Long-term study finds no new safety concerns with Dravet therapy

No new or unexpected safety issues were identified in a long-term study that tracked outcomes in people with Dravet syndrome taking the antiseizure medication Fintepla (fenfluramine).

Of 265 people with Dravet syndrome, only about one in 10 experienced a side effect that investigators judged to be related to Fintepla, and only one experienced a serious treatment-related side effect. The researchers concluded that Fintepla “had a low discontinuation rate, was associated with prolonged treatment exposure, and was well tolerated.”

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The study, “Prolonged fenfluramine use in open-label studies of Dravet or Lennox–Gastaut syndromes: Long-term safety, tolerability, patient global functioning, and considerations for interpreting effectiveness,” was published in Epilepsia. The work was funded by UCB, the company that sells Fintepla.

Dravet syndrome is a genetic disorder marked by seizures. Fintepla is an oral therapy approved in the U.S. and elsewhere to treat seizures associated with Dravet syndrome in patients ages 2 and older. The therapy is also approved to treat seizures associated with Lennox-Gastaut syndrome (LGS) in patients ages 2 and older. LGS is another severe form of epilepsy.

The new study reported results from a Phase 3 open-label extension study (NCT03936777) in which people with Dravet or LGS who had participated in earlier open-label studies of Fintepla continued long-term treatment with the oral therapy. The main goal was to monitor the therapy’s long-term safety and tolerability. Across all participants, the median treatment duration in the extension study was nearly two years, and the median total exposure, including the earlier studies, was about four years.

“Due to the lifelong nature of [Dravet and LGS], evaluation of long-term tolerability and safety of therapies is important to clinicians and patients with [Dravet] or LGS and their families,” the researchers noted.

The study included 265 people with Dravet, including 193 children and 72 adults. Most reported at least one adverse event, but the vast majority of patients did not experience one that investigators judged to be related to Fintepla. Nasopharyngitis, often called the common cold, was among the most commonly reported adverse events. Treatment-related side effects were reported in 10.4% of children and 12.5% of adults with Dravet syndrome.

A serious side effect judged to be related to Fintepla was reported in one adult with Dravet syndrome. The researchers did not specify what the side effect was.

No Dravet patients withdrew because of side effects

Over the course of the extension study, none of the Dravet patients withdrew because of side effects. Four children withdrew because of a perceived lack of effectiveness, and three patients withdrew by choice or for an unspecified reason. One Dravet patient died during the study, but investigators judged the death unrelated to Fintepla.

At the last study visit, caregivers and investigators rated patients’ overall functioning compared with the beginning of the extension study, when patients were already taking Fintepla. Nearly all patients with Dravet were rated as improved or unchanged.

“Because patients entered this [open-label extension] study already receiving [Fintepla] from a previous [Fintepla] study, [ratings] by caregiver and investigator of ‘improved or no change’ from baseline of this study should be interpreted as reassuring and positive,” the researchers said.

Overall functioning findings among patients with LGS were broadly similar to those seen in patients with Dravet, and no new or unexpected safety signals were identified in either group.

Overall, the researchers concluded that “these data confirm the favorable risk/benefit profile of [Fintepla] in pediatric and adult patients with [Dravet] or LGS, adding to the growing body of evidence that [Fintepla] results in sustained, stable, or further improved outcomes over extended periods of time for patients with these [conditions].”