Altimmune Inc. (ALT) delivered some encouraging news Friday, releasing 48-week topline data from its IMPACT Phase 2b trial testing pemvidutide in patients with metabolic dysfunction-associated steatohepatitis, commonly known as MASH. If you're wondering what MASH is, think of it as a liver disease where excess fat accumulates in the liver (the technical term is steatosis), accompanied by inflammation and damage to liver cells.

The headline here is durability. The 48-week results showed that pemvidutide achieved statistically significant improvements across multiple treatment arms in critical noninvasive tests, including Enhanced Liver Fibrosis and Liver Stiffness Measurement, when stacked up against placebo. Even better, the data demonstrated continued reductions from the 24-week mark, showing sustained antifibrotic activity with both dose levels tested.

These markers matter because they're well-established indicators of fibrosis and hepatic inflammation, strongly correlated with actual histological changes and real-world liver-related events.

Weight Loss Without The Plateau

On the weight loss front, participants receiving pemvidutide at 1.2 mg and 1.8 mg doses achieved weight reductions of 4.5% and 7.5%, respectively, compared to just 0.2% in the placebo group. Notably, there was no plateauing observed at 48 weeks with the higher 1.8 mg dose, suggesting the weight loss trajectory could continue.

Beyond weight, pemvidutide-treated participants saw statistically significant improvements in key noninvasive measures of liver health and hepatic inflammation. For liver fat content specifically, the 1.2 mg and 1.8 mg doses produced mean reductions from baseline of 45.2% and 54.7% respectively, compared to a modest 8.2% in placebo recipients.

Tolerability That Actually Beats Placebo

Here's something you don't see every day: the 48-week data maintained the favorable tolerability profile observed at 24 weeks, including a lower discontinuation rate due to adverse events than placebo itself. Adverse events leading to treatment discontinuation occurred in 0% and 1.2% of patients on pemvidutide 1.2 mg and 1.8 mg, respectively, versus 3.5% of participants on placebo. When your drug causes fewer people to quit than sugar pills, that's a good sign.

FDA Alignment And AI Integration

Altimmune also disclosed it held a productive End-of-Phase 2 meeting with the U.S. Food and Drug Administration, resulting in alignment on parameters for a registrational Phase 3 trial of pemvidutide for MASH patients with moderate to advanced liver fibrosis. The FDA was receptive to the company's plan to integrate AIM-MASH AI Assist into the Phase 3 trial, following the Agency's recent qualification of this AI tool. The technology is designed to help standardize histologic assessment and reduce the time and resources required for MASH drug development.

According to CEO Vipin Garg, pemvidutide will advance to a Phase 3 program in 2026.

Price Action: ALT stock closed down 21.19% to $3.98 on Friday.