Results of Phase 2a clinical trial of DR Cysteamine announced by Raptor Pharmaceutical

Raptor Pharmaceutical Corp. ("Raptor" or the "Company") (Nasdaq: RPTPD), announced positive findings from the completed treatment phase of its open-label Phase 2a clinical trial of delayed-release cysteamine bitartrate ("DR Cysteamine") in adolescent patients with non-alcoholic steatohepatitis ("NASH"), a progressive form of liver disease believed to affect 2% to 5% of the U.S. population. At the completion of the initial six-month treatment phase, the study achieved the primary endpoint: mean blood levels of alanine aminotransferase ("ALT"), a common biomarker for NASH, were reduced by over 50%. Additionally, over half of the study participants had achieved normalized ALT levels by the end of the treatment phase.

There are no currently approved drug therapies for NASH, and patients are limited to lifestyle changes such as diet, exercise and weight reduction to manage the disease. DR Cysteamine represents an important potential treatment option for patients with NASH. Although NASH is most common in insulin-resistant obese adults with diabetes and abnormal serum lipid profiles, its prevalence is increasing among juveniles as obesity rates rise within this patient population. Although most patients are asymptomatic and feel healthy, NASH causes decreased liver function and can lead to cirrhosis, liver failure and end-stage liver disease.

Under a collaboration agreement between Raptor and the University of California, San Diego ("UC San Diego"), the open-label Phase 2a trial of a prototype formulation of DR Cysteamine is being conducted at UC San Diego's General Clinical Research Center and entails six months of treatment followed by a six-month post-treatment monitoring period. Eligible patients with baseline ALT and aspartate aminotransferase ("AST") measurements at least twice that of normal levels were enrolled to receive twice-daily, escalating oral doses of up to 1,000 mg of DR Cysteamine. The trial currently has enrolled eleven NASH patients between 11-18 years old. No major adverse events were reported during the six-month treatment phase. Trial subjects continue to be monitored during the six-month post-treatment period currently underway. Full results are being submitted for peer review by Raptor and UC San Diego, and are expected to be presented in 2010.

Joel Lavine, M.D., Ph.D., pediatric gastroenterologist at UC San Diego and principal investigator for the NASH study, stated, "We were encouraged by the results of this study. The degree of ALT and AST reductions are indicative of likely improvements in severity of fatty liver damage. The trial results are consistent with ALT and AST reductions normally seen in patients that achieve at least 10% weight loss, even though study participants did not show a significant change in body mass index. DR Cysteamine appears to be a promising candidate for NASH and we look forward to further analyzing these patients during the post-treatment phase."

Raptor's chief medical officer, Patrice Rioux, M.D., Ph.D., said, "These interim results have established proof-of-concept and support further clinical development of DR Cysteamine in NASH. This is an area of significant unmet need, especially with growing numbers of obese children diagnosed with the disorder. While the clinical hurdle is usually high for studies in children and adolescents, we are satisfied with the long-term safety demonstrated in this age group by the currently-marketed immediate-release cysteamine bitartrate formulation. This safety track record, coupled with our interim Phase 2a efficacy data, gives us a great sense of encouragement as we advance DR Cysteamine through the clinic."

Under a license with UC San Diego, Raptor is developing DR Cysteamine for cystinosis, NASH and other potential therapeutic indications. Cysteamine is known to be a scavenger of reactive oxygen species and potent antioxidant, most likely through its ability to increase intracellular glutathione levels. Cysteamine has also demonstrated potential efficacy in preclinical and clinical studies in Huntington's Disease, Batten Disease and other indications.