A high number of co-occurring genomic alterations detected by NGS is associated with worse clinical outcomes in advanced EGFR-mutant lung adenocarcinoma: Data from LATAM population.

Background: Co-occurring genomic alterations identified downstream main oncogenic drivers have become more evident since the introduction of next-generation sequencing (NGS) analyses at diagnosis and progression. Emerging evidence has stated that co-occurring genomic alterations at diagnosis might represent de novo and primary resistance mechanisms to tyrosine kinase inhibitors (TKIs) in advanced EGFR-mutant (EGFRm) non-small lung cancer (NSCLC). In this study, we assessed the prognostic role of co-occurring genomic alterations in advanced EGFRm NSCLC.

Methods: A cohort of 111 patients with advanced NSCLC harboring EGFR-sensitive mutations detected by PCR was analyzed in 5 Latin American oncological centers from January 2019 to December 2020. All eligible patients received upfront therapy with EGFR-TKI. Co-occurring genomic alterations were determined at diagnosis in every patient by the NGS (FoundationOneCDx) comprehensive platform, which evaluates 324 known cancer-related genes.

Results: EGFR exon19 deletion was the most frequent oncogenic driver mutation (60.4 %) detected by NGS. According to the NGS assay, 31 % and 68.3 % of patients had 1-2 and ≥ 3 co-occurring genomic alterations, respectively. The most frequent co-occurring genomic alterations were TP53 mutations (64.9 %) followed by CDKN2AB alterations (13.6 %), BRCA2 (13.6 %), and PTEN (12.7 %) mutations. Baseline central nervous system disease was present in 42.7 % of patients. First- or second-generation EGFR TKIs (gefitinib, afatinib, or erlotinib) were the most common treatment in 67.5 % of patients, while osimertinib was administered in 27.9 % of cases. The median PFS in all evaluated patients was 13.63 months (95 %CI: 11.79-15.52). Using ≥ 3 co-occurring alterations as the cut-off point, patients with ≥ 3 co-occurring genomic alterations showed a median PFS, of 12.7 months (95 %CI: 9.92-15.5) vs 21.3 months (95 %CI: 13.93-NR) in patients with 2 or less co-occurring genomic alterations [HR 3.06, (95 %CI: 1.55-5.48) p = 0.0001]. Also, patients with a TP53 mutation had a shorter PFS, 13.6 (95 %CI: 10.7-15.5) vs 19.2 months (95 %CI: 12.8-NR); in wild type TP53 [HR 2.01 (95 %CI: 1.18-3.74) p = 0.12]. In the multivariate analysis, the number (≥3) of concurrent genomic alterations and ECOG PS of 2 or more were related to a significant risk factor for progression [HR 2.79 (95 %CI: 1.49-5.23) p = 0.001 and HR 2.42 (95 %CI: 1.22-4.80) p = 0.011 respectively].

Conclusion: EGFR-mutant NSCLC is not a single oncogene-driven disease in the majority of cases, harboring a higher number of co-occurring genomic alterations. This study finds the number of co-occurring genomic alterations and the presence of TP53 mutations as negative prognostic biomarkers, which confers potentially earlier resistance mechanisms to target therapy.