The enthusiasm for anti-cancer immunotherapies continues to build, with two treatments already approved by the FDA and clinical trials underway for a variety of promising new candidates. The latest approaches include targeting a protein called PD-L1, which shields tumor cells from immune system attacks. In a phase I clinical trial of a PD-L1 blocker made by MedImmune, early results suggest that this treatment shrinks melanomas as well as kidney, lung and colon tumors. Next, the researchers hope to open this trial to people with head and neck cancers as well. Another approach entails adding the gene for an immune system booster (interferon beta) to a therapeutic virus (vesicular stomatitis virus) that kills cancer cells but not normal ones. This treatment is being tested on liver cancer in a phase I trial, and early results are encouraging.