Roche's (RHHBY +1.5%) BTD-designated PD-1 inhibitor MPDL3280A shrinks tumors in 43% of bladder cancer patients that are positive for PD-L1 in a 68-patient Phase 1 trial. Of the 30 patients were PD-L1 positive, 13 experienced an objective response as defined by RECIST (43%) at six weeks. The response rate increased to 52% at 12 weeks but this was due to n falling to 25 (13/25). The mean time to response for all subjects was 42 days.
MPDL3280A is an investigational mAb designed to interfere with PD-L1 thus preventing tumor cells from binding to PD-1 and B7-1 on the surface of T cells. This helps activate the T-cells and restores their ability to target and attack cancer cells.