pci-32765 and Agammaglobulinemia

Bruton's tyrosine kinase (Btk) is essential for B cell differentiation and proliferation, but also platelets express Btk. Patients with X-linked agammaglobulinemia due to hereditary Btk deficiency do not show bleeding, but a mild bleeding tendency is observed in high dose therapy of B-cell malignancies with ibrutinib and novel second-generation irreversible Btk inhibitors (acalabrutinib and ONO/GS-4059). This review discusses recent studies that may explain this apparent paradox and gives mechanistic insights that suggest a unique potential of low dose irreversible Btk inhibitors as atherothrombosis-focused antiplatelet drugs.

Topics: Adenine; Administration, Oral; Agammaglobulinaemia Tyrosine Kinase; Agammaglobulinemia; Animals; Arteries; B-Lymphocytes; Benzamides; Blood Platelets; Cell Differentiation; Genetic Diseases, X-Linked; Hemorrhage; Humans; Imidazoles; Mice; Piperidines; Platelet Aggregation Inhibitors; Platelet Membrane Glycoproteins; Protein Kinase Inhibitors; Pyrazines; Pyrazoles; Pyrimidines; Signal Transduction; Thrombosis

BTK and ITK are cytoplasmic tyrosine kinases of crucial importance for B and T cell development, with loss-of-function mutations causing X-linked agammaglobulinemia and susceptibility to severe, frequently lethal, Epstein-Barr virus infection, respectively. Over the last few years, considerable efforts have been made in order to develop small-molecule inhibitors for these kinases to treat lymphocyte malignancies, autoimmunity or allergy/hypersensitivity. The rationale is that even if complete lack of BTK or ITK during development causes severe immunodeficiency, inactivation after birth may result in a less severe phenotype. Moreover, therapy can be transient or only partially block the activity of BTK or ITK. Furthermore, a drug-induced B cell deficiency is treatable by gamma globulin substitution therapy. The newly developed BTK inhibitor PCI-32765, recently renamed Ibrutinib, has already entered several clinical trials for various forms of non-Hodgkin lymphoma as well as for multiple myeloma. Experimental animal studies have demonstrated highly promising treatment effects also in autoimmunity. ITK inhibitors are still under the early developmental phase, but it can be expected that such drugs will also become very useful. In this study, we present BTK and ITK with their signalling pathways and review the development of the corresponding inhibitors.

Topics: Adenine; Agammaglobulinaemia Tyrosine Kinase; Agammaglobulinemia; Antineoplastic Agents; Autoimmunity; B-Lymphocytes; Epstein-Barr Virus Infections; Gene Expression Regulation, Neoplastic; Genetic Diseases, X-Linked; Humans; Inflammation; Lymphoma; Piperidines; Protein Kinase Inhibitors; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines; Signal Transduction; Small Molecule Libraries; T-Lymphocytes

Topics: Adenine; Agammaglobulinemia; Humans; Leukemia, Lymphocytic, Chronic, B-Cell; Piperidines; Protein Kinase Inhibitors; Pyrazoles; Pyrimidines

Topics: Adenine; Agammaglobulinemia; Aged; Bacterial Infections; Humans; Immunoglobulins; Leukemia, Lymphocytic, Chronic, B-Cell; Male; Piperidines; Pyrazoles; Pyrimidines; Recurrence; Sinusitis

Ibrutinib and acalabrutinib are irreversible inhibitors of Bruton tyrosine kinase used in the treatment of B-cell malignancies. They bind irreversibly to cysteine 481 of Bruton tyrosine kinase, blocking autophosphorylation on tyrosine 223 and phosphorylation of downstream substrates including phospholipase C-γ2. In the present study, we demonstrate that concentrations of ibrutinib and acalabrutinib that block Bruton tyrosine kinase activity, as shown by loss of phosphorylation at tyrosine 223 and phospholipase C-γ2, delay but do not block aggregation in response to a maximally-effective concentration of collagen-related peptide or collagen. In contrast, 10- to 20-fold higher concentrations of ibrutinib or acalabrutinib block platelet aggregation in response to glycoprotein VI agonists.

Topics: Adenine; Agammaglobulinaemia Tyrosine Kinase; Agammaglobulinemia; Benzamides; Blood Platelets; Carrier Proteins; Genetic Diseases, X-Linked; Humans; Mutation; Peptides; Piperidines; Platelet Activation; Platelet Function Tests; Platelet Membrane Glycoproteins; Protein Kinase Inhibitors; Pyrazines; Pyrazoles; Pyrimidines

Malakoplakia, a rare granulomatous disease of infectious etiology, is commonly observed in immunocompromised patients. Chronic lymphocytic leukemia (CLL) is characterized by profound immune dysregulation resulting in significant infection-related morbidity and mortality, and several drugs used in CLL treatment have a severe immunosuppressive effect. Ibrutinib, has become a new standard-of-care in patients with CLL, especially for those harboring unfavorable genetic characteristics such as 17 p deletion, with however, unknown long-term immunological consequences. Here we report a case of a patient with CLL with 17 p deletion diagnosed with malakoplakia of the urinary bladder under ibrutinib therapy who developed severe hypogammaglobulinemia during treatment administration. Presumably, ibrutinib might contribute to the development of malakoplakia on the grounds of induced immunosuppression. This case report highlights the need for regular assessment of immunogammaglobulin adequacy during treatment with ibrutinib, considering that it should be given on a permanent basis.

Topics: Adenine; Agammaglobulinemia; Aged; Chromosome Deletion; Chromosomes, Human, Pair 17; Female; Humans; Immunosuppression Therapy; Leukemia, Lymphocytic, Chronic, B-Cell; Malacoplakia; Piperidines; Pyrazoles; Pyrimidines; Urinary Bladder