RESUMO
Introduction: Up to 20% of EGFR-mutated NSCLC cases harbor uncommon EGFR mutations, including atypical exon 19 and compound mutations. Relatively little is known about the efficacy of osimertinib in these cases. Methods: Patients treated with first-line osimertinib for NSCLC with rare EGFR exon 19 (non E746_A750del) or compound mutations were included. Response assessment and time to progression were determined using Response Evaluation Criteria in Solid Tumors version 1.1 criteria. Kaplan-Meier analyses were used to estimate progression-free survival (PFS), time to treatment discontinuation (TTD), and overall survival (OS). Results: Thirty-seven patients with NSCLC harboring an atypical EGFR exon 19 mutation or compound mutation were treated with first-line osimertinib at Johns Hopkins from 2016 to 2021. Overall response rate (ORR) was 76% and median PFS, TTD, and OS were 13 months (95% confidence interval [CI]: 10-15), 22 months (95% CI: 17-32) and 36 months (95% CI, 29-48), respectively. Among atypical exon 19 mutations (n = 25), ORR was 80%, median PFS was 12 months (95% CI: 10-15), median TTD was 19 months (95% CI: 17-38), and median OS was 48 months (95% CI: 25-not reached). Compound mutations (n = 12) had an ORR of 67%, median PFS of 14 months (95% CI: 5-22), median TTD of 26 months (95% CI: 5-36), and median OS of 36 months (95% CI: 20-46). Twelve patients (32%) continued first-line osimertinib after local therapy for oligoprogression. Conclusions: Osimertinib exhibited favorable outcomes for rare EGFR exon 19 and compound mutations. The heterogeneity in outcomes among these groups of tumors with similar mutations underscores the need for continued reporting and further study of outcomes among rare variants to optimize management for each patient.
RESUMO
While tyrosine kinase inhibitors (TKI) have shown remarkable efficacy in anaplastic lymphoma kinase (ALK) fusion-positive advanced non-small cell lung cancer (NSCLC), clinical outcomes vary and acquired resistance remains a significant challenge. We conducted a retrospective study of patients with ALK-positive NSCLC who had clinico-genomic data independently collected from two academic institutions (n = 309). This was paired with a large-scale genomic cohort of patients with ALK-positive NSCLC who underwent liquid biopsies (n = 1,118). Somatic co-mutations in TP53 and loss-of-function alterations in CDKN2A/B were most commonly identified (24.1% and 22.5%, respectively in the clinical cohort), each of which was independently associated with inferior overall survival (HR: 2.58; 95% confidence interval, CI: 1.62-4.09 and HR: 1.93; 95% CI: 1.17-3.17, respectively). Tumors harboring EML4-ALK variant 3 (v3) were not associated with specific co-alterations but were more likely to develop ALK resistance mutations, particularly G1202R and I1171N (OR: 4.11; P < 0.001 and OR: 2.94; P = 0.026, respectively), and had inferior progression-free survival on first-line TKI (HR: 1.52; 95% CI: 1.03-2.25). Non-v3 tumors were associated with L1196M resistance mutation (OR: 4.63; P < 0.001). EML4-ALK v3 and somatic co-alterations in TP53 and CDKN2A/B are associated with inferior clinical outcomes. v3 status is also associated with specific patterns of clinically important ALK resistance mutations. These tumor-intrinsic features may inform rational selection and optimization of first-line and consolidative therapy. SIGNIFICANCE: In a large-scale, contemporary cohort of patients with advanced ALK-positive NSCLC, we evaluated molecular characteristics and their impact on acquired resistance mutations and clinical outcomes. Our findings that certain ALK variants and co-mutations are associated with differential survival and specific TKI-relevant resistance patterns highlight potential molecular underpinnings of the heterogenous response to ALK TKIs and nominate biomarkers that may inform patient selection for first-line and consolidative therapies.