Yes, the FDA has accepted PD-L1 as a biomarker for breast cancer, specifically in the context of triple-negative breast cancer (TNBC). This means that the FDA has approved drugs (like atezolizumab and pembrolizumab) that are specifically used for TNBC patients whose tumors express PD-L1.
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US FDA and CEL-SCI Agree on Use of PD-L1 Biomarker to Select Head and Neck Cancer Patients for Marketing Registration Study to Commence Q1 2025 --- November 7, 2024
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Couple yrs back, FDA did accept PD-L1 for TNBC.