Inclusion Criteria:  Part 1  Histologically or cytologically confirmed diagnosis of advanced/metastatic non-small cell lung cancer (NSCLC) previously treated with chemotherapy Treatment with commercial nivolumab for the first time. For second-line (2L)+NSCLC, indication approved by (National Medical Products Administration) NMPA Part 2 Histologically or cytologically confirmed diagnosis of recurrent/metastatic squamous cell carcinoma of head and neck (SCCHN) previously treated with chemotherapy Treatment with commercial nivolumab for the first time. For post-platinum recurrent or metastatic SCCHN, indication approved by NMPA  Exclusion Criteria:  Prior participation in a clinical trial within the past 4 weeks Current or pending participation in a clinical trial Current or pending systemic treatment for cancer other than 2L+ NSCLC for part 1 and SCCHN for part 2 Previously treated with immune checkpoint inhibitors  Other protocol-defined inclusion/exclusion criteria apply