Abstract

Background Anti-programmed cell death 1 (PD-1) antibody combined with chemotherapy simultaneously is regarded as the standard treatment for patients with advanced non-small cell lung cancer (NSCLC) by current clinical guidelines. Different immune statuses induced by chemotherapy considerably affect the synergistic effects of the chemo-anti-PD-1 combination. Therefore, it is necessary to determine the optimal timing of combination treatment administration. Methods The dynamic immune status induced by chemotherapy was observed in paired peripheral blood samples of patients with NSCLC using flow cytometry and RNA sequencing. Ex vivo studies and metastatic lung carcinoma mouse models were used to evaluate immune activity and explore the optimal combination timing. A multicenter prospective clinical study of 170 patients with advanced NSCLC was performed to assess clinical responses, and systemic immunity was assessed using omics approaches. Results PD-1 expression on CD8 + T cells was downregulated on day 1 (D1) and D2, but recovered on D3 after chemotherapy administration, which is regulated by the calcium influx-P65 signaling pathway. Programmed cell death 1 ligand 1 expression in myeloid-derived suppressor cells was markedly reduced on D3. RNA sequencing analysis showed that T-cell function began to gradually recover on D3 rather than on D1. In addition, ex vivo and in vivo studies have shown that anti-PD-1 treatment on D3 after chemotherapy may enhance the antitumor response and considerably inhibit tumor growth. Finally, in clinical practice, a 3-day-delay sequential combination enhanced the objective response rate (ORR, 68%) and disease control rate (DCR, 98%) compared with the simultaneous combination (ORR=37%; DCR=81%), and prolonged progression-free survival to a greater extent than the simultaneous combination. The new T-cell receptor clones were effectively expanded, and CD8 + T-cell activity was similarly recovered. Conclusions A 3-day-delay sequential combination might increase antitumor responses and clinical benefits compared with the simultaneous combination.