By Megan Brooks
NEW YORK (Reuters Health) - 6/3/2019
Men with advanced prostate cancer and cardiovascular disease (CVD) are at increased risk of dying during the first six months of treatment with abiraterone acetate (Zytiga) compared with their peers without pre-existing CVD, according to a retrospective study.
Patients with a history of CVD were typically excluded from clinical trials of abiraterone. However, a substantial proportion of patients treated with the drug in the real world have CVD.
"We found that there is risk associated with abiraterone and the survival benefit observed in the clinical trials might not hold for patients not qualified for clinical trials," Dr. Grace Lu-Yao of the Sidney Kimmel Cancer Center at Thomas Jefferson University in Philadelphia said during a media briefing February 27 ahead of presentation at the upcoming American Association for Cancer Research (AACR) annual meeting.
Using the SEER-Medicare database, she and her colleagues identified 2,845 patients (median age, 75) newly diagnosed with prostate cancer and treated with abiraterone acetate. More than two-thirds (68%) had at least one pre-existing heart condition (myocardial infarction, atrial fibrillation, congestive heart failure, stroke or ischemic heart disease).
Among patients with CVD, the crude six-month rate of death ranged from 21% to 26% depending on the type of heart condition, significantly higher than the 16% for men without pre-existing CVD.
The researchers also found a significant increase in hospitalization rates in the six months after starting abiraterone treatment, regardless of the presence of CVD.
The rate increased by 53% in patients without CVD. Among men with pre-existing CVD, the hospitalization rate ranged from 34% in those with atrial fibrillation to 55% in those with acute myocardial infarction.
AACR president and briefing moderator Dr. Elizabeth Jaffee said the study "highlights the importance of understanding pre-existing noncancer conditions and how patients will respond to cancer therapy. Clinical trials usually test new therapies in the healthiest patients and I think this has been rationalized as a safety measure by both investigators and sponsors. However, this does not provide the real-world data we need once a drug is approved."
"This study is retrospective, but it provides enough data to support a prospective collection of information in a phase IV post-approval study," said Dr. Jaffee.
The research was funded by a Pennsylvania CURE Program award and the National Cancer Institute. Dr. Lu-Yao has no relevant conflicts of interest.
AACR 2019 Annual Meeting.
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