Osimertinib as first-line (1L) treatment for epidermal growth factor receptor (EGFR) mutation-positive advanced non-small cell lung cancer (NSCLC): Final efficacy and safety results from two phase I expansion cohorts

Background: Osimertinib is a 3rd-generation, CNS-active EGFR-tyrosine kinase inhibitor (TKI) that potently and selectively inhibits both EGFR-TKI sensitising (EGFRm) and EGFR T790M resistance mutations. Earlier results from the Ph I AURA (NCT01802632) and Ph III FLAURA (NCT02296125) studies have established 1L osimertinib efficacy. We report final efficacy and safety data from two Ph I expansion cohorts who received 1L osimertinib 80 or 160 mg for advanced EGFRm NSCLC in AURA. Methods: Treatment-naïve pts with locally advanced/metastatic EGFRm NSCLC received osimertinib 80 or 160 mg once daily. Endpoints included objective response rate (ORR), progression-free survival (PFS) and safety evaluation. EGFRm status was confirmed via local and/or central laboratory testing. Key eligibility criteria included measurable disease and WHO performance status 0/1. Pts with stable asymptomatic CNS metastases were eligible. Data cutoff: 1 May 2018. Results: Overall, 60 patients (pts) were enrolled at two doses (80 mg, n = 30; 160 mg, n = 30): 75% female; 72% Asian; 43% with EGFR ex19del; 48% with L858R. Five pts were EGFR T790M mutation-positive by central test at study entry. Median follow up: 19.1 mo. ORR (95% CI): 67% (47, 83) in the 80 mg cohort, 87% (69, 96) in the 160 mg cohort, 77% (64, 87) overall. Median duration of response (95% CI): 19.3 mo (12.2, 24.7) in the 80 mg cohort, 16.7 mo (9.7, 29.0) in the 160 mg cohort, 18.0 mo (12.5, 24.7) overall. Median PFS (95% CI): 22.1 mo (12.3, 30.2) in the 80 mg cohort, 19.3 mo (11.1, 26.0) in the 160 mg cohort, 20.5 mo (13.7, 26.1) overall (78% maturity). 42% (95% CI 29, 54) and 14% (95% CI 6, 26) of pts were progression free at 24 and 48 mo, respectively. Dose reductions occurred in 27% and 60% of pts at 80 mg and 160 mg, respectively. Most common adverse events overall: (% [Grade ≥3]) diarrhoea (80 mg, 63% [3%]; 160 mg, 87% [7%]), stomatitis (80 mg, 47% [0]; 160 mg, 53% [3%]), paronychia (80 mg, 37% [0]; 160 mg, 57% [10%]). Conclusions: Consistent with previously reported results, 1L osimertinib for EGFRm advanced NSCLC results in prolonged PFS at both doses and better tolerability at the 80 mg dose. Clinical trial identification: NCT01802632 (25 February 2013). Editorial acknowledgement: Medical writing support was provided by Natasha Cary BSc, from iMed Comms, an Ashfield Company and funded by AstraZeneca. Legal entity responsible for the study: AstraZeneca. Funding: AstraZeneca. Disclosure: J.C-H. Yang: Honoraria: BI, Roche, MSD, AstraZeneca, Novartis; Consulting/advisory: BI, Novartis, AstraZeneca, Roche/Genentech, Clovis Oncology, Lilly, MSD, Merck Serono, Celgene, Astellas Pharma, Bayer, Pfizer, Ono Pharmaceutical, Bristol-Myers Squibb, Yuhan, Hansoh. S.S. Ramalingam: Advisory boards: AbbVie, Amgen, AstraZeneca, BMS, Celgene, Genentech, Lilly, Merck, Roche, Nektar, Loxo, Takeda; Research grants: Merck, Tesaro. C.K. Lee: Advisory boards: AstraZeneca, Roche, Norvatis, Pfizer. Research funding to institution: AstraZeneca for the trials in which I am currently involved. T. Kurata: Research grants: AstraZeneca, MSD; Honoraria: AstraZeneca, MSD, Ono, Bristol-Myers Squibb, Chugai, Eli Lilly. D-W. Kim: Advisory board membership, personal expenses: Novartis. T. John: Consultancy: AstraZeneca, Bristol-Myers Squibb, Boehringer Ingelheim, Takeda, Pfizer, Novartis, Merck, Roche. N. Nogami: Honoraria: AstraZeneca, Chugai Pharmaceutical, Eli Lilly Japan K.K., MSD, ONO Pharmaceutical, Pfizer Japan Inc., Taiho Pharmaceutical. Y. Ohe: Honoraria, consulting, research funding: AstraZeneca, Chugai, Dainippon Lilly, Ono, BMS Japan, Daiichi Sankyo, BI, Bayer, Ignyta, Pfizer, MSD, Taiho, Novartis, Kyorin, Kyowa Hakko Kirin, Takeda, Celltrion. Y. Rukazenkov: Employee and shareholder: AstraZeneca. P.A. Jänne: Consultancy: AstraZeneca, BI, Pfizer, Merrimack, Roche/Genentech, Chugai, AceaBiosciences, ARIAD Pharma, Ignyta, LOXO Oncology; Stock ownership: Gatekeeper Pharma; Research funding: Astellas, AstraZeneca; IP: EGFR mutations licensed to Lab Corp. All other authors have declared no conflicts of interest.