Primary Outcome Measures
Radiographic Progression Free Survival (rPFS) [Time Frame: Baseline to Radiographic Disease Progression or Death from Any Cause (Estimated up to 21 Months)] [Designated as safety issue: ]
Time to Prostate-Specific Antigen (PSA) Progression [Time Frame: Baseline to the Date of the First Observation of PSA Progression (Estimated up to 21 Months)] [Designated as safety issue: ]
Secondary Outcome Measures
Objective Response Rate (ORR): Percentage of Participants with a Complete Response (CR) or Partial Response (PR) [Time Frame: Baseline to Radiographic Disease Progression (Estimated up to 21 Months)] [Designated as safety issue: ]
Duration of Response (DOR) [Time Frame: Date of First Documented CR or PR to Date of Radiographic Disease Progression or Death from Any Cause (Estimated up to 21 Months)] [Designated as safety issue: ]
Overall Survival (OS) [Time Frame: Baseline to Date of Death Due to Any Cause (Estimated up to 40 Months)] [Designated as safety issue: ]
Time to Symptomatic Progression [Time Frame: Baseline to the Date of the First Documented Symptomatic Progression (Estimated up to 21 Months)] [Designated as safety issue: ]
Pharmacokinetics (PK): Mean Steady State Exposure of Abemaciclib [Time Frame: Postdose Cycle 1 Day 1 through Postdose Cycle 3 Day 1 (28 Day Cycles)] [Designated as safety issue: ]
PK: Mean Steady State Exposure of Abemaciclib Metabolite LSN2839567 [Time Frame: Postdose Cycle 1 Day 1 through Postdose Cycle 3 Day 1 (28 Day Cycles)] [Designated as safety issue: ]
PK: Mean Steady State Exposure of Abemaciclib Metabolite LSN3106726 [Time Frame: Postdose Cycle 1 Day 1 through Postdose Cycle 3 Day 1 (28 Day Cycles)] [Designated as safety issue: ]
PK: Mean Steady State Exposure of Abiraterone Acetate [Time Frame: Postdose Cycle 1 Day 1 through Postdose Cycle 3 Day 1 (28 Day Cycles)] [Designated as safety issue: ]