1. Organization Description of Business Harpoon Therapeutics, Inc. (the Company) is a clinical-stage immunotherapy company developing a novel class of T cell engagers that harness the power of the bodys immune system to treat patients suffering from cancer and other diseases. T cell engagers are engineered proteins that direct a patients own T cells to kill target cells that express specific proteins, or antigens, carried by the target cells. Using a proprietary Tri-specific T cell Activating Construct (TriTAC), platform, the Company is developing a pipeline of novel T cell engagers, or TriTACs, initially focused on the treatment of solid tumors and hematologic malignancies. In addition, the Company is also developing its ProTriTAC platform, which builds upon the core elements of the TriTAC platform by utilizing a prodrug approach designed to allow T cell engagers address cancer targets that would be limited by on-target toxicities. The Company was incorporated in Delaware in March 2015 and is headquartered in South San Francisco, California. Initial Public Offering On February 7, 2019, the Companys registration statement on Form S-1 relating to its initial public offering (IPO) was declared effective by the Securities and Exchange Commission (SEC) and shares of its common stock began trading on the Nasdaq Global Select Market (Nasdaq) on February 8, 2019. The public offering price of the shares sold in the IPO was $14.00 per share. The IPO closed in February 2019, pursuant to which the Company sold 5,769,201 shares of common stock, for gross proceeds of approximately $80.8 million, including the exercise in part of the underwriters option to purchase additional shares. The Company received net proceeds from the IPO of approximately $70.7 million, after underwriting discounts, commissions and offering costs. Immediately prior to the completion of the IPO on February 12, 2019, all outstanding shares of redeemable convertible preferred stock, including preferred stock warrants, were converted into 17,181,491 shares of common stock and $129.6 million was reclassified from temporary equity to additional paid-in capital on the balance sheet. Subsequent to the closing of the IPO, there were no shares of redeemable convertible preferred stock outstanding. Liquidity Since inception, the Company has incurred significant losses and has negative cash flows from operations. As of September 30, 2020, the Company had an accumulated deficit of $156.7 million. Management expects to continue to incur additional substantial losses in the foreseeable future as a result of the Companys research and development activities. As of September 30, 2020, the Company had cash, cash equivalents, and marketable securities of $162.3 million, which is available to fund future operations. The Company believes as of September 30, 2020, funding from collaborations and partners along with the Companys cash and cash equivalents, and marketable securities, provide sufficient capital resources to continue its operations for at least 12 months from the issuance date of the accompanying condensed financial statements. The Company will need to raise additional capital to support the completion of its research and development activities. The Companys activities are subject to significant risks and uncertainties, including failing to secure additional funding to continue to operationalize the Companys current technology and to advance the development of its product candidates. The global pandemic caused by an outbreak of a novel strain of coronavirus (COVID-19) has resulted, and is likely to continue to result, in national and global economic disruption and may adversely affect the Companys business. The Company is actively monitoring this situation and the possible effects on its financial condition, liquidity, operations, industry, and personnel.