J&J's JNJ-6143 Shows 75% Response Rate in Pretreated Advanced Prostate Cancer

Johnson & Johnson (JNJ) reported encouraging Phase 1 data for JNJ-6143, an investigational oral therapy for advanced prostate cancer, showing significant anti-tumor activity in heavily pretreated patients. Among 16 patients with measurable disease, 75% achieved a confirmed complete or partial response per RECIST criteria. At the 50 mg dose level, 77% of patients had a confirmed PSA decline of at least 50%, and 48% achieved reductions of at least 90%. Most treatment-related adverse events were mild to moderate. JNJ-6143, formerly HLD-0915, is a once-daily oral RIPTAC small molecule that targets BRD4 and the androgen receptor to trigger cancer cell death. It is the first RIPTAC compound to enter clinical studies and is being evaluated in Phase 1 and Phase 2 trials in metastatic prostate cancer. J&J completed its acquisition of Halda Therapeutics in December 2025, adding the drug and platform to its oncology portfolio. JNJ closed Friday's regular trading at $263.81, down $3.80 or 1.42%.