Immunotherapy, represented by immune checkpoint inhibitors (ICIs), has made a revolutionary difference in the treatment of malignant tumors, and considerably extended patients’ overall survival (OS). In the world medical profession, however, there still reaches no clear consensus on the optimal duration of ICIs therapy. As reported, immunotherapy response patterns, immune-related adverse events (irAEs) and tumor stages are all related to the diversity of ICIs duration in previous researches. Besides, there lacks clear clinical guidance on the intermittent or continuous use of ICIs. This review aims to discuss the optimal duration of ICIs, hoping to help guide clinical work based on the literature.

Objective To evaluate the association between serum complement component 1q (C1q) and the efficacy of immune checkpoint inhibitors (ICIs) in patients with advanced non-small cell lung cancer (NSCLC). Methods Baseline characteristics and laboratory data of the patients with advanced NSCLC who received ICIs in the Renmin Hospital of Wuhan University from July 2018 to January 2023, were collected for the evaluation of survival analysis. The efficacy was estimated according to the response evaluation criteria in solid tumors (RECIST) 1.1. Kaplan-Meier method and Log-rank test were used for progression-free survival (PFS) and overall survival(OS). Univariate and multivariate Cox proportional hazard regression models and t-test were used to testify the correlation of survival with serum C1q levels and clinical characteristics. Results A total of 168 patients were included in this study, of which 39 patients achieved objective response [2 of complete response (CR), 37 of partial response (PR)], and 111 patients (66.07%) had the best efficacy of stable disease (SD). The objective response rate (ORR) was 23.21% and the disease control rate (DCR) was 89.28%. There was no correlation between pre-treatment C1q and PFS (P = 0.515) or OS (P = 0.185). Patients whose PFS longer than median PFS showed lower post-treatment serum C1q levels (P = 0.025). The median PFS of patients whose post-treatment serum C1q level ≥ 75th percentile of total was significantly shorter (P = 0.029). Moreover, the change of C1q levels between pre-treatment and post-treatment was strongly associated with the PFS and OS. In addition, the median PFS of patients whose age < 75 years old (P = 0.020) or Eastern Cooperative Oncology Group performance status (ECOG-PS) score 0–1 (P = 0.001) was significantly longer. The median OS of patients whose ECOG-PS score 0–1 (P < 0.001), or without brain metastasis (P = 0.036), or accepting previous chemotherapy was significantly longer. Conclusion This research showed that increasing serum C1q and ECOG-PS ≥ 2 may be related to a worse efficacy of NSCLC immunotherapy.