(Prostate Cancer) Is Niraparib Effective?

On February 4, 2022, Dr. Matthew R. Smith and colleagues from Massachusetts General Hospital Cancer Center published results in The Lancet Oncology from the Phase 2 clinical trial (NCT02854436) evaluating the efficacy and safety of oral PARP inhibitor Niraparib monotherapy in previously treated, DNA repair gene-deficient, castration-resistant metastatic prostate cancer patients.

This Phase 2 trial was a multi-center, open-label study administering Niraparib monotherapy to previously treated patients with DNA repair gene defects and castration-resistant metastatic prostate cancer (N=289) until disease progression or unacceptable toxicity. The primary endpoint was objective response rate (ORR).

Of the 289 enrolled patients, 63% (N=182) had received three or more prior lines of therapy. Among the 223 evaluable patients, 142 were BRCA-mutation positive and 81 were BRCA-mutation negative.

Results at median follow-up of 10 months:

In BRCA-mutation positive patients (N=76): Primary endpoint ORR was 34.2%.

Safety:

Most common treatment-related adverse events: nausea (58%, N=169/289), anemia (54%, N=156), vomiting (38%, N=111). Grade 3 or higher adverse events: anemia (33%, N=95), thrombocytopenia (16%, N=47), neutropenia (10%, N=28). Serious adverse events occurred in 46% (N=134/289), including thrombocytopenia (6%, N=17) and anemia (4%, N=13).

Conclusion: Based on the Phase 2 trial results, Dr. Smith and colleagues concluded that Niraparib monotherapy demonstrated meaningful anti-tumor activity with acceptable tolerability in previously treated, DNA repair gene-deficient, castration-resistant metastatic prostate cancer patients.

Source: https://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(21)00757-9/fulltext

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