Application value of plasma exosomal long RNA in SCLC diagnosis and prognosis

8566 Background: Little research has focused on blood exosomal transcription profile in small cell lung cancer (SCLC). The aim of this study is to identify plasma exosomal specific transcriptional profile in SCLC and explore the application value of plasma exosomal long RNA (exLR) in SCLC diagnosis and prognosis. Methods: This study included 81 healthy people and 40 SCLC patients receiving standard first-line chemotherapy with etoposide and carboplatin/cisplatin. The efficacy was evaluated by progression-free survival (PFS), objective response rate (ORR) and disease control rate (DCR). 19 Patients who achieved complete response (CR) or partial response (PR) as best response during the first-line therapy and had not progressed within the following 90 days after the end of first-line therapy were defined as chemosensitive. 21 Patients who achieved stable disease (SD) as best response or received progressive disease during the first-line therapy or within the following 90 days after the end of first-line therapy were defined as chemoresistant. Baseline plasma samples were collected from 40 SCLC patients (17 patients’ samples after 2 courses were collected) and 81 healthy people. Plasma exosomes were isolated and purified; exosomal RNA were extracted for high-throughout sequencing analysis. Results: We obtained plasma exLRs profiles from 81 healthy control samples and 57 SCLC samples (baseline samples from 40 patients plus samples collected by 17 patients after 2 courses). Bioinformatics analysis found that exLRs were significantly different between the SCLC and the healthy control group; between the chemosensitive and the chemoresistant group; between the baseline samples and the paired samples after 2 courses. For 40 SCLC patients receiving first-line chemotherapy, ORR was 65.0%, DCR was 90.0% and mPFS was 6.0 months (95% CI, 4.3-7.7 months). Multivariate analysis showed that baseline brain metastases and baseline bone metastases were independent predictors of poor PFS; and 223 genes were independent predictors of PFS. There were 10 genes (AC107954.1, H2AFZP2, CALB2, IFITM9P, GFPT2, PLA1A, CHST10, AC021231.2, SETP20, HILPDA) intersected in differentially expressed genes between the SCLC and the healthy control group, differentially expressed genes between the chemosensitive and the chemoresistant group and independent predictors of PFS. These 10 genes were highly expressed in both the SCLC group and the chemoresistant group, and their high expression was an independent risk factor for poor PFS. Conclusions: This study firstly identified the plasma exLRs profiles in SCLC patients, verified the feasibility and value of identifying biomarkers based on exLRs profiles in SCLC diagnosis and prognosis.