Discussion
SCLC, tumor, hypoxia, lung cancer, tumors
DISEASE PROGRESSION, TUMOR, INFILTRATION, SCLC, HYPOXIA, RECRUITMENT, LUNG CANCER, TUMORS
In the past 30 years, platinum-based chemotherapy has been used as a first-line treatment for ES-SCLC patients (PD-1 inhibitors are able to block both PD-1/PD-L1 pathways as well as PD-1/PD-L2 pathways, whereas PD-L1 inhibitors only inhibit PD-1/PD-L1 (Chemotherapy and radiotherapy have the ability to increase the immunogenicity of tumor cells, increase major histocompatibility class I (MHC-I) molecule expression, activate immune effector factors such as nature killer cells, and promote immune response by targeting tumor immunosuppressive cells (Maintenance PD-L1 inhibitor was administrated in IMpower133 and CASPIAN studies and pembrolizumab plus chemotherapy was continued until disease progression in KEYNOTE-604 study, whereas in our study camrelizumab combined with apatinib was used for maintenance therapy. Preclinical data have shown that apatinib could relieve hypoxia, enhance CD8+ T cell infiltration, decrease the recruitment of tumor-associated macrophages in tumors and the amount of TGF-β in both tumors and serum, and generate synergistic antitumor effects with PD-L1 blockade in lung cancer (The median number of chemotherapy cycles in our study was six for IP/IC and five for EP/EC, compared to the standard four cycles. Although the latest NCCN guideline for SCLC also recommends 4 cycles of treatment for untreated ES-disease, patients may receive up to 6 cycles based on response and tolerability after 4 cycles (Notably, the subgroup analysis showed that the occurrence of irAEs was associated with a longer median PFS, which was consistent with the results of SCLC with larger samples (This study has some limitations. First, the control group was retrospectively reviewed with selective bias, so the results of this study cannot fully reflect the efficacy and safety of the EP/EC plus PD-L1 inhibitor in patients with ES-SCLC. Second, since this study was a single-center analysis, the results might be influenced by the level of diagnosis and treatment at our center. Third, the sample size was small, and finally only 53 patients with ES-SCLC were analyzed, resulting in insufficient statistical power of our study. Last, the data of OS was immature, and the patients’ survival situation should be continuously tracked. Further large-scale randomized controlled trials are warranted to confirm our results.