Clinico-pathological and genomic features of NRAS- or HRAS-mutated non-small cell lung cancer (NSCLC) identified in large-scale genomic screening project (LC-SCRUM-Asia).

9054 Background: RAS ( KRAS, NRAS and HRAS) is a targetable oncogene family in several cancers, including NSCLC, and the clinical development of various RAS-targeted therapies are ongoing. However, the clinical relevance of uncommon RAS mutations, such as NRAS and HRAS mutations, in NSCLC patients (pts) remains unclear. Methods: In a large-scale genomic screening project (LC-SCRUM-Asia), we have prospectively analyzed lung cancer pts for genomic alterations by a targeted next-generation sequencing (NGS) system, Oncomine Comprehensive Assay. We evaluated clinico-pathological and genomic characteristics in NRAS- or HRAS-mutated NSCLC pts comparing with those in KRAS-mutated pts based on the LC-SCRUM-Asia database. Results: Since March 2015 to December 2020, 9131 NSCLC pts were enrolled in the LC-SCRUM-Asia, and 8374 of them (92%) were successfully analyzed by NGS. The RAS mutation frequencies were 1134 KRAS (14%), 50 NRAS (0.6%), and 15 HRAS (0.2%). The most frequent variant of NRAS and HRAS mutations was Q61X (78%) and G13X (80%), respectively, whereas that of KRAS was G12X (84%). Patient characteristics were summarized in Table. Male was significantly frequent in NRAS- than in KRAS-group (p=0.03), and smokers were frequent in all the three groups (overall, 79%). The majority of NRAS (70%) and KRAS mutations (89%) were detected in adenocarcinoma (Ad), whereas 60% of HRAS mutations were in squamous cell carcinoma (Sq). Tumor mutation burden (TMB) was significantly higher in NRAS-mutated tumors than in KRAS-mutated tumors (p=0.03). Concomitant TP53 mutations were significantly frequent in HRAS-mutated pts than in KRAS-mutated pts (53% vs. 30%, p=0.05), and STK11 mutations were also tended to be frequent in HRAS-mutated pts than in KRAS-mutated pts (20 vs. 7%, p=0.10). Therapeutic efficacy of PD-1/PD-L1 inhibitors was not different among the three groups in the current follow-up data, but HRAS-mutated tumors did not respond to PD-1/PD-L1 inhibitors (response rate, 0%; median PFS, 1.6 months). Conclusions: NRAS- or HRAS-mutated NSCLCs were different from KRAS-mutated NSCLCs in clinico-pathological and genomic profiles. In particular, the immunotherapies were not effective for HRAS-mutated NSCLCs.[Table: see text]