Mirum Pharmaceuticals meets Phase 3 hepatitis delta trial endpoint

A Phase 3 trial met its primary endpoint for hepatitis delta as Mirum Pharmaceuticals, Inc. NASDAQMIRM reported on Tuesday that 59 per cent of weekly brelovitug recipients achieved combined viral and liver-enzyme responses. The release reported zero responders in the delayed-treatment comparator, completing the second pivotal study for a planned U.S. filing in the first half of 2027.

AZURE-4 enrolled 113 previously untreated patients across three randomized groups. Active treatment was 300 milligrams weekly or 900 milligrams every four weeks, while delayed treatment began at week 12.

Mirum is a midsized drugmaker based in California that sells rare-disease medicines and develops treatments for liver disorders.

At 4:00 p.m. EST on Nov. 6, NASDAQMIRM was quoted at US$93.72, according to Google Finance. That quotation predates Tuesday's announcement and cannot establish the market's reaction.

Both Doses Met The Combined Endpoint

The primary endpoint combined virologic response with normalization of alanine aminotransferase, or ALT, a marker of liver injury. Virologic response meant at least a hundredfold reduction in viral RNA, a level below the assay's quantification threshold, or no detectable viral RNA.

At 24 weeks, the weekly-dose response rate was 59 per cent, while the other active arm's rate was 44 per cent. Both comparisons against delayed treatment had p values of 0.0001 or lower, and missing assessments counted as nonresponses.

More than half the participants had cirrhosis. Mirum reported no new safety signals; flu-like illness occurred in 17.2 per cent of weekly recipients and 18.5 per cent with dosing every four weeks, mostly following the first dose.

"Hepatitis delta is the most severe form of viral hepatitis, and many patients are living with advanced liver disease, including cirrhosis," Tatyana Kushner, an associate professor of medicine at Weill Cornell Medicine, said in the release.

The new result follows AZURE-1's endpoint success on Sept. 28. In that study, the weekly-dose combined response was 56 per cent, compared with zero in the delayed-treatment group.

Mirum also presented longer-term results from a separate Phase 2a group with cirrhosis. All 15 patients achieved the combined endpoint after up to 108 weeks, but that smaller extension group had substantially longer follow-up than the Phase 3 cohorts.

Mirum And Vir Are Preparing Regulatory Filings

Vir Biotechnology, Inc. NASDAQVIR reported on Nov. 8 that its monthly elebsiran and tobevibart combination achieved a 44 per cent combined response at 48 weeks. Its delayed-treatment comparator had zero responders at week 12, with a p value below 0.0001.

Vir required undetectable viral RNA alongside normal ALT, whereas Mirum's viral criterion also allowed a substantial reduction in viral load. Different thresholds and follow-up periods prevent a direct efficacy ranking between the trials.

Read more: Vir Biotechnology meets Phase 3 hepatitis delta endpoint with 44 per cent response

Mirum estimates that hepatitis delta affects approximately 230,000 people in the United States and Europe in its Nov. 10 release. The infection occurs in people with hepatitis B and can progress to cirrhosis, liver cancer and liver-related death.

Mirum reported on Nov. 3 unrestricted cash, cash equivalents and investments of US$500.5 million as of Sept. 30. Third-quarter product sales were US$185.7 million, while research and development expense excluding stock compensation included US$42.1 million for brelovitug.

The next brelovitug regulatory milestone is Mirum's planned biologics licence application to the FDA in the first half of 2027. Mirum targets a potential U.S. launch in the fourth quarter of 2027, conditional on approval.