Harpoon Therapeutics Doses First Patient with HPN217, a BCMA Targeting TriTAC, for Multiple Myeloma

Harpoon Therapeutics, Inc. recently announced the first patient has been dosed with HPN217 in a Phase 1/2 clinical trial focused on relapsed, refractory multiple myeloma (RRMM). HPN217 is being developed under a global license and option agreement with AbbVie Inc. and dosing of the first patient in a clinical trial has triggered a $50-million milestone payment to Harpoon. HPN217 targets B-cell maturation antigen (BCMA), a well-validated antigen expressed on malignant multiple myeloma calls. HPN217 is Harpoon’s third product candidate to enter the clinic 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 destroy tumors.

“The initiation of a clinical trial for our third product candidate is another significant milestone for Harpoon and demonstrates the outstanding progress we are making in advancing our innovative oncology pipeline,” said Gerald McMahon, PhD, President and CEO of Harpoon Therapeutics. “The $50-million milestone payment adds additional financial resources to support the HPN217 program and other development activities that we are conducting. The first patient was treated at Colorado Blood Cancer Institute and the Sarah Cannon Research Institute at HealthONE’s Presbyterian St. Luke’s Medical Center. We are excited to be advancing HPN217 in the clinic and look forward to reporting our progress as this program matures.”

“Therapeutic choices for patients with RRMM are limited, and there is a need for additional therapeutic options,” said Natalie Sacks, MD, Chief Medical Officer of Harpoon. “Our non-clinical data suggest that HPN217 has substantial anticancer activity and provide the rationale to investigate its potential benefit as an effective immunotherapy for patients with multiple myeloma.”

This Phase 1/2 trial is a multicenter, open-label study designed to evaluate the safety, tolerability, pharmacokinetics and activity of HPN217 in patients with RRMM. The Phase 1 portion of the trial is a dose escalation phase, with the goal of determining a recommended dose for the Phase 2 portion of the trial. HPN217 will be administered to patients once weekly by intravenous infusion. The primary outcome measures will be an assessment of safety and tolerability, pharmacokinetics, and determination of a dose for the Phase 2 portion of the trial. Secondary endpoints include overall response rate, progression free and overall survival, and duration of response.

The Phase 2 portion of the trial will further evaluate the safety and activity of HPN217 in patients with RRMM. The trial is titled, A Phase 1/2 open-label, multicenter, dose escalation and dose expansion study of the safety, tolerability, and pharmacokinetics of HPN217 in patients with relapsed/refractory multiple myeloma. For additional information about the trial, visit www.clinicaltrials.gov using the identifier NCT04184050.

In November 2019, Harpoon entered into a Development and Option Agreement with AbbVie pursuant to which Harpoon granted AbbVie an option to license worldwide exclusive rights to HPN217. Harpoon will be responsible for developing HPN217 through a Phase 1/2 clinical trial. Upon exercise of the option, AbbVie would be responsible for all future clinical development, manufacturing and commercialization activities.  The licensing option for HPN217 may be exercised at any time up to the completion of the Phase 1/2 clinical trial.  The Development and Option Agreement represents a potential transaction value of up to $510 million in upfront, option and milestone payments, plus royalties on global commercial sales. In November 2019, Harpoon also expanded its existing discovery collaboration agreement by up to six additional targets for a total of eight targets.  AbbVie has the right to select four targets, representing a deal transaction value of approximately $1.2 billion plus royalties, with an option to select up to four additional targets. Harpoon would be eligible to receive up to $310 million plus royalties for each additional target selected. Harpoon received an initial upfront payment of $50 million in November 2019, with an additional $50 million payment due upon dosing the first patient with HPN217.

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. Harpoon’s first product, HPN424, targets PSMA and is in a Phase 1 trial for metastatic castration-resistant prostate cancer. Harpoon’s second product, 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. For more information, visit www.harpoontx.com.