How do you manage de novo high volume mCSPC with both BRCA2 mutation and MSI-H on somatic testing?

This is a very rare but interesting scenario. Presumably in this case, the BRCA2 mutation is a passenger event in the setting of high TMB as a result of MMRD/MSI high disease, which has been reported. Typically these BRCA alterations are monoallelic and the tumors lack homologous repair deficiency and PARP sensitivity. The standard of care here is ADT/ARSI and docetaxel (triplet therapy) for high volume mHSPC, typically with abiraterone or darolutamide based on the PEACE-1 and ARASENS trials, respectively. I would certainly consider pembrolizumab or another PD-1 inhibitor at progression to the mCRPC setting but not aware of any data supporting its use in mHSPC patients even with MSI high disease. I would not hesitate to use the PD-1 inhibit...