Starting the conversation on gene therapy for phenylketonuria: Current perspectives of patients, caregivers, and advocates

Phenylketonuria (PKU) is a rare genetic condition caused by inborn error(s) in the gene for the enzyme phenylalanine hydroxylase. Resulting loss of phenylalanine (Phe) metabolism requires strict dietary therapy and/or medication to prevent toxic accumulation of Phe. Novel investigational therapies, including gene therapies that aim to address underlying causes of PKU, are now entering clinical trials. However, perceptions of this technology in the PKU community have not been assessed. We conducted a qualitative survey recruiting adult patients, caregivers, and patient advocates from the US and 3 EU countries to assess the impact of living with PKU and the perceptions of gene therapy. Telephone interviews were conducted for up to 60 min following a standardized discussion guide. Interviewers classified each participant by their level of knowledge regarding gene therapy as either: low (little or no prior awareness); moderate (awareness of gene therapy as a concept in PKU); or high (working knowledge of gene therapy, e.g., vectors). In total, 33 participants were recruited (patients, n = 24; caregivers, n = 5; advocates, n = 4). The patient sample was well balanced among age groups, sex, and US/EU geographies. The participants' experiences and burden of living with PKU were largely negative, characterized by frustrations with current management consistent with prior reports. Most participants (n = 18/33) were identified as displaying moderate gene-therapy knowledge, 10/33 as displaying high knowledge, and 5/33 as displaying low knowledge. Both positive and negative perceptions were observed; positive perceptions were often linked to “hope” that gene therapy may represent a cure, whereas negative perceptions were linked to the “uncertainty” of outcomes. High knowledge of gene therapy appeared to trend with negative perceptions; 7/10 participants from this group reported high levels of concern over gene therapy. In contrast, participants who displayed low knowledge reported low (n = 3/5) or moderate (n = 2/5) concern, with predominantly positive perceptions. These data highlight the need for education around the theoretical risk:benefit profile of gene therapy. Despite current unknowns around gene therapy, our study demonstrates the important role of healthcare providers as educators who can use available data to provide balanced information to patients and caregivers.