PaxMedica Presents Clinical Data and New Analyses from a Phase 2 Trial of PAX-101 (IV suramin) in Children with Autism Spectrum Disorder (ASD) at the 2021 American Academy of Child and Adolescent Psychiatry (AACAP) Annual Meeting

- David Hough, MD, CMO of PaxMedica presented new trial data and analyses during the "Research Pipeline: New Findings on Diagnostics and Therapeutics" program
Published: Oct. 28, 2021 at 6:00 AM CDT

TARRYTOWN, N.Y., Oct. 28, 2021 /PRNewswire/ -- PaxMedica, Inc. ("PaxMedica" or the "Company"), a biopharmaceutical company developing medicines that help overcome the challenges of living with complex neurological conditions, today announced that it has presented additional data and analyses from its Phase 2 clinical trial evaluating PAX-101 (intravenous suramin), an investigational drug with a proposed novel mechanism of action, that the Company is developing as a potential treatment for the core and related symptoms of Autism Spectrum Disorder (ASD).  This trial, using low doses of intravenous suramin once monthly, expanded on earlier published reports of the potential for suramin as a treatment for the core and related symptoms of ASD and lends support to the important role that purine mediated mechanisms may have in the treatment of ASD.

"We are excited to share these clinical data and the results of our recent analyses with the academic and medical child and adolescent psychiatry community at AACAP," said David Hough, MD, Chief Medical Officer of PaxMedica. "There are currently no FDA approved treatments for the core symptoms of ASD and these data have generated support from the company's highly regarded scientific advisors to rapidly advance the development of PAX-101 for treatment of core and related symptoms of ASD in larger clinical studies in the US and elsewhere."

This phase 2 study was a randomized, double-blind, placebo-controlled proof of concept clinical trial that was designed to test the efficacy and safety of suramin in boys aged 4-17 years with moderate to severe ASD. The study was conducted at 6 sites in South Africa where suramin is an approved medicine.  The protocol was approved by the South Africa Health Products Regulatory Authority and each site's Institutional Review Board or Ethics Committee.

Fifty-two boys, ages 4 – 15 years were enrolled in 3 treatment arms: suramin 10 mg/kg, suramin 20 mg/kg, and placebo and were dosed by intravenous infusion at baseline, week 4, and week 8. The final study visit was at week 14. Subjects were diagnosed with ASD by DSM-5 criteria and severity was measured by the Autism Diagnostic Observation Schedule. The Aberrant Behavior Checklist (ABC) Core (subscales 2, 3, and 5) was the primary endpoint and Clinical Global Impressions – Improvement Scale (CGI-I), was a secondary endpoint. Both were assessed using intent-to-treat change scores from baseline to endpoint using analysis of variance.

The subjects were multiracial with a mean age of ~8 years with wide variability in the severity of ASD symptoms at baseline. Forty-four subjects completed the study with 8 early withdrawals [COVID-19: 5, serious adverse event (SAE): 1, other reasons: 2]. ABC Core mean ± SE of 10 mg showed a greater numeric improvement (-12.5 ± 3.18) vs. placebo (-8.9 ± 2.86) (p = 0.37) at Week 14. The 20 mg arm did not show improvement vs. placebo. In exploratory analyses of the ABC-Core, the 10 mg arm showed greater differences from placebo in younger subjects and those with less severe symptoms. CGI-I mean ± SE changes from baseline were 2.8 ± 0.30 (p=0.016) in the 10 mg/kg arm and 2.0 ± 0.28 (p=0.65) in the 20 mg/kg arm, vs. 1.7 ± 0.27 in placebo. Suramin was generally safe and well-tolerated over 14 weeks. There was one SAE, "status epilepticus," in a subject (20 mg arm) with multiple risk factors (cerebral palsy, hydrocephalus, VP shunt) for seizure, which resolved without sequelae.

In summary, this dose-ranging proof-of-concept study of intravenous low-dose suramin for treatment of core and associated symptoms of ASD showed positive results on the CGI-I with a novel treatment. The 10 mg/kg dose showed greater efficacy, tolerability, and safety than the 20 mg/kg dose. Limitations of the study include small sample size and exploratory analyses that require confirmation in a larger study.

About PAX-101 (IV suramin)
PAX-101 is an antipurinergic agent delivered as an IV infusion. The mechanism of the drug's action, when delivered in a once-monthly low dose to treat the core and related symptoms of ASD, has been proposed to act primarily through purinergic receptor blockade, reversing the effects of mitochondrial dysfunction, which has been postulated as a cause of ASD symptoms.  Other research indicates that ASD may arise from neuroinflammatory mechanisms. This relationship is not well understood and PAX-101 may also act through mechanisms that reduce neuroinflammation in this population.

About Autism Spectrum Disorder (ASD)
ASD is a complex neurodevelopmental disorder characterized by difficulties with social communication and interaction, restricted interests, and repetitive behaviors. These symptoms are present from early childhood and affect the daily functioning of individuals with ASD in school, work, and other areas of life. The term "spectrum" refers to the wide range of symptoms, skills, and levels of disability in functioning that can occur in people with ASD. ASD occurs in every racial and ethnic group, and across all socioeconomic levels.  Approximately 1 in 54 children in the U.S. is diagnosed with an autism spectrum disorder with boys being four times more likely to be diagnosed than girls.  There are presently no FDA-approved therapies for the core symptoms of autism spectrum disorder.

About PaxMedica, Inc.
PaxMedica's mission is to change the therapeutic paradigm for ASD and other neurologic disorders, including myalgic encephalomyelitis/chronic fatigue syndrome, Long Covid Syndrome, and fragile X-associated tremor/ataxia syndrome.  In addition to PAX-101, PaxMedica is developing PAX-102, a proprietary intranasal formulation of suramin. Though ASD is commonplace in many communities, no FDA-approved treatments for its core symptoms exist. PaxMedica's most clinically advanced therapeutic, PAX-101, is currently being evaluated in clinical trials to support children with ASD and treat their core and associated symptoms. For more information, visit

Forward-Looking Statements
This press release contains certain forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934 and Private Securities Litigation Reform Act, as amended, including those relating to the Company's product development, clinical and regulatory timelines, market opportunity, competitive position, possible or assumed future results of operations, business strategies, potential growth opportunities and other statements that are predictive in nature. These forward-looking statements are based on current expectations, estimates, forecasts, and projections about the industry and markets in which we operate and management's current beliefs and assumptions.

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For more information, contact:

PaxMedica, Inc. 
Howard Weisman 
Chief Executive Officer

Media Relations:
Tony Russo, Ph.D.
Russo Partners LLC
(212) 845 4251

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