Biomarkers of axonal damage to favor early diagnosis in variant transthyretin amyloidosis (A-ATTRv)

Early identification of ATTRv amyloidosis disease onset is still often delayed due to the lack of validated biomarkers of this disease. Light chain neurofilament (NfL) have shown promising results in early diagnosis in this disease, but data is still needed, including with alternative measuring methods. Our aim was to study the levels of NfL measured by ELISA. Furthermore, interstitial matrix metalloproteinase type 1 (MMP-1) serum levels were measured as a potential new biomarker in ATTRv. Serum NfL and MMP-1 were measured using ELISA assays in 90 participants (29 ATTR-V30M patients, 31 asymptomatic V30M-TTR variant carriers and 30 healthy controls). Median NfL levels among ATTRv amyloidosis patients were significantly higher (116 pg/mL vs 0 pg/mL in both comparison groups). The AUC comparing ATTRv amyloidosis patients and asymptomatic carriers was 0.90 and the NfL concentration of 93.55 pg/mL yielded a sensitivity of 79% and a specificity of 87%. NfL levels had a significant positive correlation with NIS values among patients. We found a negative significant correlation between eGFR and NfL levels. Finally, MMP1 levels were not different between groups. Evidence of NfL use for early diagnosis of ATTR-PN amyloidosis is growing. ELISA seems a reliable and available technique for it quantification. Decreased GFR could influence NfL plasma levels.

A narrative review and expert recommendations on the assessment of the clinical manifestations, follow-up, and management of post-OLT patients with ATTRv amyloidosis

Orthotopic liver transplantation (OLT) was the first treatment able to modify the natural course of hereditary transthyretin (ATTRv) amyloidosis, which is a rare and fatal disorder caused by the accumulation of misfolded transthyretin (TTR) variants in different organs and tissues and which leads to a progressive and multisystem dysfunction. Because the liver is the main source of TTR, OLT dramatically reduces the production of the pathogenic TTR variant, which should prevent amyloid formation and halt disease progression. However, amyloidosis progression may occur after OLT due to wild-type TTR deposition, especially in the nerves and heart. In this review, we discuss the disease features influencing OLT outcomes and the clinical manifestations of ATTRv amyloidosis progression post-OLT to improve our understanding of disease worsening after OLT and optimize the follow-up and clinical management of these patients. By conducting a literature review on the PubMed database, we identified patient characteristics that have been associated with worse post-OLT outcomes, including late-onset V50M and non-V50M variants, age >40 years, long disease duration, advanced neuropathy and autonomic dysfunction, and malnutrition. Regarding post-OLT mortality, deaths occurring within the first year after OLT were mainly associated with fatal graft complications and infectious diseases, whereas cardiovascular-related deaths usually occurred later. Considering the diverse clinical manifestations of ATTRv amyloidosis progression post-OLT, including worsening neuropathy and/or cardiomyopathy, autonomic dysfunction, and oculoleptomeningeal involvement, we present advice on the most relevant tests for assessing disease progression post-OLT. Finally, we discuss the use of new therapies based on TTR stabilizers and TTR mRNA silencers for the treatment of ATTRv amyloidosis patients post-OLT.

A Descriptive Analysis of ATTR Amyloidosis in Spain from the Transthyretin Amyloidosis Outcomes Survey

Introduction

Transthyretin amyloidosis (ATTR amyloidosis) is a clinically heterogeneous disease caused by mutations in the transthyretin (TTR) gene or aggregation of wild-type transthyretin (ATTRwt). In Spain, there are two large endemic foci of ATTR amyloidosis caused by the Val30Met variant, with additional cases across the country; however, these data may be incomplete, as there is no centralized patient registry. The Transthyretin Amyloidosis Outcomes Survey (THAOS) is an ongoing, global, longitudinal, observational survey of patients with ATTR amyloidosis, including both inherited and wild-type disease, and asymptomatic patients with TTR mutations. This analysis aimed to gain a deeper understanding of the clinical profile of patients with ATTR amyloidosis in Spain.

Methods

This was a descriptive analysis of the demographic and clinical characteristics of symptomatic patients enrolled at six sites geographically dispersed throughout Spain (data cutoff: January 6, 2020). Patient data at enrollment, including genotype, demographics, and clinical presentation for symptomatic patients, were recorded. Patients were grouped by predominant phenotype based on clinical measures at enrollment: predominantly cardiac, predominantly neurologic, or mixed (cardiac and neurologic).

Results

There were 379 patients (58.0% male; 63.3% symptomatic) enrolled in the six THAOS sites in Spain. Predominant genotypes were the Val30Met mutation (69.1%) or ATTRwt (15.6%). Predominant phenotype distribution was neurologic (50.4%), mixed (35.8%), and cardiac (13.8%) for all symptomatic patients (n = 240); neurologic (67.8%), mixed (21.2%), and cardiac (11.0%) for symptomatic Val30Met (n = 146); and mixed (64.9%), cardiac (22.8%), and neurologic (12.3%) for symptomatic ATTRwt (n = 57). Symptomatic patients reported a range of ATTR amyloidosis signs and symptoms at enrollment, with autonomic neuropathy and sensory neuropathy common in all phenotypes.

Conclusions

These results from THAOS highlight the phenotypic heterogeneity associated with ATTR amyloidosis in Spain and the importance of comprehensive neurologic and cardiac evaluations in all patients with ATTR amyloidosis.

Trial registration

ClinicalTrials.gov: NCT00628745.

Estimating the annual economic burden for the management of patients with transthyretin amyloid polyneuropathy in Spain

Background: Transthyretin amyloid polyneuropathy (ATTR-PN) is a fatal disease associated with substantial burden of illness. Three therapies are approved by the European Medicines Agency for the management of this rare disease. The aim of this study was to compare the total annual treatment specific cost per-patient associated with ATTR-PN in Spain.Methods: An Excel-based patient burden and cost estimator tool was developed to itemize direct and indirect costs related to treatment with inotersen, patisiran, and tafamidis in the context of ATTR-PN. The product labels and feedback from five Spanish ATTR-PN experts were used to inform resource use and cost inputs.Results: Marked differences in costs were observed between the three therapies. The need for patisiran- and inotersen-treated patients to visit hospitals for pre-treatment, administration, and monitoring was associated with increased patient burden and costs compared to those treated with tafamidis. Drug acquisition costs per-patient per-year were 291,076€ (inotersen), 427,250€ (patisiran) and 129,737€ (tafamidis) and accounted for the majority of total costs. Overall, the total annual per-patient costs were lowest for patients treated with tafamidis (137,954€), followed by inotersen (308,358€), and patisiran (458,771€).Conclusions: Treating patients with tafamidis leads to substantially lower costs and patient burden than with inotersen or patisiran.

Extracellular Volume Detects Amyloidotic Cardiomyopathy and Correlates With Neurological Impairment in Transthyretin-familial Amyloidosis

INTRODUCTION AND OBJECTIVES

Cardiac involvement determines prognosis and treatment options in transthyretin-familial amyloidosis. Cardiac magnetic resonance T₁ mapping techniques are useful to assess myocardial extracellular volume. This study hypothesized that myocardial extracellular volume allows identification of amyloidotic cardiomyopathy and correlates with the degree of neurological impairment in transthyretin-familial amyloidosis.

METHODS

A total of 31 transthyretin-familial amyloidosis patients (19 mean age, 49 ± 12 years; 26 with the Val30Met mutation) underwent a T₁ mapping cardiac magnetic resonance study and a neurological evaluation with Neuropathy Impairment Score of the Lower Limb score, Norfolk Quality of Life questionnaire, and Karnofsky index.

RESULTS

Five patients had cardiac amyloidosis (all confirmed by ^99mTc-DPD scintigraphy). Mean extracellular volume was increased in patients with cardiac amyloidosis (0.490 ± 0.131 vs 0.289 ± 0.035; P = .026). Extracellular volume correlated with age (R = 0.467; P = .008), N-terminal pro-B-type natriuretic peptide (R_S = 0.846; P < .001), maximum wall thickness (R = 0.621; P < .001), left ventricular mass index (R = 0.685; P < .001), left ventricular ejection fraction (R = -0.378; P = .036), Neuropathy Impairment Score of the Lower Limb (R_S = 0.604; P = .001), Norfolk Quality of Life questionnaire (R_S = 0.529; P = .003) and Karnofsky index (R_S= -0.517; P = .004). A cutoff value of extracellular volume of 0.357 was diagnostic of cardiac amyloidosis with 100% sensitivity and specificity (P < .001). Extracellular volume and N-terminal pro-B-type natriuretic peptide were the only cardiac parameters that significantly correlated with neurologic scores.

CONCLUSIONS

Extracellular volume quantification allows identification of cardiac amyloidosis and correlates with the degree of neurological impairment in transthyretin-familial amyloidosis. This noninvasive technique could be a useful tool for early diagnosis of cardiac amyloidosis and to track cardiac and extracardiac amyloid disease.

Rituximab as an effective alternative therapy in refractory idiopathic inflammatory myopathies

OBJECTIVES

To assess the efficacy and safety of B-lymphocyte depletion therapy (BCDT) utilising rituximab in refractory idiopathic inflammatory myositis.

METHODS

We retrospectively evaluated 16 adult patients with active dermatomyositis (DM) or polymyositis (PM) who received 1 gram rituximab intravenous infusions two weeks apart after failing to respond to conventional therapy. The clinical and biochemical response were analysed by the Myositis Intention to Treat index (MITAX) and the serum creatine kinase (CK) levels at baseline and 6 and 12 months after treatment. The primary efficacy outcome was 20% improvement in the MITAX index and 30% reduction in CK.

RESULTS

Eight patients responded to treatment and achieved both the MITAX and CK levels objectives within 6 months of rituximab therapy. Five out of these 8 responders remained clinically stable at 12 months and CK levels were still reduced or normalised. Of note, 4 patients who did not respond were re-assessed and had their diagnoses corrected. All patients showed adequate B cell depletion (BCD) with re-population occurring for a 15.4 months average (range 3-42 months). Those simultaneously treated with cyclophosphamide achieved more long-lasting depletion (average 18.6 months).

CONCLUSIONS

The heterogeneous clinical and serological characteristics of patients diagnosed with IIM probably explain why some, but not all patients respond to rituximab. Myositis overlap and anti-synthetase syndromes seem to respond better than other patient subsets.