Phase 3 CaBRA Trial: Adding Carboplatin for mHSPC With BRCA Mutations or Neuroendocrine Phenotype

In the phase 3 CaBRA trial, carboplatin is added to the docetaxel-based chemotherapy backbone used with lifelong ADT (androgen deprivation therapy) and darolutamide,  creating a quadruple-intensification  therapy for a small but very high-risk subgroup of metastatic castration-sensitive prostate cancer. The trial focuses on tumors with either BRCA alterations or neuroendocrine differentiation, two features that are both associated with more aggressive disease and earlier treatment resistance.

The rationale for the BRCA cohort is biological as much as clinical. BRCA mutations impair homologous recombination repair, which makes tumor cells less able to fix DNA damage, so they may be more sensitive to platinum chemotherapy such as carboplatin. That creates a strong reason to test platinum earlier, before the disease becomes castration-resistant.

The neuroendocrine cohort is based on a different problem. Neuroendocrine-differentiated prostate cancer often behaves less like typical androgen-driven adenocarcinoma and more like an aggressive, therapy-resistant variant, which makes standard hormone intensification less reliable. In that setting, adding a platinum drug is a logical way to target a more chemotherapy-sensitive phenotype.

The study is therefore not simply adding another drug for broad use. It is trying to match treatment to tumor biology, asking whether carboplatin can deepen the response in patients whose cancers already carry signs of aggressive behavior at diagnosis.

Clinical trial.