Landscape of gene fusions and METex14 skipping in non-small cell lung carcinoma among the Chinese population: Insights from targeted RNA sequencing.

e20041 Background: Targeted RNA Sequencing is crucial for detecting gene fusions and exon-skipping mutations in non-small cell lung carcinoma (NSCLC). This study delineates the landscape of RNA-based fusion and METex14 skipping in the Chinese NSCLC population, compares the consistency with DNA-based fusion detection, and further explores the relationship between fusion-positive cases and immune markers. Methods: We profiled 294 NSCLC tumor tissues using targeted RNA sequencing, focusing on 29 fusion genes and 6 reference genes. Of these, 229 samples were concurrently assessed for fusions using a DNA panel. Patients with gene fusions or METex14 skipping were categorized as 'FUSION-POS'. Additionally, the expression of PD-L1 was evaluated. Results: In 294 NSCLC patients, 33 types of fusions and METex14 skipping were detected from 45 patients based on RNA detection. Actionable gene fusions/METex14 skipping were present in 11.22% (33/294) of patients, with the most prevalent being ALK (4.4%), METex14 skipping (2.7%), ROS1 (1.4%), and RET (1.0%). The partners of ALK, RET and ROS1 were EML4 (n= 12)/ LCLAT1(n=1), KIF5B (n=3) /PARD3(n=1) and CD74(n=2)/LRIG3(n=1)/EZR (n=1), respectively. Notably, we also identified two patients harboring FGFR2-ATE1 fusion and CD74-NRG1 fusion, respectively. Except for MET 14skipping, ST7-MET fusion was detected in 2 patients. Comparing the consistency of actionable fusions/METex14 skipping between RNA and DNA assessments in 229 NSCLC patients, RNA detection yielded a higher number of cases (24 patients vs 15 patients, 10.5% vs 6.5%), with all 15 fusions/ METex14 skipping detected by DNA also identified by RNA. Furthermore, we observed that PD-L1 expression was significantly elevated in the FUSION-POS group within lung adenocarcinoma patients (TPS: P=0.015). Conclusions: Our findings indicate that 11.22% of Chinese LUAD patients possess actionable fusions and METex14 skipping. The detection rate of fusions/ METex14 skipping via RNA is higher than that via DNA, with RNA detection fully encompassing all fusions/ METex14 skipping identified by DNA. Meanwhile, the association between fusions and PD-L1 expression suggests potential synergies for combining targeted therapy and immunotherapy in NSCLC.