POINT RICHMOND, Calif., Sept. 12, 2012 /PRNewswire/ -- Transcept Pharmaceuticals, Inc. (Nasdaq: TSPT) today announced that it has completed enrollment in its Phase 2 clinical trial evaluating TO-2061 added as adjunctive therapy for patients with obsessive compulsive disorder (OCD) who have not adequately responded to first-line treatment with an approved OCD medication. The Company plans to announce top-line results of this study in the first quarter of 2013.
OCD affects 1 to 2 percent of the U.S. adult population and can significantly impair the lives of patients and their families. Approximately 40 percent to 60 percent of patients do not respond adequately to standard first-line treatment with currently approved OCD medications, including the selective serotonin re-uptake inhibitors (SSRIs) and the tricyclic agent, clomipramine. There is no FDA-approved adjunctive therapy for these treatment resistant patients.
TO-2061 is an investigational drug designed as an adjunctive treatment for use with approved OCD medications. TO-2061 is a low dose formulation of ondansetron, a serotonin subtype 3 (5-HT3) receptor antagonist, that has been approved for the treatment of nausea and vomiting caused by chemotherapy and radiation therapy, and for the prevention of postsurgical nausea and vomiting. Ondansetron has an established history of clinical use as a safe and effective treatment at a typical daily dose of 16 mg to 24 mg. TO-2061 is being studied at total daily doses of 1 mg to 1.5 mg.Phase 2 Study Design The Phase 2 study is a double-blind, placebo-controlled trial to evaluate the safety and efficacy of TO-2061 in 168 OCD patients who have not adequately responded to an approved OCD medication. Patients with a documented history of at least 6 weeks of inadequate response to an approved OCD medication continued to receive that first line OCD medication during an additional 6-week run-in phase of the study. Those patients who failed to respond during the run-in phase were eligible to be randomized to the 12 week double-blind active treatment phase, during which they will continue to receive their first line medication with the addition of ondansetron 0.5 mg twice per day, ondansetron 0.75 mg twice per day or placebo twice per day. The primary endpoint of the study is the difference between active and placebo treatment arms in the change from baseline as measured by the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). Low Dose Ondansetron Pilot Studies Two pilot studies of low doses of ondansetron as an adjunctive treatment in patients with OCD who have not adequately responded to their current SRI treatment have been conducted. Pilot Study A: In an open label study of 14 OCD patients who responded poorly to at least 12 weeks of SSRI treatment combined with an atypical antipsychotic, 9 nine patients, or 64 percent, responded with a 25 percent or greater reduction in the Y-BOCS score. None of the treated patients experienced symptom exacerbation or significant adverse effects. (Reference: S. Pallanti, S. Bernardi, S. Antonini, N. Singh, E. Hollander: Ondansetron augmentation in Treatment-Resistant Obsessive-Compulsive Disorder, CNS Drugs 2009.)