On December 11, 2022 Harpoon Therapeutics, Inc. (Nasdaq: HARP), a clinical-stage immuno-oncology company developing novel T cell engagers, reported updated interim data from its Phase 1 clinical trial evaluating single-agent HPN217 in relapsed/refractory multiple myeloma (RRMM) in a poster presentation at the 64th American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting and Exposition being held in person and virtually in New Orleans (Press release, Harpoon Therapeutics, DEC 11, 2022, View Source [SID1234625070]). 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.

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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 (62 patients treated across fixed dose and step dose regimens). HPN217 was active across a wide dose range (2.15 to 24 mg), with 77% (10/13) ORR observed across the highest step doses (12 and 24 mg). A majority of responders had decreases in the serum BCMA biomarker (sBCMA, a marker correlated with disease prognosis) by week two of treatment. Additionally, 86% (18/21) 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 (MRD), and all three were MRD negative (<10-5). sBCMA remained undetectable at 9 months in many responders who achieved very good partial response (VGPR) or better.

Low-grade CRS occurred in 29% of patients across the highest step dose regimens (12% Grade 1 and 18% Grade 2) and was seen primarily in the earliest doses. No Grade 3 or higher CRS or any immune effector cell associated neurotoxicity syndrome (ICANS) events have been observed.

"The encouraging initial clinical activity with deepening and durable responses observed in patients who have received multiple prior lines of therapy, combined with a generally well-tolerated safety profile, suggest the investigational T cell engager HPN217 may offer meaningful clinical benefits for patients with relapsed/refractory multiple myeloma," said Al-Ola A. Abdallah, M.D., of University of Kansas Medical Center, a Principal Investigator in this study. "I look forward to continuing to study this promising drug candidate in these patients with advanced disease for whom there remains a significant unmet need for new treatment options."

"These data provide further validation of our proprietary TriTAC T cell engager platform, demonstrating robust clinical activity for HPN217 at higher doses, while maintaining tolerability in this heavily refractory patient population," said Luke Walker, M.D., Chief Medical Officer of Harpoon Therapeutics. "These data support our continued clinical development efforts, and we look forward to continuing dose optimization with ongoing patient enrollment in the Phase 1 trial expected to reach completion in the first half of 2023."

For more details about the ASH (Free ASH Whitepaper) Annual Meeting, please visit: View Source

The poster (publication #3240) will be available on Harpoon’s website following today’s presentation.

Conference Call and Webcast Details

Harpoon’s management will host a live call/webcast on Monday, December 12, 2022, at 4:30 ET/3:30 CT/1:30 PT, to review the interim results of its Phase 1 HPN217 clinical program and provide an update on other pipeline programs. The live call may be accessed by dialing 1-877-407-9039 for domestic callers and 1-201-689-8470 for international callers with conference ID code number 13734677. A live webcast of the call will be available from the Events and Presentations section of Harpoon’s website here and will be archived there shortly after the live event.

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.

In November 2019, Harpoon Therapeutics and AbbVie announced a licensing agreement and option to advance HPN217 and expand an existing discovery collaboration. Under the terms of the agreement, AbbVie may exercise its option to license HPN217 after completion of the Phase 1 clinical trial.

In March 2022, the FDA granted Fast Track designation to HPN217, underscoring its potential to address a serious unmet medical need for patients with relapsed, refractory multiple myeloma.

About the HPN217 Clinical Trial

HPN217 is being evaluated in an ongoing Phase 1, multicenter, open-label dose escalation study designed to evaluate safety, tolerability, pharmacokinetics (PK) and clinical activity in patients with relapsed/refractory multiple myeloma who have had at least three prior systemic treatments, including a proteasome inhibitor, an immunomodulatory drug and an anti-CD38 antibody, including patients with prior exposure to BCMA therapy. Primary objectives are characterization of safety, tolerability, PK and determination of the recommended Phase 2 dose.

As of the cutoff date on October 17, 2022, maximum tolerated dose has not yet been reached in the step-dose regimen. Assessment of the Q2 cohort dosing schedule is ongoing.

For additional information about the trial, please visit www.clinicaltrials.gov using the identifier NCT04184050.