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16P - Evaluation of the Relationship between Clinicopathological Features at Diagnosis, and Acquisition of T790M Resistance Mutation in Patients with EGFR-mutant Metastatic Lung Cancer


06 Oct 2021




Izzet Dogan


Annals of Oncology (2021) 32 (suppl_6): S1345-S1371. 10.1016/annonc/annonc740


I. Dogan1, N. Khanmamadov2, N. Paksoy2, S. Vatansever2, P. Saip2, A. Aydiner2

Author affiliations

  • 1 Istanbul University Institute of Oncology, Istanbul/TR
  • 2 Istanbul University Institute of Oncology, 34093 - Istanbul/TR

Abstract 16P


Data of the acquisition of T790M resistance mutation in patients with EGFR-mutant metastatic lung cancer is limited. This study aimed to assess the relationship between clinicopathological features at diagnosis, and acquisition of T790M mutation in patients with EGFR-mutant metastatic non-small cell lung cancer.


We evaluated the EGFR-mutant metastatic lung cancer patients' data who progressed under first-line treatment with tyrosine kinase inhibitors and acquired T790M resistance mutation retrospectively. Survival analyses were assessed with Kaplan-Meier and Cox-regression methods. The relationship between the acquisition of T790M mutation and clinicopathological parameters was evaluated with logistic regression analysis.


Fifty-two patients were included in the study. The median age was 58 (range, 33-78) years. The proportion of female patients was 53.2%. The proportions of exon 19, exon 21, and rare mutations were 68.7%, 23.5%, and 7.8%, respectively. Forty-five (86.5%) patients were de-novo metastatic. The proportion of patients who had one, two, and three or more metastatic sites at diagnosis were 25.5%, 41.3%, and 33.2%, respectively. The proportio of brain, liver and adrenal gland metastasis were 29.4%, 13.7%, and 7.8%, respectively. All patients received tyrosine kinase inhibitors. After the disease progressed, the acquisition of T790M mutation was detected with liquid (75.5%) or standard biopsies (24.5%). T790M mutations were detected in 33 (63.5%) patients. In logistic regression analysis, age, gender, de-novo metastatic disease, number of metastatic sites, primary tumor localization (left or right lung), and type of tyrosine kinase inhibitor was not statistically significant for the acquisition of T790M mutations.


Due to rarity, the data on the acquisition of T790M mutations are limited. In this study, we showed that clinicopathological features were not related to the acquisition of T790M mutations.

Legal entity responsible for the study

The authors.


Has not received any funding.


All authors have declared no conflicts of interest.

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