The Foundation for Prader-Willi Research (FPWR) today announced a venture philanthropy investment in ConSynance Therapeutics, a clinical-stage biotechnology company developing CSTI-500, an investigational therapy for the treatment of behavioral dysregulation and hyperphagia in Prader-Willi syndrome (PWS).
The investment will support a Phase 2a clinical study evaluating CSTI-500 in individuals with PWS. The study is expected to begin in 2026 and will assess the therapy’s safety, tolerability, and potential effects on behavioral symptoms including temper outbursts, emotional instability, and behaviors associated with hyperphagia.
As families in the PWS community know all too well, many individuals with PWS experience severe emotional and behavioral challenges that significantly impact quality of life for both patients and families. These challenges often occur alongside hyperphagia, an intense and persistent feeling of hunger and drive to eat that is another hallmark feature of the condition and a major source of caregiving burden.
“Data from the Global PWS Registry show that behavioral outbursts and hyperphagia are among the most challenging aspects of Prader-Willi syndrome for families,” said Theresa Strong, PhD, Director of Research Programs at the Foundation for Prader-Willi Research. “By investing in programs like CSTI-500, FPWR is working to accelerate the development of therapies that directly address these unmet needs.”
A New Therapy Approach for Behavioral and Emotional Challenges in PWS
CSTI-500 is a novel small-molecule therapy designed to modulate three key neurotransmitters in the brain: serotonin, dopamine, and norepinephrine. These signaling systems play important roles in emotional regulation, impulse control, and stress response. By targeting all three pathways in a coordinated way, researchers hope the therapy may help restore balance in brain circuits that contribute to disruptions in emotional and behavioral control.
Early clinical studies of CSTI-500 have demonstrated encouraging safety and pharmacokinetic results, including a Phase 1 study conducted in individuals with PWS. These studies also confirmed that the drug engages its intended targets in the human brain, providing important validation of the biological approach.
“FPWR was founded to accelerate research that leads to meaningful treatments for people living with Prader-Willi syndrome,” said Susan Hedstrom, Executive Director of the Foundation for Prader-Willi Research. “Through our venture philanthropy program, we support promising therapeutic programs that have the potential to make a real difference for individuals and families affected by PWS.”
The ConSynance investment represents the eighth therapeutic program supported through FPWR’s venture philanthropy initiative, which has helped advance multiple clinical-stage therapies for Prader-Willi syndrome, including one that ultimately led to an FDA approved treatment. Any financial returns generated from these investments are reinvested into additional research to further advance the field.
“We are grateful for FPWR’s support and partnership as we advance CSTI-500 into the next stage of development,” said Shuang Liu, PhD, Chief Executive Officer of ConSynance Therapeutics. “The Prader-Willi syndrome community has played an important role in helping guide this work, and we look forward to continuing to collaborate as the program moves forward.”
