Given these discrepencies, and the finding by Cloughesy et al (2019) [25] of increased overall survival for patients treated with neoadjuvant anti-PD-1 at recurrence, we aimed to determine whether CD3+ TILs overall, or CD4+, CD8+ or PD-1+ TIL subsets, differed between matched samples of primary and recurrent glioblastoma and assess when anti-PD1 immunotherapy would be of most benefit. The gene discussed is CD8A; the disease is glioblastoma.