Bispecific Combo Shows Prostate Cancer Responses
Early phase 1 data for a two-drug regimen reported responses in men with metastatic castration-resistant prostate cancer.
Updated on Nov. 7, 2026 in Cancer
Phase 1 results for JNJ-87189401 combined with pasritamig were presented at the 2026 SITC Annual Meeting, showing PSA responses in patients with metastatic castration-resistant prostate cancer. The study, identified as NCT06095089, enrolled a recommended phase 2 regimen cohort of 15 patients.
Why it matters
The data suggest the combination may reduce prostate-specific antigen levels in a heavily pretreated population with limited options. Researchers are now evaluating pasritamig in a phase 3 trial in late-line disease.
The phase 1 cohort of 15 patients with a median of 4 prior therapy lines reported PSA50 responses in 73.3% and PSA90 responses in 46.7%, with no grade 3 or higher treatment-related adverse effects at the recommended dose. Longer follow-up and phase 3 results for the related KLK2-comPAS trial have not yet been reported.
The players
Pasritamig
Pasritamig is a KLK2 x CD3 bispecific antibody being developed for metastatic castration-resistant prostate cancer and is also under evaluation in a phase 3 trial.
JNJ-87189401
JNJ-87189401 is a PSMA x CD28 T-cell engager tested in combination with pasritamig in the phase 1 study.
The details
JNJ-87189401, a PSMA-directed T-cell engager, was given subcutaneously at 200 mg every 6 weeks alongside pasritamig, a KLK2-directed bispecific, given intravenously at 300 mg every 6 weeks. Cytokine release syndrome occurred in 20.0% of patients, all grade 1, and no immune effector cell-associated neurotoxicity syndrome was observed.
Timeline
2026: Phase 1 data presented at the SITC Annual Meeting.
Clinical Pipeline
The early combination data sit ahead of the phase 3 KLK2-comPAS trial, which is testing pasritamig with or without JNJ-87189401 in late-line metastatic castration-resistant prostate cancer. Results from that trial will determine whether the phase 1 response signal holds at scale.
For men with metastatic castration-resistant prostate cancer whose disease has progressed after multiple therapies, early trial data suggest a new combination approach may be an option under study. Access to investigational regimens depends on enrollment in clinical trials rather than general availability.
The takeaway
Early trial signals in heavily pretreated prostate cancer warrant follow-up from larger studies before changing care. Patients interested in investigational options should discuss trial eligibility with their oncology team.
Further reading
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Source note: This article includes information reported by OncLive.
