Investing.com -- Abivax shares plunged on Tuesday after its experimental ulcerative colitis pill posted stronger-than-expected late-stage trial results, but the headline numbers were overshadowed as the data flagged rare malignancy events.

The company’s Paris-listed shares sank more than 32% in early European trading by 07:34 GMT.

In the 44-week study, roughly half of patients on both doses of the oral drug, obefazimod, achieved clinical remission — 50.8% on the 25 milligram dose and 51.3% on the 50 milligram dose — compared with 10.4% of those on placebo. The results came in well above expectations and appeared to outperform existing therapies.

Obefazimod was broadly well tolerated over the course of the study. However, the report was clouded by a handful of malignancy events — rare, scattered cases deemed unrelated to the treatment — that nonetheless rattled investors and weighed heavily on the stock.

The trial results were "clearly above expectations and outperforming current therapies, confirming the differentiated profile of obefazimod," Stifel analysts led by Damien Choplain said in a note, adding that the malignancy events "introduced uncertainty and put the share price under pressure."

"While the malignancy signal cannot be ignored, we view it as a potential labelling overhang rather than evidence of a clear causal safety risk," they wrote.