J&J's Halda-derived prostate cancer drug shows 75% response in early Phase 1 trial

Johnson & Johnson's recent $3 billion purchase of Halda Therapeutics added an oral prostate cancer candidate, JNJ-6143, to its pipeline. The drug targets a cancer-specific protein to trigger cell death and is being tested in men with metastatic castration-resistant prostate cancer.

In the first-in-human portion of a Phase 1/2 study presented at ESMO 2026, 12 of the 16 patients with measurable disease achieved either a complete or partial tumor shrinkage, yielding a confirmed overall response rate of 75 percent. Analysts described the outcome as "immaculate."

The trial is dose-escalating, evaluating daily doses from 12.5 mg to 150 mg, and aims to enroll up to 190 patients. Results from the ongoing study will inform the next phase and potential regulatory discussions.