• Preclinical abstracts for investigational T cell engagers, HPN328 and HPN217, in mouse models provide further validation of Harpoon’s proprietary Tri-specific T cell Activating Construct (TriTAC^®) platform and support ongoing clinical efforts
  
• Additional abstracts support further investigation of Harpoon’s conditionally active next-generation T cell engager platform, ProTriTAC™, with demonstrated therapeutic potential in a broad range of TROP2- and ITGB6-expressing solid tumors

SOUTH SAN FRANCISCO, Calif., March 14, 2023 (GLOBE NEWSWIRE) -- Harpoon Therapeutics, Inc. (Nasdaq: HARP), a clinical-stage immuno-oncology company developing novel T cell engagers, today announced that it will present data from five preclinical investigations in poster presentations at the American Association for Cancer Research (AACR) Annual Meeting being held in Orlando, Fla., April 14-19, 2023.

“The breadth of data from Harpoon’s five poster presentations at AACR supports further investigation of additional tumor targets, combination approaches with TriTACs^®, as well as our next-generation technology platform with conditionally active T cell engager prodrugs, or ProTriTACs™,” said Julie Eastland, President and Chief Executive Officer of Harpoon Therapeutics. “Additionally, the preclinical data investigating the activity of TriTAC in an immunocompetent mouse model provide further validation of our ongoing and planned clinical efforts with HPN328 and HPN217, leveraging our proprietary TriTAC T cell engager platform. We look forward to further validation in the clinic as our research efforts continue.”

Details of the AACR poster presentations are as follows:

Title: Long-term anti-tumor immunity induced by HPN328, a DLL3-targeting tri-specific, half-life extended T cell engager, in a preclinical immunocompetent mouse model
Abstract Number: 4131
Session: Immunology/Determinants of Immunotherapeutic Effectiveness
Session Date, Time: Tuesday, April 18, 9 a.m. - 12:30 p.m. ET
Location: Poster Section 24

Title: Anti-tumor activity of HPN328, a DLL3-targeting tri-specific, half-life extended T cell engager, is enhanced by combining with an anti-PD-L1 antibody in an immunocompetent mouse model
Abstract Number: 5070
Session: Immunology/Combination Immunotherapies 1
Session Date, Time: Tuesday April 18, 1:30 - 5 p.m. ET
Location: Poster Section 21

Title: Anti-tumor activity of HPN217, a BCMA-targeting tri-specific T cell engager, is enhanced by γ-secretase inhibitors in preclinical models
Abstract Number: 5081
Session: Immunology/Combination Immunotherapies 1        
Session Date, Time: Tuesday April 18, 1:30 - 5 p.m. ET
Location: Poster Section 21

Title: TROP2 ProTriTAC™, a protease-activated T cell engager prodrug targeting TROP2 for the treatment of solid tumors
Abstract Number: 2928
Session: Immunology/Therapeutic Antibodies 2
Session Date, Time: Monday April 17, 1:30 - 5 p.m. ET
Location: Poster Section 23

Title: ITGB6 ProTriTAC™, a protease-activated T cell engager prodrug targeting Integrin-β6 for the treatment of solid tumors
Abstract Number: 2927
Session: Immunology/Therapeutic Antibodies 2
Session Date, Time: Monday April 17, 1:30 - 5 p.m. ET
Location: Poster Section 23

The posters will also be available on Harpoon’s website following the presentations.

For more details about the AACR Annual Meeting, please visit:
https://www.aacr.org/meeting/aacr-annual-meeting-2023/

About Harpoon Therapeutics

Harpoon Therapeutics is a clinical-stage immuno-oncology company developing a novel class of T cell engagers that harness the power of the body’s immune system to treat patients suffering from cancer and other diseases. T cell engagers are engineered proteins that direct a patient’s own T cells to kill target cells that express specific proteins, or antigens, carried by the target cells. Using its proprietary Tri-specific T cell Activating Construct (TriTAC^®) platform, Harpoon is developing a pipeline of novel TriTACs initially focused on the treatment of solid tumors and hematologic malignancies. Harpoon has also developed a proprietary ProTriTAC™ platform, which applies a prodrug concept to its TriTAC platform to create a therapeutic T cell engager that remains inactive until it reaches the tumor. Harpoon’s third proprietary technology platform, extended release TriTAC-XR, is designed to mitigate cytokine release syndrome. For additional information about Harpoon Therapeutics, please visit www.harpoontx.com.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as “look forward,” “may,” “suggest,” “expect,” “potential,” “continued,” “further,” “will,” and similar expressions (as well as other words or expressions referencing future events, conditions or circumstances) are intended to identify forward-looking statements. These forward-looking statements are based on Harpoon Therapeutics’ expectations and assumptions as of the date of this press release. Each of these forward-looking statements involves risks and uncertainties that could cause Harpoon Therapeutics’ clinical development programs, future results or performance to differ significantly from those expressed or implied by the forward-looking statements. Forward-looking statements contained in this press release include, but are not limited to, statements about the expected progress, results, and plans pertaining to Harpoon Therapeutics’ clinical trials and other statements that are not historical fact. Many factors may cause differences between current expectations and actual results, including unexpected safety or efficacy data observed during clinical studies, preliminary data and trends may not be predictive of future data or results, may not demonstrate safety or efficacy or lead to regulatory approval by the FDA or other regulatory agencies, clinical trial site activation or enrollment rates that are lower than expected, changes in expected or existing competition, changes in the regulatory environment, the uncertainties and timing of the regulatory approval process, the timing and results of unexpected litigation or other disputes, and the sufficiency of Harpoon Therapeutics’ cash resources. These and other factors that may cause Harpoon Therapeutics’ actual results to differ from those expressed or implied in the forward-looking statements in this press release are discussed in Harpoon Therapeutics’ filings with the U.S. Securities and Exchange Commission, including under “Risk Factors” in Harpoon Therapeutics’ quarterly report on Form 10-Q for the quarter ended September 30, 2022, and future filings by Harpoon Therapeutics. Except as required by law, Harpoon Therapeutics assumes no obligation to update any forward-looking statements contained herein to reflect any change in expectations, even as new information becomes available.

Contacts:

Investors:
ICR Westwicke
Robert H. Uhl
Managing Director
858-356-5932
robert.uhl@westwicke.com

Media:
Uncapped Communications
Kerry Walton
303-588-0599
kerry.walton@uncappedcommunications.com