Harpoon Therapeutics : Material Event - Form 8-K

Item 8.01

Other Events.

On March 13, 2020, Harpoon Therapeutics, Inc. (the "Company") entered into an at-the-marketissuance sales agreement (the "Agreement") with Cantor Fitzgerald & Co. ("Cantor Fitzgerald") 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"), through Cantor Fitzgerald as its sales agent.

On April 21, 2023, the Company filed a registration statement on Form S-3(Registration No. 333-272064),which became effective on May 15, 2023, including a prospectus offering up to $8,500,000 of shares of its Common Stock in accordance with the Agreement (the "Current Prospectus"). The amount registered under the Current Prospectus was, as of the filing date, subject to limitations imposed by General Instruction I.B.6. of Form S-3.As of October 26, 2023, the Company is no longer subject to General Instruction I.B.6. of Form S-3.On November 24, 2023, the Company filed Amendment No. 1 to the Current Prospectus ("Amendment No. 1") to increase the offering to $59,086,211 of shares of its Common Stock.

The purpose of this Current Report on Form 8-Kis to file an opinion in connection with the increase in the size of the offering pursuant to Amendment No. 1 to the Current Prospectus. A copy of the opinion of Cooley LLP relating to the legality of the shares of Common Stock that may be issued pursuant to the Agreement and Current Prospectus, as amended by Amendment No. 1, is attached as Exhibit 5.1 to this Current Report on Form 8-K.