This abstract provides data on 67 patients who were randomly assigned to either ADT+Abiraterone (Arm A) or Abiraterone alone (Arm B). Both groups received prednisone as is standard of care with abiraterone. The primary endpoint of this study was radiographic progression-free survival (rPFS) at 1 year. At the time of this abstract, there were 34 patients in Arm A and 33 patients in Arm B. The median prostate-specific antigen (PSA) was 31.9 in Arm A and 20.59 in Arm B. Of note, one patient in Arm A did not have castrate levels of testosterone at the beginning of the study. All patients in Arm B started with castrate levels of testosterone (<50 ng/dL).
In terms of the primary endpoint, the rPFS was 90% in Arm A and 78% in Arm B. This is a small study but these values compare favorably to the patients in COUGAR 302, where the rPFS at 1 year was around 60%. The time to PSA progression was 9.6 months in Arm A and 11.2 months in Arm B – these are similar to COUGAR 302, where the median time to PSA progression was 11.1 months. Neither the time to PSA progression or rate of rPFS at 1 year was significantly different between the two arms. Of note, 6 patients in Arm B had testosterone levels arise above castrate levels within 28 days of discontinuation of abiraterone/prednisone.
This study provides initial data on mCRPC patients undergoing therapy with abiraterone/prednisone and suggests that the efficacy may not be compromised if LHRH therapy is discontinued. It would be interesting to evaluate the quality of life metrics in addition to the cost-effectiveness analysis of this approach. Additional follow up and larger studies are necessary to fully evaluate this unique strategy.
Presented by: Carsten Henning Ohlmann, MD, Malteser Hospital Bonn, Bonn, Germany
Written by: Jason Zhu, MD. Fellow, Division of Hematology and Oncology, Duke University, @TheRealJasonZhu at the 2019 ASCO Annual Meeting #ASCO19, May 31-June 4, 2019, Chicago, IL USA
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