Recent research suggests a link between KRAS mutations and the effectiveness of ICIs, as KRAS-driven tumors may possess unique immunogenic features that influence the tumor microenvironment. These mutations can increase tumor mutation burden (TMB) and neoantigen load, potentially leading to improved responses to ICIs. This meta-analysis aims to consolidate existing evidence on the impact of KRAS mutations as a predictive factor for survival and treatment outcomes in patients with advanced NSCLC treated with ICIs. A comprehensive search strategy was designed by a biostatistician and pulmonologist, targeting PubMed, Web of Science, and Scopus databases up to May 2022. The outcomes assessed included overall survival (OS) and progression-free survival (PFS), reported as log hazard ratios (HRs) with corresponding standard errors (SEs). A pooled estimate of the HR effect size was calculated using Review Manager (RevMan, Cochrane Collaboration, London, UK). Heterogeneity among studies was evaluated using the Cochran Q test and the I² statistic. Ultimately, 10 articles were deemed suitable for inclusion in the systematic review from a total of 8722 screened titles and abstracts. The presence of KRAS+ mutations had a significant prognostic factor for better OS in NSCLC patients treated with checkpoint inhibitors (HR = 0.89, 95% CI: 0.79–0.99) and for better PFS in NSCLC patients treated with checkpoint inhibitors (HR = 0.72, 95% CI: 0.59–0.87). In conclusion, our study indicates that KRAS mutations may serve as a potential positive predictive biomarker in patients with advanced non-small-cell lung cancer treated with immune checkpoint inhibitor monotherapy.

Immune checkpoint inhibitors (ICIs) like atezolizumab have improved outcomes in advanced non-small cell lung cancer (NSCLC) patients, especially in the second-line setting after progression on platinum-based chemotherapy. However, access to ICIs remains limited in many developing nations. This study evaluated the efficacy of atezolizumab as a second-line versus later-line treatment for advanced NSCLC patients in Serbia. Methods: This retrospective study involved 147 advanced NSCLC patients treated with atezolizumab following progression on prior platinum-based chemotherapy at two academic centers in Serbia. Data on demographics and clinical, pathological, and molecular characteristics were collected. Median progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan–Meier method, and multivariable Cox proportional hazards regression identified outcome predictors. Results: The median PFS was 7.13 months, and median OS was 38.6 months. The overall response rate (ORR) was 15%, with a disease control rate (DCR) of 57.9%. No significant PFS differences were observed between patients treated with atezolizumab in the second line versus later lines. Patients with good performance status (ECOG 0–1) had significantly better PFS compared to those with poorer status (12.03 vs. 1.63 months, p < 0.0001). Conclusions: Atezolizumab is effective in both second-line and later-line settings for advanced NSCLC, particularly in patients with good performance status. This highlights the importance of patient selection based on performance status, as well as the need for wider access to ICIs in resource-limited regions.