A precision strike against rare muscle diseases

A clinical trial at The Neuro hopes a targeted antibody therapy will control autoimmune conditions with fewer side effects

February 05, 2026  |  by Sophie Lorenzo

“Steroids are like a hammer: they knock out many aspects of the immune system and their long-term use has many unwanted side effects,” explains Erin O’Ferrall, MD, a neurologist at The Neuro (Montreal Neurological Institute-Hospital). “New treatments for autoimmune diseases, like the one in this clinical trial, are more like a chisel: these are much more precise tools.”

O’Ferrall is the principal investigator for a new clinical trial at The Neuro’s Clinical Research Unit that hopes to use a precision treatment to stop 2 rare muscle diseases: immune-mediated necrotizing myopathy (IMNM), and dermatomyositis.

Targeting the complement system

In these diseases, part of the immune system known as the complement system — proteins which tag pathogens for destruction or cells for repair — become misdirected and attack an individual’s own muscles.

The treatment being tested is a monoclonal antibody therapy. This protein is made to mimic our natural antibodies, but it is designed to bind to the C1 complement and stop it in turn from targeting and destroying muscle.

Living with a rare disease

IMNM, and dermatomyositis are rare conditions that primarily affect the proximal muscles — those closest to the centre of the body. The onset of these conditions is relatively quick and can develop at any age. Because they are autoimmune diseases, they don’t only impact muscles, but can also affect organs like the lungs, heart and skin, and they can affect people over their entire lifetime.  

“Previously healthy patients arrive at their doctor’s office because in the course of just a few weeks they have developed difficulty standing up, walking upstairs, or raising their arms overhead. They may also have trouble swallowing and breathing, which can be quite scary,” explains O’Ferrall.

Like multiple sclerosis, these diseases tend to fluctuate between attacks (“relapses”) and periods of stability. Some individuals have a mild form with few symptoms progressing over many years; but for others with severe forms, it can take years to get the condition under control. 

“The standard of care for these diseases is steroids and other immune suppressant treatments. And those treatments have a lot of side effects: your blood pressure might go up, you can gain weight, develop diabetes, or cataracts, and you may lose bone mass,” explains O’Ferrall.

Hope for orphan conditions

The Quebec Ministry of Health and Social Services estimates that approximately 700,000 Quebecers are living with or carriers of a rare disease. These are also known as “orphan” diseases because they often lack specialized care or effective treatment due to the small number of people affected by each disease in any given area.

The clinical trial starting at the Neuro CRU will group together several muscle diseases that have an immune component into a single clinical trial to test this promising approach.

“This is very exciting: it’s rare that we have the opportunity to have a randomized controlled trial for these uncommon conditions. By studying the treatment across multiple diseases, we can get answers faster. And if this is successful, we can get the treatment out to people sooner,” concludes O’Ferrall.

For information about neuromuscular trials at The Neuro, visit cru.mcgill.ca/nm or contact nm.neurocru@mcgill.ca, (514) 398-5500.