Etrasimod Granted Orphan Drug Status for EoE

According to a recent news release from biopharmaceutical company Arena Pharmaceuticals, Inc. (“Arena”), the company’s investigational therapy, etrasimod, received Orphan Drug designation from the FDA. Currently, Arena is evaluating etrasimod as a potential treatment for patients with eosinophilic esophagitis (EoE).


So what exactly is etrasimod? According to Arena, etrasimod is:

an investigational, once-daily, oral, selective S1P receptor modulator designed to partially and reversibly reduce lymphocyte levels at sites of inflammation, while maintaining components of immune function.

Currently, researchers are evaluating etrasimod for EoE in a Phase 2b clinical trial. Approximately 100 patients have enrolled or will enroll. During the trial, researchers seek to understand the safety, efficacy, and tolerability of 1-2mg etrasimod.

Beyond EoE, Arena is exploring the treatment for conditions like ulcerative colitis (UC) and Crohn’s disease. The Orphan Drug designation was granted for EoE. This is especially important as there are currently no FDA-approved EoE treatments. Thus, if etrasimod is approved in the future, it fills an unmet need for patients. 

Altogether, the Orphan Drug designation is granted to drugs or biologics intended to treat Americans with “rare” diseases or conditions. In this case, “rare” refers to any condition which affects under 200,000 Americans. Alongside the designation, Arena also received a variety of benefits and incentives. For example, Orphan Drug designation comes with up to 7 years of market exclusivity (if/when the drug is approved), tax credits, fee waivers, and additional regulatory assistance from the FDA.

Eosinophilic Esophagitis (EoE)

Eosinophilic esophagitis (EoE) is a chronic allergic inflammatory and digestive system disorder which affects the esophagus. Normally, the esophagus helps transfer food or liquid from your mouth to the stomach. But in patients with EoE, a large number of eosinophils (a type of white blood cells) accumulate in the esophagus. Typically, eosinophils fight infection. When they accumulate, such as in EoE, it normally signifies allergens or allergic diseases of some form. Doctors believe that environmental allergens, immune hypersensitivity, and overactive eotaxin-3 gene expression could all play a role in EoE. In fact, an estimated 50% of patients with EoE also have asthma, food allergies, eczema, or seasonal allergies. Other risk factors include being male, being white, or having a family history of EoE.

As the eosinophils build up, these cells cause esophageal inflammation, resulting in EoE symptoms. Symptoms include:

  • Nausea and vomiting
  • Irritability (in infants)
  • Poor weight gain/growth (in infants/children)
  • Unintended weight loss
  • Food regurgitation
  • Heartburn
  • Reflux that does not respond to medicine
  • Difficulty swallowing
  • Appetite loss
  • Malnutrition
  • Stomach and/or chest pain
Jessica Lynn

Jessica Lynn

Jessica Lynn has an educational background in writing and marketing. She firmly believes in the power of writing in amplifying voices, and looks forward to doing so for the rare disease community.

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