CYCLONE 3: This phase III study is trying to determine whether adding targeted therapy (abemaciclib) to hormone therapy (abiraterone) in combination with steroids (prednisolone or prednisone) prolongs the time before prostate cancer gets worseA Phase 3, Randomized, Double-Blind, Placebo-Controlled Study of Abemaciclib in Combination With Abiraterone Plus Prednisone in Men With High-Risk Metastatic Hormone-Sensitive Prostate Cancer

Exclusion

• Prior treatment with abemaciclib or any other cyclin dependent kinase 4 and 6 (CDK4 & 6) inhibitor
• Development of metastatic prostate cancer in the context of castrate levels of testosterone
• Received any prior systemic therapy for metastatic prostate cancer (including investigational agents), except for ADT and first-generation anti-androgen
• Clinically significant cardiovascular disease as evidenced by myocardial infarction, arterial thrombotic events, or severe/unstable angina in the past 6 months, or New York Heart Association Class II to IV heart failure
• History of syncope of cardiovascular etiology, ventricular arrhythmia of pathological origin, or sudden cardiac arrest. Chronic and hemodynamically stable atrial arrhythmia well-controlled on medical therapy is permitted
• Uncontrolled hypertension
• Clinically active or chronic liver disease, moderate/severe hepatic impairment
• Known untreated central nervous system (CNS) metastasis. Participants with a history of treated brain metastases are eligible if stable for at least 8 weeks prior to randomization and off corticosteroid for at least 2 weeks prior to randomization