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Prostate CancerMarch 2022Summary reviewed May 2026

A Daily Pill Shrank Tumors in 34% of Men With Advanced Prostate Cancer

GALAHAD tested niraparib, a daily oral PARP inhibitor pill, in 289 men with metastatic castration-resistant prostate cancer carrying DNA-repair gene defects. About a third of those with BRCA mutations had tumor shrinkage.

What the trial was testing

The GALAHAD enrolled 289 patients with prostate cancer. The study was sponsored by Janssen Research & Development and tracked outcomes across the full group of patients who matched the trial's eligibility profile.

It was initial testing (phase 2). Trials at this stage are designed to produce evidence regulators and physicians can act on — not just observations to follow up later.

What the results showed

34% tumor response in BRCA-mutated metastatic prostate cancer.

The Lancet Oncology · 2022 · NCT02854436

These findings — that in BRCA-mutated metastatic prostate cancer on niraparib — were published in the The Lancet Oncology and represent the headline result of the study.

Researchers tracked outcomes across 289 patients enrolled in the trial. The result was consistent enough across the group that the team felt confident reporting it.

What this means for patients

For patients with prostate cancer, this result changes the calculus on what to ask their care team about. Whether it changes day-to-day care depends on factors like disease subtype, prior treatments, and where the patient is in their care journey.

What you can do now

Niraparib (Zejula) is FDA-approved for ovarian cancer; for prostate cancer the related PARP inhibitors olaparib (Lynparza) and rucaparib (Rubraca) are FDA-approved when BRCA or other DNA-repair mutations are present. Genetic testing on the tumor is required. Ask an oncologist about testing.

Eligibility for the treatments mentioned above depends on specific test results and clinical history. Bring this summary, the trial name, and your most recent labs or pathology report to your next visit.