Sapropterin For Phenylketonuria: A Japanese Post-Marketing Surveillance Study.

Abstract

BACKGROUND\nTo assess the long-term safety and efficacy of sapropterin in a real-world setting in Japanese patients with tetrahydrobiopterin (BH4)-responsive phenylketonuria (PKU).\n\n\nMETHODS\nThis post-marketing surveillance study enrolled all patients in Japan with confirmed BH4-responsive PKU who were administrated sapropterin between July 2008 and October 2017. Patients were observed at least every 3 months during follow-up, with key data collected on treatment exposure/duration, effectiveness according to physician judgement, serum phenylalanine levels, and adverse events.\n\n\nRESULTS\nOf 87 enrolled patients, 85 patients (male, 42.4%; outpatients, 96.5%) were included in the safety and efficacy analysis sets. Treatment started at age <4 years in 43 (50.6%) patients and the most common starting daily dose was 5-10\xa0mg/kg (n=41 [48.2%]) with the overall duration of treatment between 0.2 and 17.2 years. Serum phenylalanine levels according to loading tests reduced from a baseline level of 9.66 mg/dL (range 0.48-36.80 mg/dL) by >30% in 84 patients. Treatment was deemed effective in 79 of 85 patients (92.9%, 95% CI 85.3-97.4). One (1.2%) patient experienced an adverse drug reaction (alanine aminotransferase increased) 50 days after the start of administration, which resolved without complications with continued treatment.\n\n\nCONCLUSIONS\nSapropterin appears well tolerated and highly effective in Japanese patients treated in a real-world setting, including those who start treatment at age <4 years and pregnant women.