Comprehensive analyses of N (6)‐methyladenosine‐related long noncoding RNA profiles with prognosis, chemotherapy response, and immune landscape in small cell lung cancer

Small cell lung cancer (SCLC) is the most devastating subtype of lung cancer with no clinically available prognostic biomarkers. N (6)‐methyladenosine (m(6)A) and noncoding RNAs play critical roles in cancer development and treatment response. However, little is known about m(6)A‐related long noncoding RNAs (lncRNAs) in SCLC. We used 206 limited‐stage SCLC (LS‐SCLC) samples from two cohorts to undertake the first and most comprehensive exploration of the m(6)A‐related lncRNA profile in SCLC and constructed a relevant prognostic signature. In total, 289 m(6)A‐related lncRNAs were screened out. We then built a seven‐lncRNA‐based signature in the training cohort with 48 RNA sequencing data using univariate and multivariate Cox regression models. The signature was well validated in an independent cohort containing 158 cases with quantitative PCR data. In both cohorts, the signature divided patients into high‐ and low‐risk groups with significantly different survival rates (both p < 0.001). Our signature predicted chemotherapy survival benefit in patients with LS‐SCLC. Receiver operating characteristic and C‐index analyses indicated that the signature was better at predicting prognosis and chemotherapy benefit than other clinicopathologic features. Moreover, the signature was identified as an independent predictor of prognosis and chemotherapy response in different cohorts. Furthermore, functional analysis showed that multiple activated immune‐related pathways were enriched in the low‐risk group. Additionally, the signature was also closely related to various immune checkpoints and inflammatory responses. We generated the first clinically available m(6)A‐related lncRNA signature to predict prognosis and chemotherapy benefit in patients with LS‐SCLC. Our findings could help optimize the clinical management of patients with LS‐SCLC and inform future therapeutic targets for SCLC.