To better understand the impact of BRCA1/2 mutations on the immune phenotype of prostate cancer, we initiated a proof-of-concept study to characterize the cellular immune infiltrate of eight BRCA2 mutated in comparison with eight BRCA1/2 wild-type prostate cancer patients by T-cell receptor (TCR)-sequencing and immunohistochemistry (IHC) for CD45, CD4, CD8, FOXP3, and CD163. The gene discussed is CD4; the disease is prostate cancer.