You can buy Besidx at the lowest price in the online pharmacy Nextgen.ooo . Abemaciclib is an antineoplastic agent and a dual inhibitor of cyclin-dependent kinases 4 (CDK4) and 6 (CDK6), which are involved in the cell cycle and promote the growth of cancer cells when unregulated. On September 28, 2017, the FDA approved abemaciclib under the market name Verzenio for the treatment of HR-positive, HER2-negative advanced or metastatic breast cancer that has progressed after unsuccessful endocrine therapy. It is administered either alone to patients who have undergone endocrine therapy and chemotherapy after metastatic cancer, or in combination with fulvestrant. Following oral treatment in patients with HR-positive, HER2-negative breast cancer, abemaciclib has been shown to improve progression-free survival and objective response rates. Abemaciclib has been used in studies investigating the treatment of melanoma, lymphoma, neoplasms, solid tumors, and glioblastoma.
 
Regulation of the cell cycle is critical to maintaining proper cell growth; dysregulation of cell cycle signaling is a key component in causing cell hyperproliferation and tumorigenesis in a variety of cancers. Cell cycle progression from G1 to S phase, or crossing the G1 restriction point (R), is stimulated by the retinoblastoma tumor suppressor protein (Rb) pathway. Activation of the Rb pathway requires the interaction of cyclin-dependent kinases (CDKs) 4 and 6 with D-type cyclins, resulting in the formation of active CDK4/CDK6 and subsequent phosphorylation of Rb.
 
Rb is a tumor suppressor protein that inhibits proliferation by binding to and downregulating the activity of E2F family transcription factors. However, phosphorylation of Rb relieves E2F suppression, allowing expression of genes required for passage through the restriction point. This results in increased expression of downstream signaling molecules and protein kinase activity that promote cell cycle progression and initiation of DNA replication. Phosphorylation of Rb and other proteins by CDK4/6 further results in transcription of genes involved in cell cycle-independent activities, including signal transduction, transcriptional control of DNA repair, and mRNA processing.
 
Abemaciclib selectively inhibits CDK4 and CDK6 with low nanomolar potency, inhibits Rb phosphorylation resulting in G1 arrest and inhibition of proliferation, and is specific to cells containing Rb. Unlike other CDK inhibitors such as palbociclib and ribociclib, abemaciclib exhibits greater selectivity for CDK4 over CDK6.