ABSTRACT
Herein, we describe the discovery and optimization of a novel series that inhibits bacterial DNA gyrase and topoisomerase IV via binding to, and stabilization of, DNA cleavage complexes. Optimization of this series led to the identification of compound 25, which has potent activity against Gram-positive bacteria, a favorable in vitro safety profile, and excellent in vivo pharmacokinetic properties. Compound 25 was found to be efficacious against fluoroquinolone-sensitive Staphylococcus aureus infection in a mouse thigh model at lower doses than moxifloxacin. An X-ray crystal structure of the ternary complex formed by topoisomerase IV from Klebsiella pneumoniae, compound 25, and cleaved DNA indicates that this compound does not engage in a water-metal ion bridge interaction and forms no direct contacts with residues in the quinolone resistance determining region (QRDR). This suggests a structural basis for the reduced impact of QRDR mutations on antibacterial activity of 25 compared to fluoroquinolones.
Subject(s)
Anti-Bacterial Agents/pharmacology , DNA Gyrase/metabolism , DNA Topoisomerase IV/antagonists & inhibitors , Drug Design , Fluoroquinolones/pharmacology , Staphylococcus aureus/drug effects , Topoisomerase II Inhibitors/pharmacology , Animals , Anti-Bacterial Agents/chemistry , Drug Resistance, Bacterial/drug effects , Mice , Topoisomerase II Inhibitors/chemistryABSTRACT
Confronted with the need to significantly raise the productivity of remotely located chemistry CROs Pfizer embraced a commitment to continuous improvement which leveraged the tools from both Lean Six Sigma and queue management theory to deliver positive measurable outcomes. During 2012 cycle times were reduced by 48% by optimization of the work in progress and conducting a detailed workflow analysis to identify and address pinch points. Compound flow was increased by 29% by optimizing the request process and de-risking the chemistry. Underpinning both achievements was the development of close working relationships and productive communications between Pfizer and CRO chemists.
Subject(s)
Contract Services/organization & administration , Drug Industry/organization & administration , Research/organization & administration , Chemistry, Pharmaceutical/methods , Communication , Contract Services/standards , Drug Design , Drug Discovery/methods , Drug Industry/standards , Efficiency, Organizational , Humans , Quality Improvement , Research/standards , WorkflowABSTRACT
Apogossypolone (ApoG2) is a semi-synthesized derivative of gossypol. The principal objective of this study was to compare stability and toxicity between ApoG2 and gossypol, and to evaluate anti-lymphoma activity of ApoG2 in vitro and in vivo. ApoG2 shows better stability when compared with a racemic gossypol and can be better tolerated by mice compared to gossypol. ApoG2 showed significant inhibition of cell proliferation of WSU-DLCL(2) and primary cells obtained from lymphoma patients, whereas it displayed no toxicity on normal peripheral blood lymphocytes. For a treatment of 72 h, the IC(50) of ApoG2 was determined to be 350 nM against WSU-DLCL2 cells. Treatment with ApoG2 at 600 mg/kg resulted in significant growth inhibition of WSU-DLCL(2) xenografts. When combined with CHOP, ApoG2 displayed even more complete inhibition of tumor growth. ApoG2 binds to purified recombinant Bcl-2, Mcl-1 and Bcl-X(L) proteins with high affinity and is shown to block the formation of heterodimers between Bcl-X(L) and Bim. For a treatment of 72 h, ApoG2 induced a maximum of 32% of apoptotic cell death. Western blot experiments showed that treatment with ApoG2 led to cleavage of caspase-3, caspase-9 and PARP. Moreover, pretreatment of DLCL(2) cells with caspase-3, -9 and broad spectrum caspase inhibitors significantly blocked growth inhibition induced by ApoG2. In conclusion, ApoG2 effectively inhibits growth of DLCL(2) cells at least partly by inducing apoptosis. It is an attractive small molecule inhibitor of the Bcl-2 family proteins to be developed further for the treatment of diffuse large cell lymphoma.
Subject(s)
Apoptosis/drug effects , Gossypol/analogs & derivatives , Lymphoma, Large B-Cell, Diffuse/drug therapy , Proto-Oncogene Proteins c-bcl-2/antagonists & inhibitors , Animals , Caspase 3/metabolism , Caspase 9/metabolism , Cell Death/drug effects , Cell Line, Tumor , Cell Proliferation/drug effects , Clinical Trials, Phase II as Topic , Dose-Response Relationship, Drug , Drug Stability , Gossypol/chemistry , Gossypol/pharmacology , Humans , Inhibitory Concentration 50 , Lymphoma, Large B-Cell, Diffuse/metabolism , Mice , Mice, SCID , Molecular Structure , Poly(ADP-ribose) Polymerases/metabolism , Proto-Oncogene Proteins c-bcl-2/genetics , Proto-Oncogene Proteins c-bcl-2/metabolism , Recombinant Proteins/isolation & purification , Recombinant Proteins/metabolism , Temperature , Time Factors , Xenograft Model Antitumor Assays/methods , bcl-X Protein/antagonists & inhibitorsABSTRACT
We have designed MI-219 as a potent, highly selective and orally active small-molecule inhibitor of the MDM2-p53 interaction. MI-219 binds to human MDM2 with a K(i) value of 5 nM and is 10,000-fold selective for MDM2 over MDMX. It disrupts the MDM2-p53 interaction and activates the p53 pathway in cells with wild-type p53, which leads to induction of cell cycle arrest in all cells and selective apoptosis in tumor cells. MI-219 stimulates rapid but transient p53 activation in established tumor xenograft tissues, resulting in inhibition of cell proliferation, induction of apoptosis, and complete tumor growth inhibition. MI-219 activates p53 in normal tissues with minimal p53 accumulation and is not toxic to animals. MI-219 warrants clinical investigation as a new agent for cancer treatment.
