RG3039 is the first clinical-stage drug candidate to target the core genetic deficit in SMA in order to treat the biochemical deficits caused by decreased levels of the survival motor neuron (SMN) protein. This key protein is necessary for normal neuromuscular function but is insufficiently produced in SMA patients. RG3039 is an orally bioavailable small molecule inhibitor of an RNA processing enzyme called DcpS. RG3039 has been shown to increase production of the SMN protein in cells derived from patients. In addition, RG3039 has been shown to improve motor neuron pathology, mobility and lifespan in animal models of SMA.
Top-line results from this Phase 1 study of RG3039 are scheduled to be presented as part of a special neuroscience program at the 64 th Annual Meeting of the American Academy of Neurology (AAN). The AAN meeting is being held April 21-28, 2012 at the New Orleans Ernest N. Morial Convention Center. James P. Van Meerbeke, Research Assistant from the lab of Charlotte J. Sumner, M.D., Associate Professor of Neurology and Neuroscience, Johns Hopkins University School of Medicine, will present the abstract titled “ The Therapeutics Effects of RG3039 in Severe Spinal Muscular Atrophy – Mice and Normal Human Volunteers,” during “The Future of Neuroscience Conference: Neurologists and Neuroscientists Defining the Next Generation of CNS Therapies,” taking place on April 27.
In addition to the Phase 1 clinical trial outcomes, the AAN presentation highlights the results of earlier mouse model studies conducted with RG3039 at Johns Hopkins University and in the lab of Dr. Chien-Ping Ko at University of Southern California. In these preclinical studies, which provided proof of principle for conducting human clinical studies, administration of RG3039 resulted in a significant improvement in survival, increased maximum body weight and improved motor behavior in severe SMA mice. The effects were associated with increased SMN2 transcript levels and improved neuromuscular junction morphology and physiology. At therapeutic levels of RG3039 in mice, the target enzyme DcpS was inhibited greater than 90%. This appears to parallel outcomes from the Phase 1 human study, which achieved greater than 90% inhibition of DcpS in peripheral blood cells for 48 hours with a single dose of RG3039 and in absence of any toxicity.