title: Ibrutinib (PCI-32765), the first BTK (Bruton's tyrosine kinase) inhibitor in clinical trials.
abstract: Ibrutinib is a potent covalent kinase inhibitor that targets BTK. BTK, or Bruton's tyrosine kinase, is an obvious target for therapy of B cell diseases because inactivating mutations lead to B cell aplasia in humans and the disease X-linked agammaglobulinemia. Ibrutinib has modest cytotoxicity against CLL cells in vitro but also blocks trophic stimuli from the microenvironment. As with other inhibitors of the BCR pathway, ibrutinib causes rapid nodal reduction and response associated with rapid increase in lymphocytosis, which then returns to baseline over time. The ORR of ibrutinib in relapsed refractory CLL is 67 % with PFS 88 % at 15 months. In a cohort of untreated patients 65 years and over, the estimated 15 month PFS is 96 %. Registration trials have been initiated, and the difficult task that remains is to determine where in the course of CLL therapy this drug will have the greatest impact and benefit for patients.
authors.affiliation: Harvard Medical School and Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA. Jbrown2@partners.org
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Brown
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives; D000077329:Agammaglobulinaemia Tyrosine Kinase; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D002986:Clinical Trials as Topic; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000188:drug therapy* / Q000201:enzymology; D010880:Piperidines; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D011720:Pyrazoles / Q000627:therapeutic use*; D011743:Pyrimidines / Q000627:therapeutic use*
chemical_list: D000970:Antineoplastic Agents; D010880:Piperidines; D011720:Pyrazoles; D011743:Pyrimidines; C551803:ibrutinib; D011505:Protein-Tyrosine Kinases; D000077329:Agammaglobulinaemia Tyrosine Kinase; C000625949:BTK protein, human; D000225:Adenine