Using surgical resection samples and matched blood from GBM donors, Lucca et al. showed that TIGIT+/DNAM-1− tumor-infiltrating lymphocyte populations within GBM, which exhibited enhanced in vitro activation following TIGIT blockade, increased their presence from 25 to 60%, while such lymphocytes were typically absent within normal brain tissue [39]. The gene discussed is TIGIT; the disease is glioblastoma.