Expanded Circulating Tumor Cells from a Patient with ALK-Positive Lung Cancer Present with EML4-ALK Rearrangement Along with Resistance Mutation and Enable Drug Sensitivity Testing: A Case Study

Abstract

The emergence of liquid biopsy using circulating tumor cells (CTCs) as a resource to identify genomic alterations in cancer presents new opportunities for diagnosis, therapy, and surveillance. We identified EML4-ALK gene rearrangement in expanded CTCs from a patient with ALK-positive lung adenocarcinoma. At the time of radiographic progression, CTCs obtained from the patient revealed a drug resistance mutation (i.e., L1196M on the ALK gene). CTCs were expanded ex vivo and drug sensitivity testing was performed using two ALK inhibitors, crizotinib and ceritinib. The half maximal inhibitory concentration of ceritinib was 1664 nM compared with crizotinib (2268 nM), showing that ceritinib was a more potent ALK inhibitor. We show that it is feasible to detect serial genetic alterations in expanded CTCs and perform in vitro drug screening. These findings support the clinical utility of CTCs not only for diagnosis, but also a potential tool for drug sensitivity testing in distinct subsets of lung cancer and for personalized precision medicine.

Keywords: EML4-ALK; Expanded CTCs; L1196M; Liquid biopsy; NSCLC.

Conflict of interest statement

The authors declare no conflict of interest.

Copyright © 2016 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1. Tumor status of the patient

(A) Computed tomography scan at initial diagnosis and when the patient was resistant to crizotinib. (B) EML4-ALK rearrangement is detected in the tumor biopsy specimen at initial visit by FISH (1000× magnification).

Figure 2. Mutation analysis of expanded CTCs

Expanded CTCs, during the three clinical visits, are positive for EML4-ALK rearrangement by FISH (1000× magnification). DNA sequencing reveals L1196M mutation in expanded CTCs when the patient developed resistance to crizotinib (2nd visit) and an absence of the mutation when brain metastasis occurred (3rd visit).

Figure 3. IC50s of cells treated with crizotinib and ceritinib

Expanded CTCs are compared with pure CAFs, a resistant cell line A549 and a sensitive cell line H3122.