title: Ibrutinib (ImbruvicaTM) potently inhibits ErbB receptor phosphorylation and cell viability of ErbB2-positive breast cancer cells.
abstract: Ibrutinib (formerly PCI-32765) is a specific, irreversible, and potent inhibitor of Burton's tyrosine kinase (BTK) developed for the treatment of several forms of blood cancer. It is now an FDA-approved drug marketed under the name Imbruvica(TM) (Pharmacyclics, Inc.) and successfully used as an orally administered second-line drug in the treatment of mantle cell lymphoma. Since BTK is predominantly expressed in hematopoietic cells, the sensitivity of solid tumor cells to Ibrutinib has not been analyzed. In this study, we determined the effect of Ibrutinib on breast cancer cells. We demonstrate that Ibrutinib efficiently reduces the phosphorylation of the receptor tyrosine kinases ErbB1, ErbB2 and ErbB3, thereby suppressing AKT and MAPK signaling in ErbB2-positive (ErbB2+) breast cancer cell lines. Treatment with Ibrutinib significantly reduced the viability of ErbB2+ cell lines with IC50 values at nanomolar concentrations, suggesting therapeutic potential of Ibrutinib in breast cancer. Combined treatment with Ibrutinib and the dual PI3K/mTOR inhibitor BEZ235 synergistically reduces cell viability of ErbB2+ breast cancer cells. Combination indices below 0.25 at 50% inhibition of cell viability were determined by the Chou-Talalay method. Therefore, the combination of Ibrutinib and canonical PI3K pathway inhibitors could be a new and effective approach in the treatment of breast cancer with activated ErbB receptors. Ibrutinib could thus become a valuable component of targeted therapy in aggressive ErbB2+ breast cancer.
authors: Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, 92037, USA, n.grabinski@uke.de.
authors: Nicole
authors: N
authors: Grabinski
authors: Florian
authors: F
authors: Ewald
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives; D000077329:Agammaglobulinaemia Tyrosine Kinase; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D066246:ErbB Receptors / Q000037:antagonists & inhibitors* / Q000378:metabolism; D005260:Female; D006575:Heterocyclic Compounds, 3-Ring / Q000494:pharmacology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D010880:Piperidines; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology*; D011743:Pyrimidines / Q000494:pharmacology*; D011804:Quinolines / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors
chemical_list: D000970:Antineoplastic Agents; D006575:Heterocyclic Compounds, 3-Ring; D007093:Imidazoles; C548887:MK 2206; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010880:Piperidines; D047428:Protein Kinase Inhibitors; D011720:Pyrazoles; D011743:Pyrimidines; D011804:Quinolines; C551803:ibrutinib; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases; D000077329:Agammaglobulinaemia Tyrosine Kinase; C000625949:BTK protein, human; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D020928:Mitogen-Activated Protein Kinases; D000225:Adenine; C531198:dactolisib