Profiling of 520 Candidate Genes in 50 Surgically Treated Chinese Small Cell Lung Cancer Patients

Small cell lung cancer (SCLC) is one of the severe malignancies with high mortality. Surgically resected tumor tissues from 50 Chinese SCLC patients were collected for next-generation sequencing to detect 520 cancer-related genes. The most frequently altered genes were TP53 (94.0%), RB1 (86.0%), LRP1B (44.0%), SPTA1 (26.0%) and KMT2D (24.0%). We detected that NOTCH2, JAK2 and CDK12 (P<0.05) had a significantly higher mutation frequency in Chinese SCLC compared to the Cologne and MSKCC. The single nucleotide variation (SNV) is dominated by C>A (34.1%). We found a significant association between TMB-H (≥10.3muts/Mb) and ATM (P=0.023), CREBBP (P=0.010), KMT2D(P=0.050) and LRP1B (P=0.005) gene mutations in Chinese SCLC patients. Immunostaining was performed using the following antibodies: TTF-1, CgA, CD56, Syn, and Ki-67. Correlation analysis between the expression of 6 markers and mutations in signaling pathways showed that Syn and CgA expression were associated with 4 (cGMP-PKG, Chemokine, TGF-β and Phospholipase D) and 2 (cGMP-PKG and Phosphatidylinositol) signaling pathway mutations. Kaplan-Meier curve showed that age<55 years, mutant ARID2 and high TMB (≥7muts/Mb) were associated with a better prognosis, while the prognosis of patients with mutations in the Ras pathway was significantly improved. High TMB is an important prognostic factor for SCLC patients showed by multivariate analysis. In the combined cohort composed of current and two previous studies, survival analysis showed that SCLC patients with mutant LRP1B demonstrated better OS (P=0.0017). Patients with a high TMB (≥7muts/Mb) have a better prognosis (P=0.0053), consistent with our results in the Chinese cohort. We characterized the genomic alterations profile of Chinese SCLC patients and analyzed the correlation between genomic changes and immunohistochemical phenotypes at the signaling pathway level. Our data might provide useful information in the diagnosis and treatment for Chinese SCLC patients.

Small-cell lung cancer detection in never-smokers: clinical characteristics and multigene mutation profiling using targeted next-generation sequencing

BACKGROUND

Once regarded as a smoker's disease, small-cell lung cancer (SCLC) has been occasionally detected in never-smokers as smoking rates decrease worldwide. We investigated the clinical and genetic characteristics of SCLC in never-smokers.

PATIENTS AND METHODS

Patients diagnosed with SCLC were grouped into smokers and never-smokers. The clinical outcomes of the two groups were compared. For SCLC in never-smokers, somatic mutation profiling was carried out using the AmpliSeq™ Cancer Hotspot Panel v2 and semiconductor sequencing technology. Epidermal growth factor receptor (EGFR) mutation was confirmed by PNAClamp™.

RESULTS

In total, 391 SCLC patients treated over a 5-year period were analyzed. Fifty patients (13%) were never-smokers. The median overall survival was 18.2 months in never-smokers and 13.1 months in smokers (P = 0.054). Never-smoking history was independently a good prognostic factor [hazard ratio = 0.645, 95% confidence interval (CI) 0.456-0.914], as were limited disease (HR = 0.372, 95% CI 0.294-0.471), and lower age (HR = 0.709, 95% CI 0.566-0.888). The objective response rates to first-line etoposide/cisplatin therapy were similar between never-smokers and smokers (75% versus 81%). Of 28 genetically evaluable never-smokers, EGFR mutations were detected in four cases (two L858R, one deletion in exon 19, and one G719A). Other mutations were in TP53 (n = 26), RB1 (n = 7), PTEN (n = 5), MET (n = 4), and SMAD4 (n = 3).

CONCLUSIONS

Never-smokers with SCLC are increasingly prevalent and have a better prognosis than smokers with SCLC in Korea. Our study warrants further investigation in this group.