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Catalyst dives as FDA approves rival’s rare disease drug

  • The Food and Drug Administration has approved a rare disease drug from family-owned Jacobus Pharmaceutical, a decision that could present a competitive threat to Catalyst Pharmaceuticals.
  • Jacobus’ Ruzurgi is now cleared for patients aged 6 to 16 with LEMS, or Lambert-Eaton myasthenic syndrome, a condition in which the immune system impairs signaling between nerve and muscle cells, leading to muscle weakness. Catalyst also recently received an FDA OK for a LEMS therapy, Firdapse, but in adults.
  • While the two drugs are approved for different age ranges, an apparent concern for Catalyst investors is whether Ruzurgi will be used off-label. Additionally, the CEO of Jacobus told STAT her company intends to price Ruzurgi lower than Firdapse, which carries a wholesale acquisition cost of $375,000. Catalyst shares were down nearly 40% to $3.75 apiece Tuesday morning.

Jacobus had for years offered amifampridine, the active ingredient in Ruzurgi, free to adult LEMS patients in the U.S. through a compassionate use program. But the practice got derailed by approval of Firdapse —? which also has amifampridine as its active ingredient, just in a different salt form.

Because of its Orphan Drug Designation, Firdapse received seven years of marketing exclusivity for the adult LEMS indication. Jacobus has therefore been unable to market its drug to those patients for the past several months.

Securing approval in the pediatric setting gives Jacobus a small foothold to gain back some ground. Cantor Fitzgerald, a financial services firm, estimates that less than 5% of the 3,000 LEMS patients in the U.S. are pediatric.

Jacobus could see revenue stream in from adult patients, however, should doctors choose to prescribe them Ruzurgi.

“While this is a different label indication than Firdapse’s adult LEMS label, it will no doubt raise questions around whether Ruzurgi will be used off-label in adult patients and whether Firdapse will be able to maintain the orphan drug price point it set at launch,” wrote Piper Jaffray analyst Joseph Catanzaro in a May 6 note.

“However, we suspect that there will be legal questions around whether the approval of Ruzurgi infringes on Firdapse’s orphan drug exclusivity in LEMS,” Catanzaro added.

Notably, the FDA approved Ruzurgi based on efficacy data from a study of 32 adult LEMS patients.

Catalyst’s decision to price Firdapse high, particularly after years of Jacobus offering the drug for free, spurred criticism and scrutiny of the biotech — a wild card that could also shape the reception for Ruzurgi.

Analysts, however, appeared less concerned. 

Charles Duncan of Cantor Fitzgerald argues that the lack of “substantive published pediatric safety studies” for Ruzurgi, in contrast with the two Phase 3 clinical trials and expanded patient access for Firdapse, keeps Catalyst in a strong market position.

“We do not believe it is a slippery slope for Catalyst and Firdapse, as the company has already gained traction with a prescriber and patient base, despite only one quarter into its post-approval launch,” Duncan wrote in a note to Catalyst investors.

“Also, we see the two labels as clearly distinguished and therefore, should there be efforts to capture adult market share made for Ruzurgi, then the label would be violated,” he wrote.