Biomarker evaluation
tumour, UC
TUMOUR
Patients’ PD-L1 status was evaluated using the VENTANA PD-L1 (SP263) Assay (Ventana Medical Systems, Inc., Tuscon, Arizona, USA) in tumour samples collected at screening. Archival tissue samples were used if available, otherwise, a fresh biopsy was recommended. PD-L1-positive status was defined as ≥1% of tumour cells (TCs) with PD-L1 expression, except in the Phase 2 (combination dose expansion) UC cohort. In the Phase 2 UC cohort, patients were considered to be PD-L1-positive if immune cells (ICs) involved >1% of the tumour area and ≥25% of TCs or ICs had PD-L1 expression, or if ICs involved ≤1% of the tumour area and ≥25% of TCs or 100% of ICs expressed PD-L1, consistent with the approach used in a previously reported Phase 2 trial of tislelizumab monotherapy in locally advanced/metastatic UC [