Palomar Labs (formerly Negev Labs), a venture studio that builds companies around neuropsychiatric drug development programs with prior human validation, today announced the spinout of Ariadne Bio, Inc., its first portfolio company. Ariadne Bio launches with lead program AB-300, a clinical-stage-ready, non-hallucinogenic serotonin 2A receptor agonist in development for apathy in Parkinson’s disease. The Michael J. Fox Foundation for Parkinson’s Research (MJFF) has awarded Ariadne Bio funding to support a Phase 1b trial of AB-300, expected to begin in the second half of 2026.

The funding was awarded through The Michael J. Fox Foundation’s Parkinson’s Disease Therapeutics Pipeline Program, which supports preclinical and translational research aimed at evaluating promising therapeutic approaches and advancing them toward clinical development.

Apathy, defined clinically as a persistent reduction in goal-directed behavior, affects approximately 40% of people with Parkinson’s disease over the course of the illness, with higher rates reported in mid-to-late stages. Studies of caregiver burden in Parkinson’s consistently rank neuropsychiatric symptoms, including apathy, ahead of motor symptoms as drivers of distress. No therapy is approved specifically for apathy in any indication. Selective serotonin reuptake inhibitors (SSRIs) remain appropriate treatment for depression in Parkinson’s disease, but a growing body of evidence associates them with emotional blunting and worsening apathy.

“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,” said Shlomi Raz, Founder and Chief Executive Officer of Ariadne Bio. “We built Ariadne Bio around a single question: whether motivation can be restored pharmacologically. AB-300 is how we intend to answer it.”

Ariadne Bio is Raz’s second neuropsychiatry company. He founded Eleusis, the first company dedicated to developing medicines derived from psychedelic compounds, which Beckley Psytech acquired in 2022; Beckley Psytech strategically combined with Atai Life Sciences forming AtaiBeckley in 2025, and Eli Lilly announced a definitive agreement to acquire AtaiBeckley on July 16th, 2026. AB-300 reflects the approach he has pursued since: identify compounds with documented prior human exposure and develop them in non-hallucinogenic form for indications with no approved treatment.

At the American Society of Clinical Psychopharmacology (ASCP) annual meeting in May 2026, Ariadne Bio presented data from a preclinical model of tetrabenazine (TBZ)-induced motivational deficit, assessed by progressive-ratio lever pressing. In this widely used model of effort-based motivated behavior, AB-300 plus TBZ increased motivational behavior by 89% relative to the TBZ only group, a statistically significant improvement.

“Apathy is among the most disabling non-motor features of Parkinson’s disease, and no therapy is approved for it. AB-300, a non-hallucinogenic serotonin 2A receptor agonist, restored effort-based responding in a preclinical model characterized by dopamine depletion, with the effect most pronounced in the group showing the greatest baseline deficit. That is consistent with our hypothesis that targeted activation of serotonin 2A receptors within motivational circuits may be differentiated from approaches that broadly elevate serotonin. It also aligns with human PET imaging in untreated Parkinson’s patients, in which apathy severity correlates with serotonergic rather than dopaminergic markers. Together, these data sets provide a strong foundation to advance AB-300 into a Phase 1b in apathy associated with Parkinson’s disease,” said Daniel E. Jeffries, Ph.D., Chief Development Officer of Ariadne Bio.

According to Ariadne Bio, AB-300 is the first serotonin 2A receptor agonist drug candidate shown to restore motivated behavior in a dopamine-depleted model. In off-target screening, AB-300 shows no measurable activity at dopamine receptors or the dopamine transporter, indicating that it engages motivational circuitry through a mechanism independent of dopaminergic signaling.

“Apathy is one of the most challenging and underrecognized symptoms of Parkinson’s disease, affecting not only people living with the disease but also their families,” said Catherine Kopil, Ph.D., Vice President and Head of Clinical Research at The Michael J. Fox Foundation for Parkinson’s Research. “There are currently no approved therapies for Parkinson’s disease-related apathy, making it especially important to evaluate potential treatments directly in this population. The studies supported through this award will help generate the clinical evidence needed to evaluate this therapeutic approach and advance the development of treatments for people living with Parkinson’s disease.”

Ariadne Bio completed a Type B pre-IND meeting with the U.S. Food and Drug Administration in 2026 regarding the development of AB-300 for apathy associated with Parkinson’s disease. The Phase 1b trial will be conducted at clinical sites in Israel and Austria.

About Ariadne Bio

Ariadne Bio, Inc. is a clinical-stage-ready neuropsychiatry company developing AB-300 for apathy in Parkinson’s disease and related conditions of brain aging. The company is headquartered in New York, with clinical operations in Israel and Austria. To learn more, visit www.ariadnebio.com and follow Ariadne Bio on LinkedIn.

About Palomar Labs

Palomar Labs is a brain-health venture builder headquartered in New York, with operations in Vienna. The firm creates and funds companies that develop therapies for the aging brain, identifying overlooked medicines with prior human use and building a category-owning company around each. Palomar Labs was formerly known as Negev Labs. Learn more at palomar-labs.com and follow us on LinkedIn.

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