Efficacy and safety of different cycles of neoadjuvant immunotherapy in resectable non-small cell lung cancer: A systematic review and meta-analysis

Background: There is no standard consensus on the optimal number of cycles of neoadjuvant immunotherapy prior to surgery for patients with locoregionally advanced non-small cell lung cancer (NSCLC). We carried out a systematic review to evaluate the efficacy and safety of neoadjuvant immunotherapy with different treatment cycles in order to provide valuable information for clinical decision-making. Methods: PubMed, Embase, the Cochrane Library and ClinicalTrials.gov were systematically searched before May 2023. The included studies were categorized based on different treatment cycles of neoadjuvant immunotherapy to assess their respective efficacy and safety in patients with resectable NSCLC. Results: Incorporating data from 29 studies with 1331 patients, we found major pathological response rates of 43 % (95%CI, 34–52 %) with two cycles and 33 % (95%CI, 22–45 %) with three cycles of neoadjuvant immunotherapy. Radiological response rates were 39 % (95%CI, 28–50 %) and 56 % (95%CI, 44–68 %) for two and three cycles, respectively, with higher incidence rates of severe adverse events (SAEs) in the three-cycle group (32 %; 95%CI, 21–50 %). Despite similar rates of R0 resection between two and three cycles, the latter showed a slightly higher surgical delay rate (1 % vs. 7 %). Neoadjuvant treatment modes significantly affected outcomes, with the combination of immunotherapy and chemotherapy demonstrating superiority in improving pathological and radiological response rates, while the incidence of SAEs in patients receiving combination therapy remained within an acceptable range (23 %; 95%CI, 15–35 %). However, regardless of the treatment mode administered, an increase in the number of treatment cycles did not result in substantial improvement in pathological response rates. Conclusion: There are clear advantages of combining immunotherapy and chemotherapy in neoadjuvant settings. Increasing the number of cycles of neoadjuvant immunotherapy from two to three primarily may not substantially improve the overall efficacy, while increasing the risk of adverse events. Further analysis of the outcomes of four cycles of neoadjuvant immunotherapy is necessary.