An Orally Bioavailable and Highly Efficacious Inhibitor of CDK9/FLT3 for the Treatment of Acute Myeloid Leukemia.

Mutations in FMS-like tyrosine kinase 3 (FLT3) occur in approximately one-third of AML patients and are associated with a particularly poor prognosis. The most common mutation, FLT3-ITD, is a self-activating internal tandem duplication (ITD) in the FLT3 juxtamembrane domain. Many FLT3 inhibitors have shown encouraging results in clinical trials, but the rapid emergence of resistance has severely limited sustainable efficacy. Co-targeting of CDK9 and FLT3 is a promising two-pronged strategy to overcome resistance as the former plays a role in the transcription of cancer cell-survival genes. Most prominently, MCL-1 is known to be associated with AML tumorigenesis and drug resistance and can be down-regulated by CDK9 inhibition. We have developed CDDD11-8 as a potent CDK9 inhibitor co-targeting FLT3-ITD with Ki values of 8 and 13 nM, respectively. The kinome selectivity has been confirmed when the compound was tested in a panel of 369 human kinases. CDDD11-8 displayed antiproliferative activity against leukemia cell lines, and particularly potent effects were observed against MV4-11 and MOLM-13 cells, which are known to harbor the FLT3-ITD mutation and mixed lineage leukemia (MLL) fusion proteins. The mode of action was consistent with inhibition of CDK9 and FLT3-ITD. Most importantly, CDDD11-8 caused a robust tumor growth inhibition by oral administration in animal xenografts. At 125 mg/kg, CDDD11-8 induced tumor regression, and this was translated to an improved survival of animals. The study demonstrates the potential of CDDD11-8 towards the future development of a novel AML treatment.

A first-in-class CDK4 inhibitor demonstrates in vitro, ex-vivo and in vivo efficacy against ovarian cancer.

INTRODUCTION: Cyclin-dependent kinases 4 and 6 (CDK4/6) are fundamental drivers of the cell cycle and are involved in the initiation and progression of various cancers. Deregulation of the CDK4/6-cyclin D-retinoblastoma (Rb) pathway is common in ovarian cancer and is associated with an aggressive phenotype and poor prognosis. Patients with advanced ovarian cancer whose tumor demonstrates Rb-positivity, a low expression of p16 and overexpression of cyclin D1 are most likely to benefit from CDK4/6 inhibition. MATERIALS AND METHOD: Anti-proliferative activity and mechanistic investigations for CDDD2-94, employing palbociclib as comparator, were evaluated by MTT assay, cell cycle and apoptosis analysis, western blotting as well as senescence and colony formation assay. In vivo safety and efficacy studies were done in A2780 tumor-bearing nude mice. Combinations of CDDD2-94 with mTOR, MEK, PI3K or PARP inhibitors were evaluated in A2780 and OVCAR5 ovarian cancer cells. RESULTS: Consistent with a CDK4-targeted mechanism, CDDD2-94 arrested the G1/G0 cell cycle, induced senescence and inhibited the proliferation of Rb-proficient ovarian cancer cells. CDDD2-94 exhibited synergistic anti-proliferative activities with mTOR, MEK, PI3K or PARP inhibitors. Importantly, unlike palbociclib which caused significant reductions in the number of lymphocytes and neutrophils, CDDD2-94 had little effect. CDDD2-94, as single agent and in combination with everolimus, delayed tumor growth and significantly increased survival of mice. CONCLUSION: Given its high specificity in targeting CDK4 and excellent anti-tumor efficacy with low toxicity, CDDD2-94 has potential to be developed as a standalone agent or in combination with targeted therapeutics for the treatment of ovarian cancer.

Discovery and pharmacological characterization of a novel series of highly selective inhibitors of cyclin-dependent kinases 4 and 6 as anticancer agents.

BACKGROUND AND PURPOSE: Cyclin D-dependent kinases 4 and 6 (CDK4/6) are crucial regulators of the G1 to S phase transition of the cell cycle and are actively pursued as therapeutic targets in cancer. We sought to discover a novel series of orally bioavailable and highly selective small molecule inhibitors of CDK4/6. EXPERIMENTAL APPROACH: The discovery of pharmacological inhibitors and optimization for potency, selectivity and drug properties were achieved by iterative chemical synthesis, biochemical screening against a panel of kinases, cell-based assays measuring cellular viability, cell cycle distribution, induction of apoptosis and the level of retinoblastoma tumour suppressor protein (Rb) phosphorylation and E2 factor (E2F)-regulated gene expression and in vitro biopharmaceutical and in vivo pharmacokinetic profiling. KEY RESULTS: We discovered several lead compounds that displayed >1000-fold selectivity for CDK4/6 over other members of the CDK family. The lead compounds, 82, 91 and 95, potently inhibited the growth of cancer cells by inducing G1 arrest with a concomitant reduction in the phosphorylation of Rb at S780 and in E2F-regulated gene expression. With a remarkable selectivity for CDK4 over 369 human protein kinases, 91 was identified as a highly potent and orally bioavailable drug candidate. CONCLUSIONS AND IMPLICATIONS: We have identified unique and new inhibitors of CDK4/6 as potential drug candidates. Compound 91 represents an ideal candidate for further development as targeted cancer therapy.

Inappropriate Use of Antibiotics and Its Associated Factors among Urban and Rural Communities of Bahir Dar City Administration, Northwest Ethiopia.

BACKGROUND: Inappropriate use of antibiotics in the community plays a role in the emergence and spread of bacteria resistant to antibiotics which threatens human health significantly. The present study was designed to determine inappropriate use of antibiotics and its associated factors among urban and rural communities of Bahir Dar city administration. METHODS: A comparative cross sectional study design was conducted in urban and rural kebeles of Bahir Dar city administration from February 1 to March 28, 2014. A total of 1082 participants included in the study using a systematic random sampling technique. Data was collected using pre-tested and structured questionnaire. Data was coded and entered into SPSSS version 16 for statistical analysis. Bivariate and multivariate logistic regression model were used to identify factors associated with inappropriate use of antibiotics. RESULTS: Inappropriate use of antibiotics was 30.9% without significant difference between urban (33.1%) and rural (29.2%) communities. From the inappropriate antibiotic use practice, self-medication was 18.0% and the remaining (12.9%) was for family member medication. Respiratory tract symptoms (74.6%), diarrhea (74.4%), and physical injury/wound (64.3%) were the three main reasons that the communities had used antibiotics inappropriately. Factors associated with inappropriate use of antibiotics were low educational status, younger age, unsatisfaction with the health care services, engagement with a job, and low knowledge on the use of antibiotic preparations of human to animals. CONCLUSIONS: Inappropriate use of antibiotic exists in the study area with no significant difference between urban and rural communities. The study indicated an insight on what factors that intervention should be made to reduce inappropriate use of antibiotics in the community. Interventions that consider age groups, educational status, common health problems and their jobs together with improvement of health care services should be areas of focus to reduce inappropriate use of antibiotics.

In vivo antimalarial activity of the crude leaf extract and solvent fractions of Croton macrostachyus Hocsht. (Euphorbiaceae) against Plasmodium berghei in mice.

BACKGROUND: The issue of resistance in malarial infection makes development of novel drugs a necessity. An alternative source for discovering such drugs is natural products. Croton macrostachyus H. (Euphorbiaceae) is used in Ethiopian folklore medicine for the treatment of malaria and found to possess antimalarial activity in vitro. However, no further scientific investigations have been carried out to substantiate the claim. This study therefore aimed at investigating the in vivo antiplasmodial activity of 80% methanol extract and solvent fractions of the leaves of Croton macrostachyus H. in rodent model of malaria. METHODS: A rodent malaria parasite, Plasmodium berghei, was used to inoculate healthy male Swiss Albino mice of age 6-8 weeks and weight 23-27 g. A hydro-alcoholic crude extract and the solvent fractions (chloroform, methanol and aqueous) were administered at different doses 200, 400 and 600 mg/kg. Parameters, including parasitemia, survival time, body weight, temperature, and packed cell volume were then determined using standard tests such as Peter's and Rane's test. RESULTS: Chemoprotective effect exerted by the crude extract and fractions ranged between 44-91% and 12-76%, respectvely. The chemotherapeutic effect of the crude extract and chloroform fraction was in the range of 39-83% and 66-82%, respectively. Maximum effect in both tests was observed with the larger dose of the crude extract and chloroform fraction. The crude extract prevented loss of weight and reduction in temperature but did not affect packed cell volume. However, the chloroform fraction did also reverse reduction in packed cell volume due to the absence of saponins in the fraction. CONCLUSIONS: The results collectively indicate that the plant has a promising antiplasmodial activity against Plasmodium berghei, which upholds the earlier in vitro findings as well as its folkloric use. Thus, it could be considred as a potential source to develop new antimalarial agents.