The Food and Drug Administration (FDA) has granted Orphan Drug designation to AMB-301 for the treatment of Buerger disease, also known as thromboangiitis obliterans.

Buerger disease is characterized by narrowing or occlusion of the veins and arteries of the extremities, resulting in peripheral vascular disease. In severe cases, it may lead to limb damage and amputation. The disease typically affects young or middle aged male cigarette smokers.

AMB-301 is an investigational gene therapy vector encoding a cell adhesion molecule, E-selectin. By delivering E-selectin to damaged blood vessels, the treatment is expected to enhance blood vessel formation, restore tissue integrity, and improve limb function.

“Should clinical testing be successful, we believe our first-in-class gene therapy platform will provide new treatment options to patients suffering from [Buerger disease] and potentially other vascular diseases, said Robert L. Buchanan, CEO of Ambulero, Inc. “The Orphan Drug designation should also help expedite our [Buerger disease] clinical trial timeline.”

The FDA’s Orphan Drug designation is granted to medicines intended to treat or prevent rare diseases or disorders that affect fewer than 200,000 individuals. There are approximately 50,000 people in the US with Buerger disease.


  1. Ambulero’s gene therapy candidate AMB-301 granted US Orphan Drug designation for treatment of severe vascular disease. News release. Ambulero Inc. Accessed October 19, 2021.
  2. Buerger’s Disease. National Organization for Rare Disorders. Accessed October 19, 2021.