PaxMedica, Inc. ("PaxMedica" or the "Company") 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. 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.