Caregiver Perspectives on Patients with Mucopolysaccharidosis II Treated with Pabinafusp Alfa: Results of Qualitative Interviews in Japan

Abstract

Abstract Background Mucopolysaccharidosis type II (MPS II), or Hunter syndrome, is a rare inherited X-linked metabolic disorder predominantly affecting males. Pabinafusp alfa, an iduronate-2-sulfatase enzyme that can cross the blood-brain barrier, was approved in Japan in 2021 for use in the first enzyme replacement therapy targeting both the neuropathic and somatic symptoms of MPS II. This study explores the experiences of MPS II patients receiving pabinafusp alfa through qualitative interviews with their caregivers. Methods A semi-structured moderation guide (Voice of the Caregiver guide) was used to conduct semi-structured, qualitative interviews with caregivers at clinical sites in Japan. The interview transcripts underwent thematic analysis to identify symptoms and health-related quality of life impacts at baseline, changes since treatment began, and treatment experience. Results Seven caregivers were interviewed, representing seven children aged 8–18 years who had received pabinafusp alfa treatment for 3.3–3.5 years at the time of the interviews. The collective data suggest a general trend towards improvement, although not all caregivers observed discernible changes. Cognitive improvements encompassed language skills, concentration, self-control, eye contact, mental clarity, concept understanding, following instructions, and expressing personal needs. Changes included improvements in motor function and mobility, as well as musculoskeletal and somatic changes, such as organ involvement, joint mobility, sleep patterns, and fatigue. Four caregivers reported improvements in family quality of life, five reported treatment satisfaction, and all seven expressed a strong willingness to continue treating the children with pabinafusp alfa. Conclusion This study of caregivers’ perspectives on the qualitative experiences of patients treated with pabinafusp alfa showed treatment satisfaction and multiple quality of life improvements following therapy. These findings expand understanding of the benefit of using pabinafusp alfa to treat MPS II, and they should be helpful in defining MPS II-specific outcome measures to better determine treatment response in future clinical trials.