The Ibr‐7 derivative of ibrutinib exhibits enhanced cytotoxicity against non‐small cell lung cancer cells via targeting of mTORC1/S6 signaling

Ibrutinib is a small molecule drug that targets Bruton's tyrosine kinase in B-cell malignancies and is highly efficient at killing mantle cell lymphoma and chronic lymphocytic leukemia. However, the anti-cancer activity of ibrutinib against solid tumors, such as non-small cell lung cancer (NSCLC), remains low. To improve the cytotoxicity of ibrutinib towards lung cancer, we synthesized a series of ibrutinib derivatives, of which Ibr-7 exhibited superior anti-cancer activity to ibrutinib, especially against epithelial growth factor receptor (EGFR) wild-type NSCLC cell lines. Ibr-7 was observed to dramatically suppress the mammalian target of Rapamycin complex 1 (mTORC1)/S6 signaling pathway, which is only slightly affected by ibrutinib, thus accounting for the superior anti-cancer activity of Ibr-7 towards NSCLC. Ibr-7 was shown to overcome the elevation of Mcl-1 caused by ABT-199 mono-treatment, and thus exhibited a significant synergistic effect when combined with ABT-199. In conclusion, we used a molecular substitution method to generate a novel ibrutinib derivative, termed Ibr-7, which exhibits enhanced anti-cancer activity against NSCLC cells as compared with the parental compound.