Updates June 11 story to add company comments, changes dateline

June 12 (Reuters) - Amgen AMGN.O said it has signed up a research firm to independently review data for its drug, Tavneos, as it seeks to prove its benefits following the U.S. health regulator's proposal to withdraw it from the market.

Tavneos was approved in October 2021 to treat a rare disease called severe active ANCA-associated vasculitis, which inflames small blood vessels and can damage organs like the kidneys and lungs.

However, the U.S. Food and Drug Administration in April proposed withdrawing its approval for Tavneos, citing a lack of proven effectiveness and false statements in its original application.

A month earlier, the agency had noted 76 cases of drug-induced liver injury with evidence suggesting a causal link to Tavneos, including eight deaths.

In a letter dated June 1 and posted in the agency's records, Amgen said Duke Clinical Research Institute began an independent, blinded review in February of data from the main late-stage trial that supported Tavneos' approval.

"We will review the findings carefully and continue engagement with regulators, investigators and the healthcare community as appropriate," an Amgen spokesperson told Reuters.

The drugmaker said it plans to submit detailed data to the FDA by June 29.

Amgen said the re-adjudication data would be one part of its June 29 FDA hearing submission, along with post-marketing safety and efficacy data collected since Tavneos' approval and real-world evidence.

The company has said it believes Tavneos' benefits outweigh its risks and that withdrawing the drug would not be in the best interest of patients.

Amgen acquired Tavneos through its $3.7 billion purchase of ChemoCentryx in 2022.

About 20 deaths linked to serious liver dysfunction have been reported in Japan in patients treated with the drug, according to a safety notice ‌issued by partner Kissei Pharmaceutical in May.