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AstraZeneca gives up on Ionis’ RNA drug for heart disease

AstraZeneca will stop clinical studies of a genetic medicine for heart disease following a Phase 2 trial that showed it didn’t lower cholesterol enough to justify further study, the drug’s developer, Ionis Pharmaceuticals, said Friday.

Although monthly injections of the drug called AZD8233 reduced low-density lipoprotein, or “bad cholesterol,” by 62% when compared to a placebo, that decline didn’t “achieve pre-specified efficacy criteria” that the U.K. drugmaker had set, Ionis said in a press release.

A marketed drug that works similarly, Novartis’ Leqvio, reduced LDL by 52% in a large clinical trial. That drug, however, is injected just twice a year, offering a convenience advantage over AZD8233.

An earlier Phase 2 trial had tested a higher dose of AZD8233 that reduced LDL by 79%, but that was accompanied by increased levels of liver enzymes in some patients, which can be a sign of liver damage. The lower dose in the most recent trial was aimed at achieving those high levels of LDL reduction without liver-related side effects.

The target of AZD8233 is a protein called PCSK9, high levels of which can interfere with LDL breakdown. Amgen’s Repatha and Sanofi and Regeneron’s Praluent were the first drugs to target PCSK9, launching in 2015.

Both medicines are antibodies that directly block PCSK9, and patients must inject them as frequently as once every two weeks. AZD8233 and Leqvio, which launched earlier this year, are RNA-based drugs designed to block a gene that stimulates production of PCSK9.

While Ionis stated that AZD8233 hadn’t met the bar AstraZeneca set for the Phase 2 trial, the company didn’t say what level of cholesterol-lowering its partner was looking for. In a note to clients Friday, RBC analyst Luca Issi speculated that commercial considerations likely factored into the decision because “Leqvio is materially ahead and can be dosed less frequently.”

AstraZeneca and Ionis have been collaborating on RNA drugs for a decade, initially with a focus in cancer but later broadening to include programs for cardiovascular, metabolic and kidney diseases too. In June, the two partners announced success in a late-stage trial for a drug that treats the rare disease transthyretin amyloidosis.

In 2018, Ionis won approval of a transthyretin amyloidosis drug called Tegsedi, but that product has been outperformed by a rival medicine from rival Alnylam Pharmaceuticals, the company that originally developed Leqvio.

Ionis shares fell 4% in morning trading today, changing hands at about $43 apiece.