MET Inhibitor Capmatinib Radiosensitizes MET Exon 14-Mutated and MET-Amplified Non-Small Cell Lung Cancer

PURPOSE

The objective of this study was to investigate the effects of inhibiting the MET receptor with capmatinib, a potent and clinically relevant ATP-competitive tyrosine kinase inhibitor, in combination with radiation in MET exon 14-mutated and MET-amplified non-small cell lung (NSCLC) cancer models.

METHODS AND MATERIALS

In vitro effects of capmatinib and radiation on cell proliferation, colony formation, MET signaling, apoptosis, and DNA damage repair were evaluated. In vivo tumor responses were assessed in cell line xenograft and patient-derived xenograft models. Immunohistochemistry was used to confirm the in vitro results.

RESULTS

In vitro clonogenic survival assays demonstrated radiosensitization with capmatinib in both MET exon 14-mutated and MET-amplified NSCLC cell lines. No radiation-enhancing effect was observed in MET wild-type NSCLC and a human bronchial epithelial cell line. Minimal apoptosis was detected with the combination of capmatinib and radiation. Capmatinib plus radiation compared with radiation alone resulted in inhibition of DNA double-strand break repair, as measured by prolonged expression of γH2AX. In vivo, the combination of capmatinib and radiation significantly delayed tumor growth compared with vehicle control, capmatinib alone, or radiation alone. Immunohistochemistry indicated inhibition of phospho-MET and phospho-S6 and a decrease in Ki67 with inhibition of MET.

CONCLUSIONS

Inhibition of MET with capmatinib enhances the effect of radiation in both MET exon 14-mutated and MET-amplified NSCLC models.

Development of an Engineered Single-Domain Antibody for Targeting MET in Non-Small Cell Lung Cancer

The Mesenchymal Epithelial Transition (MET) receptor tyrosine kinase is upregulated or mutated in 5% of non-small-cell lung cancer (NSCLC) patients and overexpressed in multiple other cancers. We sought to develop a novel single-domain camelid antibody with high affinity for MET that could be used to deliver conjugated payloads to MET expressing cancers. From a naïve camelid variable-heavy-heavy (VHH) domain phage display library, we identified a VHH clone termed 1E7 that displayed high affinity for human MET and was cross-reactive with MET across multiple species. When expressed as a bivalent human Fc fusion protein, 1E7-Fc was found to selectively bind to EBC-1 (MET amplified) and UW-Lung 21 (MET exon 14 mutated) cell lines by flow cytometry and immunofluorescence imaging. Next, we investigated the ability of [89Zr]Zr-1E7-Fc to detect MET expression in vivo by PET/CT imaging. [89Zr]Zr-1E7-Fc demonstrated rapid localization and high tumor uptake in both xenografts with a %ID/g of 6.4 and 5.8 for EBC-1 and UW-Lung 21 at 24 h, respectively. At the 24 h time point, clearance from secondary and nontarget tissues was also observed. Altogether, our data suggest that 1E7-Fc represents a platform technology that can be employed to potentially both image and treat MET-altered NSCLC.