A case of double-negative prostate cancer with BRCA2 mutation and high tumor mutation burden treated sequentially with olaparib and pembrolizumab

Introduction: Double-negative prostate cancer, an androgen receptor-independent prostate cancer without features of neuroendocrine tumors, is refractory to treatment but could be an ideal candidate for individualized treatment.

Case presentation: An 85-year-old patient with metastatic castration-resistant prostate cancer without prostate-specific antigen progression presented with local recurrence and liver and lung metastases 6 months after orchiectomy and apalutamide. A liver tumor biopsy led to a diagnosis of double-negative prostate cancer. FoundationOne^® CDx showed BRCA2 mutation and high tumor mutation burden. Olaparib and pembrolizumab were administered sequentially, and the patient responded to each treatment for 5 months until radiographic progression.

Conclusion: Sequential use of olaparib and pembrolizumab may be effective for double-negative prostate cancer with BRCA2 mutations and high tumor mutation burden.