Oncogene addiction and radiation oncology: effect of radiotherapy with photons and carbon ions in ALK-EML4 translocated NSCLC

Radiat Oncol. 2018 Jan 5;13(1):1. doi: 10.1186/s13014-017-0947-0.

Abstract

Background: Patients with Echinoderm microtubule-associated protein-like 4 (EML4)-anaplastic lymphoma kinase (ALK) positive lung cancer are sensitive to ALK-kinase inhibitors. TAE684 is a potent second generation ALK inhibitor that overcomes Crizotinib resistance. Radiotherapy is an integral therapeutic component of locally advanced lung cancer. Therefore, we sought to investigate the effects of combined radiotherapy and ALK-inhibition via TAE684 in ALK-positive vs. wild type lung cancer cells.

Methods: Human non-small cell lung cancer (NSCLC) cell lines harboring wild-type ALK (A549), EML4-ALK translocation (H3122) and murine Lewis Lung Cancer (LLC) cells were investigated. Cells were irradiated with 1-4 Gy X-Rays (320 keV) and carbon ions (Spread-out Bragg Peak, SOBP (245.4-257.0 MeV/u)) at Heidelberg Ion Therapy center. TAE684 was administered at the dose range 0-100 nM. Clonogenic survival, proliferation and apoptosis via caspase 3/7 expression level were assessed in all three cell lines using time-lapse live microscopy.

Results: TAE684 inhibited the proliferation of H3122 cells in a dose-dependent manner with a half maximal inhibitory concentration (IC50) of ~ 8.2 nM. However, A549 and LLC cells were relatively resistant to TAE684 and IC50 was not reached at concentrations tested (up to 100 nM) in proliferation assay. The antiproliferative effect of TAE684 was augmented by radiotherapy in H3122 cells. TAE684 significantly sensitized H3122 cells to particle therapy with carbon ions (sensitizer enhancement ratio ~1.61, p < 0.05). Caspase 3/7 activity was evidently enhanced after combination therapy in H3122 cells.

Conclusions: This is the first report demonstrating synergistic effects of combined TAE684 and radiotherapy in EML4-ALK positive lung cancer cells. In addition to conventional photon radiotherapy, ALK-inhibition also enhanced the effects of particle irradiation using carbon ions. Our data indicate beneficial effects of combined ALK-inhibition and radiotherapy in treatment of this distinct subpopulation of NSCLC that warrant further evaluation.

Keywords: ALK inhibitors; Carbon ions; EML4-ALK-fusion; Non-small-cell lung cancer; Radiotherapy.

MeSH terms

  • Anaplastic Lymphoma Kinase
  • Animals
  • Antineoplastic Agents / pharmacology
  • Apoptosis / drug effects
  • Apoptosis / radiation effects
  • Carcinoma, Lewis Lung
  • Carcinoma, Non-Small-Cell Lung* / genetics
  • Cell Cycle Proteins / genetics
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Cell Proliferation / radiation effects
  • Cell Survival / drug effects
  • Cell Survival / radiation effects
  • Chemoradiotherapy / methods*
  • Heavy Ion Radiotherapy
  • Humans
  • Lung Neoplasms* / genetics
  • Mice
  • Microtubule-Associated Proteins / genetics
  • Oncogene Addiction*
  • Oncogene Fusion
  • Photons
  • Protein Kinase Inhibitors / pharmacology
  • Pyrimidines / pharmacology*
  • Receptor Protein-Tyrosine Kinases / genetics
  • Serine Endopeptidases / genetics

Substances

  • Antineoplastic Agents
  • Cell Cycle Proteins
  • Microtubule-Associated Proteins
  • NVP-TAE684
  • Protein Kinase Inhibitors
  • Pyrimidines
  • ALK protein, human
  • Alk protein, mouse
  • Anaplastic Lymphoma Kinase
  • Receptor Protein-Tyrosine Kinases
  • EML4 protein, human
  • Serine Endopeptidases