Study population
DISEASE
Eligible patients were ≥ 18 years of age, and could have any metastatic solid tumor type where there was demonstrated evidence of potential efficacy to anti-PD-1 pathway targeted therapy at the time of study design. All genders were eligible and patients self-reported. All patients needed to have received at least one prior systemic anti-cancer therapy; prior ICB was allowed, as long as the reason for discontinuation was not an irAE. A site of disease amenable to a fresh biopsy was required for inclusion. A two-week washout period for previous systemic therapy was required, and patients could not have a prior history or concomitant autoimmune condition.