Merck KGaA said Thursday its division Merck Serono submitted an application to the European Medicines Agency for the marketing authorization of sapropterin (INN: sapropterin dihydrochloride, formerly known as Phenoptin) as an oral treatment for significant hyperphenylalaninemia, or HPA, due to phenylketonuria, or PKU, or tetrahydrobiopterin -BH4- deficiency.
Sapropterin had previously received Orphan Medicinal Product designation for the treatment of HPA from both the EMEA and the Food and Drug Administration.
"The filing for sapropterin is an important milestone for patients with phenylketonuria or BH4 deficiency. These are serious, debilitating diseases for which there is currently no drug approved in Europe," said Roberto Gradnik, Head of Merck Serono's Operations for Europe. "This submission underscores Merck Serono's commitment to address unmet medical needs."
PKU and BH4 deficiency are caused by genetic defects in the metabolism of the amino acid phenylalanine, resulting in hyperphenylalaninemia, i.e. abnormally high levels of phenylalanine in the blood. Hyperphenylalaninemia can cause serious brain damage in infants and young children, and neurological impairment in older patients. There are at least 50,000 people diagnosed with hyperphenylalaninemia due to PKU or BH4 deficiency in the developed world. However, there is no approved drug for the treatment of this condition in Europe. The only alternative for PKU patients to manage their disease is a diet highly restricted in phenylalanine.
Data from two international, double-blind, randomized, placebo-controlled Phase III clinical trials in patients with hyperphenylalaninemia due to PKU show that treatment with sapropterin reduces blood phenylalanine levels and may reduce the need to limit phenylalanine in patients' diet. The most frequently reported potential undesirable effects were headache, runny nose, diarrhea, vomiting, sore throat, cough, abdominal pain, stuffy nose, and low levels of phenylalanine in the blood. These adverse events were generally mild to moderate and transient.
Sapropterin is being developed in partnership with BioMarin Pharmaceutical Inc. Under the terms of the agreement with BioMarin, Merck Serono has exclusive rights to market sapropterin in all territories outside the United States and Japan. BioMarin has exclusive rights to market sapropterin in the U.S.