Ibrutinib Inhibits ERBB Receptor Tyrosine Kinases and HER2-Amplified Breast Cancer Cell Growth.
Ibrutinib is a potent, small-molecule Bruton tyrosine kinase (BTK) inhibitor developed for the treatment of B-cell malignancies. Ibrutinib covalently binds to Cys481 in the ATP-binding domain of BTK. This cysteine residue is conserved among 9 other tyrosine kinases, including HER2 and EGFR, which can be targeted. Screening large panels of cell lines demonstrated that ibrutinib was growth inhibitory against some solid tumor cells, including those inhibited by other HER2/EGFR inhibitors. Among sensitive cell lines, breast cancer lines with HER2 overexpression were most potently inhibited by ibrutinib (<100 nmol/L); in addition, the IC50s were lower than that of lapatinib and dacomitinib. Inhibition of cell growth by ibrutinib coincided with downregulation of phosphorylation on HER2 and EGFR and their downstream targets, AKT and ERK. Irreversible inhibition of HER2 and EGFR in breast cancer cells was established after 30-minute incubation above 100 nmol/L or following 2-hour incubation at lower concentrations. Furthermore, ibrutinib inhibited recombinant HER2 and EGFR activity that was resistant to dialysis and rapid dilution, suggesting an irreversible interaction. The dual activity toward TEC family (BTK and ITK) and ERBB family kinases was unique to ibrutinib, as ERBB inhibitors do not inhibit or covalently bind BTK or ITK. Xenograft studies with HER2+MDA-MB-453 and BT-474 cells in mice in conjunction with determination of pharmacokinetics demonstrated significant exposure-dependent inhibition of growth and key signaling molecules at levels that are clinically achievable. Ibrutinib's unique dual spectrum of activity against both TEC family and ERBB kinases suggests broader applications of ibrutinib in oncology. Mol Cancer Ther; 15(12); 2835-44. ©2016 AACR.
Research Department, Pharmacyclics LLC, an AbbVie Company, Sunnyvale, California.
Jun
J
Chen
Research Department, Pharmacyclics LLC, an AbbVie Company, Sunnyvale, California.
Taisei
T
Kinoshita
Clinical Pharmacology and DMPK Department, Pharmacyclics LLC, an AbbVie Company, Sunnyvale, California.
Juthamas
J
Sukbuntherng
Research Department, Pharmacyclics LLC, an AbbVie Company, Sunnyvale, California. bchang@pcyc.com.
Betty Y
BY
Chang
Research Department, Pharmacyclics LLC, an AbbVie Company, Sunnyvale, California.
Laurence
L
Elias
D000225:Adenine / Q000031:analogs & derivatives; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D002453:Cell Cycle; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004195:Disease Models, Animal; D066246:ErbB Receptors / Q000037:antagonists & inhibitors* / Q000378:metabolism; D005260:Female; D006801:Humans; D051379:Mice; D010880:Piperidines; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011720:Pyrazoles / Q000494:pharmacology*; D011743:Pyrimidines / Q000494:pharmacology*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D047368:Tumor Burden; D023041:Xenograft Model Antitumor Assays
D000225:Adenine; D000970:Antineoplastic Agents; D066246:ErbB Receptors; D010880:Piperidines; D047428:Protein Kinase Inhibitors; D011720:Pyrazoles; D011743:Pyrimidines; D018719:Erb-b2 Receptor Tyrosine Kinases; C551803:ibrutinib