*2.2. Selection Criteria*

Only phase III trials conducted in patients with advanced/metastatic stage IV NSCLC not previously treated for their metastatic disease and receiving at least one PD-(L)1 inhibitor in combination with a chemotherapeutic agent were eligible for inclusion. Efficacy outcomes regarding combinations of immunotherapy plus chemotherapy expressed as PFS or OS had to be provided. Observational studies, editorials, reviews, and commentaries were excluded.
