New Surrogate Marker for ADT Evaluation Proposed

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Time interval free of biochemical failure may be a potential surrogate end point in the setting of androgen-deprivation therapy evaluation in men with prostate cancer.
Time interval free of biochemical failure may be a potential surrogate end point in the setting of androgen-deprivation therapy evaluation in men with prostate cancer.

The time interval free of biochemical failure (IBF) may be a promising surrogate end point in the setting of androgen-deprivation therapy (ADT) evaluation in men with prostate cancer, according to researchers at the University of Chicago. They reported in The Journal of Clinical Oncology that IBF may serve as a valid end point in clinical trials and may also aid in risk monitoring after initial treatment.1  

The investigators found that the length of the IBF could have a major bearing on trial duration. They cited several trials where findings could have been revealed 3 to 5 years earlier, if the IBF interval had been adopted and used a surrogate measure. James Dignam, PhD, the Department of Public Health Sciences, the University of Chicago, Chicago, Illinois, and colleagues conducted a trial with 1520 men that compared short-term ADT (4 months) with long-term ADT (28 months).They evaluated the IBF in relation to clinical end points of prostate cancer–specific survival (PCSS) and overall survival (OS).

The study showed that long-term ADT was superior to short-term ADT in terms of biochemical failure (BF) and the clinical end points. The researchers found that those men who did not develop BF for 3 years had relative risk reductions of 39% for OS and 73% for PCSS. When the investigators accounted for 3-year IBF status, it reduced the long-term ADT OS benefit from 12% to 6%. With the PCSS, the long-term ADT benefit dropped from 30% to 6% at 3 years.

The study also revealed that at 3 years, 50% of subsequent deaths attributed to prostate cancer occurred in men with BF compared with 19% of those who were free of BF. The researchers concluded that IBF appears to have a clear role in clinical decision making, and may provide guidance when more intensive surveillance or treatment is warranted.        

Reference

  1. Dignam JJ, Hamstra DA, Lepor H, et al. Time Interval to Biochemical Failure as a Surrogate End Point in Locally Advanced Prostate Cancer: Analysis of Randomized Trial NRG/RTOG 9202 [published online December 7, 2018]. J Clin Oncol. doi: 10.1200/JCO.18.00154.
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