Johnson & Johnson Pasritamig Combo Achieves 64.7% ≥50% PSA Reduction in Prostate Cancer
Johnson & Johnson’s Phase 1b study of pasritamig combined with docetaxel in mCRPC patients showed 64.7% achieved ≥50% PSA reductions and 39.2% had ≥90% reductions, with taxane-naïve patients reaching 75% and 53.6% respectively. Safety profile matched docetaxel alone, enabling outpatient administration and Phase 3 planning.
1. Study Design and Objectives
The open-label Phase 1b trial enrolled 51 metastatic castration-resistant prostate cancer patients who progressed after androgen receptor inhibitor therapy. Pasritamig was administered with standard docetaxel every three weeks in an outpatient setting to evaluate safety and identify a recommended regimen for Phase 2/3 development.
2. Efficacy Results
Overall, 64.7% of patients achieved at least a 50% reduction in prostate-specific antigen levels and 39.2% achieved at least a 90% reduction. Among taxane-naïve patients, PSA reductions of ≥50% and ≥90% rose to 75.0% and 53.6% respectively, with bone-only disease patients showing up to 88.2% and 76.5% responses.
3. Safety Profile
The combination exhibited a safety profile consistent with docetaxel monotherapy, with no new signals and no cytokine release syndrome. Common treatment-related adverse events included fatigue (60.8%), alopecia (41.2%), diarrhea and nausea (31.4% each), while grade 3+ events were largely attributable to docetaxel (29.4%) versus pasritamig (2%).
4. Next Steps and Regulatory Designations
Based on these results, Johnson & Johnson plans two Phase 3 trials: one assessing pasritamig monotherapy and another with docetaxel combination in metastatic castration-resistant prostate cancer. Pasritamig has also received Breakthrough Therapy Designation in China and Fast Track status from the U.S. FDA, supporting accelerated development.