Alto Neuroscience Initiates Phase 2 Study of a Novel PDE4 Inhibitor in Cognitive Impairment Associated With Schizophrenia

Alto Neuroscience, Inc. recently announced the initiation of a Phase 2 double-blind, placebo-controlled study of its transdermal formulation of ALTO-101, a novel PDE4 inhibitor in development for the treatment of cognitive impairment associated with schizophrenia (CIAS). Alto expects to report top-line data from the Phase 2 study in the second half of 2025.

“We are excited to initiate our sixth Phase 2 study as a company, across our pipeline programs, as we continue to redefine mental healthcare with Alto’s Precision Psychiatry Platform,” said Amit Etkin, MD, PhD, founder and CEO of Alto Neuroscience. “Cognitive impairment is disabling in many psychiatric disorders including schizophrenia, depression, and neurodegenerative diseases. ALTO-101 has the potential to address the cognitive aspects of these diseases with a known pro-cognitive mechanism, while also overcoming the side effects typically associated with PDE4 inhibitors. We look forward to completing this proof-of-concept study, as we believe ALTO-101 may benefit patients with CIAS and potentially become an important therapeutic option for a broad range of indications.”

Alto recently completed a Phase 1 study of ALTO-101 in healthy adults, demonstrating positive effects on cognition and electroencephalography (EEG) measures relevant to cognitive function. Alto’s novel transdermal formulation of ALTO-101 exhibited greater systemic drug exposure than orally administered ALTO-101 while also demonstrating a reduction in typical class-related adverse events.

The Phase 2 study announced today consists of a cross-over double-blind, placebo-controlled, dose-escalating treatment with ALTO-101 and placebo in patients with CIAS. Alto expects to enroll approximately 70 adult participants between 21-55 years old with schizophrenia and a demonstrable level of cognitive impairment. Alto will evaluate the effects of ALTO-101 on EEG markers relevant to cognitive function and will also explore its effects on cognitive performance. The primary outcome in the study is the effect of ALTO-101 on theta band activity as measured using EEG at the end of each dose period.

Alto recently presented data at the Society of Biological Psychiatry (SOBP) Annual Meeting demonstrating that theta band activity has both the greatest correlation with cognitive function in patients with schizophrenia among a comprehensive set of EEG measures as well as greatest case-control sensitivity. The findings on these measures, which were prospectively replicated, support the suitability of the primary outcome measure being evaluated in the present study to demonstrate robust proof-of-concept of ALTO-101 as a potential treatment for CIAS.

ALTO-101 is a novel small molecule PDE4 inhibitor being developed for cognitive impairment associated with schizophrenia, a disease state defined by negative and cognitive symptoms with no currently available targeted treatments. Through a proprietary transdermal delivery system, ALTO-101 is designed to provide steady state concentrations to improve drug safety, tolerability, and pharmacokinetics. The proprietary transdermal delivery system for ALTO-101 has been developed in partnership with MEDRx. In Phase 1 clinical trials, ALTO-101 demonstrated human brain penetration, robust CNS-relevant pharmacodynamic effects, and was well tolerated across therapeutically relevant dose ranges.

Schizophrenia is a serious, persistent, and often disabling mental illness impacting how a person thinks, feels, and behaves. The illness affects nearly 24 million people worldwide, including 2.8 million people in the United States. It is characterized by multiple symptom domains, including: positive symptoms (hallucinations and delusions), negative symptoms (difficulty enjoying life and withdrawal from others), and cognitive impairment (deficits in memory, concentration, and decision-making). A large proportion of people living with schizophrenia struggle to live independent lives and often rely on life-long caregiver support. Approximately 70% of people with schizophrenia have cognitive impairment associated with the illness, and there are currently no approved treatments to specifically address the negative and cognitive symptoms associated with schizophrenia.

Alto Neuroscience is a clinical-stage biopharmaceutical company with a mission to redefine psychiatry by leveraging neurobiology to develop personalized and highly effective treatment options. Alto’s Precision Psychiatry Platform™ measures brain biomarkers by analyzing EEG activity, neurocognitive assessments, wearable data, and other factors to better identify which patients are more likely to respond to Alto product candidates. Alto’s clinical-stage pipeline includes novel drug candidates in depression, PTSD, schizophrenia, and other mental health conditions. For more information, visit