Characterization of compound 584, an Abl kinase inhibitor with lasting effects

Background: Resistance to imatinib is an important clinical issue in the treatment of Philadelphia chromosomepositive leukemias which is being tackled by the development of new, more potent drugs, such as the dual Src/Abl tyrosine kinase inhibitors dasatinib and bosutinib and the imatinib analog nilotinib. In the current study we describe the design, synthesis and biological properties of an imatinib analog with a chlorine-substituted benzamide, namely compound 584 (cmp-584). Design and Methods: To increase the potency, we rationally designed cmp-584, a compound with enhanced shape complementarity with the kinase domain of Abl. cmp-584 was synthesized and characterized in vitro against a panel of 67 serine/threonine and tyrosine kinases using radioactive and enzyme-linked immunosorbent kinase assays. We studied inhibitory cellular activity using Bcr/Abl-positive human cell lines, murine transfectants in proliferation experiments, and a murine xenotransplanted model. Kinase assays on isolated Bcr/Abl protein were also performed. Finally, we used a wash-out approach on whole cells to study the binding kinetics of the inhibitor. Results: cmp-584 showed potent anti-Abl activity both on recombinant protein (IC50: 8 nM) and in cell-based assays (IC50: 0.1-10 nM). The drug maintained inhibitory activity against platelet-derived growth factor receptors and c-KIT and was also active against Lyn (IC50: 301 nM). No other kinase of the panel was inhibited at nanomolar doses. cmp-584 was 20- to 300-fold more active than imatinib in cells. This superior activity was evident in intact cells, in which full-length Bcr-Abl is present. In vivo experiments confirmed the activity of cmp-584. Wash-out experiments showed that short exposure to the drug impaired cell proliferation and Bcr-Abl phosphorylation for a substantially longer period of time than imatinib. Conclusions: The present results suggest a slower off-rate (dissociation rate) of cmp-584 compared to imatinib as an explanation for the increased cellular activity of the former. ©2008 Ferrata Storti Foundation

In vitro and in vivo activity of SKI-606, a novel Src-Abl inhibitor, against imatinib-resistant Bcr-Abl⁺ neoplastic cells

Resistance to imatinib represents an important scientific and clinical issue in chronic myelogenous leukemia. In the present study, the effects of the novel inhibitor SKI-606 on various models of resistance to imatinib were studied. SKI-606 proved to be an active inhibitor of Bcr-Abl in several chronic myelogenous leukemia cell lines and transfectants, with IC(50) values in the low nanomolar range, 1 to 2 logs lower than those obtained with imatinib. Cells expressing activated forms of KIT or platelet-derived growth factor receptor (PDGFR), two additional targets of imatinib, were unaffected by SKI-606, whereas activity was found against PIM2. SKI-606 retained activity in cells where resistance to imatinib was caused by BCR-ABL gene amplification and in three of four Bcr-Abl point mutants tested. In vivo experiments confirmed SKI-606 activity in models where resistance was not caused by mutations as well as in cells carrying the Y253F, E255K, and D276G mutations. Modeling considerations attribute the superior activity of SKI-606 to its ability to bind a conformation of Bcr-Abl different from imatinib

Inhibition of RET tyrosine kinase by SU5416

Thyroid neoplasia is frequently associated with rearranged during transfection (RET) proto-oncogene mutations that cause hyperactivation of RET kinase activity. Selective inhibition of RET-mediated signaling should lead to an efficacious therapy. SU5416 is a potent inhibitor of vascular endothelial cell growth factor receptor, c-Kit, and FLT-3 receptor tyrosine kinases presently used in clinical trials. We found that SU5416 inhibits RET with similar potency, both in cell-free assays and in cells, thus causing proliferation arrest in oncogenic RET-transfected cells and in papillary thyroid carcinoma (PTC) cells expressing the RET/PTC1 oncogene, but not in RET-negative control cells. SU5416 inhibited RET-mediated signaling through the extracellular signal regulated kinase (ERK) and JNK pathways. In addition, we show that a naturally occurring MEN2 mutation at codon 804 confers resistance to SU5416, but not to the related compound SU4984. We provide a possible explanation to these results by using molecular docking. Finally, SU5416 was also assessed against an array of 52 tyrosine and serine/threonine kinases.</p

Italian consensus Guidelines for the management of hepatitis B virus infections in patients with rheumatoid arthritis

Hepatitis B (HBV) infection, which is prevalent worldwide, is also frequently seen in patients with rheumatoid arthritis (RA). The Italian Society of Rheumatology (SIR) and the Italian Society of Infectious and Tropical Diseases (SIMIT) endorsed a national consensus process to review the available evidence on HBV management in RA patients and to produce practical, hospital-wide recommendations

Italian consensus recommendations for the management of hepatitis C infection in patients with rheumatoid arthritis

Objectives: The recent introduction of direct-acting antiviral agents (DAAs) which can eliminate Hepatitis C virus (HCV) had revolutionized the treatment of HCV infections also in a complex clinical setting such as the patients with rheumatoid arthritis (RA). HCV elimination is also opportune due to the availability of more efficient immunosuppressive drugs, whose effect on the course of HCV infection is largely unknown. Methods: Consensus process was endorsed by the Italian Society of Rheumatology (SIR) and the Italian Society of Infectious and Tropical Diseases (SIMIT) to review the available evidence and produce practical, hospital-wide recommendations. The consensus panel consisted of 18 infectious diseases consultants, 20 rheumatologists and one clinical epidemiologist, who used the criteria of the Oxford Centre for Evidence-based Medicine to assess the quality of the evidence and the strength of their recommendations. Results: A core-set of statements about management of patients with RA and infection by HCV have been developed to help clinicians in their clinical practice. Conclusions: A screening for HCV should be performed in all RA patients and it is mandatory before starting an immunosuppressive therapy. Finally, a DAA treatment should be considered in all HCV-infected patients.Significance and Innovations HCV antibodies should be investigated at the time of diagnosis of RA and, in any case, before starting immunosuppressive therapy with disease-modifying antirheumatic drugs (DMARDs). HCV eradication with DAA should be attempted as soon as possible, depending on patient conditions allowing a continuous oral treatment lasting 8–12 weeks Conventional and biological DMARDs are allowed in patients with HCV infection, but they should be used cautiously in presence of advanced liver disease

Italian consensus guidelines for the management of hepatitis B virus infections in patients with rheumatoid arthritis

No abstract availabl

Prise en charge de l'infection par le virus de l'hépatite B chez les patients atteints de polyarthrite rhumatoïde: conférence de consensus italienne

No abstract availabl