SUMMARY: The FDA on April 19, 2018, approved TAGRISSO® (Osimertinib) for the first-line treatment of patients with metastatic Non Small Cell Lung Cancer (NSCLC), whose tumors have Epidermal Growth Factor Receptor (EGFR) exon 19 deletions or exon 21 L858R mutations, as detected by an FDA-approved test.
Lung cancer is the second most common cancer in both men and women and accounts for about 14% of all new cancers and 27% of all cancer deaths. The American Cancer Society estimates that for 2018 about 234,030 new cases of lung cancer will be diagnosed and over 154,050 patients will die of the disease. Lung cancer is the leading cause of cancer-related mortality in the United States. Non Small Cell Lung Cancer (NSCLC) accounts for approximately 85% of all lung cancers. Of the three main subtypes of Non Small Cell Lung Cancer (NSCLC), 30% are Squamous Cell Carcinomas (SCC), 40% are Adenocarcinomas and 10% are Large cell carcinomas. With changes in the cigarette composition and decline in tobacco consumption over the past several decades, Adenocarcinoma now is the most frequent histologic subtype of lung cancer. Approximately 10-15% of Caucasian patients and 35-50% of Asian patients with Adenocarcinomas, harbor activating EGFR (Epidermal Growth Factor Receptor) mutations and 90% of these mutations are either exon 19 deletions or L858R point mutations in exon 21. EGFR-Tyrosine Kinase Inhibitors (TKIs) such as TARCEVA® (Erlotinib), IRESSA® (Gefitinib) and GILOTRIF® (Afatinib), have demonstrated a 60-70% response rate as monotherapy when administered as first line treatment, in patients with metastatic NSCLC, who harbor the sensitizing EGFR mutations. However, majority of these patients experience disease progression within 9-14 months. This resistance to frontline EGFR TKI therapy has been attributed to acquired T790M “gatekeeper” point mutation in EGFR, identified in 50-60% of patients. Put another way, T790M is not relevant in about 40% of patients whose disease progression may be related to other mechanisms.
TAGRISSO® is a third-generation Epidermal Growth Factor Receptor (EGFR) TKI presently approved by the FDA, for the treatment of patients with metastatic EGFR T790M mutation-positive NSCLC, who had progressed on prior systemic therapy, including an EGFR-TKI. Previously published studies had suggested that TAGRISSO® may also be effective as initial therapy for EGFR mutation-positive advanced NSCLC.
The recent new indication for TAGRISSO® was based on FLAURA, which is a randomized, double blind, phase III clinical trial, conducted to compare the efficacy and safety of first line TAGRISSO® to TARCEVA® or IRESSA® (which are considered standard first line therapies), in NSCLC patients with activating mutations EGFR exon 19 deletions or L858R substitution mutation on exon 21. This study randomized 556 advanced NSCLC treatment naïve patients, with EGFR exon 19 or 21 mutations in a 1:1 ratio, to TAGRISSO® 80 mg orally once daily (N=279) or Standard of Care EGFR-TKI, IRESSA® 250 mg or TARCEVA® 150 mg, orally once daily (N=277). Patients were stratified by mutation status (exon 19 vs 21 mutations) and race (Asian vs non-Asian). Patients with CNS metastases who were neurologically stable, were allowed in this study. The Primary endpoint was Progression Free Survival (PFS).
The median PFS was 18.9 months with TAGRISSO® compared to 10.2 months for the standard therapy (HR=0.46; P<0.001), suggesting a 54% reduction in the risk of disease progression, compared with Standard of Care. TAGRISSO® extended the median Time To Progression by about 9 months. This PFS benefit was consistent across all subgroups of patients, including those with and without CNS metastases at study entry. The Objective Response Rate (ORR) with TAGRISSO® was 80% compared with 76% for TARCEVA® and IRESSA®. The median Duration of Response with TAGRISSO® was 17.2 months versus 8.5 months in the comparator arm. The median Overall Survival was not reached. Grade 3 and 4 toxicities were lower for TAGRISSO® (34%) compared with 45% for TARCEVA® and IRESSA®. Toxicities led to treatment discontinuation for 13% and 18% of patients in the TAGRISSO® and comparator groups, respectively.
It was concluded that TAGRISSO® demonstrated superior efficacy, with a near doubling in median Progression Free Survival, and better tolerability, compared to the Standard of Care, when given as first-line therapy, for patients with advanced EGFR mutation positive NSCLC. Studies are underway, assessing treatments, following resistance to TAGRISSO®.
Osimertinib in Untreated EGFR-Mutated Advanced Non–Small-Cell Lung Cancer. Soria J-C, Ohe Y, Vansteenkiste J, et al. for the FLAURA Investigators. N Engl J Med 2018; 378:113-125