Roche's ($RHHBY) Ventana Medical Systems and MedImmune said they will jointly develop an assay to help test a MedImmune immunotherapy for non-small cell lung cancer. Neither side is disclosing financial details. Specifically, they'll develop a PD-L1 (SP263) immunohistochemistry assay to enroll patients in clinical trials for MedImmune's MEDI4736, an anti-PD-L1 therapy. According to the companies, signals from PD-L1 help tumors avoid immune system detection. The idea is that MedImmune's treatment could combat this by targeting PD-L1, and Roche/Ventana will develop a test that screens for patients who may benefit most from the cancer immunotherapy. Release