Real-world data from expanded access programmes in health technology assessments: a review of NICE technology appraisals 121 6♦ The submission of data for the gene therapy Strimvelis comprised a mix of evidence sources: ‘The safety and efficacy of Strimvelis have been evaluated in a programme comprising 2 pilot studies, 1 pivotal study, a compassionate use programme (CUP), and a long-term follow-up (LTFU) study.’ The company preferred to report the results of the clinical trials together, as an ‘integrated population’, with results from the Named Patient Programme (NPP) presented alongside as supportive evidence. The company stated that it did not include the NPP data in the integrated population because the population of the NPP was substantially different to the population in the other trials, and that it could not access all the patient-level data because the NPP was a clinician-initiated process. The ERG critiqued this decision: ‘However, the ERG did not consider it appropriate that data from the Named Patient Population were excluded from the narrative synthesis of clinical effectiveness evidence. This is particularly important given the small sample size of the Strimvelis Integrated Population (n=18) and therefore the need to consider all available data when evaluating the effectiveness of this treatment.’ Indeed, the Company even requested (to no avail) the ERG to remove the wording ‘NPP study’, as ‘Noting the NPP as a study wrongly indicates that the NPP is part of the Strimvelis clinical programme and therefore at the same level in terms of availability and quality of evidence. NICE however specifically requested more information on these patients. ‘A3. Please provide a narrative summary of the data (e.g., in terms of overall survival, intervention-free survival, adverse events etc.) available from the named patient programme using the same format as in the main clinical effectiveness section on the Strimvelis Integrated Population.’ As the named-patient program was investigator-initiated, access to data was limited: ‘A3. Table 1 contains the requested information, as available, for patients in the NPP. Data on the proportion of patients with viral infection at baseline are not available. As the ERG has noted, the NPP is not run by GSK, which limits access to data and as such it is difficult to speculate on wider applicability of these immature and incomplete data. The programme is ongoing and data are not scheduled for formal analysis until all patients have reached 3 years of follow-up’. Strimvelis is recommended as a treatment option for treating adenosine deaminase deficiency– severe combined immunodeficiency (ADA–SCID) when no suitable human leukocyte antigenmatched related stem cell donor is available.
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