Results from Phase 2a clinical trial of Raptor Pharmaceutical's cysteamine bitartrate published

Raptor Pharmaceutical Corp. ("Raptor" or the "Company") (Nasdaq: RPTP), today announced the publication of results from a Phase 2a clinical trial of a prototype formulation of its proprietary delayed-release cysteamine bitartrate ("DR Cysteamine") in patients with nephropathic cystinosis ("cystinosis"). Ranjan Dohil, M.D., Professor of Pediatrics at the University of California, San Diego, was lead author of the study to be published in the Journal of Pediatrics and available online.

The Phase 2a study demonstrated proof-of-concept for DR Cysteamine, which is Raptor's proprietary, delayed-release, enteric-coated microbead formulation of immediate release cysteamine bitartrate contained in a gelatin capsule. Immediate-release cysteamine bitartrate ("IR Cysteamine") is the current standard of care for treating cystinosis. The results indicated that when given twice daily, the prototype DR Cysteamine formulation was effective at maintaining low white blood cell ("WBC") cystine levels (<2 nmol half-cystine/mg protein) in subjects with cystinosis. Results also indicated that the prototype DR Cysteamine effectively maintained trough WBC cystine levels within a satisfactory range when patients received approximately 60% of the previous total daily dose of IR Cysteamine.

Dr. Dohil stated, "We are seeking to improve tolerability and reduce dosing frequency requirements of IR Cysteamine which have been documented challenges for cystinosis patients, leading to widely reported instances of poor treatment compliance. We believe the results of the Phase 2a study bring us significantly closer to a potential treatment solution for cystinosis patients. The results from our trial indicate prototype delayed-release cysteamine formulation lead to improved tolerability and efficacy when administered twice-daily and at a lower total daily dose than IR Cysteamine. Based on these results, I believe that Raptor's final DR Cysteamine formulation has the potential to improve compliance and long-term treatment outcomes for cystinosis patients."

Based on these Phase 2a results, Raptor conducted a Phase 2b clinical trial using its final commercial formulation of DR Cysteamine and recently announced the following top-line Phase 2b results: DR Cysteamine demonstrated improved tolerability and the potential to reduce total daily dosage and administration frequency compared to IR Cysteamine.

• Pharmacokinetic evaluation showed that DR Cysteamine had a terminal half-life more than three times longer than the terminal half-life of IR Cysteamine.
• Twice-daily DR Cysteamine may achieve the same pharmacodynamic result while using a total daily dose 30% lower than IR Cysteamine administered four times daily.
• No adverse events recorded during the clinical trial were determined by the principal investigator to be possibly or probably related to DR Cysteamine. Nine adverse events recorded in the clinical trial were determined to be possibly or probably related to IR Cysteamine.
• The proprietary, final formulation of DR Cysteamine confirmed earlier clinical trials conducted by Dr. Dohil using an enteric-coated prototype formulation of cysteamine bitartrate, which was funded by the Cystinosis Research Foundation ("CRF").

During the first quarter of 2010, Raptor plans to meet with the Food and Drug Administration ("FDA") and European Medicines Agency ("EMEA") to discuss plans for a repeat-dose, pivotal, Phase 3 clinical trial in cystinosis patients. Upon receiving FDA and EMEA agreements on protocol, Raptor intends to initiate its Phase 3 clinical trial at multiple sites in the US and Europe.

Cystinosis is an inborn metabolic error characterized by the abnormal transport of cystine, an amino acid, out of the lysosomes. Failure to treat cystinosis can cause serious health consequences, including renal failure and resultant kidney transplant, growth failure, rickets, photophobia and blindness. Symptom onset typically occurs within the first year of life, when cystine crystals accumulate in various tissues and organs, including the kidneys, brain, liver, thyroid, pancreas, muscles and eyes.

SOURCE Raptor Pharmaceutical Corp.