High mutations in fatty acid metabolism contribute to a better prognosis of small‐cell lung cancer patients treated with chemotherapy

Background The majority of patients with small‐cell lung cancer (SCLC) show a good response in the early stages of treatment, but more than 90% of patients will develop drug resistance. Therefore, biomarkers are urgently needed to identify patients who can benefit from systemic treatment. Methods We prospectively enrolled 52 extensive‐stage SCLC patients before treatment from a local hospital to identify mutations related to patient prognosis, and verified them in the published Jiang's cohort and George's cohort. Results We found that patients with high mutations (mut‐high) in the fatty acid (FA) metabolism pathway had a longer progression‐free survival (PFS) in the local hospital cohort (HR = 0.446, 95% CI, 0.207–0.959, p = 0.0387) and a longer overall survival (OS) in Jiang's cohort (HR = 0.549, 95% CI, 0.314–0.960, p = 0.0351) than patients with low mutations (mut‐low). Multivariate analysis suggested that mut‐high status was an independent prognostic factor in both cohorts. George's cohort verified that mut‐high status was associated with a longer OS than mut‐low status (HR = 0.730, 95% CI 0.440–1.220, p = 0.2277). The possible mechanisms were as follows: the frequency of mutated FA synthase (FASN) in the mut‐high group was greater than that in the mut‐low group, and pathways related to the cell cycle, DNA repair, and oxidative phosphorylation were enriched in the mut‐high group. Conclusions The prognosis of SCLC patients treated with chemotherapy was better among patients with more mutations in the FA metabolism pathway, and the underlying mechanisms could be found at the genome and transcriptome levels.