In the past century, lung cancer has become one of the most prevalent malignant neoplasms. The prognosis for patients with metastatic and locally advanced non-small cell lung cancer (NSCLC) was extremely pessimistic. The overall survival on standard platinum-based chemotherapy did not exceed 10 months. The treatment tactics choice, namely choice of specific chemotherapeutic regimen, was empirical. The situation has changed dramatically with the study of molecular-genetic disorders that contribute to a tumor development and targeted therapy availability. Until recently, the main approach to the treatment of patients with NSCLC with activating mutations was the use of first-generation tyrosine kinase inhibitors (TKI), then, in the case of disease progression, the administration of next generations drugs or chemotherapy. However, this trend has been changing lately, new generation of targeted drugs have a significant advantage in time till progression, better intracranial control, a more favorable safety profile, that establish them as first-line treatment. Recent data confirms also an improvement of overall survival. This article discusses the situation in EGFR-postive NSCLC.

Targeted therapy has opened a new era in treatment of patients with non-small-cell lung cancer associated with mutations of the epidermal growth factor receptor (EGFR) gene. However, most patients after starting targeted therapy develop progression within 10-12 months. The basic mechanisms of acquired resistance are known, the secondary mutation in exon 20 of EGFR gene is the leading cause in more than a half of the cases. To detect this mutation is important to repeat molecular testing, that, consequently, requiring re-biopsy. Liquid biopsy is considered as an alternative to re-biopsy. Osimertinib is a third generation EGFR-tyrosine kinase inhibitor, possessing antitumor activity, both, in respect of T790M-positive tumors and of tumors with mutations in exons 18, 19 and 21. In the randomized AURA3 trial, the use of osimertinib was effective in 71% of patients, the median progression free survival was 11 months after the progression on1st-line targeted therapy and was statistically significant than in case of chemotherapy application. Patients with brain metastases also show response to osimertinib treatment. In our study, 29 patients received osimertinib after the progression on targeted therapy of the 1st and 2nd generation tyrosine kinase inhibitors. Objective response was reported in 44.8% (complete response - 3.4%), stabilization - 51.7% and progression - 3.5%. We will show the results concerning the time without progression in the near future. The tolerance of treatment is good. Osimertinib has been approved for 1st-line targeted therapy treatment of patients with the T790M mutation upon progression in Russian Federation, thus we have new opportunities to improve the results of the treatment in this group of patients.