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Extrapolation of Survival Benefits in Patients with Transthyretin Amyloid Cardiomyopathy Receiving Tafamidis: Analysis of the Tafamidis in Transthyretin Cardiomyopathy Clinical Trial.

ABSTRACT: INTRODUCTION:In the Tafamidis in Transthyretin Cardiomyopathy Clinical Trial (ATTR-ACT; ClinicalTrials.gov number NCT01994889), tafamidis reduced the risk of all-cause mortality in patients with transthyretin amyloid cardiomyopathy (ATTR-CM) by 30% versus placebo. Median overall survival was not achieved in either treatment arm (57.1 and 70.5% of patients in the placebo and tafamidis groups, respectively, survived at 30 months), limiting assessment of the potential survival benefits of treatment. METHODS:A survival extrapolation analysis was conducted following technical support guidelines from the National Institute for Health and Care Excellence. Multiple models (i.e., exponential, Weibull, gamma, log-logistic, log-normal, Gompertz, generalized gamma, and generalized F) were applied to systematically fit different candidate curves to existing patient-level data from the 30-month treatment period in ATTR-ACT. The relative goodness-of-fit for each candidate curve was then tested by Akaike's and Bayesian information criteria to select a single model that was fitted to the placebo and pooled tafamidis treatment arms. RESULTS:A gamma distribution was selected as best fitting model and fitted to both treatment arms. The resulting estimated median overall survival was 35.16 months for placebo and 52.64 months for tafamidis (difference 17.48 months). CONCLUSIONS:This extrapolation of survival data from ATTR-ACT further supports the efficacy of tafamidis in patients with ATTR-CM. Owing to the limitations of this analysis, these survival estimates should be interpreted with caution; however, they are consistent with recently presented findings from a combined analysis of data from ATTR-ACT and interim data from an ongoing long-term extension study (median follow-up 36 months; ClinicalTrials.gov number NCT02791230). TRIAL REGISTRATION:ClinicalTrials.gov: NCT01994889.

SUBMITTER: Li B

PROVIDER: S-EPMC7584686 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

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Extrapolation of Survival Benefits in Patients with Transthyretin Amyloid Cardiomyopathy Receiving Tafamidis: Analysis of the Tafamidis in Transthyretin Cardiomyopathy Clinical Trial.

Li Benjamin B Alvir Jose J Stewart Michelle M

Cardiology and therapy 20200610 2

<h4>Introduction</h4>In the Tafamidis in Transthyretin Cardiomyopathy Clinical Trial (ATTR-ACT; ClinicalTrials.gov number NCT01994889), tafamidis reduced the risk of all-cause mortality in patients with transthyretin amyloid cardiomyopathy (ATTR-CM) by 30% versus placebo. Median overall survival was not achieved in either treatment arm (57.1 and 70.5% of patients in the placebo and tafamidis groups, respectively, survived at 30 months), limiting assessment of the potential survival benefits of t ...[more]

PMID: 32524297

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Project description:BackgroundIn patients with transthyretin amyloid cardiomyopathy, tafamidis reduces all-cause mortality and cardiovascular hospitalizations and slows decline in quality of life compared with placebo. In May 2019, tafamidis received expedited approval from the US Food and Drug Administration as a breakthrough drug for a rare disease. However, at $225 000 per year, it is the most expensive cardiovascular drug ever launched in the United States, and its long-term cost-effectiveness and budget impact are uncertain. We therefore aimed to estimate the cost-effectiveness of tafamidis and its potential effect on US health care spending.MethodsWe developed a Markov model of patients with wild-type or variant transthyretin amyloid cardiomyopathy and heart failure (mean age, 74.5 years) using inputs from the ATTR-ACT trial (Transthyretin Amyloidosis Cardiomyopathy Clinical Trial), published literature, US Food and Drug Administration review documents, healthcare claims, and national survey data. We compared no disease-specific treatment ("usual care") with tafamidis therapy. The model reproduced 30-month survival, quality of life, and cardiovascular hospitalization rates observed in ATTR-ACT; future projections used a parametric survival model in the control arm, with constant hazards reduction in the tafamidis arm. We discounted future costs and quality-adjusted life-years by 3% annually and examined key parameter uncertainty using deterministic and probabilistic sensitivity analyses. The main outcomes were lifetime incremental cost-effectiveness ratio and annual budget impact, assessed from the US healthcare sector perspective. This study was independent of the ATTR-ACT trial sponsor.ResultsCompared with usual care, tafamidis was projected to add 1.29 (95% uncertainty interval, 0.47-1.75) quality-adjusted life-years at an incremental cost of $1 135 000 (872 000-1 377 000), resulting in an incremental cost-effectiveness ratio of $880 000 (697 000-1 564 000) per quality-adjusted life-year gained. Assuming a threshold of $100 000 per quality-adjusted life-year gained and current drug price, tafamidis was cost-effective in 0% of 10 000 probabilistic simulations. A 92.6% price reduction from $225 000 to $16 563 would be necessary to make tafamidis cost-effective at $100 000/quality-adjusted life-year. Results were sensitive to assumptions related to long-term effectiveness of tafamidis. Treating all eligible patients with transthyretin amyloid cardiomyopathy in the United States with tafamidis (n=120 000) was estimated to increase annual healthcare spending by $32.3 billion.ConclusionsTreatment with tafamidis is projected to produce substantial clinical benefit but would greatly exceed conventional cost-effectiveness thresholds at the current US list price. On the basis of recent US experience with high-cost cardiovascular medications, access to and uptake of this effective therapy may be limited unless there is a large reduction in drug costs.

Project description:AimsTafamidis treatment positively affects left ventricular (LV) structure and function and improves outcomes in patients with transthyretin amyloid cardiomyopathy (ATTR-CM). We aimed to investigate the relationship between treatment response and cardiac amyloid burden identified by serial quantitative 99mTc-DPD SPECT/CT. We furthermore aimed to identify nuclear imaging biomarkers that could be used to quantify and monitor response to tafamidis therapy.Methods and resultsForty wild-type ATTR-CM patients who underwent 99mTc-DPD scintigraphy and SPECT/CT imaging at baseline and after treatment with tafamidis 61 mg once daily [median, 9.0 months (interquartile range 7.0-10.0)] were divided into two cohorts based on the median (-32.3%) of the longitudinal percent change in standardized uptake value (SUV) retention index. ATTR-CM patients with a reduction greater than or equal to the median (n = 20) had a significant decrease in SUV retention index (P < 0.001) at follow-up, which translated into significant benefits in serum N-terminal prohormone of brain natriuretic peptide levels (P = 0.006), left atrial volume index (P = 0.038), as well as LV [LV global longitudinal strain: P = 0.028, LV ejection fraction (EF): P = 0.027, LV cardiac index (CI): P = 0.034] and right ventricular (RV) [RVEF: P = 0.025, RVCI: P = 0.048] functions compared with patients with a decrease less than the median (n = 20).ConclusionTreatment with tafamidis in ATTR-CM patients results in a significant reduction in SUV retention index, associated with significant benefits for LV and RV function and cardiac biomarkers. Serial quantitative 99mTc-DPD SPECT/CT imaging with SUV may be a valid tool to quantify and monitor response to tafamidis treatment in affected patients.Translational perspective99mTc-DPD SPECT/CT imaging with determination of SUV retention index as part of a routine annual examination can provide evidence of treatment response in ATTR-CM patients receiving disease-modifying therapy. Further long-term studies with 99mTc-DPD SPECT/CT imaging may help to evaluate the relationship between tafamidis-induced reduction in SUV retention index and outcome in patients with ATTR-CM and will demonstrate whether highly disease-specific 99mTc-DPD SPECT/CT imaging is more sensitive than routine diagnostic monitoring.

Project description:To evaluate the efficacy and safety of 18 months of tafamidis treatment in patients with early-stage V30M transthyretin familial amyloid polyneuropathy (TTR-FAP).In this randomized, double-blind trial, patients received tafamidis 20 mg QD or placebo. Coprimary endpoints were the Neuropathy Impairment Score-Lower Limbs (NIS-LL) responder analysis (<2-point worsening) and treatment-group difference in the mean change from baseline in Norfolk Quality of Life-Diabetic Neuropathy total score (TQOL) in the intent-to-treat (ITT) population (n = 125). These endpoints were also evaluated in the efficacy-evaluable (EE; n = 87) population. Secondary endpoints, including changes in neurologic function, nutritional status, and TTR stabilization, were analyzed in the ITT population.There was a higher-than-anticipated liver transplantation dropout rate. No differences were observed between the tafamidis and placebo groups for the coprimary endpoints, NIS-LL responder analysis (45.3% vs 29.5% responders; p = 0.068) and change in TQOL (2.0 vs 7.2; p = 0.116) in the ITT population. In the EE population, significantly more tafamidis patients than placebo patients were NIS-LL responders (60.0% vs 38.1%; p = 0.041), and tafamidis patients had better-preserved TQOL (0.1 vs 8.9; p = 0.045). Significant differences in most secondary endpoints favored tafamidis. TTR was stabilized in 98% of tafamidis and 0% of placebo patients (p < 0.0001). Adverse events were similar between groups.Although the coprimary endpoints were not met in the ITT population, tafamidis was associated with no trend toward more NIS-LL responders and a significant reduction in worsening of most neurologic variables, supporting the hypothesis that preventing TTR dissociation can delay peripheral neurologic impairment.This study provides Class II evidence that 20 mg tafamidis QD was associated with no difference in clinical progression in patients with TTR-FAP, as measured by the NIS-LL and the Norfolk QOL-DN score. Secondary outcomes demonstrated a significant delay in peripheral neurologic impairment with tafamidis, which was well tolerated over 18 months.

Dataset Information

Extrapolation of Survival Benefits in Patients with Transthyretin Amyloid Cardiomyopathy Receiving Tafamidis: Analysis of the Tafamidis in Transthyretin Cardiomyopathy Clinical Trial.

Publications

Extrapolation of Survival Benefits in Patients with Transthyretin Amyloid Cardiomyopathy Receiving Tafamidis: Analysis of the Tafamidis in Transthyretin Cardiomyopathy Clinical Trial.

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