Co-occurring gene alterations associated with efficacy of osimertinib in EGFR-mutated lung cancer: Based on a large-scale genomic screening project (LC-SCRUM-Asia).

Abstract

9103 Background: Osimertinib is a standard drug for first-line treatment of patients with advanced non–small cell lung cancer (NSCLC) harboring EGFR mutations (mt). While tumor mutational burden (TMB)-high and co-occurring genetic alterations (alt) have been reported to be negatively associated with the efficacy of other EGFR-TKIs, the impact of co-occurring genetic alt with EGFR major mt on the efficacy of osimertinib remains unclear. Methods: In a multi-institutional genomic screening project (LC-SCRUM-Asia), we have analyzed lung cancer patients for genomic alt by a targeted next-generation sequencing (NGS) system, Oncomine Comprehensive Assay and Genexus/OPA. We retrospectively evaluated the association between the genomic profile and efficacy of first-line osimertinib for EGFR-mutated NSCLC based on the LC-SCRUM-Asia database. Results: Between March 2015 and January 2022, 12,705 NSCLC patients were enrolled in the LC-SCRUM-Asia database, and EGFR mt was detected in 2,232 patients. Of these, 324 patients, including 171 with ex19del (53%) and 153 with L858R (47%), received first-line treatment with osimertinib. The patient characteristics were as follows: median age, 69 years (range 31-97); females, 64%; never-smokers, 57%; adenocarcinoma, 97%; and performance status 0-1, 99%. The frequency of compound EGFR mt and TMB were higher in the L858R (LR) group than in the ex19del (Ex19) group (compound mt (%), 12 vs. 4; mean TMB (mt/Mb), 3.4 vs. 2.5). There were no differences in the frequencies of other co-occurring genetic alt between the two groups. Higher TMB, alt of genes encoding receptor tyrosine kinase (RTK), including FGFR1, RET, MET etc., and amp of cell-cycle related genes were significantly associated with shorter progression-free survival (PFS) in the entire group (median PFS: TMB > 3 vs. ≤3 mt/Mb = 11.4 vs. 17.1 months; p = 0.023; RTK gene alt+ vs. alt- = 9.7 vs. 15.2 months; p = 0.014; cell-cycle gene amp+ vs. amp- = 10.6 vs. 15.6 months, p = 0.001). EGFR subgroup analysis showed that a higher TMB was significantly associated with a shorter PFS in the LR group (> 3 vs. ≤3 mt/Mb = 10.0 vs. 17.1 months, p < 0.001), but not in the Ex19 group. On the other hand, alt of genes encoding RTK and amp of cell-cycle related genes were significantly associated with a shorter PFS in the Ex19 group (RTK gene alt+ vs. alt- = 8.4 vs. 17.8 months, p = 0.008; cell-cycle gene amp+ vs. amp- = 10.6 vs. 17.5 months, p = 0.003), but not in the LR group. Multivariate analysis identified RTK gene alt in the Ex19 group and higher TMB in the LR group as being independently associated with a shorter PFS. Conclusions: First-line osimertinib treatment was less effective in NSCLC patients harboring Ex19 with other RTK gene alt or LR with a higher TMB, indicating that co-occurring genetic alt affecting the efficacy of osimertinib differ between NSCLC patients harboring Ex19 and LR.

Do patient characteristics affect EGFR tyrosine kinase inhibitor treatment outcomes? A network meta‐analysis of real‐world survival outcomes of East Asian patients with advanced non‐small cell lung cancer treated with first‐line EGFR‐TKIs

“…This finding explains why tumors with these EGFR mutations were more responsive to TKIs 31–34 . In addition, the hypothesis that coexistence of uncommon mutations with L858R might affect its hypersensitivity to EGFR‐TKIs, particularly afatinib, is supported by several studies 35–38 . Interestingly, Robichaux et al demonstrated that the prevalence of atypical EGFR mutations is higher than expected in the NSCLC patients.…”

“…[31][32][33][34] In addition, the hypothesis that coexistence of uncommon mutations with L858R might affect its hypersensitivity to EGFR-TKIs, particularly afatinib, is supported by several studies. [35][36][37][38] Interestingly, Robichaux et al demonstrated that the prevalence of atypical EGFR mutations is higher than expected in the NSCLC patients. The authors proposed a new classification system to the EGFR mutations that has four subgroups based on the sensitivity and structural changes, which had higher utility than traditional exon-based groups in predicting response to EGFR inhibitors.…”