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Analyzing Surrogate Endpoints for Overall Survival in Metastatic Hormone-Sensitive Prostate Cancer

By: Joshua D. Madera, MD
Posted: Wednesday, May 8, 2024

Because of the extended time required to obtain an accurate estimate of the rate of overall survival in patients with metastatic hormone-sensitive prostate cancer, clinical studies investigating surrogate endpoints have determined that clinical and radiographic progression-free survival rates may be suitable estimates, according to a study based on individual patient data from nine randomized trials published in the Journal of Clinical Oncology. Both clinical and radiographic progression-free survival had surrogate threshold effects greater than 0.80, suggesting their viability as surrogates, explained Susan Halabi, PhD, of Duke University Medical Center, Durham, North Carolina, and colleagues.

“A major challenge in designing trials in men with metastatic hormone-sensitive prostate cancer is the choice of the primary endpoint,” the investigators declared. “Although the results were slightly higher for clinical progression-free survival, our preference is to use radiographic progression-free survival, as it is a more objective endpoint than clinical progression-free survival.”

From 1994 to 2012, individual patient data from a total of 6,390 men with metastatic hormone-sensitive prostate carcinoma were collected from randomized clinical trials. Patients were treated with various individual androgen-deprivation therapy strategies or combined androgen-deprivation therapy plus docetaxel. Patients were monitored regularly to assess the rate of clinical progression-free survival, which was defined as the period from randomized assignment until evidence of clinical symptoms, radiographic disease progression, initiation of new treatment, or death. Patients also underwent regular imaging to determine the rate of radiographic progression-free survival, which was defined as the period from randomized assignment until evidence of radiographic disease progression or death.

The study authors reported the clinical progression-free survival and radiographic progression-free survival as 2.3 years and 2.4 years, respectively. These estimates were compared with the observed rate of overall survival, which was revealed as 4.3 years. Furthermore, surrogate threshold effects of 0.81 and 0.80 were identified for clinical progression-free survival and radiographic progression-free survival, respectively.

Disclosure: For full disclosures of the study authors, visit ascopubs.org.


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