The Complexities of Rare Disease Studies: A Personal Perspective on Duchenne Muscular Dystrophy
A mother's personal experience with her son's Duchenne muscular dystrophy treatment highlights the challenges of designing rare disease studies and the importance of regulatory flexibility.
The journey of a family dealing with a rare disease like Duchenne muscular dystrophy is filled with countless tiny decisions that can make or break a study. As a mother of a son with this condition, I have seen firsthand the impact of these decisions on his life and treatment. My son has been taking Capricor's deramiocel for five years, and despite initial concerns about his independence, he is now starting his second year of master's degree study.
The Challenges of Study Design
Designing a rare disease study involves making hundreds of tiny decisions, each with its own set of risks and uncertainties. Sponsors must make these decisions with the best knowledge they have at the time, but with no way of predicting the impact of each decision with certainty. One example of this is narrowing inclusion criteria, which can give a better chance at statistical significance but introduces risk on reaching enrollment.
Balancing Regulatory Flexibility and Rigor
The FDA's recent decision to allow Capricor to submit additional upper limb data and analyses to refocus on the primary outcome highlights the importance of regulatory flexibility in rare disease studies. This decision demonstrates that the agency is willing to weigh the completion and submission of a new biologic licensing application against the lives and function that would be lost during the time required for completion. The question remains, what is the appropriate balance between the strictest possible definition of pre-specification and the necessary ability to learn as we go?
The Importance of Understanding Patient Outcomes
As regulators navigate the complexities of rare disease studies, it is essential that they prioritize understanding what's really happening to patients on treatment. This requires using appropriate and rigorous methods to analyze data and determine the effectiveness of a treatment. The FDA's decision to allow additional data and analyses to be submitted is a step in the right direction, and it is crucial that they continue to exercise regulatory flexibility while maintaining rigor in their evaluation of rare disease treatments.
The use of specific outcome measures, such as the performance of upper limb, which is divided into measurements of shoulder, arm, and hand function, can be a challenge in rare disease studies. The table below illustrates the trade-offs involved in using different outcome measures:
