PHILADELPHIA – Treatment with the PCSK9 inhibitor alirocumab linked with a significant cut in the rates of peripheral artery disease events and ischemic strokes without increasing the rate of hemorrhagic strokes, and alirocumab treatment also showed a trend toward an association with a reduced rate of venous thromboembolic events in prespecified, ancillary analyses of data collected from more than 18,000 patients in the ODYSSEY Outcomes trial.
The analyses that looked at peripheral artery disease (PAD) events and venous thromboembolism (VTE) events also suggested that the apparent ability of alirocumab to reduce their incidence may have been largely mediated through a reduction in Lp(a) lipoprotein, with less of a contribution from the drug’s primary action of reducing LDL cholesterol,, said at the American Heart Association scientific sessions.
When used on top of intensive statin treatment, as in the ODYSSEY Outcomes trial, treatment with the PCSK9 inhibitor alirocumab “may be useful to prevent PAD events, particularly in patients with high levels of Lp(a),” said Dr. Schwartz, professor of medicine at the University of Colorado Denver in Aurora. In the analysis he reported, patients treated with alirocumab for a median of 2.8 years had a statistically significant 31% reduced rate of PAD or VTE event and a significant 31% reduced rate of PAD events alone, compared with control patients who received placebo, he reported. Alirocumab treatment was also associated with a 33% lower rate of VTE events only, but the overall rate of these events was low, and this difference just missed statistical significance with a P value of .06.
“Levels of Lp(a), but not LDL cholesterol, predicted the risk of PAD events,” and in patients on alirocumab treatment “the magnitude of Lp(a) reduction, but not LDL-cholesterol reduction, was associated with a reduction in PAD events and VTE.” The reduction in PAD events linked with alirocumab treatment “may be related to Lp(a) lowering,” Dr. Schwartz suggested.
The link between alirocumab treatment and a reduction in ischemic stroke with no increase in hemorrhagic strokes appeared in a separate prespecified analysis from ODYSSEY Outcomes that looked at the rates of ischemic stroke, hemorrhagic stroke, and their combined incidence during the median 2.8 year of study follow-up. Patients treated with alirocumab had a statistically significant 27% reduction in their rate of ischemic strokes compared with patients on placebo, and a statistically significant 28% relative reduction in the rate of any stroke with alirocumab treatment,, said in a separate report at the meeting. The rate of hemorrhagic strokes was small, and showed a nominal 17% reduction in patients treated with alirocumab, compared with controls, a difference that was not statistically significant.
Further analysis of the stroke outcomes also showed that these reductions in total strokes occurred with alirocumab treatment at roughly similar rates regardless of baseline level of LDL cholesterol or history of a prior cerebrovascular event. Analysis also showed that the rate of hemorrhagic strokes was consistently low regardless of the on-treatment level of LDL cholesterol. Even among patients whose LDL cholesterol level fell below 25 mg/dL on alirocumab treatment, the incidence of hemorrhagic strokes during follow-up was 0.1%, “a very reassuring finding,” said Dr. Jukema, professor of cardiology at Leiden (The Netherlands) University. The stroke analyses did not examine possible linkages of these effects with changes in level of Lp(a).
(Evaluation of Cardiovascular Outcomes After an Acute Coronary Syndrome During Treatment With Alirocumab) included 18,924 patients who had experienced an acute coronary syndrome event within the prior 12 months and had an LDL cholesterol level of at least 70 mg/dL despite maximally tolerated statin treatment and randomized them to treatment with alirocumab or placebo. The primary endpoint was the combination of coronary heart disease death, nonfatal MI, ischemic stroke, and hospitalization for unstable angina, which alirocumab effectively reduced compared with placebo ( ).
The PAD analysis tallied the combined rate of acute limb ischemia, revascularization, or amputation related to PAD, and the VTE cases included patients who developed deep vein thrombosis or pulmonary embolism. All cases were nonadjudicated reports from participating investigators. Because Lp(a) makes up a portion of LDL cholesterol, Dr. Schwartz and associates calculated adjusted values for LDL cholesterol that were independent of Lp(a).
In a multivariable analysis that adjusted for demographic and clinical characteristics as well as baseline Lp(a) and the calculated level of LDL cholesterol, every 1 mg/dL decrease in Lp(a) linked with a statistically significant, nearly 1% decrease in the rate of either a PAD or VTE event, while the change in LDL cholesterol had no significant relationship with this endpoint, said Dr. Schwartz.
The impact of Lp(a) lowering was most dramatic among the subgroups of patients who entered the study with the highest levels of Lp(a). “In the lowest quartile [for baseline level of Lp(a)] the effect of treatment [with alirocumab] was inconsequential; all of the action was in the upper two quartiles,” he said. Dr. Schwartz highlighted that 90% of patients in the study were on an “intense” statin dosage, and 97% received some statin treatment. Against that treatment background, the findings showed that patients still had residual cardiovascular disease risk that did not appear to respond to changes in LDL cholesterol but which did appear to respond to a reduction in Lp(a) produced by alirocumab. Dr. Schwartz further suggested that alirocumab’s reduction of Lp(a) might also mediate the drug’s apparent effect on reducing VTE incidence, possibly because Lp(a) is structurally similar to plasminogen and hence can have prothrombotic effects.
ODYSSEY Outcomes was sponsored by Sanofi and Regeneron, the companies that market alirocumab (Praluent). Dr. Schwartz has received research support from Sanofi and from Resverlogix, Roche, and The Medicines Company. Dr. Jukema has been a speaker for and received research support from Sanofi Regeneron, and has also been a speaker for Amgen, MSD, and Roche and has also received research support from Biotronik
SOURCE: Schwartz GG et al. AHA 2019, Abstract 309; Jukema JW et al. AHA 2019, Abstract 334.