Harpoon Therapeutics announced the U.S. Food and Drug Administration (FDA) has granted Orphan Drug Designation for HPN217 for the treatment of multiple myeloma. HPN217, a tri-specific T cell activating recombinant protein construct (TriTAC?) targets B-cell maturation antigen (BCMA), a well-validated antigen expressed on malignant multiple myeloma cells. Harpoon has four drug product candidates in clinical development for the treatment of solid and hematologic malignancies based on its proprietary TriTAC platform.

“Orphan Drug Designation for multiple myeloma represents a significant milestone in the development of HPN217 and recognizes its potential to address a significant unmet medical need for the patients suffering from this condition,” said Jerry McMahon, Ph.D., President and Chief Executive of Harpoon Therapeutics. “I am pleased with the clinical progress we are making with this program and we are planning to present interim data from the ongoing Phase 1/2 dose escalation trial later this year.”

The FDA's Orphan Drug Designation program provides orphan status to drugs defined as those intended for the safe and effective treatment, diagnosis or prevention of rare diseases that affect fewer than 200,000 people in the United States. Orphan Drug Designation qualifies the sponsor of the drug for certain development incentives, including tax credits for qualified clinical testing, prescription drug user fee exemptions and seven-year marketing exclusivity upon FDA approval.

In April 2020, Harpoon announced dosing of the first patient with HPN217 (BCMA TriTAC) in a Phase 1/2 clinical trial focused on relapsed/refractory multiple myeloma (RRMM). HPN217 is covered by a global development and option agreement with AbbVie. Dose escalation for HPN217 in the Phase 1/2 clinical trial is progressing rapidly. HPN217 has been well tolerated, and no DLTs had been observed as of the most recent December 1, 2020 data cutoff date. A presentation of interim data is anticipated in 2021, with initiation of a dose expansion cohort in the second half of 2021.