ALTIMMUNE INC

Altimmune, Inc. is a late clinical-stage biopharmaceutical company developing novel therapies for serious liver diseases. Our lead product candidate, pemvidutide (formerly known as ALT-801), is a balanced 1:1 glucagon/GLP-1 dual receptor agonist in development for the treatment of metabolic dysfunction-associated steatohepatitis ("MASH"), alcohol use disorder ("AUD") and alcohol-associated liver disease ("ALD"). We may also pursue additional indications for pemvidutide that leverage its differentiated clinical profile. Except where the context indicates otherwise, references to "we," "us," "our," "Altimmune", or the "Company" refer to the company and its subsidiaries.

We obtained pemvidutide as part of the acquisition Spitfire Pharma Inc., in July of 2019. Pemvidutide was designed as a MASH therapeutic based on the understanding that targeting both metabolic and liver-specific effects could lead to an improved and differentiated candidate. Early work provided compelling preclinical efficacy data obtained from a mouse model of MASH. Following a first-in-human clinical trial where we observed initial signs of weight loss and pronounced liver effects, we evaluated pemvidutide in participants with fatty liver disease, or metabolic-dysfunction associated liver disease (MASLD), where we observed robust reductions in liver fat content and weight loss. These results confirmed the earlier study and paved the way for the biopsy-driven IMPACT Phase 2b trial in MASH. To better characterize the quality of the weight loss and cardiometabolic effects of pemvidutide, the MOMENTUM Phase 2 trial in overweight and obese participants was conducted and showed significant weight loss characterized by relative sparing of lean muscle mass and improvements in serum lipids associated with cardiovascular disease. In addition to the recently completed IMPACT trial, pemvidutide is currently being evaluated in participants with AUD and, separately, ALD. There is evidence that pemvidutide may decrease the craving for alcohol in these individuals, with the added benefit that pemvidutide may reverse the harmful effects that alcohol has on the liver in these patients.

Pemvidutide is a novel, investigational peptide with balanced 1:1 glucagon/GLP-1 dual receptor agonist activity in clinical development for the treatment of MASH, AUD and ALD. We believe pemvidutide is the only glucagon/GLP-1 dual receptor agonist with a balanced 1:1 potency at glucagon and the GLP-1 receptors, in effect placing glucagon activity on an even footing with GLP-1 activity. The activation of glucagon receptors results in direct effects on the liver, including reductions in liver fat, inflammation and fibrosis, whereas the activation of GLP-1 receptors mediates suppression of appetite and reduction of cravings as well as metabolic effects such as weight loss.

As of December 31, 2025, over 700 patients have been exposed to pemvidutide in 8 completed studies and 2 ongoing studies. In clinical trials to date, pemvidutide has demonstrated rapid reductions in liver fat, markers of liver inflammation, and early MASH resolution along with improvements in non-invasive tests ("NITs") such as Enhanced Liver Fibrosis ("ELF") score and Liver Stiffness Measurement ("LSM") demonstrating antifibrotic activity. In addition, pemvidutide has shown clinically meaningful weight loss while exhibiting class-leading lean mass preservation. Pemvidutide has also shown a favorable tolerability and safety profile in clinical trials to date. Based on the clinical data we have accumulated, we believe pemvidutide may be able to address several serious liver diseases, and pemvidutide has received Breakthrough Therapy Designation for MASH from the FDA based on data obtained from IMPACT trial at 24 weeks, indicating it has shown early clinical evidence of substantial improvement over existing therapies.