The U.S. Food and Drug Administration(FDA) expanded the approved use of Nucala (mepolizumab) to treat adult patients with eosinophilic granulomatosis with polyangiitis (EGPA), a rare autoimmune disease that causes vasculitis, an inflammation in the wall of blood vessels of the body. This new indication provides the first FDA-approved therapy specifically to treat EGPA.

According to the National Institutes of Health, EGPA (formerly known as Churg-Strauss syndrome) is a condition characterized by asthma, high levels of eosinophils (a type of white blood cell that helps fight infection), and inflammation of small- to medium-sized blood vessels. The inflamed vessels can affect various organ systems including the lungs, gastrointestinal tract, skin, heart and nervous system. It is estimated that approximately 0.11 to 2.66 new cases per 1 million people are diagnosed each year, with an overall prevalence of 10.7 to 14 per 1,000,000 adults.

"Prior to today's action, patients with this challenging, rare disease did not have an FDA-approved treatment option," said Badrul Chowdhury, M.D., Ph.D., director of the Division of Pulmonary, Allergy, and Rheumatology Products in the FDA's Center for Drug Evaluation and Research. "The expanded indication of Nucala meets a critical, unmet need for EGPA patients. It's notable that patients taking Nucala in clinical trials reported a significant improvement in their symptoms."

The FDA granted this application Priority Review and Orphan Drug designations. Orphan Drug designation provides incentives to assist and encourage the development of drugs for rare diseases.

Nucala was previously approved in 2015 to treat patients age 12 years and older with a specific subgroup of asthma (severe asthma with an eosinophilic phenotype) despite receiving their current asthma medicines. Nucala is an interleukin-5 antagonist monoclonal antibody (IgG1 kappa) produced by recombinant DNA technology in Chinese hamster ovary cells.

Nucala is administered once every four weeks by subcutaneous injection by a health care professional into the upper arm, thigh, or abdomen.

The safety and efficacy of Nucala was based on data from a 52-week treatment clinical trial that compared Nucala to placebo. Patients received 300 milligrams (mg) of Nucala or placebo administered subcutaneously once every four weeks while continuing their stable daily oral corticosteroids (OCS) therapy. Starting at week four, OCS was tapered during the treatment period. The primary efficacy assessment in the trial measured Nucala's treatment impact on disease remission (i.e., becoming symptom free) while on an OCS dose less than or equal to 4 mg of prednisone. Patients receiving 300 mg of Nucala achieved a significantly greater accrued time in remission compared with placebo. A significantly higher proportion of patients receiving 300 mg of Nucala achieved remission at both week 36 and week 48 compared with placebo. In addition, significantly more patients who received 300 mg of Nucala achieved remission within the first 24 weeks and remained in remission for the remainder of the 52-week study treatment period compared with patients who received the placebo.

The most common adverse reactions associated with Nucala in clinical trials included headache, injection site reaction, back pain, and fatigue.

Nucala should not be administered to patients with a history of hypersensitivity to mepolizumab or one of its ingredients. It should not be used to treat acute bronchospasm or status asthmaticus. Hypersensitivity reactions, including anaphylaxis, angioedema, bronchospasm, hypotension, urticaria, rash, have occurred. Patients should discontinue treatment in the event of a hypersensitivity reaction. Patients should not discontinue systemic or inhaled corticosteroids abruptly upon beginning treatment with Nucala. Instead, patients should decrease corticosteroids gradually, if appropriate.

Health care providers should treat patients with pre-existing helminth infections before treating with Nucala because it is unknown if Nucala would affect patients' responses against parasitic infections. In addition, herpes zoster infections have occurred in patients receiving Nucala. Health care providers should consider vaccination if medically appropriate.