Neurocrine Biosciences has reported that its investigational therapy NBI-827104 failed to meet its primary endpoint in the Phase II STEAMBOAT clinical trial in paediatric epileptic encephalopathy patients.

The double-blind, randomised, placebo-controlled Phase II trial assessed NBI-827104’s safety, efficacy, tolerability, and pharmacokinetics against a placebo in paediatric patients with epileptic encephalopathy with continuous spike-and-wave (EE-CSWS) during sleep.

In the trial, the potent, selective, and orally active brain-penetrating T-type calcium channel blocker (Cav 3.1, Cav 3.2, Cav 3.3) NBI-827104 was found to be generally well tolerated.

The STEAMBOAT trial evaluated NBI-827104 when given once a day for up to 13 weeks in paediatric patients with EE-CSWS, a rare paediatric developmental and/or epileptic encephalopathy.

Reduction from baseline against placebo in the ratio of spike-wave index (SWI) when measured following six weeks of study treatment was the trial’s primary endpoint.

The SWI is a measure of the percentage of sleep affected by epileptic activity in patients.

During the first hour of non-rapid eye movement (NREM) sleep, it was measured in the Phase II trial by independent and centralised readings of overnight video-electroencephalograms (EEGs).

Neurocrine Biosciences chief medical officer Eiry Roberts said: “While we did not meet the primary endpoint for this Phase II study, we remain committed to advancing care for patients living with epilepsy, including rare paediatric forms.

“We will continue to analyse the rich data set generated from this study to determine next steps. We are grateful to everyone involved in the study, especially our study participants, their families, and our investigators.”

The international rights to NBI-827104, which is in development for the potential EE-CSWS treatment, were acquired by Neurocrine from Idorsia in May 2020.

In October this year, Neurocrine randomised the first subject in its Phase II clinical trial of NBI-1117568 in adult schizophrenia patients.