CHICAGO – Adding abiraterone acetate plus prednisone to androgen deprivation therapy in hormone-naive high-risk prostate cancer patients significantly improves overall survival, according to “practice-changing” results from the phase III LATITUDE trial and the multiarm, multistage STAMPEDE trial.
In the double-blind, randomized, placebo-controlled LATITUDE trial, 597 patients with newly diagnosed high-risk metastatic prostate cancer who received 1,000 mg of abiraterone acetate daily plus 5 mg of prednisone daily in addition to androgen deprivation therapy experienced a 38% reduction in the risk of death and a 53% reduction in the risk of radiographic progression or death at a median follow-up of 30.4 months, compared with 602 such patients who received placebo and androgen deprivation, Karim Fizazi, MD, PhD, of the Institut Gustave Roussy, Villejuif, France, reported at the annual meeting of the American Society of Clinical Oncology.
Significant improvements also were seen in the treatment vs. placebo group for all secondary endpoints, including time to prostate-specific-antigen progression (hazard ratio, 0.30), time to pain progression (HR, 0.70), time to next symptomatic skeletal event (HR, 0.70), time to chemotherapy (HR, 0.44), and time to subsequent prostate cancer therapy (HR, 0.42), Dr. Fizazi said.
He discussed the findings, including side effects, and ongoing and future studies, in a video interview.
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“Based on these findings, I believe that using abiraterone up front, together with androgen deprivation therapy, will become the next standard of care for these men,” he said.
Similarly, in the STAMPEDE trial, abiraterone acetate plus prednisone was associated with significantly improved overall survival in 960 high-risk prostate cancer patients starting hormone therapy, compared with 957 such patients receiving placebo and standard-of-care hormone therapy, according to Nicholas D. James, BSc MBBS, PhD, of the Institute of Cancer and Genomic Sciences, University of Birmingham, England.
“Overall, we’ve got about a 30% improvement in survival times for the upfront use of abiraterone. For our metastatic patients, we haven’t reached the median survival yet for the abiraterone patients, but it’s around 3.5 years median survival in the control arm, and we’re projecting that’s going to go up to 6.5 or 7 years in the abiraterone patients,” he said in a video interview, adding that he and his colleagues think this will be one of the biggest survival gains ever reported in adults in such a setting.
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Dr. James also discussed findings with respect to secondary endpoints, including a 70% improvement in failure-free survival in the treatment vs. placebo group – an improvement that he called an “absolutely spectacularly big gain” – and skeletal-related events, which decreased by 55% in the treatment group.
Both investigators discussed ongoing and recently completed studies that could shed additional light on the use of abiraterone in prostate cancer patients, including plans to look at the effects of giving both abiraterone and docetaxel together.
“My prediction will be that we will be giving both treatments in due course,” Dr. James said, adding, “I think these findings will certainly be practice changing.”