From securing research funding to recruiting enough participants, rare diseases can be challenging to study as they affect just a small percentage of the population.
There is no single definition or threshold for what constitutes a rare disease. In the United States, for example, a rare disease is defined as one that affects fewer than 200,000 people. In Japan, a rare disease is one that affects fewer than 50,000 people. In Brazil, a rare disease is defined as a ratio that affects 65 per 100,000 people.
To raise awareness of rare diseases, Canada, the US, India, and many European countries recognize the last day of February as Rare Disease Day. Since 2024 is a leap year, Rare Disease Day falls on a rare date: February 29.
EGPA
Eosinophilic granulomatosis with polyangiitis (EGPA), also known as Churg-Strauss Syndrome, is a rare autoimmune disease caused by inflammation of small and medium sized blood vessels. This can lead to damage of the lungs, skin, heart, gastrointestinal tract, and nerves. Most patients with EGPA experience breathing and lung issues.
Recently, an international team that included researchers from St. Joseph’s Healthcare Hamilton and McMaster University published their findings on a novel therapeutic for EGPA – a biologic drug called benralizumab. The study was published in the New England Journal of Medicine.
The team conducted a clinical trial of over 140 patients from around the world with this rare disease. They directly compared two biologic drugs: mepolizumab, which is currently approved by the FDA to treat EGPA, and benralizumab.
“Our findings show that benralizumab was just as effective as mepolizumab at reducing exacerbations and providing disease remission during the 52 weeks of the study,” says Dr. Parameswaran Nair, a respirologist at the Firestone Institute for Respiratory Health and professor with McMaster’s Department of Medicine.
Dr. Nair led the Canadian team as one of the principal investigators of the study. He worked closely with Dr. Nader Khalidi, a St. Joe’s rheumatologist and professor with McMaster’s Department of Medicine, to design the study and recruit patients.
Dr. Nair is a respirologist at St. Joe's who conducts research on severe eosinophilic diseases.
“The single 30mg subcutaneous dosing of benralizumab offers an advantage to patients over the three 100mg subcutaneous dosing of mepolizumab,” says Dr. Nair.
The researchers also noted that approximately 16 percent more patients in the benralizumab group were able to abstain from using oral corticosteroids compared to the mepolizumab group. Typically, patients with EGPA use oral corticosteroids like prednisone for symptom control despite the adverse effects.
“Without biologics, we’re relying predominantly on oral corticosteroids to control EGPA symptoms. Prolonged treatment with prednisone reduces the risk of a relapse of EGPA symptoms, but it comes with progressive toxic effects,” says Dr. Khalidi. “In our study, treatment with benralizumab allowed more patients to discontinue prednisone over a 52 week period compared to mepolizumab.”
Dr. Khalidi with a patient in his clinic at St. Joe's.
The study builds on a long history of research on eosinophilic conditions and biologic drugs from the Firestone Institute for Respiratory Health at St. Joe’s.
Pioneering work into the study of severe eosinophilic asthma by Dr. Freddy Hargreave led to a method for enumerating eosinophils in sputum samples for accurate asthma diagnoses.
For patients with severe prednisone-dependent asthma, Drs. Hargreave, Nair, and their colleagues were the first to demonstrate the efficacy of mepolizumab in 2009. By 2017, Dr. Nair had further demonstrated the efficacy of benralizumab for the same condition. Both landmark studies were published in the New England Journal of Medicine.
Now, through the efforts of Dr. Nair and Dr. Khalidi, St. Joe’s was able to recruit the highest number of EGPA patients for the clinical trial compared to the other participating centres. Their findings will undoubtedly affect the choice of biologic drug used to treat EGPA in current and future patients.
“It is very gratifying that our research program at the Firestone Institute at St. Joe’s has led to the development of these new treatment options for patients with severe eosinophilic disease,” says Dr. Nair.
Funding for this study was provided by AstraZeneca.
Related: Researchers Identify New Choice of Therapy for Rare Autoimmune Disease EGPA (Media Release)