Multicenter phase 2 trial of checkpoint inhibitors with or without SBRT for advanced solid tumors

Although immune checkpoint inhibitors (ICIs) targeting PD-(L)1 have improved the outcomes in many cancer types, the majority of patients fail to respond to ICI monotherapy. Hypofractionated radiotherapy has the potential to improve the therapeutic ratio of ICIs. The phase 2 randomized CHEERS trial at five centers in Belgium compared ICI monotherapy alone or combined with SBRT among 96 patients with locally advanced or metastatic solid cancers. The median progression-free survival was 2.8 months with ICI alone versus 4.4 months with ICI plus SBRT, a difference that was not statistically significant. The authors conclude that adding subablative multisite SBRT to ICI monotherapy was safe but did not result in a clinically meaningful benefit (visual abstract).