AstraZeneca announced that the European Commission (EC) has granted conditional marketing authorisation for TAGRISSO™ (AZD9291, osimertinib) 80mg once-daily tablets for the treatment of adult patients with locally advanced or metastatic epidermal growth factor receptor (EGFR) T790M mutation-positive non-small cell lung cancer (NSCLC).
Osimertinib is indicated for patients with T790M mutation-positive NSCLC, irrespective of previous treatment with an EGFR tyrosine kinase inhibitor (TKI). Eligibility for treatment with osimertinib will be dependent on mutation status, to be determined through a validated diagnostic test based on a tumour tissue sample or plasma. Availability of a blood-based test for circulating tumour DNA (ctDNA) means that physicians and patients have multiple options to test for a T790M mutation.
Mutations in the EGFR receptor can lead to uncontrolled cell growth and tumour formation. Osimertinib targets both the EGFR mutation that triggers cancer development and T790M, a mutation that makes tumours resistant to existing treatment with EGFR-TKIs. Nearly two out of three patients with NSCLC whose disease progresses after treatment with an EGFR inhibitor develop the T790M mutation, for which treatment options are limited. A small number of patients (approximately 3-5%) have the T790M mutation at NSCLC diagnosis.
The EU approval for osimertinib is based on data from two Phase II studies (AURA extension and AURA2) and the AURA Phase I expansion study, which demonstrated efficacy in 474 patients with EGFRm T790M NSCLC who had progressed on or after an EGFR-TKI. In the combined Phase II studies, the objective response rate (ORR, a measurement of tumour shrinkage) was 66%, and in the Phase I study it was 62%. Progression-free survival (PFS) was 9.7 months in the combined Phase II studies and 11 months in the Phase I trial. Median duration of response (DOR) in the Phase I study was 9.7 months, and in the combined Phase II studies, median DOR was not reached.
