Harpoon Therapeutics to Present Updated Interim Clinical Data for TriTAC® HPN424 at the 2021 ASCO Annual MeetingManagement to host webcast and conference call to provide a pipeline update at 4 p.m. ET / 1 p.m. PT on June 4, 2021

SOUTH SAN FRANCISCO, Calif., May 19, 2021 (GLOBE NEWSWIRE) -- Harpoon Therapeutics, Inc. (NASDAQ: HARP), a clinical-stage immunotherapy company developing a novel class of T cell engagers, announced today that updated interim Phase 1 data for HPN424 for prostate cancer will be presented at the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting beginning on June 4,2021. The poster presentation will show interim data for HPN424 from its ongoing dose escalation Phase 1/2a clinical trial in patients with metastatic castration-resistant prostate cancer (mCRPC) and will be highlighted in a poster discussion session. HPN424 targets prostate-specific membrane antigen (PSMA) and is based on Harpoon’s proprietary Tri-specific T cell Activating Construct (TriTAC^®) platform designed to recruit a patient’s own immune cells to target and kill tumor cells.

Full details of the presentation are as follows:

Abstract/Poster Title: Results of an ongoing phase 1/2a dose escalation study of HPN424, a tri-specific half-life extended PSMA-targeting T cell engager, in patients with metastatic castration-resistant prostate cancer (mCRPC)
First Author: Johann S. De Bono, M.D., Ph.D.
Session: Genitourinary Cancer – Prostate, Testicular, and Penile
Date and Time: June 4, available on demand beginning at 9 a.m. ET
Abstract Number: 5013
Location: ASCO Meeting Library at https://meetinglibrary.asco.org/session/13632

A copy of the presentation will be available on the company’s website at https://ir.harpoontx.com/events-and-presentations.

Conference Call and Webcast

Harpoon’s management will host a webcast and conference call at 4 p.m. ET / 1 p.m. PT on Friday, June 4, 2021 to review the data and provide an update on other pipeline programs. The live call may be accessed by dialing 866-951-6894 for domestic callers or 409-216-0624 for international callers and using conference ID # 2657278.

A live webcast of the call will be available from the Events and Presentations section of the company’s website at https://ir.harpoontx.com/events-and-presentations and will be archived there shortly after the live event.

About the Phase 1/2a Clinical Trial for HPN424

This Phase 1/2a trial is a multicenter, open-label study designed to evaluate the safety, tolerability, pharmacokinetics and activity of HPN424 in patients with mCRPC who are progressing. The trial is titled, “Study of HPN424 in Patients with Advanced Prostate Cancer.” For additional information about the trial, please visit www.clinicaltrials.gov using the identifier NCT03577028.

The initial phase of the trial is a dose escalation phase, with the goal of determining a recommended dose for the expansion phase of the trial. HPN424 is being administered to patients once weekly by intravenous infusion. The primary outcome measures are an assessment of safety and tolerability, pharmacokinetics, and determination of a dose for the expansion phase of the trial. Secondary endpoints include overall response rate, progression free and overall survival, and duration of response. The expansion portion of the trial will further evaluate the safety and activity of HPN424 in patients with mCRPC.

About Harpoon Therapeutics

Harpoon Therapeutics is a clinical-stage immunotherapy 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. HPN424 targets PSMA and is in a Phase 1/2a trial for metastatic castration-resistant prostate cancer. HPN536 targets mesothelin and is in a Phase 1/2a trial for cancers expressing mesothelin, initially focused on ovarian and pancreatic cancers. HPN217 targets BCMA and is in a Phase 1/2 trial for relapsed, refractory multiple myeloma. HPN328 targets DLL3 and is in a Phase 1/2 trial for small cell lung cancer and other DLL3-associated tumors. 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. For additional information about Harpoon Therapeutics, please visit www.harpoontx.com.

Cautionary Note on 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 “may,” “will,” “expect,” “plan,” “potential,” “anticipate,” “target,” “estimate,” “intend” 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 progress, timing, scope and anticipated results of preclinical and clinical trials, the timing of the presentation of data, the association of data with potential treatment outcomes, the development and advancement of product candidates, anticipated 2021 development milestones for its product candidates and the timing thereof, the anticipated potential impacts to Harpoon Therapeutics’ business from the ongoing COVID-19 pandemic, 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, clinical trial site activation or enrollment rates that are lower than expected, unanticipated or greater than anticipated impacts or delays due to COVID-19, 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’ annual report on Form 10-K for the year ended December 31, 2020 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:

Harpoon Therapeutics, Inc.
Georgia Erbez
Chief Financial Officer
650-443-7400
media@harpoontx.com

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