However, after PD-1 blockade with Nivolumab, these cells regained their proliferative and cytotoxic potential in vitro, measured by higher expression of granzyme B and perforin, while CD8+ T cells from tumor samples with low infiltration of IL-9+ cells did not respond to anti–PD-1 treatment (67). The gene discussed is PDCD1; the disease is neoplasm.