In the phase II basket trial of dual anti-cytotoxic T-lymphocyte–associated antigen 4 (CTLA4) and anti-programmed cell death protein 1 (PD-1) blockade (ipilimumab and nivolumab) in rare tumours (DART), 19 patients with high-grade NENs were included (18 with extra-pulmonary primaries). Here, PDCD1 is linked to neoplasm.