Catalyst Will Seek FDA Approval of Firdapse for Children

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by Margarida Maia PhD |

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Catalyst Pharmaceuticals plans to file an application with the U.S. Food and Drug Administration (FDA) requesting that the use of Firdapse (amifampridine), an approved oral therapy for adults with Lambert-Eaton myasthenic syndrome (LEMS), be expanded to children.

The announcement came after the company received a favorable decision from a federal appeals court in its appeal to reverse the FDA’s approval of Ruzurgi (amifampridine) — a therapy similar to Firdapse and approved for children, ages 6–16, with LEMS.

According to the company, Ruzurgi’s approval should not have been granted because it violated Catalyst’s rights to orphan drug exclusivity, which entitled the company to exclusively market Firdapse for a period of seven years in the U.S.

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In its third quarter financial update, Catalyst also announced record net sales for Firdapse. Therapy sales amounted to $35.9 million, representing a 6.7% increase compared with this year’s second quarter and a 23.1% increase compared with the third quarter of 2020.

“We reported a record quarter for net sales for Firdapse, further underscoring the strength of our commercial capabilities while advancing our efforts in support of the orphan drug exclusivity of Firdapse for the treatment of LEMS,” Patrick J. McEnany, chairman and CEO of Catalyst, said in a press release.

“We continued to execute on all key growth initiatives, including plans to expand the label for Firdapse to include all LEMS patients, including the very few pediatric patients diagnosed with LEMS,” added McEnany.

Catalyst holds the licensing rights for Firdapse in the U.S. and Japan, where it has teamed up with DyDo Pharma. As part of their collaboration to develop and market Firdapse, the companies are planning to start a small clinical trial in early 2022 that is designed to obtain sufficient data to support the therapy’s approval in the country.

At the same time, Catalyst continues to work on a long-acting candidate formulation of amifampridine for the treatment of LEMS. The company also expanded its portfolio of intellectual property rights by publishing a second patent that extends the intellectual property over Firdapse to 2034, with more patents pending.

“Our quarterly achievements demonstrate continued performance excellence supported by several key strategic decisions that have positioned Catalyst firmly for the future,” said McEnany. “In saying that, we are excited about the path ahead as we continue to execute across all fronts to drive sustainable growth for the long term.”

After falling short in a Phase 3 clinical trial (NCT03304054) that aimed to evaluate the efficacy and safety of Firdapse in patients with myasthenia gravis (MG) harboring antibodies against muscle-specific kinase (MuSK), Catalyst decided to end the development program. However, patients with MuSK-MG who are currently on Firdapse will continue receiving support to treat their symptoms through investigator-initiated programs, as per FDA regulations.