What is Time To Progression (TTP) and Time To Treatment Failure (TTF) in clinical trials?

Definitions

Time to progression (TTP) refers to the period from randomization to the manifestation of objective tumor progression, but excluding occurrences of death. 

Time to treatment failure (TTF) indicates the duration from randomization to the failure of treatment or withdrawal from the trial. The reasons for trial withdrawal could include patient's request, disease progression, death, or adverse events.

Positioning/Advantages and Disadvantages

Equivalent to Progression-Free Survival (PFS). Both TTP and TTF are positioned similarly to PFS endpoints. The analysis of these two endpoints is often considered as sensitivity analyses, with their findings not serving as primary evidences for confirmatory research conclusions but can be utilized in supporting the main endpoint PFS results.

The distinctions among Time to Progression (TTP), Time to Treatment Failure (TTF), and Progression-Free Survival (PFS)

TTP, when compared to PFS, excludes death. While it can reflect the anticancer effects of the drug more objectively, its correlation with OS (Overall Survival) is lower than that of PFS since it does not include death. 

TTF, in comparison to PFS, synthesizes the effectiveness and safety characteristics of the drug, encompasses treatment failure for any reason and includes death. However, the judgement of therapy cessation might be subjective and not as objective as radiological assessments.