Prostate cancer patients with different baseline cardiovascular risk had similar reductions in cardiovascular event rates when treated with the LHRH antagonist degarelix versus an LHRH agonist.
Michael Borre, MD
Prostate cancer patients with different baseline cardiovascular risk had similar reductions in cardiovascular event rates when treated with the LHRH antagonist degarelix (Firmagon) versus an LHRH agonist, according to a pooled analysis of randomized trials that was presented at the 2015 AUA Annual Meeting.
The magnitude of risk reduction with degarelix approached 60% for men with higher baseline cardiovascular risk in the United States and Canada and for European men with lower baseline risk. The baseline prevalence of cardiovascular disease was similar among men in North America and Europe.
The results add to those of previous analyses of the trials, which showed a reduced risk of cardiovascular events or death among men treated with degarelix, lead author Michael Borre, MD, reported at the AUA conference.
“Despite a similar proportion of patients with preexisting cardiovascular disease by region, baseline cardiovascular risk factors were more common in the US and Canada versus Europe,” said Borre, associate professor of Urology at Aarhus University Hospital. “The geographic differences in the 1-year cardiovascular event risk are likely due to the different patient clinical characteristics.
“Despite a lower cardiovascular event rate in Europe compared with the US and Canada, the degree of reduction in the risk of cardiovascular events with degarelix compared with an LHRH agonist was similar in both regions.”
Asked for a possible explanation for the results, Borre said speculation has centered on potential differences in medication distribution across atherosclerotic plaques with an LHRH agonist versus antagonist.
Pooled data from six phase III clinical trials showed a lower risk of cardiovascular events and or death with degarelix versus LHRH agonists. The risk of cardiovascular events and death with androgen deprivation therapy for prostate cancer is greatest in men who have a history of cardiovascular disease.
Borre and colleagues sought to determine whether baseline cardiovascular risk and regional differences influenced the rate of cardiovascular events with degarelix and LHRH agonists. They analyzed available data from three of the six trials, two of which had a duration of 12 months and one of which had a duration of 7 to 14 months. The trials involved a cumulative total of 1737 randomized patients.
The analytic population consisted of 1118 men with no history of cardiovascular disease and 619 with a positive history. Overall, men with a high-risk cardiovascular profile had a 12-month cardiovascular event rate of 4.5% versus 1.2% of low-risk men (P <.001).
The incidence of cardiovascular events was higher in high-risk men regardless of whether they had cardiovascular disease at baseline, said Borre. In the subgroup of men with cardiovascular disease at baseline, a high cardiovascular risk profile was associated with a 6.9% event rate at 12 months versus 2.8% in those with a low-risk profile (P = .049).
Comparison of regional differences in cardiovascular risk showed that men in North America and those in Europe had similar age, BMI, testosterone levels, and rates of cardiovascular disease. However, men in the US and Canada were more likely to have multiple cardiovascular risk factors as compared with their European counterparts.
Among men with cardiovascular disease at baseline, those in the United States and Canada had a 12-month event rates of 9.4% versus 3.5% for the European cohort (P = .006). Nonetheless, the relative hazard for degarelix versus LHRH agonist therapy was similar across geographic regions, as the pooled estimate of treatment hazard ratio was 0.42 for both regions (P = .021).
“Cardiovascular risk factors at baseline were more common in the US and Canada versus Europe,” said Borre. “The risk [of cardiovascular events and death] appears to be driven by the risk factors.”
Borre M, Keane T, Bosnyak Z, et al. Regional differences in cardiovascular status and events in prostate cancer patients treated with a luteinising hormone-releasing hormone agonist vs antagonist: results of a pooled analysis. Presented at: 2015 AUA Annual Meeting; May 15-19, 2015; New Orleans, LA. Abstract MP73-03.