Japan: 20 deaths after taking Amgen drug – Also available in Greece

Twenty people in Japan who received Amgen’s drug avacopan for rare autoimmune diseases have died, while at least 22 patients developed severe liver damage, potentially fatal, according to Japanese pharmaceutical company Kissei Pharmaceutical, which markets the Amgen medication in the country.

Kissei on Friday instructed doctors to stop prescribing the drug to new patients.

According to the company, the 20 deaths involved patients who had developed severe liver dysfunction. Thirteen of those cases were linked to a rare condition known as vanishing bile duct syndrome, in which the ducts carrying bile from the liver are destroyed.

Kissei clarified that a direct causal relationship between the drug and all the deaths has not been confirmed, according to the Wall Street Journal.

An Amgen spokesperson said the 20 deaths were recorded among more than 8,500 patients who have received the drug in Japan, noting that in some cases no direct link between the deaths and Tavneos had been established.

The spokesperson also added that in the United States, where more than 8,000 patients have received the treatment, no deaths related to severe liver damage have been reported.

CSL, which holds the commercial rights to the drug outside the United States and licensed it to Kissei for Japan, stated that it “takes every patient safety issue extremely seriously” and is cooperating with regulatory authorities.

“Kissei has begun informing healthcare professionals, urging them to avoid using the drug in new patients and to carefully reassess continuation of treatment in existing patients, explaining the risks of liver dysfunction and alternative treatment options,” the company said.

The drug is used to treat a group of rare autoimmune diseases that cause inflammation in small blood vessels. The U.S. Food and Drug Administration (FDA) approved the drug in 2021.

The medication was launched in Japan in 2022. That same year, Amgen acquired ChemoCentryx, the company that developed Tavneos, for $3.7 billion.

In January, the FDA asked Amgen to voluntarily withdraw the drug from the U.S. market, but the company refused.

In March, the U.S. regulator announced that it had identified 76 cases worldwide of severe liver damage linked to Tavneos, including eight deaths. Most of the cases had been reported in Japan. Of the 76 cases, seven involved vanishing bile duct syndrome, and three of those patients died.

At the end of April, the FDA formally initiated proceedings to withdraw the drug.

The regulatory authority has also stated that ChemoCentryx included misleading information in the drug’s original approval application.

In a letter to doctors in April, Amgen argued that it “has not identified issues in the primary patient data and remains confident” in Tavneos’ effectiveness.

The company acknowledged, however, that severe liver injuries had already been observed during clinical trials and that hepatotoxicity is a known risk of the drug, as stated in the medication’s official warnings.

Avacopan generated $119 million in sales for Amgen in the first quarter of the year, up 32% year-on-year, though it still represented less than 2% of the company’s total drug sales.

Amgen stated in its April earnings report that the drug “demonstrates efficacy and a favorable benefit-risk profile,” also claiming that vanishing bile duct syndrome has not affected patients in the United States.

It is clarified that the drug is also available in Greece.