Hayward, Calif.-based Reflexion Medical Inc. reported a clinical collaboration with Merck & Co. Inc., of Kenilworth, N.J., to evaluate the safety and efficacy of Keytruda (pembrolizumab) in combination with biology-guided radiotherapy (BgRT) in multiple late-stage cancers. The goal is to establish whether treating multiple tumors with BgRT, a novel external beam radiotherapy treatment (EBRT) modality in development, is safe and amplifies Keytruda’s therapeutic effect.