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CSL heart drug misses goal in large study

An experimental plasma-based infusion developed by CSL failed to keep people at high cardiovascular risk from having heart attacks, strokes or dying from heart-related complications in a major clinical trial, the company said Sunday.

The results of the trial, called AEGIS-II, strike another blow to a treatment approach aimed at improving heart health by raising high-density lipoprotein cholesterol — the so-called “good cholesterol” — or its major components.

The trial of the infusion, called CSL112, enrolled 18,000 people who had suffered a heart attack and were at high risk of a second one because of medical factors like diabetes, age or other signs of cardiovascular disease.

Half of the participants were randomized to receive four infusions of CSL112 starting within five days of first medical contact and completed within the following month. The other half received placebo infusions. Trial researchers followed them for 90 days, a period that sees high rates of repeat heart attacks.

Study results didn’t show a difference in the rate of cardiovascular complications or death, CSL said, also noting researchers didn’t find any major safety concerns.

As a result, the company said it has dropped plans to ask regulators for the drug’s approval.

HDL helps heart health by removing low-density lipoprotein, or “bad” cholesterol, from the blood. For years, drugmakers hypothesized that a drug that raises HDL could help prevent heart attacks, but their efforts have been largely unsuccessful. Eli Lilly, Merck & Co., Pfizer and Roche each developed drugs known as CETP inhibitors that raised HDL, but they all failed in large trials.

In CSL’s case, CSL112 was a formulation of apolipoprotein A-I, the main protein carried in HDL, which was derived from human plasma.

“AEGIS-II is the most ambitious study in our company’s history and we are proud of the quality of the study we delivered and the enhanced capabilities we developed to do so,” said Bill Mezzanotte, CSL’s head of research and development, in a statement. “We plan to apply these capabilities as well as our plasma protein platform to future unmet medical need in cardiovascular and metabolic conditions as well as those in our other strategic therapeutic areas.”

CSL spent $1.2 billion on research and development in its fiscal year ended June 30, 2023, on total revenue of $13.3 billion.

CSL’s shares, which are traded on the Australian stock exchange, declined 5% in trading Monday.