Impact of large-scale nationwide genomic screening project for small cell lung cancer (LC-SCRUM-Japan).

Abstract

8559 Background: A variety of genetic analyses have been performed in small cell lung cancer (SCLC), however the clinical relevance of them remains unclear. We prospectively analyzed clinical samples of small-cell lung cancer using a nationwide genomic screening project (LC-SCRUM-Japan). Methods: Submitted tumor samples were subjected to a next-generation sequencing (NGS) system, Oncomine™ Comprehensive Assay, enabling the simultaneous analysis of 143 (ver.1) or 161 (ver.3) cancer-related genes. Results: From July 2015 to January 2019, 707 SCLC patients had been enrolled. The median age was 68 years. 77% were male and 94% were smokers. Among 588 samples completed analysis, we identified high prevalence of inactivating TP53/RB1 mutations in 426 (72%) /194 (33%) of cases, respectively. MYC/MYCL1/MYCN amplifications were detected in 21 (4%) /30 (5%) /9 (2%) of cases, respectively. This NGS analysis also showed that 32 (5%) of cases had well-known genetic alterations in receptor tyrosine kinase genes: 9 EGFR mutations, 9 KRAS mutations and 14 FGFR1 copy number gains. Mutations in the PI3K pathway were detected in 44 (7%) of the tumors. Among them, 8 cases enrolled in the investigator-initiated phase II study of gedatolisib (UMIN 000020585). Survival data was available in 463 patients receiving platinum-based chemotherapy. Multivariate analysis revealed that the presence of PIK3CA mutation (HR; 2.56; 95% CI 1.19 – 5.52; p = 0.016) and MYCN amplification (HR; 4.36; 95% CI 1.91 – 9.97; p < 0.001) were significantly associated with unfavorable survival. The frequency of amplifications in MYC family genes was higher in the samples obtained ≥ 90 days after the first-line platinum-based chemotherapy (18.1%) than in those < 90 days (8.1%, p = 0.01), suggesting MYC family amplification as one of the resistance mechanisms. Conclusions: This large-scale nationwide screening system is helpful for identifying therapeutically relevant genetic alterations, prognostic prediction, and exploring resistance mechanism in SCLC. Updated screening results will be presented at the 2019 ASCO Annual Meeting. Clinical trial information: UMIN000018656.