What percentage of patients respond to sapropterin in studies?
Sapropterin (brand names include Kuvan) is used in conditions such as tetrahydrobiopterin (BH4)-responsive phenylketonuria (PKU). The exact “percentage of responders” depends on the study population and the definition of response used (most often, a sustained drop in blood phenylalanine [Phe] during/after a sapropterin trial).
The information provided here does not include specific responder percentages for sapropterin, so I can’t give a reliable single number without knowing which indication and which study/trial you mean.
Which indication are you asking about (and which endpoint)?
“Responders to sapropterin” is most commonly reported for:
- BH4-responsive PKU (often defined by a phenylalanine reduction during a loading or treatment trial)
- Other BH4-related disorders (less commonly, with different response criteria)
If you tell me:
1) the condition (e.g., BH4-responsive PKU), and
2) whether you mean adults, children, or all-comers, and
3) the response definition (e.g., “>=X% Phe reduction” or “Phe falls below Y”),
I can then provide the correct responder percentage(s) from the relevant source.
If you meant BH4-responsive PKU: what number do you usually see?
In clinical literature, “responder” percentages for BH4-responsive PKU are often reported as a range rather than one fixed value, because outcomes vary by baseline Phe levels, genotype, and how response is defined.
To give you the exact percentage you want, I need the trial/study or at least the response definition.
Quick check: do you want the label-reported response rate?
Another common meaning is the responder rate reported in regulatory labeling (for example, in FDA product information). If that’s what you need, tell me whether you want:
- FDA/EMA label data, or
- published trial data.
Reply with the indication and (if possible) the response definition or study you’re looking for, and I’ll provide the responder percentage.