phio pharmaceuticals corp., a biotechnology company, develops immuno-oncology therapeutics in the united states. it offers intasyl therapeutic platform focuses on silencing tumor-induced suppression of the immune system. the company develops ph-762 which targets the checkpoint protein pd-1 on immune cells for used in adoptive cell transfer (act); ph-804 that targets the suppressive immune receptor tigit, which is a checkpoint protein present on t cells and natural killer cells for used in act; and ph-790 which targets pd-l1 protein that keeps immune cells from attacking nonharmful cells in the body. it has collaborations with the gustave roussy and medigene ag, as well as with helmholtz zentrum mã¼nchen. the company was formerly known as rxi pharmaceuticals corporation and changed its name to phio pharmaceuticals corp. in november 2018. phio pharmaceuticals corp. was incorporated in 2011 and is headquartered in marlborough, massachusetts.