LOS ANGELES – Tuesday's plenary session at the American Academy of Neurology annual meeting was dedicated to clinical trials, with researchers reporting progress in treating diseases including the common such as stroke and traumatic brain injury, and the rare such as hereditary transthyretin-mediated amyloidosis and lysosomal storage disorder CLN2.

The "abstract of distinction" award went to the presentation, titled "A Randomized, Placebo-Controlled Phase 3 Study of the Safety and Efficacy of Solriamfetol (JZP-110) for the Treatment of Excessive Sleepiness (ES) in Participants with Narcolepsy Types 1 and 2 (NT1/2)."

Narcolepsy, a dysregulation of the sleep-wake cycle, is a relatively rare disorder. The Clarivate Analytics Incidence & Prevalence Database shows it affects fewer than 200,000 individuals in the U.S.

It is a chronic condition that starts early, with a median age of onset of around 16.

The median age at diagnosis, however, is closer to 30, meaning that "many patients have a great deal of disability for many years of their life" before they are treated, presenter Michael Thorpy, director of the Sleep-Wake Disorders Center at the Montefiore Medical Center, told the audience.

Developer Jazz Pharmaceuticals plc is developing solriamfetol (Jzp-100) to potentially bring those individuals some relief. The company filed for approval of the drug for the treatment of excessive sleepiness in narcolepsy or obstructive sleep apnea in March.

Insofar as the general public knows about narcolepsy at all – in one study, only half of individuals had heard of narcolepsy, and of those, only half felt they could explain what it was, making it likely that narcolepsy is underdiagnosed – the most likely image is of a person who suddenly falls asleep in the middle of an animated conversation.

Though it has provided for comedic fodder in more than one Hollywood movie, that image is incorrect on several fronts.

Only about half of individuals with narcolepsy can have paradoxical responses to arousal, a symptom called cataplexy. And cataplexy is a form of paralysis, rather than sleep, though some individuals do fall asleep after a cataplexy attack.

The key features of narcolepsy, though, are excessive sleepiness, a propensity to fall asleep, and impaired wakefulness.

In his talk, Thorpy reported that in a 12-week double-blind parallel group study, the two higher doses of solriamfetol tested improved maintenance of wakefulness within a week, an effect that lasted for the duration of the study. All three doses also reduced sleepiness in trial participants, and all doses improved patients' self-reported perceptions of their state, with more than 80 percent of patients in the highest two doses reporting an improvement in global state.

Like so many drugs, solriamfetol started out in one indication and ended in another. It affects the uptake of dopamine and norepinephrine, though it is a phenylalanine derivative rather than an amphetamine. It was originally studied for the treatment of depression, where it did not pan out. But during those trials, investigators noticed it had wake-promoting activity.

While narcolepsy's core feature is excessive sleepiness, many neurological disorders, including such giants as Parkinson's disease, include excessive sleepiness as one of their symptoms.

Thorpy said that "the wake-promoting effect [of solriamfetol] seems fairly nonspecific," meaning that the drug could work in other indications besides narcolepsy and obstructive sleep apnea.