VANCOUVER, British Columbia — A drug class already routinely prescribed to cancer patients may also prove useful in the treatment of muscular dystrophy, according to researchers from the University of British Columbia.
The drug in question is a colony-stimulating factor 1 receptor inhibitor, or CSF1R inhibitor for short. Study authors report the drug helped slow the progress of Duchenne muscular dystrophy among a group of lab mice. The drug appeared to accomplish this feat by increasing the resiliency of their muscle fibers.
“This is a class of drug that is already being used in clinical trials to treat rare forms of cancer,” says first study author Dr. Farshad Babaeijandaghi, a postdoctoral fellow at UBC, in a university release. “To find that it could potentially serve a double purpose as a treatment for muscular dystrophy is incredibly exciting. It shows a lot of promise, and with further testing, could help extend and improve quality of life for patients.”
What is Duchenne muscular dystrophy?
DMD is a severe genetic disorder causing progressive muscle weakness and degeneration sparked by disruptions to the protein dystrophin. Normally, that protein helps keep muscle cells intact.
It’s common for initial DMD symptoms to show themselves during early childhood, with patients experiencing increased loss of muscle function as they grow older. As DMD worsens over time, numerous patients end up using mobility aids like wheelchairs to function on a day-to-day basis. Eventually, the disease effects both heart and lung functioning as well.
Modern medicine has seen the average life expectancy for a DMD patient improve in recent decades, but there is still no cure for DMD.
“Muscular dystrophy is a devastating disease that impacts children at a young age. While this is not a cure, it could significantly delay disease progression, helping people stay mobile and out of wheelchairs for longer,” notes senior study author Dr. Fabio Rossi, a professor at UBC’s school of biomedical engineering and department of medical genetics. “It could be used in conjunction with other treatments and emerging gene therapy approaches aimed at the genetic defect.”
‘The improvement in muscle resiliency was profound’
The findings surprised the study authors, who originally set out to examine the role of resident macrophages (a variety of white blood cell) in the regeneration of muscle tissues.
Experiments with mice showed that CSF1R inhibitors, which can deplete resident macrophages, resulted in muscle fibers actually becoming more resistant to the type of contraction-induced tissue damage due to DMD. The drug appears to change the type of muscle fibers in the rodents’ bodies from damage-sensitive type IIB fibers to more damage-resistant type IIA/IIX fibers.
“Many people will have heard that there are different types of muscle fibers, including fast-twitch and slow-twitch muscles. By administering this drug, we observed that the muscle fibers actually started to transition to a slower-twitch type that is more resistant to damage caused by muscle contractions,” Dr. Rossi explains.
After that discovery, researchers decided to test the drug on mice with DMD. Rodents given the drug displayed higher frequencies of damage-resistant muscle fibers and were able to perform physical tasks (running moderately on a treadmill) while incurring less muscle damage than other mice not given the drug.
“The results were actually quite dramatic. The improvement in muscle resiliency was profound,” Dr. Babaeijandaghi adds.
Moving forward, more research is necessary to clarify if CSF1R can treat DMD in humans. Still, this initial work is very promising – and numerous short-term clinical studies have already indicated that the drug is safe for use in humans.
“Developing a new drug can be a long process,” Dr. Rossi concludes. “But with the safety profile for this drug already being proven in human studies, it could mean we’re on a fast track to a new treatment for muscular dystrophy.”
The findings appear in the journal Science Translational Medicine.