Harpoon presents interim results from Phase 1 evaluating single-agent HPN217

Harpoon Therapeutics presented updated interim data from its Phase 1 clinical trial evaluating single-agent HPN217 in relapsed/refractory multiple myeloma in a poster presentation at the 64th American Society of Hematology Annual Meeting and Exposition being held in person and virtually in New Orleans. HPN217 targets B-cell maturation antigen and is based on Harpoon’s proprietary Tri-specific T cell Activating Construct platform designed to recruit a patient’s own immune cells to kill tumor cells. The interim results, as of the data cut-off date of October 17, 2022, showed that HPN217 demonstrated continued evidence of clinical activity and a tolerable safety profile in heavily pre-treated patients with RRMM. HPN217 was active across a wide dose range, with 77% ORR observed across the highest step doses. A majority of responders had decreases in the serum BCMA biomarker by week two of treatment. Additionally, 86% of responders remain on study treatment with sustained response, with many responders on treatment for over a year. Three patients in the study were evaluated for minimal residual disease, and all three were MRD negative. sBCMA remained undetectable at 9 months in many responders who achieved very good partial response or better. Low-grade CRS occurred in 29% of patients across the highest step dose regimens and was seen primarily in the earliest doses. No Grade 3 or higher CRS or any immune effector cell associated neurotoxicity syndrome events have been observed.