The FDA approved Foundation Medicine’s FoundationOne CDx assays as companion diagnostics for Pfizer’s Talzenna plus Xtandi in metastatic castration-resistant prostate cancer with homologous recombination repair (HRR) gene mutations. The update formalizes patient selection for the combination therapy under a defined biomarker. For pathology labs and testing workflows, the approval clarifies reimbursement and regulatory eligibility for the specific CDx-marketed version of the test, rather than off-label use of results from non-approved platforms. The move also reinforces the continuing centrality of genomic diagnostics in prostate cancer treatment algorithms, especially for biomarker-driven responses in HRR-altered disease. A separate item duplicated the same approval announcement, emphasizing the regulator’s focus on CDx alignment for clinical decision-making.