OBJECTIVES

X-linked myotubular myopathy (XLMTM) is an ultra-rare, life-threatening muscle disease with no approved therapies. AT132 is a novel gene therapy being investigated for the treatment of XLMTM. If licensed, AT132 will undergo cost-effectiveness assessment, requiring HRQoL data on multiple XLMTM health states. This study captures and reports such data.

METHODS

Nine vignettes describing life with XLMTM corresponding to nine health states defined by levels of respiratory and motor function were developed. The vignettes describe XLMTM patient status (self-care, movement, motor function, pain, breathing, mood and communication) for each health state. The vignette descriptions were developed based upon three sources: 1) parent reported data on patient functioning from ASPIRO, a multinational, randomised, open-label study of the safety and efficacy of AT132 (NCT03199469), 2) input from seven XLMTM clinical experts, and 3) qualitative data from interviews with 10 parents who described the daily impact of XLMTM on their children. Vignettes were assessed by the general public in face to face interviews using a visual analogue scale assessment, the time trade off interview (TTO) and a proxy rated EQ-5D-5L. Data were summarised.

RESULTS

Results were significant and consistent with the qualitative data in terms of the impact of XLMTM on children with the condition. The TTO results ranged from -0.07 for a child who is unable to sit and requires invasive ventilation for at least 16 hours a day to 0.90 for a child who can stand and walk and does not require invasive ventilation. The equivalent values from the EQ-5D assessment were -0.27 and 0.77.

CONCLUSIONS

This project found consistent evidence regarding the significant and substantial negative impact of XLMTM on patient HrQOL. The most severe health states were consistently rated below zero. The vignette approach was able to describe and summarise the patient experience and highlights the substantial unmet need for new therapies.