P2.13-13 Real-World Study of Osimertinib in EGFR T790M-Mutated Non-Small Cell Lung Cancer (NSCLC): ASTRIS Canadian Cohort Analysis

Abstract

ASTRIS is an open-label, single-arm, multinational, real world study of osimertinib for patients with advanced/metastatic epidermal growth factor receptor-mutated (EGFRm) T790M-positive non-small cell lung cancer (NSCLC) who previously received therapy with an EGFR tyrosine kinase inhibitor (EGFR-TKI) (NCT02474355). Data cut-off (DCO) for the second interim analysis was 20 October 2017, with 3014 patients enrolled (full analysis set), including 99 patients in Canada. Adult patients with locally advanced/metastatic EGFRm NSCLC, not amenable to curative surgery/radiotherapy, with confirmation of T790M and prior EGFR-TKI therapy were enrolled. Patients were included with World Health Organization performance status of 0 to 2, as well as those with asymptomatic stable central nervous system (CNS) metastases. Patients received osimertinib 80 mg once daily until loss of clinical benefit. The primary efficacy outcome was overall survival (OS), with secondary outcomes of investigator-assessed response rate (RR), progression-free survival (PFS), and time to treatment discontinuation (TTD). From study start (14 January 2016) to DCO (20 October 2017), 99 patients were enrolled at 12 Canadian centres. Median age was 64 years (30-89 years). Patients were 68% female, 57% Asian, and had ECOG 0/1/2 of 22%/65%/13%. Twenty-five patients had CNS metastases at screening. Gefitinib was the most commonly used previous EGFR-TKI (gefitinib, erlotinib and afatinib were 80%, 14%, and 14%, respectively). Thirty-nine percent had previous chemotherapy; 6% previous immunotherapy; 46% previous radiotherapy. All patients had T790M: 75% tissue, 7% blood and 18% cytology. Biomarker testing methods varied, with the majority (61%) identified by Entrogen EGFR kit. At DCO, 45 patients had discontinued treatment. OS data were immature. Median PFS was 11.0 months (95% CI, 8.9-13.3). Median TTD was 14.9 months (95% CI, 11.2-not calculated). RR was 67.0% (95% CI, 56.7-76.2); sub-analyses showed RR of 69.9% (58.0-80.1), 66.7% (22.3, 95.7) and 55.6% (30.8, 78.5) for patients with T790M by tissue, blood and cytology, respectively. Serious adverse events (AEs) were reported for 18% of patients. AEs leading to dose modifications and discontinuations were reported for 12% and 5% of patients, respectively. The Canadian results from this real world study of osimertinib in advanced/metastatic EGFRm T790M-positive NSCLC, which includes heavily pretreated patients and various approaches to biomarker testing, were comparable to outcomes reported in the phase III study AURA3 (NCT02151981). These findings provide further support for osimertinib as standard of care for EGFRm T790M-positive NSCLC.