HARPOON THERAPEUTICS DOSES FIRST PATIENT WITH A MESOTHELIN-TARGETING T CELL ENGAGER (HPN536) IN PHASE 1/2A CLINICAL TRIAL FOR OVARIAN AND OTHER SOLID TUMOR CANCERS

HPN536 is the second TriTAC T cell engager to enter clinical development from the Harpoon pipeline

Trial initiated at Sarah Cannon Research Institute in Nashville, Tenn. - a leading drug development organization

SOUTH SAN FRANCISCO, Calif., April 18, 2019 (GLOBE NEWSWIRE) -- Harpoon Therapeutics, Inc. (NASDAQ: HARP), a clinical-stage immunotherapy company developing a novel class of T cell engagers, announced today that the first patient has been dosed with HPN536 in a Phase 1/2a clinical trial initially focused on ovarian cancer. HPN536 targets mesothelin, which is expressed on malignant cells of ovarian and pancreatic carcinoma, mesothelioma, non-small cell lung cancer and breast cancer. HPN536 is Harpoon’s second product candidate to enter the clinic and is based on Harpoon’s proprietary Tri-specific T cell Activating Construct (TriTAC™) platform that has been designed to recruit a patient’s own immune cells to destroy tumors.

“We are pleased with the rapid progress of our clinical programs, based on our proprietary TriTAC platform, with patient dosing now underway for our second product candidate, HPN536, that targets mesothelin. The dose escalation portion of the trial will focus on patients with ovarian cancer, where mesothelin is over expressed in a high percentage of patients. HPN536 is a targeted, off the shelf immunotherapy that has been optimized for delivery to solid tumors and designed to provide a novel way to engage a patient’s own immune cells to fight cancer for patients who have limited treatment options.”

Natalie Sacks, M.D., Chief Medical Officer of Harpoon Therapeutics

“We are excited to participate in this trial of such a promising agent that will hopefully benefit patients with ovarian cancer and other mesothelin-expressing solid tumors such as pancreatic and lung cancers.”

Howard A. Burris, M.D., President and Chief Medical Officer for Sarah Cannon

Sarah Cannon Research Institute at Tennessee Oncology in Nashville, Tenn., is a participating site in the trial.

“Harpoon’s unique approach to T cell engagement may offer appealing advantages over other T cell therapies and, in addition, provide meaningful efficacy with improved patient management based on the convenience of once weekly intravenous dosing. We look forward to exploring this target, where CAR (chimeric antigen receptor) expressing T cells targeting mesothelin have shown early evidence of clinical benefit in data presented at the American Association of Cancer Research Annual Meeting in Atlanta earlier this month.”

Gerald McMahon, Ph.D., President and CEO of Harpoon

About the Phase 1/2a Trial for HPN536

HPN536 is a 50-kD single polypeptide that contains three binding domains - to human mesothelin, human serum albumin and human CD3.The Phase 1/2a trial is a multicenter, open-label study designed to evaluate the safety, tolerability, pharmacokinetics and activity of HPN536 in up to 80 patients with mesothelin-expressing cancers. The Phase 1 portion of the trial is a dose escalation phase, with the goal of determining a dose for additional clinical investigations. This first phase is expected to enroll up to 20 patients, initially focusing on patients suffering from ovarian cancer. HPN536 will be administered to patients once weekly by intravenous infusion. The primary outcome measure will be an assessment of safety and tolerability, and determination of a dose for the Phase 2 portion of the trial. Following dose escalation, the study will further evaluate the safety and activity of HPN536 in up to three additional parallel cohorts of 20 patients each with ovarian, pancreatic and mesothelioma cancer. For additional information about the trial, please visit clinicaltrials.gov using the identifier NCT03872206.

Please visit Harpoon's website for further information.