Abemaciclib: A Comprehensive Review of its Pharmacology, Clinical Efficacy, and Regulatory Status in Cancer Therapy

1. Introduction to Abemaciclib

1.1. Overview, Chemical Properties, and DrugBank Identification

Abemaciclib, an orally administered small molecule, is a significant therapeutic agent in oncology, primarily for specific types of breast cancer [User query]. Its unique chemical and pharmacological properties underpin its clinical utility.

Key identifiers and properties include:

• Drug Name: Abemaciclib [User query]
• DrugBank ID: DB12001 [User query]
• Drug Type: Small Molecule [User query]
• CAS Number: 1231929-97-7 [User query]
• Molecular Formula: C27​H32​F2​N8​ [1]
• Molecular Weight: 506.61 g/mol [1]

These identifiers are crucial for its consistent recognition in scientific literature, clinical trials, and regulatory documentation. The chemical structure, characterized by the presence of fluorine atoms and multiple nitrogen-containing rings, contributes to its binding affinity and pharmacokinetic profile.

1.2. Background and Rationale for Development

Abemaciclib was developed as an antitumor agent specifically targeting cyclin-dependent kinases 4 (CDK4) and 6 (CDK6).[3] These kinases are pivotal in regulating the cell cycle, and their dysregulation, often observed in various cancers, leads to uncontrolled cell proliferation and tumor growth.[3] The therapeutic rationale for developing CDK4/6 inhibitors like abemaciclib stems from the understanding that aberrant CDK4/6 activity, frequently driven by cyclin D overexpression or loss of endogenous inhibitors (e.g., p16INK4a), is a key driver in many hormone receptor-positive (HR+) breast cancers. By inhibiting these kinases, abemaciclib aims to restore cell cycle control and suppress cancer progression.