CNS response to osimertinib in patients (pts) with T790M-positive advanced NSCLC: Data from a randomized phase III trial (AURA3).

Abstract

9005 Background: CNS metastases (mets) are common in pts with advanced NSCLC. Preclinical studies have shown CNS penetration of osimertinib, and clinical data from a pooled analysis of 2 Phase II trials (AURA extension: NCT01802632, AURA2: NCT02094261) showed activity in the CNS. We report the first evidence of osimertinib efficacy in CNS mets from a randomized Phase III study (AURA3; NCT02151981) in pts with T790M-positive advanced NSCLC who have progressed on or after prior EGFR-TKI therapy. Methods: Pts were randomized 2:1 to osimertinib 80 mg once daily or platinum-based doublet chemotherapy every 3 wks for up to 6 cycles; maintenance pemetrexed was allowed. Pts with stable, asymptomatic CNS mets were eligible for enrolment. A prespecified subgroup analysis was conducted in pts with CNS mets present on baseline brain scan, as assessed by blinded independent central neuroradiology review (BICR), to define CNS objective response rate (ORR), duration of response (DoR) and progression-free survival (PFS) by RECIST v1.1. The CNS full analysis set (cFAS) included pts with ≥1 measurable and/or non-measurable CNS mets present on baseline brain scan by BICR; the CNS evaluable for response set (cEFR) included only pts with ≥1 measurable CNS mets. Results: As of 15 April 2016, 116/419 (28%) pts were included in the cFAS. In the cEFR (n = 46), CNS ORR was 70% (21/30; 95% CI 51, 85) with osimertinib and 31% (5/16; 95% CI 11, 59) with chemotherapy (OR, 5.13; 95% CI 1.44, 20.64; p = 0.015). In the cFAS, CNS ORR was 40% (30/75; 95% CI 29, 52) with osimertinib and 17% (7/41; 95% CI 7, 32) with chemotherapy (OR, 3.24; 95% CI 1.33, 8.81; p = 0.014). In the cEFR and cFAS, median CNS DoR was 8.9 months (m) (95% CI 4.3, NC and 4.3, NC) for osimertinib and 5.7 m (95% CI NC, NC and 4.4, 5.7; respectively) for chemotherapy. Median CNS PFS in the cFAS was significantly longer with osimertinib than with chemotherapy (11.7 vs 5.6 m; HR 0.32; 95% CI 0.15, 0.69; p = 0.004). Conclusions: Consistent with the overall response to osimertinib reported in pts with T790M-positive advanced NSCLC, osimertinib was superior to chemotherapy in the treatment of pts with CNS mets; CNS response rate was higher, responses were more durable and CNS PFS was longer. Clinical trial information: NCT02151981.