On December 11, 2023 Harpoon Therapeutics, Inc. (Nasdaq: HARP), a clinical-stage immunotherapy company developing novel T cell engagers, reported data from the Phase 1 study of HPN217 in patients with RRMM in an oral presentation at the 65th American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting and Exposition in San Diego (Press release, Harpoon Therapeutics, DEC 11, 2023, View Source [SID1234638446]). Harpoon also announced the selection of 12 mg as the HPN217 RP2D.
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During the trial, 97 patients with RRMM who had received at least three prior therapies were enrolled across 15 dose escalation cohorts and three expansion regimens. As of the data cut-off of October 17, 2023, the data demonstrated:
Clinical activity across a wide dose range (2.15 mg to 24 mg). The maximum tolerated dose (MTD) was not reached at the target dose using a step up approach.
Optimal activity and safety profile was seen at 12 mg, which was declared the RP2D.
The Overall Response Rate (ORR) across 12 mg cohorts was 63% (12/19, 95% CI: 38, 84). In addition, the depth of response was most significant at 12 mg, with 53% (10/19) of patients having a Very Good Partial Response (VGPR) or better.
The median time to first response in the 12 mg and 24 mg cohort was 1.2 months, and the median duration of response for all responders was 20.5 months as of the data cutoff date. Out of all the responders, 58% (22/38) remain on treatment.
In the 12 mg and 24 mg cohorts, nine patients were previously exposed to BCMA-targeting agents, and six of those patients responded to the HPN217 treatment.
The incidence of cytokine release syndrome (CRS) was lowest (16%) in the 12 mg cohorts, all Grade 1-2. No immune effector cell associated neurotoxicity syndrome (ICANS) events were observed at the 12 mg dose.
"The data presented at ASH (Free ASH Whitepaper) today demonstrates that HPN217 has the potential to provide a meaningful benefit for patients with relapsed/refractory multiple myeloma, even in patients with prior anti-BCMA therapy," said Sumit Madan, M.D., Hematologist and Oncologist at Banner MD Anderson Cancer Center and Associate Professor (Adj) of Myeloma and Lymphoma at UT MD Anderson Cancer Center. "The low rate of CRS seen in this study is noteworthy and can help enable future studies of HPN217 in combination and in earlier lines of therapy."
"The HPN217 Phase 1 data set represents important progress for the program and validates the potential of HPN217 to deliver a wider therapeutic index. We observed a compelling 63% response rate in patients treated with the 12 mg target dose, with only a 16% rate of CRS," said Luke Walker, M.D., Chief Medical Officer for Harpoon Therapeutics. "These data and our interactions with the FDA have enabled us to declare a RP2D that can be used to support further clinical development."
For more details about the ASH (Free ASH Whitepaper) Annual Meeting, please visit: View Source
For additional information about the trial, please visit www.clinicaltrials.gov using the identifier NCT04184050.
The presentation will also be available on Harpoon’s website under Publications following the session.
About HPN217
HPN217 targets B-cell maturation antigen (BCMA) 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 kill tumor cells. BCMA, a clinically validated target, is a tumor necrosis factor receptor super family member and is a receptor protein expressed on nearly all multiple myeloma cells.