Gene therapy for X-linked myotubular myopathy: the challenges

Lessons Learned From Clinical Studies in Centronuclear Myopathies: The Patient Perspective-A Qualitative Study

BACKGROUND

Since 2014, several clinical studies focusing on centronuclear myopathies have been conducted, including a prospective natural history study, a gene transfer clinical trial and a clinical trial using an antisense oligonucleotide. Dedicated patient organizations have played an important role in this process. The experience of members of these organizations, either as a study participant, parent or as a patient organization member communicating with the sponsors are potentially very informative for future trial design.

METHODS

We investigated the burden of and the lessons learned from the first natural history studies and clinical trials from a patient perspective using a qualitative approach. We arranged 4 focus groups with a total of 37 participants from 3 large international patient organizations: ZNM-ZusammenStark!, the Myotubular Trust, and the MTM-CNM Family Connection. 4 themes, based on a systematic literature search were discussed: Expectations and preparation, Clinical study participation, Communication and Recommendations for future clinical trials. The focus group recordings were transcribed, anonymized, and uploaded to Atlas-ti version 8.1 software. The data were analyzed using a thematic content analysis.

RESULTS

Overall, participants were realistic in their expectations, hoping for small improvements of function and quality of life. The realization that trial participation does not equate to a treatment was challenging. Participating in a clinical study had a huge impact on many aspects of daily life, both for patients and their immediate families. First-hand insights into the burden of the design and its possible effect on performance were provided, resulting in numerous compelling recommendations for future clinical studies. Furthermore, participants stressed the importance of clear communication, which was considered to be especially vital in cases of severe adverse events. Finally, while patients were understanding of the importance of adhering to the regulations of good clinical practice, they indicated that they would strongly appreciate a greater understanding and/or acknowledgment of the patient perspective and a reflection of this perspective in future clinical trial design.

CONCLUSION

The acknowledgment and inclusion of patients' perspectives and efficient and effective communication is expected to improve patient recruitment and retention in future clinical studies, as well as more accurate assessment of the patient performance related to suitable planning of the study visits.

Delivery of Adeno-Associated Virus Vectors to the Central Nervous System for Correction of Single Gene Disorders

Genetic disorders of the central nervous system (CNS) comprise a significant portion of disability in both children and adults. Several preclinical animal models have shown effective adeno-associated virus (AAV) mediated gene transfer for either treatment or prevention of autosomal recessive genetic disorders. Owing to the intricacy of the human CNS and the blood-brain barrier, it is difficult to deliver genes, particularly since the expression of any given gene may be required in a particular CNS structure or cell type at a specific time during development. In this review, we analyzed delivery methods for AAV-mediated gene therapy in past and current clinical trials. The delivery routes analyzed were direct intraparenchymal (IP), intracerebroventricular (ICV), intra-cisterna magna (CM), lumbar intrathecal (IT), and intravenous (IV). The results demonstrated that the dose used in these routes varies dramatically. The average total doses used were calculated and were 1.03 × 1013 for IP, 5.00 × 1013 for ICV, 1.26 × 1014 for CM, and 3.14 × 1014 for IT delivery. The dose for IV delivery varies by patient weight and is 1.13 × 1015 IV for a 10 kg infant. Ultimately, the choice of intervention must weigh the risk of an invasive surgical procedure to the toxicity and immune response associated with a high dose vector.