A new drug called MPDL3280A appears to shrink tumors in patients with a range of different cancers, including lung cancer and melanoma. In an ongoing clinical trial, MPDL3280A shrank tumors in 21% of patients with advanced cancer. Response rates were even higher in subsets of patients with lung cancer (22%) or melanoma (29%). Treatment benefits lasted from 3 to 15 months and counting; 26 of the 29 patients who benefited continue to respond to this day. There was wide variation in how quickly patients responded to treatment, with some experiencing significant improvement within days, and others after weeks of unresponsiveness. MPDL3280A was generally well tolerated, with few cases of severe side effects.