Antiinflammatory Therapy with Canakinumab for Atherosclerotic Disease
Comprehensive Overview
Published in the New England Journal of Medicine in 2017, this study, known as the CANTOS trial, asked whether directly reducing inflammation, separate from lowering cholesterol, could reduce the risk of another heart attack or stroke in people who had already survived a heart attack, a long-suspected but never directly proven idea called the inflammatory hypothesis of atherosclerosis. Researchers conducted a randomized, double-blind, placebo-controlled trial of canakinumab, an antibody that blocks the inflammatory signaling protein interleukin-1 beta, in 10,061 patients with a prior heart attack and elevated high-sensitivity C-reactive protein, a blood marker of persistent inflammation, despite already receiving standard cholesterol-lowering treatment. Participants received one of three doses of canakinumab, 50, 150, or 300 milligrams injected under the skin every 3 months, or placebo, and were followed for a median of 3.7 years. The primary outcome was the first occurrence of nonfatal heart attack, nonfatal stroke, or cardiovascular death, adjudicated by a committee unaware of which treatment each patient had received. The topline result was that canakinumab markedly lowered inflammatory markers without changing cholesterol levels at all, and the middle dose met the trial's strict statistical bar for reducing cardiovascular events.
Outcomes and Implications
The most important finding was that the 150-milligram dose of canakinumab was the only one to clear the trial's strict, multiplicity-adjusted statistical threshold, reducing the primary composite outcome of heart attack, stroke, or cardiovascular death by a hazard ratio of 0.85 compared with placebo, and reducing the key secondary outcome, which added hospitalizations for unstable angina requiring urgent revascularization, by a hazard ratio of 0.83. Both the 50-milligram and 300-milligram doses lowered inflammatory markers just as effectively but did not meet the prespecified bar for statistical significance on the primary outcome. Notably, none of the doses changed LDL or HDL cholesterol levels, confirming that any cardiovascular benefit came from reducing inflammation itself rather than from any lipid-lowering effect. Canakinumab was not without risk: it was associated with a significantly higher rate of fatal infection than placebo, reflecting the immune-suppressing nature of blocking interleukin-1 beta, and there was no significant difference in death from any cause between the canakinumab and placebo groups. An unexpected finding was that cancer mortality, particularly from lung cancer, was significantly lower with canakinumab than placebo, consistent with earlier evidence linking interleukin-1 to tumor growth. The authors conclude that targeting the interleukin-1 beta inflammatory pathway with canakinumab, independent of any effect on cholesterol, significantly lowered the rate of recurrent cardiovascular events, offering the first direct clinical proof that inflammation itself is a treatable driver of atherosclerotic disease, while cautioning that this benefit must be weighed against an increased infection risk.