In fact, a recent study indicated that the total number of T cells, as well as the CD4 and CD8 populations, are increased in the peripheral blood of HL patients who are treated with a PD-1-blocking antibody, supporting the notion that the T-cell-mediated response12 could be a major mechanism accounting for the efficacy of anti-PD-1 antibodies. The gene discussed is PDCD1; the disease is Hodgkins lymphoma.