In the United States, Orphan Drug designation is granted to drugs or biologics intended to treat, diagnose, or prevent rare or life-threatening conditions. A “rare” condition is defined as one affecting fewer than 200,000 people within the United States. As a benefit, drug developers earn incentives such as fee waivers, tax credits, increased regulatory assistance, and seven years of marketing exclusivity upon drug approval. In a late July 2022 news release, biopharmaceutical company Omeros Corporation (“Omeros”) shared that the FDA granted Orphan Drug designation to its therapy OMS906 for paroxysmal nocturnal hemoglobinuria (PNH). 

A Brief Overview of OMS906

So what exactly is OMS906? This humanized monoclonal antibody targets a key activator within the alternative pathway of the complement system: mannan-binding lectin-associated serine protease-3 (MASP-3). The complement system has been implicated in several disease states, and plays a role in inflammatory responses. Omeros explains that:

MASP-3 inhibition does not interfere with the classical complement pathway, a critical component of the acquired immune response to infection.

Preclinical and Phase 1 trial data has found that:

• OMS906 could potentially treat patients while simultaneously decreasing the risk of infection, providing a benefit over other therapies. 
• The treatment seems – so far – to be relatively safe and well-tolerated. It also offers an easier dosing schedule than other PNH-related therapies.

Moving forward, Omeros hopes to launch a number of studies evaluating OMS906 in different indications. For example, one study will evaluate OMS906 for patients with PNH who have not responded well to ravulizumab treatment, while another study will explore the therapy for those with previously-untreated C3 glomerulopathy (C3G) or PNH. 

What is Paroxysmal Nocturnal Hemoglobinuria (PNH)? 

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hematopoietic stem cell disorder characterized by red blood cell destruction (hemolysis) and bone marrow dysfunction. This disorder results from PIGA gene mutations and also affects white blood cells and platelets. These spontaneously acquired mutations cause the immune system to mistakenly attack healthy cells rather than PNH cells. An estimated 30% of PNH diagnoses are caused by aplastic anemia treatment. The median age for diagnosis is 35-40 years old. Symptoms associated with this disorder may include:

• Anemia (low red blood cell count)
• Thrombocytopenia (low platelet count)
• Blood clots
• Fatigue and irritability 
• Chest pain
• Pallor (pale skin)
• Dark or bloody urine, often late at night or in the morning
• Difficulty breathing and/or swallowing
• Male sexual dysfunction
• High heart rate
• Headache
• Abdominal and esophageal spasms
• Kidney disease