For a patient with metastatic urothelial cancer who has progressed on platinum-based chemotherapy, do you test for tumor PD-L1 expression prior to choosing atezolizumab as second-line treatment?

Currently, atezolizumab is the only drug FDA approved for treatment of patients with metastsatic urothelial cancer progressive despite first-line platinum based chemotherapy. Prior to the approval of atezolizumab, commonly used agents were taxanes or pemetrexed based on small to moderate sized singl...