Although programmed cell death 1 (PD-1)/programmed death ligand 1 (PD-L1) inhibitors have shown some efficacy in treating advanced NSCLC, their benefits are limited to only a subset of patients. Advanced NSCLC is generally treated with a chemotherapy and immunotherapy series. Here we evaluated whether PD-1/PD-L1 inhibitors affect the antitumor effects of salvage chemotherapy administered after immunotherapy (SCAI) in patients with NSCLC. This study included patients with available SCAI response data. We compared the SCAI objective response rates (ORRs) with the ORRs after the last chemotherapy administered before immunotherapy (LCBI). In total, 73 patients met the inclusion criteria and were included in the analyses. Of these patients, 10 received PD-1/PD-L1 inhibitors as first-line therapy and the remaining 63 had available LCBI response data. Of the 73 patients treated with SCAI, 39 (53.4%) achieved the ORR, whereas the ORR of LCBI was 34.9% (22 of 63) (p = 0.03). We also compared the ORRs of the SCAI and LCBI groups after stratification into platinum doublet therapy versus nonplatinum monotherapy. The ORRs for platinum doublet SCAI and LCBI therapies were 66.7% (16 of 24) and 39.5% (17 of 43), respectively (p = 0.03), whereas for nonplatinum SCAI and LCBI monotherapies they were 46.9% (23 of 49) and 25.0% (5 of 20), respectively (p = 0.09). The ORR for SCAI was significantly higher than that for LCBI. These data indicate that anti–PD-1/PD-L1 inhibitors could make tumors more vulnerable to subsequent chemotherapy.