Harpoon Therapeutics Presents Interim Phase 1 Data from an Ongoing Dose Escalation Trial for the PSMA-targeting TriTAC® HPN424 at the ASCO20 Virtual Scientific Program
- The on-going dose escalation Phase 1 study has enrolled 44 patients with progressive, metastatic castration-resistant prostate cancer in 11 cohorts.
- Initial safety data showed that HPN424 is generally well-tolerated, and cytokine-related adverse events have been transient and manageable.
- Pharmacokinetic data supports weekly dosing and pharmacodynamic data supports T cell activation and target engagement consistent with the expected mechanism of action.
- Signals of clinical activity include multiple patients remaining on study for more than 24 weeks, and serum PSA declines.
- Management to host webcast and conference call to review the interim Phase 1 data and provide a pipeline update today at
4 p.m. ET/ 1 p.m. PT
The presentation highlights interim results in 44 patients across 11 dosing cohorts treated with HPN424 from the ongoing dose escalation portion of a Phase 1 clinical trial. As of the
- HPN424 is generally well-tolerated and support long-term treatment, and cytokine-related adverse events have been transient and manageable.
- Pharmacokinetic data support weekly dosing and pharmacodynamic data support T cell activation as measured by reduction in circulating tumor cells, increased serum cytokine levels and T cell margination after HPN424 administration.
- Early signals of clinical activity include eight patients who remained on study treatment for greater than 24 weeks. In addition, eight patients exhibited decreases in PSA levels compared to baseline, including two who showed PSA (prostate-specific antigen) reductions of at least 50%.
“We are particularly encouraged by data supporting the predicted mechanism of action of HPN424, and the early signs of clinical activity in this heavily pretreated population,” stated
“We are excited to share the first clinical data from our HPN424 clinical program. Early data suggest that this novel, half-life extended T cell engager can be administered safely. Several patients remained on treatment for 24 weeks or more, which is notable in this late-stage cancer population,” said
Trial Design and Interim Results from the HPN424 Phase 1 Clinical Trial
This Phase 1 trial is a multicenter, open-label study designed to evaluate the safety, tolerability, pharmacokinetics and activity of HPN424 in patients with mCRPC who are progressing at the time of enrollment and have had at least two prior systemic treatments for metastatic disease. 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 3x3 design when Grade 2 toxicity was observed. HPN424 is being administered to patients once weekly by intravenous infusion. 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 assessments include PSA, CT and bone scans performed every 9 weeks.
As of the
HPN424 demonstrated dose proportional increase in Cmax and AUC with a current estimate of median T1/2 of 24.9 hours (range: 9.0 – 312 hours). Dose-dependent, transient increases in peripheral cytokine and chemokine levels were observed, including increases in interleukin 6, peaking at 5 hours post infusion and returning to baseline 24 hours post-administration. Maximal cytokine/chemokine levels attenuated with each successive dose within six weeks. Baseline circulating tumor cells (CTC) ranged from 0-160 cells/ml of whole blood. Reduction in CTC was seen in 12 of 27 patients with evaluable CTC compared to baseline.
Eight of 26 patients (31%) with at least 24 weeks in follow-up remained on study beyond 24 weeks. Eight patients showed a PSA decline from baseline ranging from -4 to -76%, including patients with initial rises in PSA after study entry. Two patients had confirmed PSA partial responses with declines of 50% or greater.
Patients continue to be enrolled in the escalation phase of the trial, with a goal to identify a dose for an expansion phase planned for the second half of 2020. The expansion phase of the trial will further evaluate the safety and activity of HPN424 in patients with mCRPC. The trial is titled, “A Phase 1 Open-label, Multicenter, Dose Escalation and Dose Expansion Study of the Safety, Tolerability, and Pharmacokinetics of HPN424 in Patients with Advanced Prostate Cancer Refractory to Androgen Therapy”. For additional information about the trial, please visit www.clinicaltrials.gov using the identifier NCT03577028.
Conference Call and Webcast Today
Harpoon’s management team will host a webcast and conference call today at
877-407-9716 for domestic callers
201-493-6779 for international callers
A live webcast of the call will be available from the Events and Presentations section of the company’s website at https://ir.harpoontx.com/events-and-presentations and will be archived there shortly after the live event.
Cautionary Note on Forward-looking Statements
This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as “may,” “will,” “expect,” “plan,” “anticipate,” “target,” “estimate,” “intend” and similar expressions (as well as other words or expressions referencing future events, conditions or circumstances) are intended to identify forward-looking statements. These forward-looking statements are based on Harpoon Therapeutics’ expectations and assumptions as of the date of this press release. Each of these forward-looking statements involves risks and uncertainties that could cause Harpoon Therapeutics’ clinical development programs, future results or performance to differ significantly from those expressed or implied by the forward-looking statements. Forward-looking statements contained in this press release include, but are not limited to, statements about the progress, timing, scope and anticipated results of clinical trials, the timing of the presentation of data, the association of data with potential treatment outcomes, the development and advancement of product candidates, and the timing of development milestones for product candidates. Many factors may cause differences between current expectations and actual results, including unexpected safety or efficacy data observed during clinical studies, clinical trial site activation or enrollment rates that are lower than expected, unanticipated or greater than anticipated impacts or delays due to COVID-19, changes in expected or existing competition, changes in the regulatory environment, the uncertainties and timing of the regulatory approval process, and unexpected litigation or other disputes. Other factors that may cause Harpoon Therapeutics’ actual results to differ from those expressed or implied in the forward-looking statements in this press release are discussed in Harpoon Therapeutics’ filings with the
Chief Financial Officer
Source: Harpoon Therapeutics