A comparative analysis of international health technology assessments for novel gene silencing therapies: patisiran and inotersen

OBJECTIVES: Using the case study of patisiran and inotersen, we conducted a narrative comparative analysis of the health technology assessment (HTA) agency appraisals of these two first-in-class transthyretin gene silencers, which represent exceptional advances in the treatment of hereditary transthyretin-mediated (hATTR) amyloidosis, a rare and multisystemic disease. Despite the impact of each product on the treatment landscape, the majority of HTAs are only considered standard of care as a comparator, resulting in a void of information and limited comprehension of the clinical and pharmacoeconomic differences between the two treatments. METHODS: A search was conducted internationally for HTA reports, and only instances where assessment decisions for both treatments were publicly available were included in the present analysis. The HTA reports were analyzed broadly for the assessment of clinical and pharmacoeconomic evidence. Only economic models considering both patisiran and inotersen were included in this analysis. RESULTS: A total of nine agencies with public assessment reports for both treatments were identified. HTA agency assessments for both treatments were essentially positive; however, differences were noted in the final recommendations, place in treatment or reimbursed indications, and in the narrative of the evaluations. Only the Canadian Agency for Drugs and Technologies in Health (CADTH) assessment for patisiran evaluated an economic model comparing the two treatments. CONCLUSIONS: The differences summarized in this comparative analysis may provide a more comprehensive overview of the two treatments.