Abivax SA (Abivax (ABVX)) had a rough Tuesday morning. The biotech's stock cratered more than 35% in premarket trading, and the reason is a classic case of good news, bad news — with the bad news winning the day.
The company released data from its Phase 3 ABTECT maintenance trial for obefazimod, its experimental drug for moderately to severely active ulcerative colitis. On the efficacy front, things looked great. The trial enrolled 580 patients who had already responded to induction treatment, and at Week 44, both the 25 mg and 50 mg doses hit the FDA's primary endpoint of clinical remission. Remission rates were 50.8% and 51.3%, respectively, compared to just 10.4% for placebo. That's a placebo-adjusted remission rate of about 40% for both doses — highly statistically significant. The drug also nailed all key secondary endpoints, showing robust disease control across multiple measures.
So why the sell-off? Because the safety data had a few unwelcome guests: cancer cases.
In the 50 mg group, investigators reported one case each of prostate cancer, breast cancer, and colonic dysplasia — that's a 0.5% incidence per event. Non-melanoma skin cancers also popped up: two cases each of basal cell carcinoma and squamous cell carcinoma in the 50 mg group, and one squamous cell carcinoma in the 25 mg group. (For context, one basal cell carcinoma case also appeared in the placebo group.)
Abivax said obefazimod maintained a "favorable safety profile" with "no new safety signals." But Jefferies analysts weren't so sure. According to CNBC, they warned that the cancer cases could weigh heavily on investor sentiment, even if they ultimately turn out to be unrelated to the drug. The safety signal, they said, may remain an overhang — especially since Abivax doesn't have any major value-driving data readouts or catalysts on the horizon for the next year.
The company's next big moment is a New Drug Application (NDA) submission to the FDA, planned for late Q4 2026. That could be a pivotal catalyst, but it's still months away. Until then, the market has to sit with those cancer numbers.
Technically, the stock is feeling the pain. Abivax shares were trading at $90.07, well below their 20-day simple moving average of $122.85 — a 26.7% gap that screams bearish. The MACD indicator is above its signal line, suggesting downside pressure might be easing, but the overall trend remains negative. Key resistance sits at $98.50, while support is at $87.50.
As of premarket Tuesday, the stock was down 35.25% at $83.97. For a biotech with a promising drug but a cloud of safety concerns, it's a reminder that in this business, efficacy alone doesn't always carry the day.
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