Relationship Between Progression-Free Survival and Overall Survival Benefit: A Simulation Study

Area of Science:

• Clinical Trial Analysis
• Biostatistics
• Survival Analysis

Background:

• Progression-free survival (PFS) is a common endpoint in clinical trials.
• Translating PFS benefits into overall survival (OS) benefits is crucial for demonstrating treatment efficacy.
• Patient crossover between treatment arms can impact survival analyses.

Purpose of the Study:

• To evaluate the conditions under which a PFS benefit translates to an OS benefit.
• To investigate the impact of crossover rates and survival post-progression (SPP) on the OS benefit.
• To identify thresholds for crossover rates that may confound OS results.

Main Methods:

• A simulation study using a joint model for PFS and OS.
• Evaluation of different crossover rates, SPP lengths, and PFS differences.
• Analysis of the probability of observing an OS benefit given a PFS benefit.

Main Results:

• The probability of detecting an OS benefit is highly dependent on crossover rates and SPP length.
• Crossover rates ≤50% decreased the probability of detecting an OS benefit by up to 15%.
• Crossover rates >50% substantially reduced the probability of detecting an OS benefit, with longer SPP exacerbating this effect.

Conclusions:

• Crossover rate and SPP length are critical factors influencing the translation of PFS to OS benefits.
• A crossover rate threshold of 50% was identified as potentially confounding OS effects.
• High crossover rates (>50%) combined with longer SPP significantly diminish the likelihood of observing an OS benefit.