piperidines and ribociclib

Imbalance of the cyclin D and cyclin-dependent kinase (CDK) pathway in cancer cells may result in diversion away from a pathway to senescence and toward a more proliferative phenotype. Cancer cells may increase cyclin D-dependent activity through a variety of mechanisms. Therapeutic inhibition of CDKs in tumors to negate their evasion of growth suppressors has been identified as a key anticancer strategy. In this review, we outline the development of CDK inhibitory therapy in breast cancer, including the initial experience with the pan-CDK inhibitor flavopiridol and the next generation of oral highly selective CDK4 and CDK6 inhibitors PD0332991 (palbociclib), LEE011 (ribociclib), and LY2835219 (abemaciclib). Data from phase I and II studies in estrogen receptor-positive (ER+) breast cancer demonstrate promising efficacy with manageable toxic effects, chiefly neutropenia. We discuss these studies and the phase III studies that are accruing or nearing completion. We describe the application of such therapy to other breast cancer settings, including HER2-positive breast cancer and the adjuvant treatment of early breast cancer. We also discuss potential concerns surrounding the combination of CDK inhibitors with chemotherapy and their effects on repair of double-strand DNA breaks in cancer cells. Oral highly selective CDK inhibitors show great promise in improving the outcomes of patients with ER+ breast cancer, although caution must apply to their combination with other agents and in the early breast cancer setting.

Topics: Aminopyridines; Breast Neoplasms; Cell Cycle; Clinical Trials as Topic; Cyclin-Dependent Kinase 4; Cyclin-Dependent Kinase 6; DNA Breaks, Double-Stranded; Estrogen Receptor alpha; Female; Flavonoids; Humans; Piperazines; Piperidines; Protein Kinase Inhibitors; Purines; Pyridines

Sulfoximines have gained considerable recognition as an important structural motif in drug discovery of late. In particular, the clinical kinase inhibitors for the treatment of cancer, roniciclib (pan-CDK inhibitor), BAY 1143572 (P-TEFb inhibitor), and AZD 6738 (ATR inhibitor), have recently drawn considerable attention. Whilst the interest in this underrepresented functional group in drug discovery is clearly on the rise, there remains an incomplete understanding of the medicinal-chemistry-relevant properties of sulfoximines. Herein we report the synthesis and in vitro characterization of a variety of sulfoximine analogues of marketed drugs and advanced clinical candidates to gain a better understanding of this neglected functional group and its potential in drug discovery.

Topics: Aminopyridines; Ataxia Telangiectasia Mutated Proteins; Cyclin-Dependent Kinases; Drug Design; Estradiol; Fulvestrant; Imatinib Mesylate; Piperazines; Piperidines; Protein Kinase Inhibitors; Purines; Pyrazoles; Pyridines; Sulfoxides; Vardenafil Dihydrochloride