​ 4.33 ​

Weighted-average discount rate ​ 7.2 % 7.3 %

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Maturities of operating lease liabilities are as follows:

​ ​ ​ ​

Year ending December 31, ​

Total operating lease payments ​ 1,722,607

Less: imputed interest ​ (187,495)

Total operating lease liabilities (see Note 7 and 9) ​ $ 1,535,112

7. Accrued Expenses and Other Current Liabilities

Accrued expense and other current liabilities consist of the following:

​ ​ ​ ​ ​ ​ ​

​ ​ December 31,

Lease obligation, current portion (see Note 6) ​ 411,450 ​ 356,716

8. 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 (the “shares”) 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”):

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The Regulatory Milestones will be payable in shares of the Company’s Common Stock, with the number of shares of the Company’s Common Stock to be issued in connection with each milestone amount, if any, dependent on the share price at the time of achievement. The number of any shares issued in consideration for the IND Milestone Consideration Amount will be determined based on lower of (A) the average of the closing prices of our Common Stock as reported on the Nasdaq Global Market for the twenty (20) consecutive trading days prior to the IND Reference Date or (B) $2.95. The value of any shares issued in consideration for the Phase 2 Milestone Consideration Amount shall be determined based the lower of (A) on the average of the closing trading prices of our Common Stock as reported on the Nasdaq Global Market for the twenty (20) consecutive trading days immediately preceding the date of the occurrence of the Phase 2 Milestone Event or (B) $3.54.

The future contingent payments related to the Regulatory Milestones are stock-based payments accounted for under ASC 480. Such stock-based payments are subject to a lock-up whereby 50% of the shares are released at 3 months and 50% are released at 6 months. The future contingent payments related to the Sales Milestones are predominately cash-based payments accounted for under FASB Accounting Standards Codification Topic 450, Contingencies. Accordingly, the Company will recognize the Sales Milestones when the contingency is probable and the amount is reasonably estimated.

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 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. No Regulatory Milestones were achieved during the year ended December 31, 2021; however, the milestone which would trigger the Phase 2 Milestone Consideration Amount remains outstanding.

The Company estimates the future contingent consideration for the Regulatory Milestones based upon a Monte Carlo simulation valuation model that is risk adjusted based on the probability of achieving the milestones and a discount for lack of marketability. The Company remeasures the fair value of the contingent consideration at each reporting period. During the fourth quarter of 2020, the Company achieved the IND Milestone and paid the obligation in shares according to the calculation discussed above. Below is a summary of the contingent consideration activity:

​ ​ ​ ​ ​ ​ ​

​ ​ Year Ended December 31,

The net increase in fair value throughout 2021 was primarily attributable to timing of the probability of milestone achievement. The net increase in fair value throughout the year ended December 31, 2020 was primarily attributable to an increase in the closing share price of the Company’s common stock and in the probability of milestone achievement, partially offset by the fair value of the IND Milestone payment settled in common stock. Any changes in fair value have been recorded within research and development expense during the respective periods presented. As of December 31, 2021, we classified the total contingent consideration of $6.1 million as current liabilities. The balance sheet classification between current and non-current liabilities was based upon our reasonable expectation as to the timing of settlement of the Phase 2 Milestone payment to the former owners.

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9. Notes Payable and Other Liabilities

Paycheck Protection Program

On April 7, 2020, the Company applied for a loan from ServisFirst Bank, as lender, pursuant to the Paycheck Protection Program of the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”) as administered by the U.S. Small Business Administration (the "SBA"). On April 13, 2020, the Loan was approved and the Company received the proceeds from a loan in the amount of $632,000 (the “PPP Loan”).

The PPP Loan, which took the form of a promissory note (the “Promissory Note”), was set to mature on April 7, 2022 and bore interest at a rate of 1% per annum. Monthly principal and interest payments, less the amount of any potential forgiveness, was to commence on November 7, 2020. All or a portion of the Loan may have been forgiven by the SBA and lender upon application by the Company upon documentation of expenditures in accordance with the SBA requirements. On July 21, 2020, the Company voluntarily extinguished the Promissory Note by paying the outstanding principal and accrued interest in cash.

The Company’s other long-term liabilities are summarized as follows:

​ ​ ​ ​ ​ ​ ​

​ ​ December 31,

Economic Incentive Grants

The Company has two conditional economic incentive grants for a total of $250,000 from Montgomery County, Maryland and the State of Maryland. The Montgomery County grant was received in May 2018, with a term expiring on February 28, 2028. The State of Maryland grant was received in October 2019, with a 10-year term expiring on December 31, 2029. These grants are conditional primarily based on the Company maintaining its current headquarter locations in addition to employing a required number of employees at different reporting dates through the term of the grants. The Company is accruing 3% interest on both grants and has recorded $7,563 and $7,583 in interest expense for the years ended December 31, 2021 and 2020, respectively.

10. Common Stock

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 Sale Agents (the “2021 ATM Offering”). Any Shares offered and sold in the 2021 ATM Offering will be issued pursuant to the Company’s Registration Statement on Form S-3 filed with the SEC on December 31, 2020, which was declared effective on January 11, 2021, the prospectus supplement relating to the 2021 ATM Offering filed with the SEC on February 25, 2021 and any applicable additional prospectus supplements related to the 2021 ATM Offering that form a part of the Registration Statement.

As of December 31, 2021, the Company has sold 4,800,454 shares of Common Stock under the 2021 Agreement resulting in approximately $64.8 million in net proceeds, with $58.0 million remaining available to be sold under the 2021 Agreement. As of December 31, 2021, the Company recorded approximately $0.1 million of offering costs which offset the proceeds received from the shares sold through December 31, 2021. The Company capitalized approximately $0.1 million of deferred offering costs which will offset future proceeds received under the 2021 Agreement.

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On March 27, 2020, the Company entered into an Equity Distribution Agreement (the “2020 Agreement”) with JMP Securities LLC, serving as placement agent (the “Placement Agent”) 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, having an aggregate offering price of up to $50.0 million (the “Shares”) through the Placement Agent (the “2020 ATM Offering”). Any Shares offered and sold in the 2020 ATM Offering were issued pursuant to the Company’s Registration Statement on Form S-3 filed with the SEC on April 4, 2019, which was declared effective on April 12, 2019, the prospectus supplement relating to the 2020 ATM Offering filed with the SEC on March 27, 2020 and any applicable additional prospectus supplements related to the 2020 ATM Offering that form a part of the Registration Statement. The aggregate market value of Shares eligible for sale in the 2020 ATM Offering and under the 2020 Agreement were subject to the limitations of General Instruction I.B.6 of Form S-3, to the extent required under such instruction. The Company offered Shares having an aggregate offering price of $18.9 million pursuant to the prospectus supplement filed with the SEC on March 27, 2020. On June 1, 2020, the Company filed an amendment to the 2020 Agreement which amended the prospectus supplement dated March 27, 2020 to increase the aggregate offering price to $50.0 million. As of December 31, 2020, the Company sold 5,594,455 shares of Common Stock under the amended 2020 Agreement resulting in $48.2 million in net proceeds. The 2020 Agreement was fully utilized during the year ended December 31, 2020, and no Shares were sold under the 2020 Agreement during the year ended December 31, 2021.

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 do not expire and are exercisable at any time except that the Exchange Warrants cannot 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, the Company recorded the retirement of the common stock exchanged as a reduction of common shares outstanding and a corresponding debit to additional paid-in-capital and accumulated deficit at the fair value of the Exchange Warrants on the issuance date. The Exchange Warrants were classified as equity in accordance with ASC 480 and the fair value of the Exchange Warrants was recorded as a credit to additional paid-in-capital and is not subject to remeasurement. The Company determined that the fair value of the Exchange Warrants is substantially similar to the fair value of the retired shares on the issuance date due to the negligible exercise price for the Exchange Warrants. As of December 31, 2021, none of the Exchange Warrants have been exercised.

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

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to ASC 480 and do not meet the definition of a derivative pursuant to FASB Accounting Standards Codification Topic 815, Derivatives and Hedging (“ASC 815”). The Pre-Funded Warrants are indexed to the Company’s common stock and meet all other conditions for equity classification under ASC 480 and ASC 815. Accordingly, the Pre-Funded Warrants are classified as equity and are accounted for as a component of additional paid-in capital at the time of issuance. As of December 31, 2021, no Pre-Funded Warrants were exercised.

Registered Direct Offering

On March 12, 2019, the Company issued a combined total of 4,361,370 common units and pre-funded units to certain institutional investors in a registered direct offering (the “Registered Direct Offering”). Each common unit in the Registered Direct Offering was sold at a price of $3.21 and consisted of one share of common stock and 0.70 of a warrant to purchase one share of common stock at an exercise price of $3.21. Each warrant sold in the Registered Direct Offering was exercisable immediately and expired five years from the date of issuance. Each pre-funded unit in the Registered Direct Offering was sold at a public offering price of $3.20 and consisted of a pre-funded warrant to purchase one share of common stock at an exercise price of $0.01 per share and 0.70 of a warrant to purchase one share of common stock at an exercise price of $3.21. All of the pre-funded warrants were exercised during 2019. The net proceeds of the Registered Direct Offering were $12.7 million, after deducting the underwriting discount and estimated offering expenses payable by the Company.

The warrants issued in the Registered Direct Offering were recognized as equity classified freestanding financial instruments. The Registered Direct Offering triggered a down round adjustment to the exercise price of the warrants issued in the 2018 Unit Offering (refer to Note 11) from $4.1798 to $2.7568. During the year ended December 31, 2019, the Company treated the value of the effect of the reduction in exercise price as a deemed dividend of $452,925 which reduced income available to common shareholders. The value of a down round feature is measured as the difference between the financial instrument’s fair value (without the down round feature) using the pre-trigger exercise price and the financial instrument’s fair value (without the down round feature) using the reduced exercise price.

11. Warrants

The following common stock warrants were outstanding at December 31, 2021:

​ ​ ​ ​ ​ ​ ​ ​ ​ ​

​ ​ Number of ​ ​ ​ ​ ​ ​ ​

​ ​ Common ​ Per Share ​ ​ ​ ​

​ ​ Stock ​ Exercise ​ ​ ​ ​

​ ​ Warrants ​ Price ​ Issuance Date ​ Expiration Date

​ ​

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The following common stock warrants were outstanding at December 31, 2020:

​ ​ ​ ​ ​ ​ ​ ​ ​ ​

​ ​ Number of ​ ​ ​ ​ ​ ​ ​

​ ​ Common ​ Per Share ​ ​ ​ ​

​ ​ Stock ​ Exercise ​ ​ ​ ​

​ ​ Warrants ​ Price ​ Issuance Date ​ Expiration Date

*Liability classified warrants ​

The following is a description of the common stock warrants issued prior to January 1, 2019:

Replacement Warrants

In May 2017, the Company issued 155 common stock warrants to replace outstanding common stock warrants in connection with the Company’s merger with PharmAthene, Inc.

Redeemable Preferred Stock Warrants

In August 2017, in connection with a redeemable preferred stock issuance, the Company granted warrants to holders of redeemable preferred stock to purchase up to 78,181 shares of the Company’s common stock. Warrants issued with the redeemable preferred stock are classified as a liability and were initially recorded at their grant date fair value, and remeasured on each subsequent balance sheet date. The warrant liability is classified as a component of other long-term liabilities on the consolidated balance sheets. During the year ended December 31, 2019, the Company exchanged 1,550 of these warrants for a combination of common stock and cash, leaving 62 of these warrants outstanding as of December 31, 2019. During the second quarter of 2020, the 62 common stock warrants were repriced to 1,420 common stock warrants due to the at-the-market offerings which triggered an anti-dilution provision under the warrant agreement with the Company’s holders of redeemable preferred stock. As of December 31, 2021, all of the redeemable preferred stock warrants were exercised.

2018 Unit Offering

On October 2, 2018, the Company issued a combined total of 2,400,000 common units and pre-funded units in a public offering (the “2018 Unit Offering”). Each common unit in the 2018 Unit Offering was sold at a public offering price of $5.00 and consisted of one share of common stock and a warrant to purchase one share of common stock at an exercise price of $6.00. Each warrant sold in the 2018 Unit Offering was exercisable immediately and expired five years from the date of issuance. Each pre-funded unit in the 2018 Unit Offering was sold at a public offering price of $4.99 and consisted of a pre-funded warrant to purchase one share of common stock at an exercise price of $0.01 per share and a warrant to purchase one share of common stock at an exercise price of $6.00. The pre-funded warrants were immediately exercisable and were able to be exercised at any time until all of the pre-funded warrants were exercised in full. All of the pre-funded warrants were exercised prior to December 31, 2018.

The warrants issued in the 2018 Unit Offering are each subject to anti-dilution protection. Accordingly, to the extent the Company was to issue additional common stock or securities convertible into common stock at an issuance price lower than exercise price of the warrants, the exercise price of the warrants would be adjusted to the lower of (i) the issuance price or (ii) the lowest volume weighted-average price of the Company’s common stock on the five trading days following the announcement of the new offering.

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In conjunction with the 2018 Unit Offering, the Company issued 196,650 warrants to the underwriter. The underwriter warrants had an exercise price per share equal to 125% of the public offering price per common unit in this offering and could be exercised on a cashless basis. As of December 30, 2021, all of the underwriter warrants were exercised in full.

2018 Registered Direct Offering

On October 10, 2018, the Company issued a combined total of 4,629,630 common units and pre-funded units to certain institutional investors in a registered direct offering (the “2018 Registered Direct Offering”). Each common unit in the 2018 Registered Direct Offering was sold at a price of $5.40 and consisted of one share of common stock and a warrant to purchase one share of common stock at an exercise price of $5.40. Each warrant sold in the 2018 Registered Direct Offering was exercisable immediately and expired five years from the date of issuance. Each pre-funded unit in the 2018 Registered Direct Offering was sold at a public offering price of $5.39 and consisted of a pre-funded warrant to purchase one share of common stock at an exercise price of $0.01 per share and a warrant to purchase one share of common stock at an exercise price of $5.40. The pre-funded warrants were immediately exercisable and were able to be exercised at any time until all of the pre-funded warrants are exercised in full. All of the pre-funded warrants were exercised prior to December 31, 2018.

The 2018 Registered Direct Offering triggered a down round adjustment to the exercise price of the warrants issued in the 2018 Unit Offering from $6.00 to $4.1798.

A summary of warrant activity is as follows:

​ ​ ​ ​ ​

​ ​ Year Ended December 31,

12. Stock-Based Compensation

Stock Options

The Company established the 2001 Employee Stock Option Plan to provide incentive stock options and non-qualified stock options to employees, and the 2001 Non-employee Stock Option Plan to provide non-qualified stock options to the members of the board of directors and advisory board, and non-employees. The 2001 Employee Stock Option Plan and the 2001 Non-employee Stock Option Plan are collectively referred to as the “2001 Plans.” In connection with the PharmAthene Merger Agreement in 2017, the Company issued options from its 2001 Plans to replace options previously granted. The Company de-designated common stock available for issuance under the 2001 Plans. No additional options or restricted stock will be granted under these plans. Options outstanding and unvested restricted stock granted or replaced under these plans will continue to vest over the remaining vesting period through the earlier of exercise, expiration, or forfeiture. The replacement options issued after the 2017 mergers will continue to vest over the remaining vesting period through the earlier of exercise, expiration, or forfeiture. Also, in connection with the 2017 mergers, the 2001 Plans were assumed by the Company.

In addition, the Company assumed the PharmAthene, Inc. Amended and Restated 2007 Long-Term Incentive Compensation Plan (the “2007 Plan”). Awards outstanding under the 2007 Plan remained outstanding in accordance with their applicable terms and conditions. No additional awards will be made under the 2007 Plan.

The Company established the 2017 Omnibus Incentive Plan (the “Omnibus Plan”) to provide incentive stock options, non-qualified stock options, restricted stock, and other stock-based awards denominated in shares of the Company’s common stock, and performance-based cash awards to eligible employees, consultants, and directors. In 2018, the Company’s shareholders approved an amendment to the Omnibus Plan to increase the number of shares reserved for

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issuance from 1,500,000 to 5,000,000. The aggregate share reserve will be increased on January 1 of each year commencing in 2018 and ending on and including January 1, 2027 up to an amount equal to the lowest of (i) 4% of the total number of shares of common stock outstanding on a fully diluted basis as of December 31 of the immediately preceding calendar year, and (ii) such number of shares of common stock, if any, determined by the Company’s board of directors. The maximum shares of common stock that may be granted to each employee or consultant in any fiscal year under the Omnibus Plan is the lesser of 800,000 shares per type of award or a maximum compensation amount of $5,000,000 under a Black-Scholes valuation model. The maximum common stock that may be granted to directors under the Omnibus Plan during any fiscal year is 500,000 shares.

On November 29, 2018, the Board approved and adopted the Altimmune Inc. 2018 Inducement Grant Plan (the “Inducement Plan”). The Inducement Plan provides for the grant of equity or equity-based awards in the form of non-qualified stock options, restricted stock awards and other stock-based awards. The Inducement Plan was adopted by the Board without stockholder approval pursuant to Rule 5635(c)(4) of the NASDAQ Listing Rules.

The Board has reserved 2,000,000 shares of the Company’s common stock for issuance pursuant to awards granted under the Inducement Plan (subject to customary adjustments in the event of a change in capital structure of the Company), and the Inducement Plan will be administered by the Compensation Committee. In accordance with Rule 5635(c)(4) of the NASDAQ Listing Rules, awards under the Inducement Plan may be only made to an employee who has not previously been an employee or member of the Board or any parent or subsidiary, or following a bona fide period of non-employment by the Company or a parent or subsidiary, if he or she is granted such award in connection with his or her commencement of employment with the Company or a subsidiary and such grant is an inducement material to his or her entering into employment with the Company or such subsidiary.

The 2001 Plans, the 2007 Plan, the Omnibus Plan and the Inducement Plan are collectively referred to as the “Plans.” During the year ended December 31, 2021 under the Plans, a total of 1,225,700 options to purchase shares of common stock were granted. As of December 31, 2021, there were 990,819 and 1,394,206 shares of common stock available for future grants under the Omnibus Plan and the Inducement Plan, respectively.

The fair value of stock option issued to employees was estimated at the date of grant using Black-Scholes with the following weighted-average assumptions:

​ ​ ​ ​ ​ ​

​ ​ For the Year Ended December 31,

Expected term (years) 6.0 5.9 ​

Risk-free interest rate 0.8 % 1.2 %

Expected dividend yield 0.0 % 0.0 %

Expected volatility: As there is not sufficient historical volatility for the expected term of the stock options, the Company uses an average historical share price volatility, inclusive of its own volatility, based on an analysis of reported data for a peer group of comparable companies which were selected based upon industry similarities.

Expected term (years): Expected term represents the number of years that the Company’s option grants are expected to be outstanding. There is not sufficient historical share exercise data to calculate the expected term of the stock options; therefore, the Company elected to utilize the simplified method to value option grants. Under this approach, the weighted-average expected life is presumed to be the average of the vesting term and the contractual term of the option.

Risk-free interest rate: The Company determined the risk-free interest rate by using a weighted-average equivalent to the expected term based on the daily U.S. Treasury yield curve rate in effect as of the date of grant.

Expected dividend yield: The Company does not anticipate paying any dividends in the foreseeable future.

The fair value of each non-employee stock option is estimated at the date of grant using Black-Scholes with assumptions generally consistent with those used for employee stock options, with the exception of expected term, which is over the contractual life.

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A summary of stock option activity under the Plans is presented below:

​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

​ ​ ​ ​ Weighted-Average ​ ​

​ ​ ​ ​ Weighted- ​ Remaining ​ ​ ​

​ ​ Number of ​ Average ​ Contractual Term ​ Aggregate Intrinsic

​ ​ Stock Options ​ Exercise Price ​ (Years) ​ Value

The per share weighted-average grant date fair value of stock options granted during the years ended December 31, 2021 and 2020 were $11.79 and $4.75 per share, respectively. The total intrinsic value of stock options exercised during the years ended December 31, 2021 and 2020 was $0.7 million and $0.9 million, respectively. The total fair value of awards vested during the years ended December 31, 2021 and 2020 was $4.7 million and $1.1 million, respectively. At December 31, 2021, there was $10.0 million of unrecognized compensation cost related to stock options, which is expected to be recognized over a weighted-average period of 2.3 years.

Restricted Stock

In October 2016, the Company authorized and granted a restricted stock award of 2,651 shares at an aggregate purchase price of $1,067. The weighted-average grant date fair value of the restricted stock award was $310.80 per share. The restricted stock vested ratably at the end of each quarter over four years starting on December 31, 2016 with 50% of the original issued shared subject to accelerated vesting upon a deemed liquidation event. During the year ended December 31, 2020, 213 of the restricted shares fully vested, which completed the vesting of this share award.

In November 2018, the Company authorized and granted the Chief Executive Officer a restricted stock award of 322,907 shares on his date of hire. The weighted-average grant date fair value of the restricted stock award was $3.59 per share. The restricted stock vests over a four-year period, 25% of the shares vesting on the one-year anniversary, and the remaining 75% vesting in 36 substantially equal monthly installments and will be fully vested on December 1, 2022; provided, however, that the executive officer has not experienced a termination prior to the applicable vesting date. The fair value of the 80,726 restricted shares that vested during the year ended December 31, 2021 totaled $1.0 million.

In June 2020, the Company authorized and granted 109,525 shares of restricted stock awards which vested over three months. The weighted-average grant date fair value of the restricted stock award was $9.19 per share. During the year ended December 31, 2020, all of the 109,525 of restricted shares fully vested, which completed the vesting of this share award.

In September 2020, the Company authorized and granted 15,000 shares of restricted stock units which vest over a four-year period, 25% of the shares vesting on the one-year anniversary, and the remaining 75% vesting in 36 substantially equal monthly installments and will be fully vested on September 22, 2024. The weighted-average grant date fair value of the restricted stock award was $14.35 per share. The fair value of the 4,687 restricted shares that vested during the year ended December 31, 2021 totaled $0.1 million.

In February 2021, the Company authorized and granted 181,279 shares of restricted stock units which vest over four years and will be fully vested on February 1, 2025. The weighted-average grant date fair value of the restricted stock award was $16.71 per share. No restricted shares vested during the year ended December 31, 2021.

In June 2021, the Company authorized and granted 15,000 shares of restricted stock units which vest over a four-year period, 25% of the shares vesting on the one-year anniversary, and the remaining 75% vesting in 36 substantially equal monthly installments and will be fully vested on June 30, 2025. The weighted-average grant date fair value of the restricted stock award was $9.85 per share. No restricted shares vested during the year ended December 31, 2021.

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In December 2021, the Company authorized and granted 50,000 shares of restricted stock units which vest over four years and will be fully vested on December 31, 2025. The weighted-average grant date fair value of the restricted stock award was $9.16 per share. No restricted shares vested during the year ended December 31, 2021.

A summary of restricted stock activities is presented below:

​ ​ ​ ​ ​ ​

​ ​ Weighted-

Source: SEC EDGAR (public domain) · 10-K for the period ended 2021-12-31, filed 2022-03-15 · accession 0001558370-22-003659

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