Young children being treated with autologous CD34+ cells transduced to express adenosine deaminase [ADA] (Strimvelis) and a small patient population both contribute to a general lack of data regarding the success of the drug.
The first ex vivo
stem cell gene therapy approved by the European Medicines Agency (EMA), Strimvelis is indicated as a single treatment for patients with ADA-severe combined immunodeficiency (ADA-SCID) who lack a suitable matched related bone marrow donor.
Because existing primary immunodeficiency registries are custom-made to transplantation outcomes and fail to capture the breadth of safety and efficacy endpoints required by the EMA for the long-term monitoring of gene therapies, researchers from GlaxoSmithKline will collect data from a group of young children treated with the drug at a single investigator site at the San Raffaele Telethon Institute for Gene Therapy in Milan, Italy. 1
Currently, Strimvelis is offered only at the single center in Milan, and while the drug is believed to provide an absolute cure for ADA-SCID, its commercial potential has gone largely unproven due to difficulty organizing cross-border reimbursement. In March 2017, the first patient was administered the drug.
The observational registry was established to monitor the safety and effectiveness of Strimvelis in up to 50 patients over a minimum of 15 years. It creates a model for the safety monitoring of gene therapies in the future. A novel, patient-focused design has been applied to speak to the issues faced by long-term follow-up of patients treated with gene therapies for rare diseases.
Each patient enrolled in the registry will be studied for a baseline of 15 years after treatment with Strimvelis. The registry will close when the 50th patient has been followed for 15 years. Safety information on any events relating to fertility and pregnancy outcomes, oncogenesis and survival will continue to be solicited every other year past a subject’s 15-year post-gene therapy anniversary until the registry is concluded. Effectiveness will be evaluated by outcomes including survival, intervention-free survival and growth.
The team of researchers anticipates that most subjects enrolled into the registry will be followed-up for longer than 15 years.
This registry is anticipated to provide a valuable resource for other companies with plans to develop future therapies for rare diseases. As the Strimvelis registry evolves, it is expected to include outcomes from all available patients with ADA-SCID, independent of treatment received. This will allow for wider comparisons to be made as it pertains to the treatments available to patients with ADA-SCID.
Using sensible and cost-efficient approaches, it is the team’s goal that the Strimvelis registry will encourage further innovation in registry design within orphan drug development. The hope of the researchers is that it will achieve the retention rates and data completeness required for long-term follow-up for this patient population.
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Stirnadel-Farrant H, Kudari M, et al. Gene therapy in rare diseases: the benefits and challenges of developing a patient-centric registry for Strimvelis
in ADA-SCID. Orphanet Journal of Rare Diseases. 2018: 13:58. https://doi.org/10.1186/s13023-018-0804-8.