Opdivo first-quarter sales were still strong at $1.1bn, largely driven by lung cancer use and helping to drive overall performance, but potential approval of Merck's competing Keytruda with chemotherapy in first-line lung cancer is right around the corner.

Scrip spoke with five companies about their places in the crowded IO field in which big pharma and small biotech firms alike are seeking the best options for harnessing the immune system to fight cancer.

Immuno-oncology’s challenge is to orchestrate a biomarker program in a highly competitive drug development landscape knowing that prior to having significant clinical experience, the program is unlikely to yield the kinds of binary measurements used to define and select a patient population for a targeted therapy.