Men with prostate cancer, cardiovascular disease have higher mortality after taking abiraterone acetate

Grace Lu-Yao

Men with pre-existing cardiovascular disease who received abiraterone acetate for advanced prostate cancer had higher mortality rates than men without cardiovascular disease who received the therapy, according to results of a population-based study scheduled for presentation at American Association for Cancer Research Annual Meeting.

“Patients with a history of significant cardiovascular disease or uncontrolled hypertension are almost always excluded from clinical trials of abiraterone acetate,” Grace Lu-Yao, PhD, associate director for population science at Sidney Kimmel Cancer Center – Jefferson Health in Philadelphia, said in a press release. “However, in the real-world setting, these conditions are very common among men with prostate cancer.”

Abiraterone acetate (Zytiga, Janssen Oncology), an androgen deprivation therapy, received initial FDA approval in 2011 for use in combination with prednisone by men with metastatic castration-resistant prostate cancer who previously underwent chemotherapy containing docetaxel. It was approved in February 2018 for use with prednisone by men with metastatic high-risk, castration-sensitive prostate cancer.

To determine real-world treatment outcomes, Lu-Yao and colleagues used the SEER-Medicare linked database to identify 2,845 men (median age, 75 years) diagnosed with prostate cancer between 1991 and 2013 and who received abiraterone acetate between 2011 and 2014.

Six-month overall mortality and changes in hospitalization rates after starting abiraterone acetate served as primary endpoints. The researchers calculated incidence rate ratios (IRRs) for hospital visits by dividing posttreatment rates by pretreatment rates.

The researchers found that 1,924 (67.6%) of the men analyzed had at least one pre-existing cardiovascular disease (CVD) condition. These conditions included acute myocardial infarction, atrial fibrillation, congestive heart failure, stroke and ischemic heart disease.

Results showed higher crude risk for overall mortality 6 months after starting abiraterone acetate among men with pre-existing cardiovascular conditions, including ischemic heart disease (21.4%), stroke (22.1%), congestive heart failure (23.4%), atrial fibrillation (24.4%) and acute myocardial infarction (25.6%), compared with no CVD (15.8%).

Hospitalization rates increased among all men 6 months after treatment compared with 6 months prior to treatment. The rate increased 53% among men not treated with chemotherapy who had no pre-existing CVD, whereas increases among those with pre-existing CVD ranged from 34% for those with atrial fibrillation and 55% for those with acute myocardial infarction.

Researchers calculated IRRs for hospital visits of 1.44 (95% CI, 1.12-1.86) for men with acute myocardial infarction; 1.27 (95% CI, 1.09-1.48) for men with atrial fibrillation; 1.35 (95% CI, 1.21-1.51) for men with congestive heart failure; 1.3 (95% CI, 1.07-1.57) for men with stroke; 1.22 (95% CI, 1.01-1.48) for men with ischemic heart disease; and 1.43 (95% CI, 1.3-1.57) for men with no CVD.

The authors acknowledged several limitations to the study, including the inability to address treatment efficacy among these men, the presence of confounding factors such as variable disease states, and the inability to quantify projected survival without control groups.

“As we move abiraterone acetate treatment to patients with earlier stages of the disease and longer life expectancy, it is important to evaluate whether the benefits outweigh the risks based on the health status of the patients, and to ensure that patients are carefully monitored for potential side effects,” Lu-Yao said. – by Jennifer Byrne

Reference:

Lu-Yao G, et al. Abstract 4469. Scheduled for presentation at: AACR Annual Meeting; March 29-April 3, 2019; Atlanta.

Disclosures: Lu-Yao reports her spouse, who is not involved with the present study, is an officer of Sun Pharmaceutical Industries Inc. The other authors report no relevant financial disclosures.