Confirmed Efficacy of Rucaparib in BRCA-Mutated mCRPC

Rucaparib continues to strengthen its position in BRCA-mutated metastatic castration-resistant prostate cancer (mCRPC), an advanced form of prostate cancer that progresses despite hormonal therapy, with TRITON3 trial confirming not only its efficacy but also a predictable and manageable safety profile. In this phase 3 study of chemotherapy-naïve patients progressing after one prior androgen receptor pathway inhibitor (ARPI), toxicity patterns were consistent with the PARP inhibitor class and largely driven by hematologic effects.

Fatigue was the most common adverse event, affecting over 60% of patients, but was generally low grade. More clinically relevant was anemia, reported in 46% of patients and resulting in a transfusion rate of 28%. This highlights a meaningful supportive care burden and reinforces the need for proactive monitoring and early dose management. Gastrointestinal events such as diarrhea and constipation were also common but typically mild.

Transient elevations in liver enzymes occurred early during treatment and resolved without intervention, consistent with a non-pathologic pharmacodynamic effect rather than true hepatotoxicity. Dose interruptions and reductions were frequent, yet discontinuation rates remained relatively low at under 14%, indicating that most toxicities can be effectively managed without stopping treatment.

The incidence of myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) was 1%, aligning with known class risks of PARP inhibitors. Overall, rucaparib shifts the toxicity profile away from acute chemotherapy-related effects toward a chronic, hematologic management model. In practice, its use is less limited by tolerability itself and more by the logistical demands of managing anemia over time.

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