Molecular-targeted drugs are generally effective against
tumors containing driver oncogenes, such as EGFR, ALK, and NTRK1. However, patients harboring these oncogenes frequently experience a progression of
brain metastases during treatment. Here, we present an in vivo imaging model for
brain tumors using human
cancer cell lines, including the EGFR-L858R/T790M-positive H1975
lung adenocarcinoma cells, the NUGC4
hepatocyte growth factor (HGF)-dependent
gastric cancer cells, and the KM12SM
colorectal cancer cells containing the TPM3-NTRK1 gene fusion. We investigated the efficacy of targeted drugs by comparison with their effect in extracranial models. In vitro, H1975 cells were sensitive to the third-generation
epidermal growth factor receptor inhibitor
osimertinib. Moreover, HGF stimulated the proliferation of NUGC4 cells, that was inhibited by
crizotinib, which has anti-MET activity. KM12SM cells were sensitive to the
tropomyosin-related
kinase-A inhibitors
crizotinib and
entrectinib. In in vivo H1975 cell models,
osimertinib inhibited the progression of both brain and subcutaneous
tumors. Furthermore, in in vivo NUGC4 cell models,
crizotinib remarkably delayed the progression of
brain tumors, and that of
peritoneal carcinomatosis. Interestingly, in in vivo KM12SM cell models, treatment with
crizotinib delayed the progression of liver
metastases, but not that of
brain tumors. Conversely, treatment with
entrectinib discernibly delayed the progression of both
tumor types. Thus, the effect of targeted drugs against
brain tumors can differ from the one reported in extracranial
tumors. Moreover, the same multikinase inhibitory drug can display different efficacies in
brain tumor models containing different drivers. Therefore, our in vivo imaging model for
brain tumors may prove useful for preclinical drug screening against
brain metastases.