Indirect treatment comparison (ITC) of the efficacy of vutrisiran and tafamidis for hereditary transthyretin-mediated amyloidosis with polyneuropathy

Plain Language SummaryHereditary transthyretin-mediated (ATTRv/hATTR) amyloidosis is a rare genetic disease that runs in families, affecting about 50,000 people worldwide. This condition results in abnormal protein deposits building up, causing damage to multiple nerves (polyneuropathy) and other organs, which can shorten lifespan and have other harmful effects. Polyneuropathy symptoms include weakness, numbness, pain, dizziness, and diarrhea. Over time, everyday activities become more difficult as patients become increasingly disabled and dependent on others. Several treatments have been approved for the polyneuropathy of ATTRv amyloidosis. Many of these work in different ways to impact the disease process. An indirect treatment comparison is a well-established statistical method used by healthcare decision-makers to compare treatments when head-to-head trials are unavailable. Indirect treatment comparisons using a common approach, the Bucher method, yield similar conclusions to head-to-head studies over 90% of the time. This method was used to compare clinical trial data for tafamidis and vutrisiran, two approved treatments for ATTRv amyloidosis with polyneuropathy. The findings show that vutrisiran is more effective than tafamidis at addressing the polyneuropathy of ATTRv amyloidosis as measured by changes to sensory or motor nervous system functioning and nutritional status. Also, vutrisiran showed greater maintenance of health-related quality of life compared to tafamidis. The expected benefits of vutrisiran over tafamidis are large enough to be noticeable and clinically meaningful to a patient or clinician. This highlights the potential advantages of vutrisiran compared to tafamidis with regard to preservation of physical function and quality of life when treating ATTRv amyloidosis with polyneuropathy. BackgroundVutrisiran and tafamidis are approved therapies for treating hereditary transthyretin-mediated (ATTRv/hATTR) amyloidosis with polyneuropathy, a rapidly progressive and fatal disease. To assist healthcare decision-makers, an indirect treatment comparison (ITC) was undertaken to explore the comparative efficacy of vutrisiran and tafamidis.Research design and methodsIndividual patient data (vutrisiran vs. placebo) and published results (tafamidis vs. placebo) from phase 3 randomized controlled trials were used in a Bucher analysis to assess differences in treatment effects between vutrisiran and tafamidis on: Neuropathy Impairment Score-Lower Limbs (NIS-LL), Norfolk Quality of Life-Diabetic Neuropathy (Norfolk QOL-DN) score, NIS-LL Response, and modified Body Mass Index (mBMI).ResultsGreater treatment effects were observed at 18 months with vutrisiran vs. tafamidis for all endpoints, with statistically significant improvements in polyneuropathy (relative mean change in NIS-LL: -5.3 [95% confidence interval (CI): -9.4, -1.2; p = 0.011]), health-related quality of life (HRQOL, relative mean change in Norfolk QOL-DN: -18.3 [95% CI: -28.6, -8.0; p < 0.001]), and nutritional status (relative mean change in mBMI: 63.9 [95% CI: 10.1, 117.7; p = 0.020]).ConclusionsThis analysis suggests vutrisiran has greater efficacy on multiple measures of polyneuropathy impairment and HRQOL compared to tafamidis in patients with ATTRv amyloidosis with polyneuropathy.