Abivax Obefazimod Trial Shows Strong Remission; Stock Drops
Abivax obefazimod trial showed large maintenance remission gains but reported malignancies sparked a sharp sell-off and raised regulatory uncertainty.
KEY TAKEAWAYS
- Both obefazimod doses met Week-44 clinical remission, 50.8% and 51.3% versus 10.4% placebo.
- Company disclosed malignancies, mainly non-melanoma skin cancers and other cancers, concentrated in older high-dose patients.
- Shares plunged about 31% and Jefferies downgraded to Hold and cut its price target to $90 from $160.
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Abivax S.A. reported on June 1, 2026, that its Phase 3 ABTECT maintenance trial of obefazimod demonstrated statistically significant clinical remission at Week 44 in patients with moderately to severely active ulcerative colitis. Despite the strong efficacy, disclosures of malignancies in the trial shifted investor focus and triggered a sharp sell-off.
ABTECT Maintenance Trial Results and Safety Profile
The ABTECT Phase 3 maintenance study was a 44-week, double-blind, placebo-controlled trial involving adults with moderate-to-severe ulcerative colitis who had responded to induction therapy with obefazimod. Patients were re-randomized to once-daily doses of 25 mg or 50 mg obefazimod or placebo.
Both obefazimod doses met the primary endpoint of clinical remission at Week 44, with remission rates of 50.8% for the 25 mg group and 51.3% for the 50 mg group, compared with 10.4% for placebo. The company reported that both doses also achieved all key secondary endpoints, including endoscopic improvement, histologic-endoscopic mucosal improvement, and corticosteroid-free clinical remission. Abivax described the results as statistically significant and clinically meaningful.
The company characterized obefazimod’s safety profile as generally favorable, with no new safety signals observed and the treatment generally well tolerated. However, it disclosed cases of malignancy, including non-melanoma skin cancers and other cancers, occurring more frequently in the higher-dose arm and predominantly in older patients. Abivax described these events as rare, largely unrelated to treatment, and consistent with background risk in an older ulcerative colitis population.
Market Reaction and Analyst Response
Investor attention centered on the malignancy reports despite the strong efficacy data. Abivax shares fell about 31% in the immediate sell-off following the announcement. Jefferies downgraded the stock to Hold from Buy and cut its price target to $90 from $160, citing concerns that the observed malignancies could complicate regulatory review and commercial adoption.
Abivax said the ABTECT program remains on track and plans to use the totality of induction and maintenance data to support marketing-authorization applications in the U.S. and Europe. The company intends to present full maintenance-trial data and detailed safety analyses at upcoming medical congresses and submit them for peer-reviewed publication. Long-term safety continues to be evaluated in open-label extension studies with up to three years of exposure.
Obefazimod, a once-daily oral small molecule that modulates miR-124 expression, is positioned as a potential alternative to injectable biologics currently used in ulcerative colitis treatment. The company acknowledged that regulators are likely to scrutinize the malignancy data closely given the chronic-use setting.
