bms-387032 and Neoplasms

Inhibition of cyclin-dependent kinases (CDKs) has become an effective therapeutic strategy for treating various diseases, especially cancer. Over almost three decades, although great efforts have been made to discover CDK inhibitors, many of which have entered clinical trials, only four CDK inhibitors have been approved. In the process of CDK inhibitor development, many difficulties and misunderstandings have hampered their discovery and clinical applications, which mainly include inadequate understanding of the biological functions of CDKs, less attention paid to pan- and multi-CDK inhibitors, nonideal isoform selectivity of developed selective CDK inhibitors, overlooking the metabolic stability of early discovered CDK inhibitors, no effective resistance solutions, and a lack of available combination therapy and effective biomarkers for CDK therapies. After reviewing the mechanisms of CDKs and the research progress of CDK inhibitors, this perspective summarizes and discusses these difficulties or lessons, hoping to facilitate the successful discovery of more useful CDK inhibitors.

Topics: Antineoplastic Agents; Cell Cycle; Cyclin-Dependent Kinase 4; Cyclin-Dependent Kinases; Drug Discovery; Humans; Neoplasms; Protein Kinase Inhibitors

Cyclin-dependent kinase 9 (CDK9), which regulates transcriptional elongation, is an attractive therapeutic target for many cancers, especially for cancers driven by transcriptional dysregulation. In particular, CDK9 promotes RNA polymerase II pause/release, a rate-limiting step in normal transcriptional regulation that is frequently dysregulated in cancers. Emerging evidence indicates that selective CDK9 inhibition or degradation may provide a therapeutic benefit against certain cancers. Indeed, the development of CDK9 modulators (inhibitors and degraders) has attracted great attention, with several molecules currently under clinical development. This review provides an overview of recent advances in CDK9 modulators in general, with special emphasis on compounds under clinical evaluation and new emerging strategies, such as proteolysis targeting chimeras (PROTACs).

Topics: Animals; Antineoplastic Agents; Chemistry, Pharmaceutical; Cyclin-Dependent Kinase 9; Drug Development; Humans; Molecular Docking Simulation; Neoplasms; Protein Kinase Inhibitors; Protein Structure, Secondary

Cyclin-dependent kinase 2 (CDK2) drives the progression of cells into the S- and M-phases of the cell cycle. CDK2 activity is largely dispensable for normal development, but it is critically associated with tumor growth in multiple cancer types. Although the role of CDK2 in tumorigenesis has been controversial, emerging evidence proposes that selective CDK2 inhibition may provide a therapeutic benefit against certain tumors, and it continues to appeal as a strategy to exploit in anticancer drug development. Several small-molecule CDK2 inhibitors have progressed to the clinical trials. However, a CDK2-selective inhibitor is yet to be discovered. Here, we discuss the latest understandings of the role of CDK2 in normal and cancer cells, review the core pharmacophores used to target CDK2, and outline strategies for the rational design of CDK2 inhibitors. We attempt to provide an outlook on how CDK2-selective inhibitors may open new avenues for cancer therapy.

Topics: Animals; Antineoplastic Agents; Clinical Trials as Topic; Cyclin-Dependent Kinase 2; Drug Design; Humans; Neoplasms; Protein Binding; Protein Conformation; Protein Kinase Inhibitors

There are around 20 Cyclin-dependent kinases (CDKs) known till date, and various research groups have reported their role in different types of cancer. The X-ray structures of some CDKs especially CDK2 was exploited in the past few years, and several inhibitors have been found, e.g., flavopiridol, indirubicin, roscovitine, etc., but due to the specificity issues of these inhibitors (binding to all CDKs), these were called as pan inhibitors. The revolutionary outcome of palbociclib in 2015 as CDK4/6 inhibitor added a new charm to the specific inhibitor design for CDKs. Computer-aided drug design (CADD) tools added a benefit to the design and development of new CDK inhibitors by studying the binding pattern of the inhibitors to the ATP binding domain of CDKs. Herein, we have attempted a comparative analysis of structural differences between several CDKs ATP binding sites and their inhibitor specificity by depicting the important ligand-receptor interactions for a particular CDK to be targeted. This perspective provides futuristic implications in the design of inhibitors considering the spatial features and structural insights of the specific CDK.

Topics: Amino Acid Sequence; Animals; Computer-Aided Design; Crystallography, X-Ray; Cyclin-Dependent Kinases; Drug Design; Humans; Models, Molecular; Neoplasms; Protein Conformation; Protein Kinase Inhibitors; Sequence Alignment

CDK9 is a protein in constant development in cancer therapy. Herein we present an overview of the enzyme as a target for cancer therapy. We provide data on its characteristics and mechanism of action. In recent years, CDK9 inhibitors that have been designed with molecular modeling have demonstrated good antitumoral activity in vitro. Clinical studies of the drugs flavopiridol, dinaciclib, seliciclib, SNS-032 and RGB-286638 used as CDK9 inhibitors are also reviewed, with their additional targets and their relative IC50 values. Unfortunately, treatment with these drugs remains unsuccessful and involves many adverse effects. We could conclude that there are many small molecules that bind to CDK9, but their lack of selectivity against other CDKs do not allow them to get to the clinical use. However, drug designers currently have the tools needed to improve the selectivity of CDK9 inhibitors and to make successful treatment available to patients.

Topics: Bridged Bicyclo Compounds, Heterocyclic; Cell Cycle; Cyclic N-Oxides; Cyclin-Dependent Kinase 9; Flavonoids; Humans; Indolizines; Molecular Targeted Therapy; Neoplasms; Oxazoles; Piperidines; Protein Kinase Inhibitors; Purines; Pyrazoles; Pyridinium Compounds; Roscovitine; Thiazoles; Urea

Cell cycle kinases are comprised of cyclin-dependent kinases (Cdks), non-Cdk kinases such as Plk-1 and Aurora and checkpoint proteins such as Chk1 and Chk2. Though ubiquitous to dividing cells, many cell cycle kinases are amplified or over-expressed in malignancy and are potential targets for anti-cancer therapies. Cdk inhibiting drugs (such as flavopiridol, UCN-01, E7070, R-Roscovitine and BMS-387032) have shown preclinical and clinical anticancer activity. However, many of these agents are promiscuous and undiscerning, targeting other non-cell cycle kinases and affecting normal cells, thereby causing significant toxicity. To overcome this, a new generation of Cdk inhibitors are in development with greater target specificity, as well as others that inhibit non-Cdk cell cycle kinases, both directly and indirectly. The outcome of early clinical trials involving these agents is awaited, but these certainly represent a promising new area of anticancer drug development.

Topics: Adenosine Triphosphate; Animals; Antineoplastic Agents; Binding Sites; Cyclin-Dependent Kinases; Flavonoids; Humans; Neoplasms; Oxazoles; Piperidines; Protein Kinase Inhibitors; Purines; Roscovitine; Staurosporine; Sulfonamides; Thiazoles

SNS-032, (formerly BMS-387032) is a potent and selective inhibitor of cyclin-dependent kinases (CDK) 2, 7 and 9. The primary objective of the study was to establish the maximum tolerated dose (MTD), the maximum administered dose (MAD), dose limiting toxicity (DLT), and the recommended phase 2 dose for SNS-032 when administered as a weekly 1-h infusion. The secondary objective was to assess the safety and tolerability of SNS-032 and to evaluate its bioavailability as an oral solution.. Patients with metastatic solid tumors or refractory lymphoma were treated with a starting dose of 4 mg/m2 intravenously administered over 1-h with a cycle defined as 3 weekly doses of SNS-032 every 21 days. Three patient cohorts were utilized in the dose-escalation schema. Pharmacokinetic studies were performed. For the 13 and 16 mg/m2 dose cohorts, the first dose of cycle 2 was given as an oral solution to estimate the oral bioavailability of the drug in humans.. A total of 21 patients were enrolled. Twenty treated patients received a total of 39 cycles of treatment. The most common treatment-related adverse events occurring with greater than 20% incidence were fatigue (25%) and nausea (20%). Following intravenous administration, plasma concentrations declined in a biphasic manner, resulting in mean terminal half-lives between 5 and 10 hours. The mean Cmax and AUC0-inf increased nearly linearly with dose, ranging from 0.067 to 0.287 microg/ml and 0.103 to 0.553 microg h/ml, respectively. The CL and Vss remained unchanged with increasing dose levels, averaging 38 l/h/m2 and 212 l/m2, respectively. Average oral bioavailability was 19% (range: 4-33%). Three (15%) patients experienced a best response of stable disease. Study enrollment was terminated during dose-escalation due to a change in the development strategy for the study drug.. SNS-032 administered as a weekly 1-h infusion was well tolerated, although study enrollment was terminated during dose-escalation and the MTD of SNS-032 administered intravenously on days 1, 8, and 15 of each treatment cycle was not reached. Tumor progression or stable disease was determined to be the best response in all evaluable patients. At the dose levels tested, the oral bioavailability of SNS-032 ranged from 4-33%. The data suggest that oral administration of SNS-032 may be feasible, though the tolerability and bioavailability of the oral formulation would have to be formally assessed.

Topics: Administration, Oral; Adult; Aged; Anemia; Angiogenesis Inhibitors; Area Under Curve; Biological Availability; CDC2-CDC28 Kinases; Dose-Response Relationship, Drug; Female; Half-Life; Humans; Infusions, Intravenous; Male; Middle Aged; Neoplasm Metastasis; Neoplasms; Neutropenia; Oxazoles; Radiotherapy, Adjuvant; Thiazoles; Time Factors; Treatment Outcome

Cyclin dependent kinase (CDK) inhibitors have been the topic of intense research for nearly 2 decades due to their widely varied and critical functions within the cell. Recently CDK9 has emerged as a druggable target for the development of cancer therapeutics. CDK9 plays a crucial role in transcription regulation; specifically, CDK9 mediated transcriptional regulation of short-lived antiapoptotic proteins is critical for the survival of transformed cells. Focused chemical libraries based on a plethora of scaffolds have resulted in mixed success with regard to the development of selective CDK9 inhibitors. Here we review the regulation of CDK9, its cellular functions, and common core structures used to target CDK9, along with their selectivity profile and efficacy in vitro and in vivo.

Topics: Animals; Cyclin-Dependent Kinase 9; Drug Discovery; Flavonoids; Humans; Macrocyclic Compounds; Models, Molecular; Neoplasms; Protein Kinase Inhibitors; Purines; Pyrazoles; Pyrimidines; Triazines