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FDA approves Tonix’ Phase 2 Trial of TNX-2900 for Prader-Willi Syndrome

The FDA has cleared Tonix Pharmaceuticals’ Investigational New Drug (IND) application to support clinical development of TNX-2900 (intranasal potentiated oxytocin), a proprietary magnesium (Mg2+)-enhanced formulation of intranasal oxytocin, to treat Prader-Willi Syndrome (PWS) in children and adolescents. TNX-2900 for the treatment of PWS was granted Orphan Drug designation by the FDA in 2022.

The Phase 2 study approved by the IND is a dose-finding study involving approximately 36 PWS patients divided into four groups with approximately nine PWS patients per group. One group will receive placebo and three groups will receive different dosage regimens of TNX-2900. Tonix intends to seek a partner to advance TNX-2900 for PWS in clinical development.

“We are pleased that TNX-2900 is cleared for clinical studies for the treatment of PWS in children and adolescents as there remains a significant need for new therapies, particularly for PWS hyperphagia, which currently has no approved treatments,” said Dr Seth Lederman, CEO of Tonix Pharmaceuticals. “PWS is the most common genetic cause of life-threatening childhood obesity. We believe adding Mg2+ to the formulation has the potential to improve intranasal oxytocin’s therapeutic action.”

The IND application for TNX-2900 was supported by preclinical data demonstrating that Mg2+ enhances the potency of oxytocin. Oxytocin is a naturally-occurring hormone that reduces appetite and eating and regulates hunger, anxiety and prosocial behaviour. PWS is a genetic disorder associated with abnormalities of the oxytocin system5. Several previous clinical studies in PWS of intranasal oxytocin without Mg2+-potentiation have shown trends toward improvement, but the results have been inconsistent. Tonix believes that Mg2+-potentiation of intranasal oxytocin in PWS may improve consistency in clinical trials because in animal studies Mg2+-potentiation appears to eliminate the high-dose suppression of oxytocin’s inverted “U”-shaped dose response.

TNX-2900 is based on Tonix’s patented intranasal potentiated oxytocin formulation intended for use by adults and adolescents. Tonix’s patented potentiated oxytocin formulation is believed to increase specificity for oxytocin receptors relative to vasopressin receptors as well as to enhance the potency of oxytocin. Tonix is also developing a different intranasal formulation, designated TNX-1900, for prophylaxis of chronic migraine as well as for adolescent obesity, binge eating disorder, bone health in autism and social anxiety disorder.


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