This is a branch of immuno-oncology that has been overshadowed by more fruitful endeavors, such as the immune checkpoint inhibitors Opdivo (nivolumab) from Bristol-Myers Squibb BMY +0.51% and Keytruda (pembrolizumab) from Merck , both of which are now certified cancer blockbusters. But several companies are developing cancer-killing viruses, known in the scientific community as “oncolytic” viruses, and some of those efforts are starting to show promise. Read more . . .