PTC’s Vatiquinone Fails Second Trial in as Many Months

Pictured: MRI scan of human brain/iStock, Nur Ceren Demir

PTC Therapeutics’ investigational drug vatiquinone missed its primary endpoint in the MIT-E trial, failing to decrease observable motor seizure episodes in patients with mitochondrial disease-associated seizures, the company announced Thursday.

The news comes more than a month after PTC reported that vatiquinone likewise fell short of its primary efficacy bar in the MOVE-FA study of Friedrich’s ataxia (FA) patients. The same day, the company launched a restructuring and pipeline prioritization initiative that involved the discontinuation of several early-stage assets and an 8% headcount reduction.

MIT-E is a randomized, double-blinded and placebo-controlled Phase II/III study that enrolled 68 children with genetically confirmed mitochondrial disease-associated seizures (MDAS). The first 24 weeks of the trial was a placebo-controlled phase, which was followed by a 48-week open-label phase. Vatiquinone was given orally three times a day.

The study’s primary endpoint was a drop in observable motor seizures in the first 24 weeks of the study. While vatiquinone failed to significantly distinguish itself from placebo in this regard, PTC observed “evidence of treatment effect” in decreasing the frequency of seizures in the overall study population and in children with Leigh syndrome.

Vatiquinone also reduced status epilepticus and disease-related hospitalizations in this Leigh syndrome subgroup.

Still, despite these benefits, the results from MIT-E “do not support the advancement of vatiquinone for the treatment of MDAS,” according to PTC’s announcement.

The company will continue to engage with the FDA and figure out a regulatory path forward for vatiquinone in FA. PTC CEO Matthew Klein said during an investor call last month that the candidate still induced significant improvements in patients’ bulbar and upright stability, while a sub-analysis also demonstrated significant benefits in fatigue.

These signals of efficacy, along with a good tolerability profile and the unmet medical need in the FA space, will help PTC build its regulatory case with the FDA, Klein said.

PTC has reported positive trial outcomes beyond vatiquinone. Last week, the company revealed interim data from its Phase II PIVOT-HD trial in Huntington’s disease, showing that its candidate PTC518 could reduce mutant huntingin levels by 30%. Treatment with the investigational oral, small molecule drug did not lead to an increase in cerebrospinal fluid levels of the neurofilament light chain protein.

In May 2023, a week before vatiquinone’s failure in MOVE-FA, PTC notched a win in phenylketonuria, with its investigational drug sepiapterin reducing blood phenylalanine levels by 63% in the APHENITY trial.

Tristan Manalac is an independent science writer based in metro Manila, Philippines. He can be reached at [email protected] or [email protected].

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