An intriguing study that is currently enrolling patients investigates the effect of retifanlimab, a PD-1 inhibitor, with or without epacadostat, an indoleamine 2,3-dioxygenase (IDO) inhibitor, in combination with bevacizumab and radiation in recurrent glioblastoma (150). The gene discussed is PDCD1; the disease is glioblastoma.