Investigational Drug
JNJ-78278343
TrialFetch AI Analysis
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Overview
Pasritamig (JNJ-78278343) is an investigational antibody being studied for metastatic castration-resistant prostate cancer (mCRPC). Human results are available from an early-phase study of pasritamig alone and a preliminary study combining it with docetaxel. These studies do not yet establish whether it improves survival or outcomes compared with existing treatment. (pmc.ncbi.nlm.nih.gov)
Mechanism of action
Pasritamig is a bispecific T-cell engager: it binds human kallikrein 2 (KLK2) on prostate cancer cells and CD3 on T cells, aiming to direct the T cells against the cancer cells. (pmc.ncbi.nlm.nih.gov)
Efficacy
- Pasritamig alone: In a phase 1 study of 174 treated patients, 14 of 33 patients (42.4%) in the recommended-dose efficacy group had at least a 50% decline in prostate-specific antigen (PSA50); 12 of 33 (36.4%) had a confirmed PSA50 response. Median radiographic progression-free survival in that group was 7.85 months. Across all dose groups, the objective tumor response rate was 7 of 84 (8.3%) among patients with measurable disease. (pmc.ncbi.nlm.nih.gov)
- With docetaxel: A preliminary phase 1b conference abstract reported confirmed PSA50 responses in 33 of 51 patients (64.7%) and confirmed PSA declines of at least 90% in 18 of 51 (35.3%). The single-arm design cannot show how much of this activity was attributable to pasritamig rather than docetaxel. (ascopubs.org)
Safety
In the 45-patient recommended-dose safety group receiving pasritamig alone, the most frequent treatment-related events were infusion reactions (24.4%), fatigue (15.6%), and cytokine release syndrome (8.9%; all grade 1). None discontinued treatment because of a treatment-related event. In the 51-patient combination study, 27.5% had grade 3 or higher treatment-related events, 13.7% discontinued treatment following an adverse event, and no cytokine release syndrome was reported. These findings remain limited by the small, early-phase study populations. (pmc.ncbi.nlm.nih.gov)
Further reading
Last updated: Sep 2026
Active trials using JNJ-78278343
Found 6 active trials using this drug:
TrialFetch AI summary: Patients with metastatic castration-resistant prostate adenocarcinoma involving bone and/or lymph nodes, without clear visceral metastases, receive pasritamig plus JNJ-86974680. Pasritamig is a KLK2×CD3 bispecific antibody that redirects T cells against prostate cancer cells; JNJ-86974680 is an oral A2A receptor antagonist intended to counter adenosine-mediated immune suppression.
ClinicalTrials.gov ID: NCT07319871
TrialFetch AI summary: Patients with metastatic castration-resistant prostate adenocarcinoma who have progressed after one or two androgen receptor pathway inhibitors and have not received chemotherapy for prostate cancer are randomized to docetaxel plus pasritamig or docetaxel with prednisone. Pasritamig is an investigational KLK2×CD3 bispecific antibody that redirects T cells against prostate cancer cells.
ClinicalTrials.gov ID: NCT07225946
TrialFetch AI summary: Patients with metastatic castration-resistant prostate adenocarcinoma involving bone and/or lymph nodes, without clear visceral metastases, are eligible after progression on an androgen-receptor pathway inhibitor and generally after appropriate life-prolonging therapies. They receive best supportive care plus either pasritamig, an investigational KLK2×CD3 bispecific antibody that redirects T cells against prostate cancer, or placebo.
ClinicalTrials.gov ID: NCT07164443
TrialFetch AI summary: Patients with metastatic castration-resistant prostate adenocarcinoma, ECOG performance status 0–1, and ongoing castration receive pasritamig (JNJ-78278343), a KLK2×CD3 T-cell–redirecting bispecific antibody, plus ARX517 (JNJ-95298177), a PSMA-targeted antibody–drug conjugate with a tubulin-inhibiting payload.
ClinicalTrials.gov ID: NCT07082920
TrialFetch AI summary: Adults with metastatic castration-resistant prostate adenocarcinoma, PSA ≥2 ng/mL, and ECOG performance status 0–1 receive JNJ-87189401, a PSMA×CD28 bispecific antibody designed to costimulate T cells, plus pasritamig (JNJ-78278343), a KLK2×CD3 bispecific antibody designed to recruit T cells against prostate cancer cells. Ongoing androgen deprivation is required unless the patient has undergone orchiectomy.
ClinicalTrials.gov ID: NCT06095089
TrialFetch AI summary: Adults with metastatic prostate adenocarcinoma and ECOG 0–1 are eligible; most cohorts require castration-resistant disease and prior androgen receptor pathway inhibitor treatment, while a separate apalutamide cohort enrolls patients with hormone-sensitive disease. The study combines pasritamig, an investigational KLK2×CD3 bispecific antibody that redirects T cells to prostate cancer cells, with the investigational PD-1 inhibitor cetrelimab, a taxane, or an androgen receptor pathway therapy.
ClinicalTrials.gov ID: NCT05818683
