Radiographic progression-free survival as a surrogate endpoint of overall survival in men with metastatic castrate-resistant prostate cancer.

Authors

Susan Halabi

Susan Halabi

Duke University Medical Center, Durham, NC

Susan Halabi , Akash Roy , Qian Yang , Wanling Xie , William Kevin Kelly , Christopher Sweeney

Organizations

Duke University Medical Center, Durham, NC, Duke University, Durham, NC, Dana-Farber Cancer Institute, Boston, MA, Sidney Kimmel Cancer Center at Thomas Jefferson University, Philadelphia, PA, Lank Center for Genitourinary Oncology, Dana-Farber Cancer Institute, Boston, MA

Research Funding

No funding received
None

Background: Radiographic progression-free survival (rPFS) is commonly used as a co-primary endpoint in randomized clinical trials in men with metastatic castrate-resistant prostate cancer (mCRPC). However, rPFS has not been established as a valid surrogate endpoint of overall survival (OS) in men with mCRPC. Here, we hypothesized that rPFS is a reliable surrogate for OS in mCRPC. We also explored whether PFS is a valid surrogate endpoint of OS at the aggregate trial level. Methods: We performed a systematic search of the literature encompassing the period January 2004-December 2020 using PubMed and clinical trials.gov to identify completed phase III trials in mCRPC post-docetaxel. Eligible trials had to be randomized phase III therapeutic trials that reported OS, PFS or rPFS. OS was measured from the date of random assignment to date of death from any cause or date of last follow-up. rPFS was defined as the time from random assignment to date of disease progression on CT and/or Tc bone scan per trial definition or death from any cause, whichever occurred first. PFS included PSA progression as a component of the composite endpoint. Trial level surrogacy was evaluated by fitting linear regression on the treatment effect of rPFS (or PFS) and OS (in other words, the weighted linear regression of the log(hazard ratio) of OS on the log(hazard ratio) of rPFS). It was pre-specified that rPFS would be considered a valid surrogate for OS if R² was 0·7 or higher. Results: We identified 33 in men with mCRPC post docetaxel approval. We assessed the association between PFS and OS in 29,456 patients from 30 trials. Overall, a moderate correlation was observed at the trial level between OS and PFS (R2 = 0.46, 95 %CI = 0.20-0.68) in these trials. In 18 trials with 16,818 mCRPC patients where rPFS was considered as a key endpoint, a moderate correlation between the treatment effects on rPFS and OS was observed at the trial level (R2= 0.65, 95% CI = 0.23-0.87). Conclusions: This meta-analysis demonstrates moderate correlation between treatment effects of rPFS and OS in patients with mCRPC. However, rPFS did not meet the pre-specified surrogacy threshold of 0.7. Clinical trial information: several.

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Abstract Details

Meeting

2021 ASCO Annual Meeting

Session Type

Poster Session

Session Title

Genitourinary Cancer—Prostate, Testicular, and Penile

Track

Genitourinary Cancer—Prostate, Testicular, and Penile

Sub Track

Prostate Cancer– Advanced/Castrate-Resistant

Clinical Trial Registration Number

several

Citation

J Clin Oncol 39, 2021 (suppl 15; abstr 5057)

DOI

10.1200/JCO.2021.39.15_suppl.5057

Abstract #

5057

Poster Bd #

Online Only

Abstract Disclosures