Community Translations

Paradigm-changing osimertinib approval in front-line for advanced NSCLC

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©2018 Frontline Medical Communications



The US Food and Drug Administration awarded regulatory approval this spring to the third-generation epidermal growth factor receptor (EGFR) inhibitor osimertinib for the treatment of patients with exon 19 deletion- or exon21 L858R mutation-positive advanced non–small-cell lung cancer (NSCLC) not previously treated for advanced disease.

Osimertinib is designed to target both sensitizing and resistant mutant forms of EGFR, but not the wildtype protein, in an effort to improve safety and efficacy compared with other standard of care (SoC) EGFR inhibitors. It was previously approved in the second-line setting in NSCLC following failure of prior EGFR inhibitor therapy in 2015. The current approval represents a paradigm shift in the front-line treatment of advanced NSCLC, reinforcing the role of osimertinib, which has been recommended in this setting by the National Comprehensive Cancer Network Guidelines in Oncology for more than a year.

Approval was based on the phase 3, multicenter, international, randomized, double-blind, active-controlled FLAURA trial. A total of 556 patients were randomized 1:1 to receive an oral daily dose of 80 mg osimertinib or gefitinib 250 mg or erlotinib 150 mg. The trial was conducted during December 2014 through March 2016 at 132 sites in 29 countries.

Eligible patients were aged 18 or over and had locally advanced or metastatic NSCLC, had not previously received treatment for advanced disease, were eligible for first-line treatment with erlotinib or gefitinib, had locally or centrally confirmed EGFR exon 19 deletion or L858R mutations alone or concurrently with other EGFR mutations, and a World Health Organization Performance Status of 0 (fully active, able to carry on all predisease performance without restriction) or 1 (restricted in strenuous activity but ambulatory and able to carry out light work), and a minimum life expectancy of 12 weeks.

Patients with central nervous system metastases were eligible if their condition was neurologically stable. Patients who had previous definitive treatment or glucocorticoid therapy had to have completed it at least 2 weeks before the start of the trial. Patients were excluded from the trial if they had any previous treatment with any systemic anticancer therapy for advanced NSCLC, had major surgery within 4 weeks of the first dose of the study drug, had radiation therapy to more than 30% of the bone marrow or a wide field of radiation within 4 weeks of the first dose of the study drug, or were currently receiving potent inhibitors or inducers of cytochrome P450 3A4.

Osimertinib cut the risk of disease progression or death by more than 50% compared with standard TKI therapy. The estimated median progression-free survival (PFS) was 18.9 months with osimertinib, compared with 10.2 months for erlotinib or gefitinib (hazard ratio [HR]: 0.46; P < .0001). PFS benefit extended across all prespecified subgroups, including patients with CNS metastases (median PFS: 15.2 months vs 9.6 months; HR: 0.47; P = .0009). Confirmed overall response rate was 77% and 69% in the study and SoC groups, respectively, and estimated duration of response (DoR) was 17.6 months and 9.6 months. At the time of analysis, there were too few deaths to compare overall survival.

The most common adverse events (AEs) experienced by patients treated with osimertinib were diarrhea, rash, dry skin, nail toxicity, stomatitis, and reduced appetite. Serious AEs occurred in 4% of patients treated with osimertinib, most commonly involving pneumonia, interstitial lung disease/pneumonitis, and pulmonary embolism (PE). The rate of grade 3/4 AEs was 33.7% in the osimertinib group and 44.8% in the SoC group. Patients treated with osimertinib were less likely to discontinue treatment due to AEs (13.3% vs 18.1% of those receiving SoC).

Mechanism of action for osimertinib

Osimertinib is marketed as Tagrisso by AstraZeneca and the recommended dose is 80 mg orally once daily, with or without food. The prescribing information details warnings and precautions relating to interstitial lung disease and pneumonitis, QTc interval prolongation, cardiomyopathy, keratitis, and embryofetal toxicity.

Treatment with osimertinib should be withheld in patients presenting with worsening of respiratory symptoms indicative of ILD and permanently discontinued if ILD is confirmed. Electrocardiograms and electrolytes should be monitored periodically in patients with congenital long QTc syndrome, congestive heart failure, electrolyte abnormalities or in patients taking medications known to prolong QTc interval. Treatment should be permanently discontinued in those who develop QTc interval prolongation with signs and symptoms of life-threatening arrhythmia.

Cardiac monitoring, including assessment of left ventricular ejection fraction should be performed at baseline and throughout treatment in patients with cardiac risk factors and treatment should be permanently discontinued in patients who develop symptomatic congestive heart failure. Patients with signs and symptoms of keratitis should be referred to an ophthalmologist. Osimertinib can cause fetal harm and patients should be advised of the potential risk and the need for effective contraception use during treatment and for 6 weeks after the final dose is administered.

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