Harpoon Therapeutics Presents Interim Clinical Data from its Ongoing Phase 1/2 Study and New Preclinical Results for BCMA-targeting TriTAC® HPN217 at the 63rd ASH Annual Meeting and Exposition
Encouraging clinical activity in higher dose cohorts with 63% ORR and 88% DCR reported in 2150 µg/week cohort with 8 disease evaluable patients with relapsed/refractory multiple myeloma
Tolerable safety profile with cytokine release syndrome (all Grade 1 or 2) observed in 9 of 37 patients (24%)
Patient enrollment and dose escalation is ongoing to define the RP2D and MTD
Management to host webcast and conference call to review the HPN217 data presented at ASH and provide a pipeline update on
- HPN217 is generally well tolerated with one dose limiting toxicity (DLT) reported of Grade 4 AST elevation that resolved, MTD has not been reached
- HPN217 is clinically active at higher dose levels with clinical benefit, disease control rate (DCR) of 88%, demonstrated in 7 of 8 disease evaluable patients in the 2150 µg/week cohort
- 2 stringent complete responses (SCRs) have been observed, one in each of the higher dose 2150 and 2860 µg/week cohorts
- Transient and manageable cytokine release syndrome (CRS) reported in 9 of 37 patients (24%) were all Grade 1 or 2
- Introduction of step dose regimens has allowed for the administration of higher target doses, currently at 3240 µg/week
“These encouraging data for HPN217 demonstrate robust clinical activity at higher doses, strong target engagement, and a manageable safety profile in this heavily refractory patient population,” said
Interim Results from the Ongoing HPN217 Phase 1/2 Trial Presented at ASH
This Phase 1/2 trial is a multicenter, open-label study designed to evaluate safety, tolerability, pharmacokinetics and clinical activity in patients with R/R MM who have had at least three prior systemic treatments including a proteasome inhibitor, an immunomodulatory drug and an anti-CD38 antibody. The initial ongoing phase of the trial is dose escalation, with the goal of determining a recommended dose for the expansion phase. The escalation phase began with single patient cohorts and transitioned to a 3+3 design when Grade 2 toxicity was observed. HPN217 is being administered to patients once weekly by intravenous infusion and the primary outcome measures are an assessment of safety and tolerability, pharmacokinetics and pharmacodynamics. Secondary endpoints include duration of response, progression free and overall survival. Tumor assessment is based on
As of the
Clinical benefit was observed in the patients receiving higher doses. In 8 disease evaluable patients enrolled at 2150 µg/week an ORR of 63% was reported (5/8 patients) consisting of 1 stringent CR, 1 VGPR, and 3 PRs. including 1 patient with prior BCMA-targeting therapy exposure. The disease control rate, (DCR), was 88% based on 7/8 patients. For the 2860 µg/week cohort consisting of 5 evaluable patients, the ORR was 2/5 (40%) including a second stringent CR, with a DCR of 60%. As of the data cutoff, all responders remained on study treatment.
HPN217 demonstrated a dose proportional increase in Cmax and AUC with a median serum half-life of 74 hours (range of 38 – 197 hours), confirming half-life extension. Half-life, clearance rate, and volume of distribution were dose-independent, suggesting linear PK kinetics. Pharmacodynamic analysis shows a dose-dependent, transient increase in serum cytokines and chemokines (IL-6, IL-8, IL-10, TNFα).
Patients continue to be enrolled in the escalation phase of the trial, with a goal to identify a recommended Phase 2 dose for an expansion phase. The expansion phase of the trial will further evaluate the safety and activity of HPN217 in patients with R/R MM. This trial is titled, “A Phase 1/2 Open-label, Multicenter, Dose Escalation and Dose Expansion Study of the Safety, Tolerability, and PK of HPN217 in Patients With R/R MM”. For additional information about the trial, please visit www.clinicaltrials.gov using the identifier NCT04184050.
Preclinical Data for HPN217 Presented at ASH
The poster titled “The Effects of BCMA Expression, Soluble BCMA, and Combination Therapeutics on the Anti-Tumor Activity of HPN217, a BCMA-Targeting Tri-Specific T Cell Engager Against Multiple Myeloma” showcased translational studies to examine factors that may impact the therapeutic efficacy of HPN217. These factors include the target BCMA, in membrane-bound or soluble form, and concomitant or combination therapeutics such as gamma secretase inhibitor (GSI) and dexamethasone.
Preclinical data from this presentation for HPN217 demonstrated:
- In a patient derived cell culture system, HPN217 was able to mediate multiple myeloma cell killing by autologous T cells in 80% of the cultures
- Presence of dexamethasone appeared to have limited effect on the anti-tumor activity of HPN217-redirected T cells
- GSI increased the expression of BCMA on multiple myeloma cells and enhanced the effect of HPN217
Preclinical evaluation of HPN217 in combination with approved and experimental multiple myeloma therapeutics is ongoing
Conference Call and Webcast Details
Harpoon’s management will host a webcast and conference call on
A live webcast of the call will be available from the Events and Presentations section of the company’s website here and will be archived there shortly after the live event.
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. HPN424 targets PSMA and is in a Phase 1/2a trial for metastatic castration-resistant prostate cancer. 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. HPN328 targets DLL3 and is in a Phase 1/2 trial for small cell lung cancer and other DLL3-associated tumors. Harpoon has also developed a proprietary ProTriTAC™ platform, which applies a prodrug concept to its TriTAC platform to create a therapeutic T cell engager that remains inactive until it reaches the tumor. The company’s third proprietary technology platform, extended release TriTAC-XR, is designed to mitigate cytokine release syndrome. For additional information about
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Chief Financial Officer
Source: Harpoon Therapeutics