Sapropterin therapy is a treatment option for patients with phenylketonuria (PKU), a genetic disorder characterized by the body's inability to break down an amino acid called phenylalanine (Phe) [1][2]. The patient's response to sapropterin therapy can vary.

According to a study published in the National Center for Biotechnology Information (NCBI), sapropterin therapy has been shown to lower blood Phe levels in some PKU patients [2]. The drug works by increasing the activity of the enzyme that breaks down Phe, thus reducing its levels in the body [1].

However, not all patients respond to sapropterin therapy. A study published in the Journal of Inherited Metabolic Disease found that only about 30% of PKU patients have a significant response to the drug [3]. The response to sapropterin therapy is influenced by several factors, including the patient's genotype, the severity of their PKU, and their age [2].

In general, patients who respond to sapropterin therapy experience a decrease in blood Phe levels, which can help prevent the neurological complications associated with PKU [2]. However, it is important to note that sapropterin therapy is not a cure for PKU and must be used in conjunction with a Phe-restricted diet [1].

In summary, sapropterin therapy can be an effective treatment option for some PKU patients, leading to a decrease in blood Phe levels. However, not all patients respond to the therapy, and its effectiveness can vary based on several factors.

Sources:

[1] <https://www.drugpatentwatch.com/p/tradename/SAPROPTERIN>

[2] <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6769157/>

[3] <https://pubmed.ncbi.nlm.nih.gov/17846916/>