Raptor Pharmaceutical reported positive data from a Phase III equivalence study comparing its delayed release (DR) cysteamine candidate, RP103, with immediate-release cysteamine bitartrate (Cystagon®/Mylan Pharmaceuticals) in the treatment of the genetic lysosomal storage disease nephropathic cystinosis. Data from 38 evaluable patients showed that treatment using twice-daily RP103 was as effective at maintaining white blood cell cystine levels as Cystagon administered strictly every six hours. Patients receiving RP103 also required a lower overall daily dose of RP103 than of Cystagon.
Raptor is now carrying out a six-month extension study in which patients completing the Phase III trial may elect to continue on RP103 therapy. The firm says the extended safety data will be included in its future NDA filing.
A separate study has confirmed the bioequivalence of RP103 administered either as whole capsules or by sprinkling the capsule contents onto food. Raptor says this data means it may be able to expand enrollment into the extension study to include patients who are too young to swallow whole capsules, and were therefore ineligible for the original Phase III trial protocol.
The firm is separately carrying out a Phase II/III study evaluating DR cysteamine in capsule form for the treatment of Huntington disease. A tablet formulation of DR cysteamine (RP104) has completed a Phase IIa trial in the treatment of nonalcoholic steatohepatitis (NASH). Results from this study showed that therapy using RP104 led to a marked decline in both alanine aminotransferase (ALT) and aspartate aminotransferase levels. Levels of the disease markers cytokeratin 18 and adiponectin were reduced by 45% and 35%, respectively. Raptor is developing DR cysteamine for all relevant indications under a 2007 license granted by the University of California, San Diego.
Raptor’s clinical pipeline also includes Convivia™, an oral formulation of 4-methylpyrazole (4-MP), which is in Phase II development for the potential treatment of acetaldehyde toxicity resulting from ALDH2 deficiency. The inherited metabolic disorder affects some 40–50% of East Asian populations, Raptor notes. 4-MP is the active pharmaceutical ingredient in an existing intravenous product developed for unrelated indications. In June 2010 Raptor signed an exclusive agreement with Uni Pharma to commercialize Convivia in Taiwan, with an option for South Korea. Under terms of the deal Uni Pharma is responsible for clinical development, registration, and commercialization of Convivia in its designated markets.
Raptor has separately licensed the AMPA receptor inhibitor tezampanel from Eli Lilly for development as a potential antiplatelet therapy. Phase I healthy volunteer trials are ongoing to evaluate the drug's effects on platelet activation and aggregation.