Abivax Shares Surge 39.9% on Positive Ulcerative Colitis Drug Data

Updated data indicates the cancer rates matched those typically observed in ulcerative colitis patients. That helped the stock jump 39.9% on Tuesday.

The contrast between June's steep decline and Tuesday's sharp recovery illustrates how sensitive biotech stocks are to evolving clinical data. Abivax's current market cap of about 8 billion euros reflects the high stakes for a drug that could address a significant unmet need in ulcerative colitis.

Ulcerative colitis is a chronic inflammatory bowel disease affecting millions worldwide, causing persistent inflammation of the colon and rectum. Many patients fail to achieve lasting remission with existing therapies, creating a large market opportunity for effective oral treatments like obefazimod. The 44-week maintenance trial provides crucial evidence that extended treatment can benefit patients who do not respond quickly.

Longer Treatment Helps Some Patients

"These findings suggest that a meaningful proportion of patients who do not initially respond may still derive substantial benefit from longer treatment exposure," the company said.

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The study was a maintenance trial designed to evaluate remission rates in ulcerative colitis patients over a 44-week period. This gives hope that even if the drug does not work right away, it may work over time.

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Cancer Risk Appears Manageable

The earlier data from June had scared investors. These seven cancer cases were assessed as either not related or unlikely to be related to the drug.

CEO Marc de Garidel said: "The expanded cumulative safety data further strengthens our confidence in the long-term safety profile of obefazimod and reinforces the favorable benefit-risk profile for our program as we prepare for our planned [new drug application] submission later this year."

Jefferies analysts called the update "supportive," but voiced skepticism that this data would be enough for investors, given "cancer risk may be tough to discount, sparse catalyst path, cash needs, catalyst path ex-M&A."

What to Watch

Abivax intends to file a New Drug Application (NDA) with the FDA for obefazimod during Q4 2026. A launch is possible in 2027, but many expect the company to be acquired before then. A study testing obefazimod in Crohn's disease patients is anticipated around mid-2027.

The stock has gained nearly 1,700% in 2025, though it was down 14% year-to-date coming into Tuesday trading. The company now has a market capitalization of about 8 billion euros. The next key milestone is the planned FDA submission in the fourth quarter of 2026.

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