Firdapse Approved in Canada to Treat People With LEMS

Health Canada has approved the use of oral Firdapse (amifampridine) to treat people with Lambert-Eaton myasthenic syndrome (LEMS).

Catalyst Pharmaceuticals‘ request for Firdapse’s approval in Canada was assigned priority review. The oral therapy (given in 10 mg tablets) is already available for adults in the U.S., the European Union, and elsewhere.

“At Catalyst, we are dedicated to changing the lives of patients suffering from rare neuromuscular diseases, and we are proud that we have brought forward an approved therapeutic option for patients in Canada suffering with LEMS. We anticipate continuing to interact with Health Canada as we try to expand the Firdapse label to include other indications,” Gary Ingenito, MD, PhD, Catalyst’s chief medical and regulatory officer, said in a press release.

The company is in discussion with a distribution partner to bring Firdapse to patients in the country “as rapidly as possible,” an executive said.

Firdapse’s application included safety and efficacy data from two completed Phase 3 clinical trials in adults with LEMS, NCT01377922 and NCT02970162.

Results showed statistically significant improvements in several measures of neurological function, such as the Quantitative Myasthenia Gravis score and compound muscle action potential, both of which are clinically relevant to people with this disease.

LEMS is caused by the production of autoantibodies — immune proteins that mistakenly target the body’s own tissues or organs — against voltage-gated calcium channels (VGCC) located at the end of nerve cells. These channels normally allow nerve cells to take up calcium, needed for the release of acetylcholine, which is a chemical messenger that induces muscle contraction by helping nerve cells communicate with muscles.

Firdapse is a small-molecule therapy that blocks another channel, called the voltage-dependent potassium channel, opening remaining VGCCs to allow calcium ions to enter nerve cells. The treatment is currently the only oral medication available for LEMS patients ages 17 and older. 

Under the Canadian public health system, each province and territory has its own insurance plan. Coverage of prescription medications varies among them, as each sets its particular plan.

Despite concerns that the ongoing COVID-19 pandemic might disrupt Catalyst’s ability to provide patients in North America with Firdapse, the company stated it has experienced no known supply chain disruptions. It maintains that its North American inventory will last through at least June 2021.