PDCD1 and neoplasm: However, to date, the effect of tumour hypoxia on treatment response is only being evaluated in one immunotherapy trial (NCT03003637), in which adult patients are treated with nivolumab, a programmed cell death 1 (PD-1) inhibitor, in combination or not with ipilimumab, a cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitor, in addition to standard of care.151