Nephropathic cystinosis is the most common and severe form of cystinosis. It is a metabolic disease characterized by an accumulation of the amino acid cystine within lysosomes in the cells, leading to widespread damage to organs and tissues.
Nephropathic cystinosis usually presents in early infancy as Fanconi syndrome, a serious disorder of the kidneys’ proximal tubules involving excessive excretion of nutrients and minerals such as glucose, amino acids, phosphates, potassium, and sodium. Neuropathic cystinosis can lead to excessive urination, resulting in acute dehydration. The loss of nutrients impairs growth and may result in soft, bowed bones. Untreated children will experience complete kidney failure by about the age of 10. However, nephropathic cystinosis is not only a renal disorder but a multisystemic disease that could lead to ocular and neurologic impairment, muscle deterioration, diabetes, thyroid and nervous system problems, and infertility in affected men.
Transmission is autosomal recessive: two altered copies of the gene from both parents are needed to manifest the disease. It is an ultra-rare disease, with an estimated incidence of around 1/100,000- 1/200,000 live births.
How is nephropathic cystinosis treated?
The primary treatment is cystine-depletion therapy (the pharmacological lowering of the cystine content in the lysosomes) through cysteamine that, when initiated early, can slow or even stop the progression to renal failure and the development of extra-renal manifestations.
PROCYSBI® (cysteamine bitartrate) is the first EMA-approved cystine-depleting therapy dosed every 12 hours for nephropathic cystinosis.
PROCYSBI® is a delayed-release form of cysteamine bitartrate that works by continuously reducing the toxic concentration of cystine in the cells. The product is indicated for the treatment of proven nephropathic cystinosis. PROCYSBI® is intended to keep cystine concentration under control to limit or prevent the damage too much cystine can cause to cells, tissue, and organs. Chiesi Farmaceutici, after the acquisition of the European subsidiary of Horizon Pharma in June 2017, owns the marketing rights for PROCYSBI® delayed-release capsules in Europe, the Middle East, and Africa (EMEA). Horizon maintains marketing rights for PROCYSBI® in the United States, Canada, and Latin America.
Procysbi®, delayed-release cysteamine bitartrate capsules, is indicated for the treatment of proven nephropathic cystinosis. It is orally administered every 12 hours due to the delayed-release.
In addition to cystine-depletion therapy, electrolytes and vitamin supplements are administered. Hormones and specific treatments are administered to support growth and to limit hypothyroidism, diabetes, and hypogonadism. Renal transplantation is the treatment of choice for end-stage renal disease in cystinosis.