KRAS mutation predict response and outcome in advanced non-small cell lung carcinoma without driver alterations receiving PD-1 blockade immunotherapy combined with platinum-based chemotherapy: a retrospective cohort study from China.

Background: The selection of patients for immunotherapy remains challenging given the lack of highly specific and highly sensitive biomarkers. Kirsten rat sarcoma (KRAS) mutation is the most frequent molecular alteration found in advanced non-small cell lung carcinoma (NSCLC). We explored whether KRAS mutation status predicted the effects of first-line immune checkpoint inhibitor (ICI) treatment and platinum-based chemotherapy in Chinese patients with advanced NSCLC. Methods: Clinical data were extracted from medical records of patients with advanced NSCLC at the First Affiliated Hospital of Guangzhou Medical University in China between January 2019 and March 2020. Overall survival (OS) and progression-free survival (PFS) rates were compared via log-rank tests, and independent prognostic factors were identified via Cox regression. Results: Patients with advanced NSCLC without driver alterations who were treated with ICI and platinum-based chemotherapy (N=80) were identified, including 28.7% with KRAS mutations and 71.3% with non-KRAS mutations. Tumor programmed death-ligand 1 (PD-L1) expression was analyzed using a 1% cutoff, and 32.5% of patients were negative and 67.5% were positive. The median tumor mutational burden (TMB) was 7.29 mutations per megabase (muts/Mb) (range, 0.08-44.8 muts/Mb), with 32.5% of cases <5 muts/Mb and 67.5% ≥5 muts/Mb. The median PFS and OS for the entire cohort were 9.8 (95% CI: 9.1-10.5) and 17.6 (95% CI: 14.4-20.8) months, respectively. The 6-month PFS rate was 67.5% and the 1-year OS rate was 72.5%. Thirty-five patients survived until the last follow-up. The OS and PFS of patients with KRAS mutations were significantly higher than those in the non-KRAS mutant group (P<0.05). The Cox multivariate analyses showed that brain metastasis [hazard ratio (HR) =0.232, 95% CI: 0.102-0.530; P=0.001], TMB (HR =5.675, 95% CI: 1.948-16.535; P=0.001), KRAS mutation (HR =2.552, 95% CI: 1.141-5.708; P=0.023) were independent predictors of OS in patients treated with ICIs and platinum-based chemotherapy. Liver metastasis (HR =0.344, 95% CI: 0.191-0.619; P<0.001) and KRAS/tumor protein p53 (TP53) co-mutation (HR =0.220, 95% CI: 0.067-0.725; P=0.013) were the prognostic factor for PFS of qualified patients. Conclusions: This work provides evidence that KRAS mutation in advanced NSCLC may be served as a potential predictive biomarker for immunotherapeutic efficacy.