P14 Detection of EGFR/T790M Mutation in Advanced NSCLC Post TKI Treatment: First Experience of Liquid Biopsy in Argentina

BACKGROUND: A histopathological and mutational diagnosis has become a priority in the correct choice of the most appropriate cancer therapy for NSCLC. In the absence of a molecular analysis, the therapeutic choice will be directed towards platinum-based chemotherapy, thus preventing, in the presence of a specific mutation, the benefits deriving from the administration of a target therapies (TT).AIM: the present analysis was carried out with the aim of estimating the clinical impact, expressed in terms of progression free survival (PFS), associated with the use of the combined strategy (tissue biopsy and liquid biopsy) or the tissue strategy in the EGFR+ mNSCLC population.METHODS: A pre-existing cost-consequence model was adapted to estimate the annual number of mNSCLC patients with or without the EGFR mutation in order to decide the oncological treatment to be administered in first (1L) or second line (2L). In 1L, against the presence of the EGFR mutation, the administration of a Tyrosine Kinase Inhibitor (TKI), such as osimertinib, gefitinib, erlotinib or afatinib, was considered; in the absence of the EGFR mutation, the administration ofstandard platinum-based chemotherapy was instead considered. With reference to 2L, in the presence of the EGFR T790M mutation, only osimertinib was considered. In the absence of the EGFR T790M mutation, the administration of the standard platinum-based chemotherapy was also considered. The PFS data associated with each of the drugs considered were extrapolated from the respective clinical studies. Key variables were tested in the sensitivity analysis.RESULTS: The adoption of the combined strategy (tissue biopsy and liquid biopsy), by virtue of a greater number of patients treated with TKIs, would make it possible to increase the average PFS in the range of 1.1-3,7 months in the 1L and by 1.4 months in the 2L.CONCLUSION: These results show how the adoption of a correct diagnostic strategy is critical in order to optimize the choice of the therapeutic path in the 1L and 2L of mNSCLC. The addition of the liquid biopsy to the classic diagnostic path (tissue biopsy) would in fact allow to obtain an increase in therapeutic efficacy (average PFS).

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EGFR status evaluation by liquid biopsy during first-line therapy in patients with advanced NSCLC.

Journal of Clinical Oncology ◽

10.1200/jco.2017.35.15_suppl.e20524 ◽

2017 ◽

Vol 35 (15_suppl) ◽

pp. e20524-e20524

Author(s):

Francesca Zanelli ◽

Maria Pagano ◽

Candida Bonelli ◽

Bruno Casali ◽

Alberto Cavazza ◽

...

Keyword(s):

Disease Progression ◽

Liquid Biopsy ◽

Egfr Mutation ◽

Advanced Nsclc ◽

First Line ◽

Liquid Biopsies ◽

T790m Mutation ◽

First Line Therapy ◽

Line Therapy ◽

Nsclc Patients

e20524 Background: over the past decade, personalized management based on the molecular features of tumours in patients with advanced non small-cell lung cancer (NSCLC) has entered routine clinical practice. The poor performance of many advanced NSCLC patients may limit invasive biopsies. The liquid biopsy is a diagnostic procedure performed on cancer-derived material obtained in blood samples. In this abstract, we will describe our experience with liquid biopsies. Methods: In the Reggio Emilia Clinical Cancer Centrefrom March 2016 to December 2016, 42 patients with advanced NSCLC were analyzed that had had or had already started first line therapy. The liquid biopsy was repeated at each imaging response evaluation by thoracic-abdominal compound tomography (CT) scan performed every 3 months. In the liquid biopsy, the mutational status of EGFR was analyzed with real time PCR (KIT cobas EGFR mutation test v2 CE-IVD Roche); in tissue, it was evaluated by pyrosequencing. Results: 21/42 liquid biopsies were EGFR-mutated (12/21 eson 19 and 9/21 eson 21). In 3/21 (14.3%) cases, the tissue biopsies showed wild type (WT) EGFR. 6 liquid biopsies were also performed at time 0 (diagnosis). All liquid biopsies of EGFR WT remained WT during treatment and imaging evaluation. The median number of liquid biopsy tests for patients was 2 (range 1-3). In 4/21 cases, T790M was performed: 3 cases in both liquid biopsies and tissue, and 1 case in tissue but not in liquid biopsy. TKi therapy was ineffective in this patient with T790M mutation detected in tissue, but not in liquid biopsy. In all patients, the disappearance of the T790M mutation during TKi therapy was related to disease progression. In 11 cases, modification of EGFR mutation status during treatment anticipated CT scan evidence of disease progression (median = three months). Conclusions: the liquid biopsy is an excellent resource. In our experience the liquid biopsy is the sensitive method of choice during treatment of advanced NSCLC patients. EGFR modification status during TKi therapy showed advanced disease progression.

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