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Immunotherapies that activate costimulatory receptors on T cells have failed so far in the clinic, but the first phase III trial of an agonist antibody in cancer has just begun and second-generation candidates are advancing.
Blocking antibodies have transformed oncology over the past quarter century. But agonist antibodies that boost downstream signalling have proved much harder to develop, despite great promise. In November, GlaxoSmithKline opened a phase III trial for its ICOS-binding GSK3359609, however, making it the first ever anticancer agonist antibody targeting a costimulatory receptor on T cells to make it to a pivotal trial.