Raptor Pharmaceutical has reported positive results from a RP103 (cysteamine bitartrate delayed-release) extension study in which nephropathic cystinosis patients finishing the Phase III trial chose to continue therapy.
A total of 40 patients were examined for white blood cell (WBC) cystine levels, plasma cysteamine levels, estimated glomerular filtration rate (eGFR), quality of life (PedsQL) and use of antacids.
Northwestern University Feinberg School of Medicine kidney diseases head Dr Craig Langman said cystine reduction therapy is effective, but is a lifelong commitment.
"Even brief delays in daily therapy permit toxic cystine accumulation, exposing tissues to renewed and progressive deterioration," Langman said.
"The currently approved immediate release formulation of cysteamine bitartrate taken every six hours is effective but difficult to use over the long-term."
According to the study data, WBC cystine levels were maintained constantly below the therapeutic target in patients with nephropathic cystinosis using RP103 for up to 24 months.
According to the company, the total daily dose of RP103 given each 12 hours to achieve optimal WBC cystine levels was on average 72% of the initial immediate release cysteamine bitartrate dose, after 20 month treatment.
Steady eGFR levels signify that the kidney function was conserved throughout the study and patients are able decrease the use of anti-acid medications by almost 50%.
Considerable improvements in all measured quality of life parameters were reported in the extension study.