Pre-existing CVD tied to increased mortality risk in men treated with abiraterone acetate
Men with advanced prostate cancer who have pre-existing cardiovascular disease (CVD) may have an elevated mortality risk after treatment with abiraterone acetate compared with men who do not have CVD, according to a study presented at AACR 2019.
Using data from the Surveillance, Epidemiology, and End Result (SEER) database, researchers identified 2,845 men with advanced prostate cancer who were treated with abiraterone acetate between 2011 and 2014 (median age, 75 years). Of these, 67.6 percent (n=1,924) had at least one pre-existing cardiovascular condition (ie, acute myocardial infarction [MI], atrial fibrillation [AF], congestive heart failure [CHF], stroke, or ischaemic heart disease).
In the 6 months following initiation of abiraterone acetate therapy, the all-cause mortality rate was 15.9 percent among those without pre-existing CVD. In contrast, men with existing cardiovascular conditions had an elevated risk of mortality after starting treatment with abiraterone acetate (21.4 percent for those with ischaemic heart disease, 22.1 percent for those with stroke, 23.4 percent for those with CHF, 24.2 percent for those with AF, and 25.6 percent for those with acute MI. [AACR 2019, abstract 4469]
All patients had an elevated risk of hospitalization 6 months after initiating abiraterone acetate therapy, regardless of their pre-existing CVD status (incident rate ratio [IRR], 1.43, 95 percent confidence interval [CI], 1.30–1.57 [no CVD], IRR, 1.22, 95 percent CI, 1.01–1.48 [ischaemic heart disease], IRR, 1.27, 95 percent CI, 1.09–1.48 [AF], IRR, 1.30, 95 percent CI, 1.07–1.57 [stroke], IRR, 1.35, 95 percent CI, 1.21–1.51 [CHF], and IRR, 1.44, 95 percent CI, 1.12–1.86 [acute MI]).
The hospitalization risk was further increased among patients who did not receive chemotherapy and received abiraterone acetate at an earlier stage of disease (IRR, 1.53 [no CVD], IRR, 1.5 [ischaemic heart disease], IRR, 1.34 [AF], IRR, 1.52 [stroke], IRR, 1.48 [CHF], and IRR, 1.55 [acute MI]).
“Our data show that patients who have pre-existing CVD experienced higher mortality after receiving abiraterone acetate compared with those who do not, and the bulk of the survival differences occurred in the first 6 months [with little difference in survival after 6 months],” said study investigator Professor Grace Lu-Yao, Associate Director of Population Science at the Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania, US.
“The increased post-treatment hospitalization rate shows that there is risk associated with abiraterone acetate for all patients. Abiraterone acetate use without prior chemotherapy was associated with a 34 to 55 percent increase in post-treatment hospitalization rate [among those with pre-existing CVD],” she added.
“Our study highlights the importance of carefully monitoring patients after prescribing abiraterone acetate,” she said.
“Patients with a history of significant CVD or uncontrolled hypertension are almost always excluded from clinical trials of abiraterone acetate. A substantial portion of patients treated in the real world do not quality for trial eligibility,” said Lu-Yao, highlighting that these conditions are common in men with prostate cancer. As such, it would be beneficial for men with these conditions to be included in clinical trials so as to be more representative of a real-world setting, she suggested.
“It is very important that patients with advanced prostate cancer understand that the outcomes of abiraterone acetate treatment observed in clinical trials may not apply to patients in the real world, especially those not meeting the eligibility criteria of the clinical trials,” she said.