Ariadne Bio has launched with funding from The Michael J Fox Foundation to advance AB-300, an investigational treatment for apathy associated with Parkinson’s disease.

Drug targets apathy in Parkinson’s disease

Ariadne Bio has been spun out by Palomar Labs to develop AB-300, a non-hallucinogenic serotonin 2A receptor agonist for apathy in Parkinson’s disease.

The Michael J Fox Foundation for Parkinson’s Research has awarded the company funding through its Parkinson’s Disease Therapeutics Pipeline Program to support a Phase 1b clinical trial.

The study is expected to begin in the second half of 2026 at sites in Israel and Austria.

Apathy is characterised by a persistent reduction in goal-directed behaviour and affects approximately 40% of people with Parkinson’s disease over the course of the illness, according to Ariadne Bio. There are currently no approved therapies specifically for apathy in Parkinson’s disease.

AB-300 is designed to activate serotonin 2A receptors without producing hallucinogenic effects. The company is investigating whether this approach can influence motivational circuits without directly targeting the dopaminergic pathways commonly associated with Parkinson’s disease.

The drug remains investigational and has not yet been administered to humans.

Preclinical data support clinical development

Ariadne Bio presented preclinical data at the American Society of Clinical Psychopharmacology annual meeting in May 2026.

The company tested AB-300 in a tetrabenazine-induced model of motivational deficit, using progressive-ratio lever pressing to assess effort-based motivated behaviour.

AB-300 combined with tetrabenazine increased motivated behaviour by 89% compared with the tetrabenazine-only group, with the company reporting a statistically significant improvement.

The effect was most pronounced in the group with the greatest baseline deficit, according to Ariadne Bio.

The company also reported that off-target screening found no measurable activity at dopamine receptors or the dopamine transporter.

Shlomi Raz, founder and CEO of Ariadne Bio, said: “A significant portion of people with Parkinson’s will lose the drive to do the things that make life worth living, and not a single approved medicine is designed to bring it back.”

He added: “We built Ariadne Bio around a single question: whether motivation can be restored pharmacologically. AB-300 is how we intend to answer it.”

The findings are preclinical and do not establish whether AB-300 will improve apathy or be safe in people with Parkinson’s disease.

Phase 1b planned for 2026

Ariadne Bio has completed a Type B pre-investigational new drug meeting with the US Food and Drug Administration regarding development of AB-300 for Parkinson’s disease-related apathy.

The planned Phase 1b programme will provide the first clinical assessment of the drug. The company says the study will initially assess safety and pharmacokinetics before progressing to Parkinson’s disease patients and dose selection.

The controlled part of the programme is intended to assess whether AB-300 produces a measurable signal in apathy alongside functional measures.

The programme is supported by The Michael J Fox Foundation, which funds early-stage Parkinson’s research to generate data that can support subsequent clinical development.

Ariadne Bio is the first portfolio company to be spun out by Palomar Labs, formerly known as Negev Labs. The company was founded by Shlomi Raz, who previously founded Eleusis, a company focused on developing medicines derived from psychedelic compounds.

AB-300 represents a different approach to serotonin 2A receptor drug development, with Ariadne Bio seeking to retain the target’s potential therapeutic effects without the hallucinogenic effects associated with psychedelic compounds.