RESUMEN
The expression of Bruton tyrosine kinase (BTK) in B cells and innate immune cells provides essential downstream signaling for BCR, Fc receptors, and other innate immune cell pathways. The topical covalent BTK inhibitor PRN473 has shown durable, reversible BTK occupancy with rapid on-rate and slow off-rate binding kinetics and long residence time, resulting in prolonged, localized efficacy with low systemic exposure in vivo. Mechanisms of PRN473 include inhibition of IgE (FcεR)-mediated activation of mast cells and basophils, IgG (FcγR)-mediated activation of monocytes, and neutrophil migration. In vivo, oral PRN473 was efficacious and well tolerated in the treatment of canine pemphigus foliaceus. In this study, we evaluated in vitro selectivity and functionality, in vivo skin Ab inflammatory responses, and systemic pharmacology with topically administered PRN473. Significant dose-dependent inhibition of IgG-mediated passive Arthus reaction in rats was observed with topical PRN473 and was maintained when given 16 h prior to challenge, reinforcing extended activity with once-daily administration. Similarly, topical PRN473 resulted in significant dose-dependent inhibition of the mouse passive cutaneous anaphylaxis IgE-mediated reaction. Multiday treatment with topical PRN473 in rodents resulted in low-to-no systemic accumulation, suggesting that efficacy was mainly due to localized exposure. Reduced skin Ab inflammatory activity was also confirmed with oral PRN473. These preclinical studies provide a strong biologic basis for targeting innate immune cell responses locally in the skin, with rapid onset of action following once-daily topical PRN473 administration and minimal systemic exposure. Dose-dependent inhibition in these preclinical models of immune-mediated skin diseases support future clinical studies.
Asunto(s)
Agammaglobulinemia Tirosina Quinasa , Reacción de Arthus , Anafilaxis Cutánea Pasiva , Inhibidores de Proteínas Quinasas , Enfermedades de la Piel , Animales , Femenino , Humanos , Ratones , Ratas , Administración Cutánea , Administración Oral , Agammaglobulinemia Tirosina Quinasa/antagonistas & inhibidores , Reacción de Arthus/tratamiento farmacológico , Reacción de Arthus/inmunología , Reacción de Arthus/patología , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Evaluación Preclínica de Medicamentos , Anafilaxis Cutánea Pasiva/efectos de los fármacos , Inhibidores de Proteínas Quinasas/administración & dosificación , Piel/efectos de los fármacos , Piel/inmunología , Piel/patología , Enfermedades de la Piel/tratamiento farmacológico , Enfermedades de la Piel/inmunología , Enfermedades de la Piel/patologíaRESUMEN
Bruton tyrosine kinase (BTK) is expressed in B cells and innate immune cells, acting as an essential signaling element in multiple immune cell pathways. Selective BTK inhibition has the potential to target multiple immune-mediated disease pathways. Rilzabrutinib is an oral, reversible, covalent BTK inhibitor designed for immune-mediated diseases. We examined the pharmacodynamic profile of rilzabrutinib and its preclinical mechanisms of action. In addition to potent and selective BTK enzyme and cellular activity, rilzabrutinib inhibited activation and inflammatory activities of B cells and innate cells such as macrophages, basophils, mast cells, and neutrophils, without cell death (in human and rodent assay systems). Rilzabrutinib demonstrated dose-dependent improvement of clinical scores and joint pathology in a rat model of collagen-induced arthritis and demonstrated reductions in autoantibody-mediated FcγR signaling in vitro and in vivo, with blockade of rat Arthus reaction, kidney protection in mouse Ab-induced nephritis, and reduction in platelet loss in mouse immune thrombocytopenia. Additionally, rilzabrutinib inhibited IgE-mediated, FcεR-dependent immune mechanisms in human basophils and mast cell-dependent mouse models. In canines with naturally occurring pemphigus, rilzabrutinib treatment resulted in rapid clinical improvement demonstrated by anti-inflammatory effects visible within 2 wk and all animals proceeding to complete or substantial disease control. Rilzabrutinib is characterized by reversible covalent BTK binding, long BTK residence time with low systemic exposure, and multiple mechanistic and biological effects on immune cells. Rilzabrutinib's unique characteristics and promising efficacy and safety profile support clinical development of rilzabrutinib for a broad array of immune-mediated diseases.
Asunto(s)
Agammaglobulinemia Tirosina Quinasa/antagonistas & inhibidores , Antiinflamatorios/uso terapéutico , Basófilos/inmunología , Plaquetas/inmunología , Riñón/patología , Mastocitos/inmunología , Nefritis/tratamiento farmacológico , Pénfigo/tratamiento farmacológico , Inhibidores de Proteínas Quinasas/uso terapéutico , Púrpura Trombocitopénica Idiopática/tratamiento farmacológico , Animales , Modelos Animales de Enfermedad , Perros , Evaluación Preclínica de Medicamentos , Humanos , Inmunoglobulina E/metabolismo , Riñón/efectos de los fármacos , Ratones , Ratones de la Cepa 129Asunto(s)
Antiinflamatorios/química , Antineoplásicos/química , Inflamación/tratamiento farmacológico , Leucemia de Células B/tratamiento farmacológico , Proteínas Tirosina Quinasas/antagonistas & inhibidores , Agammaglobulinemia Tirosina Quinasa , Animales , Antiinflamatorios/farmacología , Antineoplásicos/farmacología , Dominio Catalítico , Ensayos Clínicos como Asunto , Evaluación Preclínica de Medicamentos , Industria Farmacéutica , Humanos , Inflamación/enzimología , Leucemia de Células B/enzimología , Modelos Moleculares , Conformación Proteica , Proteínas Tirosina Quinasas/química , Relación Estructura-ActividadRESUMEN
P38alpha is a protein kinase that regulates the expression of inflammatory cytokines, suggesting a role in the pathogenesis of diseases such as rheumatoid arthritis (RA) or systemic lupus erythematosus. Here, we describe the preclinical pharmacology of pamapimod, a novel p38 mitogen-activated protein kinase inhibitor. Pamapimod inhibited p38alpha and p38beta enzymatic activity, with IC(50) values of 0.014 +/- 0.002 and 0.48 +/- 0.04 microM, respectively. There was no activity against p38delta or p38gamma isoforms. When profiled across 350 kinases, pamapimod bound only to four kinases in addition to p38. Cellular potency was assessed using phosphorylation of heat shock protein-27 and c-Jun as selective readouts for p38 and c-Jun NH(2)-terminal kinase (JNK), respectively. Pamapimod inhibited p38 (IC(50), 0.06 microM), but inhibition of JNK was not detected. Pamapimod also inhibited lipopolysaccharide (LPS)-stimulated tumor necrosis factor (TNF) alpha production by monocytes, interleukin (IL)-1beta production in human whole blood, and spontaneous TNFalpha production by synovial explants from RA patients. LPS- and TNFalpha-stimulated production of TNFalpha and IL-6 in rodents also was inhibited by pamapimod. In murine collagen-induced arthritis, pamapimod reduced clinical signs of inflammation and bone loss at 50 mg/kg or greater. In a rat model of hyperalgesia, pamapimod increased tolerance to pressure in a dose-dependent manner, suggesting an important role of p38 in pain associated with inflammation. Finally, an analog of pamapimod that has equivalent potency and selectivity inhibited renal disease in lupus-prone MRL/lpr mice. Our study demonstrates that pamapimod is a potent, selective inhibitor of p38alpha with the ability to inhibit the signs and symptoms of RA and other autoimmune diseases.
Asunto(s)
Inhibidores de Proteínas Quinasas/farmacología , Inhibidores de Proteínas Quinasas/uso terapéutico , Piridonas/farmacología , Pirimidinas/farmacología , Proteínas Quinasas p38 Activadas por Mitógenos/antagonistas & inhibidores , Animales , Artritis Reumatoide/tratamiento farmacológico , Evaluación Preclínica de Medicamentos , Humanos , Inflamación/tratamiento farmacológico , Concentración 50 Inhibidora , Interleucina-1beta/antagonistas & inhibidores , Interleucina-6/antagonistas & inhibidores , Enfermedades Renales/prevención & control , Ratones , Monocitos/inmunología , Monocitos/metabolismo , Osteoporosis/prevención & control , Isoformas de Proteínas , Piridonas/uso terapéutico , Pirimidinas/uso terapéutico , Líquido Sinovial/inmunología , Líquido Sinovial/metabolismo , Resultado del Tratamiento , Factor de Necrosis Tumoral alfa/antagonistas & inhibidoresRESUMEN
A novel class of highly selective inhibitors of p38 MAP kinase was discovered from high throughput screening. The synthesis and optimization of a series of 5-amino-N-phenyl-1H-pyrazol-4-yl-3-phenylmethanones is described. An X-ray crystal structure of this series bound in the ATP binding pocket of unphosphorylated p38alpha established the presence of a unique hydrogen bond between the exocyclic amine of the inhibitor and threonine 106 which likely contributes to the selectivity for p38. The crystallographic information was used to optimize the potency and physicochemical properties of the series. The incorporation of the 2,3-dihydroxypropoxy moiety on the pyrazole scaffold resulted in a compound with excellent drug-like properties including high oral bioavailability. These efforts identified 63 (RO3201195) as an orally bioavailable and highly selective inhibitor of p38 which was selected for advancement into Phase I clinical trials.