The disclosure provides a method for treating a subject afflicted with a tumor derived from a non-small cell lung cancer (NSCLC) comprising administering to the subject a therapeutically effective amount of (a) an anti-PD-1 antibody or antigen-binding portion thereof or an anti-PD-L1 antibody or antigen-binding portion thereof and (b) an anti-CTLA-4 antibody or an antigen binding portion thereof, wherein the tumor has a high tumor mutation burden (TMB) status. The TMB status can be determined by sequencing nucleic acids in the tumor and identifying a genomic alteration, e.g., a somatic nonsynonymous mutation, in the sequenced nucleic acids.