Transplantation as disease modifying therapy in the era of gene therapy medicinal products - health policy considerations.

backgroundNew gene therapy medicinal products [GTMP] are being considered as alternatives to liver transplant [LTx] for some patients with inherited metabolic diseases [IMDs] but pose unique challenges for health policy makers.

methodsPublished data on LTx and GTMP in human patients with urea cycle defects [UCD], glycogen storage disease type 1a [GSD1a], methylmalonic aciduria [MMA] and propionic aciduria [PA] were reviewed for efficacy, safety, data quality and health policy considerations.

resultsLTx can reduce [MMA, PA] or eliminate [UCD, GSD1a] metabolic decompensation and improve quality of life. Risk of death peaks in the first year but long-term survival post LTx is similar to medical management. Initial data for GTMP show reduction in metabolic decompensation [MMA, PA, UCD] with more modest impacts in GSD1a. Long-term safety and efficacy data [available for LTx] may not be available at the time of market authorization for GTMP. Age is one health policy challenge as clinical trials for GTMP may target one age group but other age groups may request consideration for treatment. Quality concerns regarding data analysis exist for both modalities. Cost effectiveness of LTx is likely to be significantly more favorable than for GTMP. Access limitations are severe for both treatments, with high opportunity costs [price for GTMP, organ availability for LTx] mandating the need to engage the public as stakeholders in addition to patients, families, manufacturers and clinicians.

conclusionsLTx remains an effective treatment choice in the era of GTMP given the significant health policy challenges associated with these novel therapies.