Abstract
Neurotrophic receptor tyrosine kinase 1 (NTRK1) gene rearrangement leads to constitutive activation of NTRK1, which induces high-transforming ability. NTRK-rearranged cancers have been identified in several cancer types, such as glioblastoma, non-small cell lung cancer, and colorectal cancer. Although there are currently no clinically approved inhibitors that target NTRK1, several tyrosine kinase inhibitors (TKI), such as entrectinib and LOXO-101, are in clinical trials. The purpose of this study was to identify potential mechanisms of resistance to NTRK inhibitors and find potential therapeutic strategies to overcome the resistance. We examined the sensitivity of TPM3-NTRK1-transformed Ba/F3 cells and TPM3-NTRK1-harboring KM12 cells to multiple NTRK inhibitors. Acquired NTRK inhibitor-resistant mutations were screened by N-ethyl-N-nitrosourea mutagenesis with Ba/F3-TPM3-NTRK1 cells or by the establishment of NTRK-TKI-resistant cells from KM12 cells continuously treated with NTRK-TKIs. We identified multiple novel NTRK-TKI resistance mutations in the NTRK1 kinase domain, including G595R, and insulin growth factor receptor type 1 (IGF1R) bypass pathway-mediated resistance. After identifying the resistance mechanisms, we performed drug screening with small-molecule inhibitors to overcome the resistance. As a result, we found that ponatinib and nintedanib effectively inhibited the survival of TPM3-NTRK1-G667C but not G595R mutants, both of which showed resistance to entrectinib or larotrectinib (LOXO-101). Furthermore, cabozantinib with an IGF1R inhibitor such as OSI-906 could overcome bypass pathway-mediated resistance. We developed a comprehensive model of acquired resistance to NTRK inhibitors in cancer with NTRK1 rearrangement and identified cabozantinib as a therapeutic strategy to overcome the resistance. Mol Cancer Ther; 16(10); 2130-43. ©2017 AACR.
Highlights
The neurotrophic receptor tyrosine kinase 1 (NTRK1) gene was first identified as a fusion oncogene, trkA, in a colorectal cancer in 1986 [1]
From the establishment of cabozantinib- resistant KM12 cells and analysis using the resistant cells, we found that insulin growth factor receptor type 1 (IGF1R) mediated resistance to cabozantinib and other NTRK-tyrosine kinase inhibitors (TKI) and that combination therapy targeting IGF1R and NTRK1 completely reversed the resistance
We found that a G595R mutation harbored by NTRK1-TKI-resistant cells emerged in monoclonal KM12 cells, and that a TKI-resistant minor population, called the "persister clone," existed in both parental and single clonederived KM12 cells, which could be eradicated by the combination of IGF1R with NTRK1 inhibitors
Summary
The neurotrophic receptor tyrosine kinase 1 (NTRK1) gene was first identified as a fusion oncogene, trkA (tropomyosin receptor kinase), in a colorectal cancer in 1986 [1]. NTRK1, 2, and 3 are receptors of nerve growth factor (NGF), brainderived growth factor (BDNF), and neurotrophin 3 (NTF-3), respectively. They are mainly expressed in human neuronal tissues and play critical roles in the development and homeostasis of the nervous system. The NTRK1 fusion oncogenes, such as tropomyosin 3 (TPM3) and NTRK1, both located on chromosome 1, induce constitutive activation of NTRK1 tyrosine kinase mediated by constitutive expression by the promoter of the fusion partner gene and oligomerization using domains, such as the coiled-coil domain, in the fusion partner protein. A case of entrectinib resistance mediated by secondary mutations in NTRK1 (G595R and G667C mutations), and a case of entrectinib resistance by the G623R mutation in NTRK3 (corresponding to G595R in NTRK1) in mammary analogue secretory carcinoma (MASC) were recently reported [14, 15]
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