Impact of Baseline Neuropathy Severity on Vutrisiran Treatment Response in the Phase 3 HELIOS-A Study.

INTRODUCTION: Hereditary transthyretin (ATTRv, v for variant) amyloidosis is a rare, progressive, fatal disease with multisystem manifestations, caused by pathogenic variants in the transthyretin (TTR) gene. Vutrisiran, an RNA interference therapeutic that results in rapid TTR knockdown, improved neuropathy and quality of life (QOL) versus external placebo in patients with ATTRv amyloidosis with polyneuropathy in the phase 3 HELIOS-A study (NCT03759379). This post hoc analysis evaluates the impact of baseline neuropathy severity on response to vutrisiran treatment. METHODS: Patients were randomized (3:1) to vutrisiran (n = 122; 25 mg subcutaneous injection once every 3 months) or patisiran (n = 42; 0.3 mg/kg intravenous infusion once every 3 weeks), which served as a reference group. In this post hoc analysis, patients were grouped into quartiles of increasing baseline Neuropathy Impairment Score (NIS): Quartile (Q)1 ≥ 5.0 to ≤ 20.5; Q2 > 20.5 to ≤ 44.1; Q3 > 44.1 to ≤ 73.1; Q4 > 73.1 to ≤ 127.0. Mean change from baseline to Month 18 was summarized by quartile for a range of efficacy endpoints. RESULTS: Across all baseline NIS quartiles, vutrisiran demonstrated benefit versus external placebo in measures of neuropathy severity (modified NIS + 7), QOL (Norfolk Quality of Life-Diabetic Neuropathy), disability (Rasch-built Overall Disability Scale), gait speed (10-m walk test), and nutritional status (modified body mass index). Overall, patients in lower versus higher NIS quartiles (less severe neuropathy) at baseline maintained better scores at Month 18. The external placebo group progressively worsened in all measures at Month 18. CONCLUSIONS: Vutrisiran demonstrated benefit in neurologic function and other key efficacy measures versus external placebo across all four baseline neuropathy severity quartiles. Patients initiating vutrisiran earlier in their disease course retained the highest neurologic function level after 18 months, highlighting the importance of early diagnosis and treatment. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov: NCT03759379.

Impact of vutrisiran on exploratory cardiac parameters in hereditary transthyretin-mediated amyloidosis with polyneuropathy.

AIMS: HELIOS-A was a Phase 3, open-label study of vutrisiran, an RNA interference therapeutic, in patients with hereditary transthyretin (ATTRv) amyloidosis with polyneuropathy. This analysis evaluated vutrisiran's impact on exploratory cardiac endpoints in HELIOS-A patients. METHODS AND RESULTS: Patients were randomized 3:1 to subcutaneous vutrisiran 25 mg every 3 months or intravenous patisiran 0.3 mg/kg every 3 weeks (reference group) for 18 months. Exploratory cardiac endpoints included change from baseline in N-terminal prohormone of brain-type natriuretic peptide (NT-proBNP) and echocardiographic parameters versus external placebo (APOLLO study). The modified intent-to-treat (mITT) population comprised randomized patients receiving any study drug (n = 122). A cardiac subpopulation with evidence of cardiac amyloid involvement (n = 40) was prespecified. 99mTc scintigraphy exploratory assessments in a planned vutrisiran-treated cohort at select sites were compared with baseline. At Month 18, vutrisiran demonstrated beneficial effects on NT-proBNP versus external placebo in the mITT and cardiac subpopulations (adjusted geometric mean fold change ratio [95% confidence interval] 0.480 [0.383-0.600], p = 9.606 × 10-10 and 0.491 [0.337-0.716], p = 0.0004, respectively). Benefits or trends towards benefit in echocardiographic parameters versus external placebo were observed for both populations. In 99mTc scintigraphy assessments, 32/47 (68.1%) and 31/48 (64.6%) patients exhibited reduced normalized left ventricular total uptake and heart-to-contralateral lung ratio, respectively. Perugini grade was reduced or unchanged versus baseline in 55/57 (96.5%) evaluable patients. No increase in cardiac adverse events was observed with vutrisiran versus external placebo. CONCLUSIONS: Vutrisiran demonstrated evidence of potential benefit on cardiac manifestations in patients with ATTRv amyloidosis with polyneuropathy, with an acceptable safety profile.

Effect of Eplontersen on Cardiac Structure and Function in Patients With Hereditary Transthyretin Amyloidosis.

BACKGROUND: Hereditary transthyretin amyloidosis (ATTRv) is associated with polyneuropathy, cardiomyopathy, or both. The effects of eplontersen on cardiac structure and function were assessed. METHODS AND RESULTS: NEURO-TTRansform was an open-label trial involving 144 adults with ATTRv polyneuropathy (49 patients [34%] with cardiomyopathy) receiving eplontersen throughout and compared with a historical placebo group (n = 60; 30 patients [50%] with cardiomyopathy) from the NEURO-TTR trial at week 65. Treatment effect (eplontersen vs placebo), presented as mean difference (95% confidence interval) was analyzed after adjusting for age, sex, region, baseline value, ATTRv disease stage, previous ATTRv treatment, and V30M transthyretin variant. There were notable differences at baseline between the eplontersen group and historical placebo. In the cardiomyopathy subgroup, 65 weeks of eplontersen treatment was associated with improvement from baseline relative to placebo in left ventricular ejection fraction of 4.3% (95% confidence interval 1.40-21.01; P = .049) and stroke volume 10.64 mL (95% confidence interval 3.99-17.29; P = .002) while the remainder of echocardiographic parameters remained stable. CONCLUSIONS: Eplontersen was associated with stable or improved measures of cardiac structure and function vs historical placebo in patients with ATTRv polyneuropathy and cardiomyopathy. Further investigation into eplontersen's effect on transthyretin amyloid cardiomyopathy is being conducted in the CARDIO-TTRansform trial.

APOLLO-B, a study of patisiran in patients with transthyretin cardiac amyloidosis: primary long-term results from the open-label extension period

INTRODUCTION: The Phase 3 APOLLO-B study evaluates patisiran in patients (pts) with transthyretin (ATTR) cardiac amyloidosis over a 12-month (M) double-blind (DB) period, followed by an open-label extension (OLE) period when all pts receive patisiran (NCT03997383). Hypothesis: Patisiran provides long-term benefit in pts with ATTR cardiac amyloidosis. Aims: Describe safety and efficacy of patisiran during the APOLLO-B OLE (18M+). METHODS: Pts (18-85 yrs) with ATTR cardiac amyloidosis and heart failure history were randomized 1:1 to patisiran or placebo (pbo). Pts completing DB period were eligible to receive patisiran in the OLE for ≤36M. Results summarized based on DB treatment arm. Exploratory assessments include change from study baseline (CFB) in 6-minute walk test (6MWT), KCCQ-OS, NT-proBNP, and troponin I. RESULTS: In the DB period, 359 pts (pbo n=178; patisiran n=181) received study drug (median [range] age, 76.0 [41, 85] yrs; male, 89%; wtATTR, 80%; tafamidis at baseline, 25%); 334 (93%) entered the OLE. In patisiran arm, M12 and M18 results, respectively, were similar for each endpoint: 6MWT and KCCQ-OS (mean [SEM] CFB) −8.09 [5.73] vs −9.21 [6.04] meters (m) and 0.60 [1.36] vs 0.22 [1.48]; NT-proBNP and troponin I (geometric mean fold-CFB [95%CI]) 1.10 [1.03, 1.17] vs 1.17 [1.07, 1.27] and 1.11 [1.05, 1.18] vs 1.09 [1.01, 1.17]). In pbo arm, patisiran initiation in OLE was associated with a slower rate of worsening or relative stability across endpoints; CFB at M12 vs M18, respectively: 6MWT, −25.43 [5.61] vs −31.08 [5.45] m; KCCQ-OS, −3.41 [1.33] vs −4.02 [1.49]; NT-proBNP, 1.39 [1.28, 1.51] vs 1.53 [1.38, 1.71]; and troponin I, 1.29 [1.21, 1.38] vs 1.21 [1.13, 1.30]. Patisiran had an acceptable safety profile; no new concerns. OLE analyses are ongoing; updated data to be presented. CONCLUSIONS: The M18 results provide evidence that beneficial effects observed in DB period on functional capacity, health status, and quality of life were maintained by continued treatment with patisiran during the OLE. Pbo-treated pts initiating patisiran at M12 showed slowed worsening or stabilization in most endpoints at M18. Early treatment initiation is important: pbo-treated pts did not recover functional capacity or health lost prior to initiating OLE patisiran.

Patisiran Treatment in Patients with Transthyretin Cardiac Amyloidosis.

BACKGROUND: Transthyretin amyloidosis, also called ATTR amyloidosis, is associated with accumulation of ATTR amyloid deposits in the heart and commonly manifests as progressive cardiomyopathy. Patisiran, an RNA interference therapeutic agent, inhibits the production of hepatic transthyretin. METHODS: In this phase 3, double-blind, randomized trial, we assigned patients with hereditary, also known as variant, or wild-type ATTR cardiac amyloidosis, in a 1:1 ratio, to receive patisiran (0.3 mg per kilogram of body weight) or placebo once every 3 weeks for 12 months. A hierarchical procedure was used to test the primary and three secondary end points. The primary end point was the change from baseline in the distance covered on the 6-minute walk test at 12 months. The first secondary end point was the change from baseline to month 12 in the Kansas City Cardiomyopathy Questionnaire-Overall Summary (KCCQ-OS) score (with higher scores indicating better health status). The second secondary end point was a composite of death from any cause, cardiovascular events, and change from baseline in the 6-minute walk test distance over 12 months. The third secondary end point was a composite of death from any cause, hospitalizations for any cause, and urgent heart failure visits over 12 months. RESULTS: A total of 360 patients were randomly assigned to receive patisiran (181 patients) or placebo (179 patients). At month 12, the decline in the 6-minute walk distance was lower in the patisiran group than in the placebo group (Hodges-Lehmann estimate of median difference, 14.69 m; 95% confidence interval [CI], 0.69 to 28.69; P = 0.02); the KCCQ-OS score increased in the patisiran group and declined in the placebo group (least-squares mean difference, 3.7 points; 95% CI, 0.2 to 7.2; P = 0.04). Significant benefits were not observed for the second secondary end point. Infusion-related reactions, arthralgia, and muscle spasms occurred more often among patients in the patisiran group than among those in the placebo group. CONCLUSIONS: In this trial, administration of patisiran over a period of 12 months resulted in preserved functional capacity in patients with ATTR cardiac amyloidosis. (Funded by Alnylam Pharmaceuticals; APOLLO-B ClinicalTrials.gov number, NCT03997383.).

Eplontersen for Hereditary Transthyretin Amyloidosis With Polyneuropathy.

Importance: Transthyretin gene silencing is an emerging treatment strategy for hereditary transthyretin (ATTRv) amyloidosis. Objective: To evaluate eplontersen, an investigational ligand-conjugated antisense oligonucleotide, in ATTRv polyneuropathy. Design, Setting, and Participants: NEURO-TTRansform was an open-label, single-group, phase 3 trial conducted at 40 sites across 15 countries (December 2019-April 2023) in 168 adults with Coutinho stage 1 or 2 ATTRv polyneuropathy, Neuropathy Impairment Score 10-130, and a documented TTR variant. Patients treated with placebo from NEURO-TTR (NCT01737398; March 2013-November 2017), an inotersen trial with similar eligibility criteria and end points, served as a historical placebo ("placebo") group. Interventions: Subcutaneous eplontersen (45 mg every 4 weeks; n = 144); a small reference group received subcutaneous inotersen (300 mg weekly; n = 24); subcutaneous placebo weekly (in NEURO-TTR; n = 60). Main Outcomes and Measures: Primary efficacy end points at week 65/66 were changes from baseline in serum transthyretin concentration, modified Neuropathy Impairment Score +7 (mNIS+7) composite score (scoring range, -22.3 to 346.3; higher scores indicate poorer function), and Norfolk Quality of Life Questionnaire-Diabetic Neuropathy (Norfolk QoL-DN) total score (scoring range, -4 to 136; higher scores indicate poorer quality of life). Analyses of efficacy end points were based on a mixed-effects model with repeated measures adjusted by propensity score weights. Results: Among 144 eplontersen-treated patients (mean age, 53.0 years; 69% male), 136 (94.4%) completed week-66 follow-up; among 60 placebo patients (mean age, 59.5 years; 68% male), 52 (86.7%) completed week-66 follow-up. At week 65, adjusted mean percentage reduction in serum transthyretin was -81.7% with eplontersen and -11.2% with placebo (difference, -70.4% [95% CI, -75.2% to -65.7%]; P < .001). Adjusted mean change from baseline to week 66 was lower (better) with eplontersen vs placebo for mNIS+7 composite score (0.3 vs 25.1; difference, -24.8 [95% CI, -31.0 to -18.6; P < .001) and for Norfolk QoL-DN (-5.5 vs 14.2; difference, -19.7 [95% CI, -25.6 to -13.8]; P < .001). Adverse events by week 66 that led to study drug discontinuation occurred in 6 patients (4%) in the eplontersen group vs 2 (3%) in the placebo group. Through week 66, there were 2 deaths in the eplontersen group consistent with known disease-related sequelae (cardiac arrhythmia; intracerebral hemorrhage); there were no deaths in the placebo group. Conclusions and Relevance: In patients with ATTRv polyneuropathy, the eplontersen treatment group demonstrated changes consistent with significantly lowered serum transthyretin concentration, less neuropathy impairment, and better quality of life compared with a historical placebo. Trial Registration: ClinicalTrials.gov Identifier: NCT04136184; EU Clinical Trials Register: EudraCT 2019-001698-10.

Impact of Vutrisiran on Quality of Life and Physical Function in Patients with Hereditary Transthyretin-Mediated Amyloidosis with Polyneuropathy.

INTRODUCTION: Hereditary transthyretin (ATTRv; v for variant) amyloidosis, also known as hATTR amyloidosis, is a progressive and fatal disease associated with rapid deterioration of physical function and patients' quality of life (QOL). Vutrisiran, a subcutaneously administered RNA interference (RNAi) therapeutic that reduces hepatic production of transthyretin, was assessed in patients with ATTRv amyloidosis with polyneuropathy in the pivotal HELIOS-A study. METHODS: The phase 3 open-label HELIOS-A study investigated the efficacy and safety of vutrisiran in patients with ATTRv amyloidosis with polyneuropathy, compared with an external placebo group from the APOLLO study of the RNAi therapeutic patisiran. Measures of QOL and physical function were assessed. RESULTS: At month 18, vutrisiran improved Norfolk Quality of Life-Diabetic Neuropathy (Norfolk QOL-DN) total score (least squares mean difference [LSMD] in change from baseline [CFB]: -21.0; p = 1.84 × 10-10) and Norfolk QOL-DN domain scores, compared with external placebo. This benefit relative to external placebo was evident across all baseline polyneuropathy disability (PND) scores and most pronounced in patients with baseline PND scores I-II. Compared with external placebo, vutrisiran also demonstrated benefit in EuroQoL-Visual Analog Scale (EQ-VAS) score (LSMD in CFB: 13.7; nominal p = 2.21 × 10-7), 10-m walk test (LSMD in CFB: 0.239 m/s; p = 1.21 × 10-7), Rasch-built Overall Disability Score (LSMD in CFB: 8.4; p = 3.54 × 10-15), and modified body mass index (mBMI) (LSMD in CFB: 140.7; p = 4.16 × 10-15) at month 18. Overall, Norfolk QOL-DN, EQ-VAS, and mBMI improved from pretreatment baseline with vutrisiran, whereas all measures worsened from baseline in the external placebo group. At month 18, Karnofsky Performance Status was stable/improved from baseline in 58.2/13.1% with vutrisiran versus 34.7/8.1% with external placebo. CONCLUSION: Vutrisiran treatment provided significant clinical benefits in multiple measures of QOL and physical function in patients with ATTRv amyloidosis with polyneuropathy. Benefits were most pronounced in patients with earlier-stage disease, highlighting the importance of early diagnosis and treatment. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov: NCT03759379.

Characterising diflunisal as a transthyretin kinetic stabilizer at relevant concentrations in human plasma using subunit exchange.

Transthyretin (TTR) dissociation is the rate limiting step for both aggregation and subunit exchange. Kinetic stabilisers, small molecules that bind to the native tetrameric structure of TTR, slow TTR dissociation and inhibit aggregation. One such stabiliser is the non-steroidal anti-inflammatory drug (NSAID), diflunisal, which has been repurposed to treat TTR polyneuropathy. Previously, we compared the efficacy of diflunisal, tafamidis, tolcapone, and AG10 as kinetic stabilisers for transthyretin. However, we could not meaningfully compare diflunisal because we were unsure of its plasma concentration after long-term oral dosing. Herein, we report the diflunisal plasma concentrations measured by extraction, reversed phase HPLC separation, and fluorescence detection after long-term 250 mg BID oral dosing in two groups: a placebo-controlled diflunisal clinical trial group and an open-label Japanese polyneuropathy treatment cohort. The measured mean diflunisal plasma concentration from both groups was 282.2 µM ± 143.7 µM (mean ± standard deviation). Thus, quantification of TTR kinetic stabilisation using subunit exchange was carried out at 100, 200, 300, and 400 µM diflunisal concentrations, all observed in patients after 250 mg BID oral dosing. A 250 µM diflunisal plasma concentration reduced the wild-type TTR dissociation rate in plasma by 95%, which is sufficient to stop transthyretin aggregation, consistent with the clinical efficacy of diflunisal for ameliorating transthyretin polyneuropathy.

Efficacy and safety of vutrisiran for patients with hereditary transthyretin-mediated amyloidosis with polyneuropathy: a randomized clinical trial.

BACKGROUND: The study objective was to assess the effect of vutrisiran, an RNA interference therapeutic that reduces transthyretin (TTR) production, in patients with hereditary transthyretin (ATTRv) amyloidosis with polyneuropathy. METHODS: HELIOS-A was a phase 3, global, open-label study comparing the efficacy and safety of vutrisiran with an external placebo group (APOLLO study). Patients were randomized 3:1 to subcutaneous vutrisiran 25 mg every 3 months (Q3M) or intravenous patisiran 0.3 mg/kg every 3 weeks (Q3W) for 18 months. RESULTS: HELIOS-A enrolled 164 patients (vutrisiran, n = 122; patisiran reference group, n = 42); external placebo, n = 77. Vutrisiran met the primary endpoint of change from baseline in modified Neuropathy Impairment Score +7 (mNIS+7) at 9 months (p = 3.54 × 10-12), and all secondary efficacy endpoints; significant improvements versus external placebo were observed in Norfolk Quality of Life-Diabetic Neuropathy, 10-meter walk test (both at 9 and 18 months), mNIS+7, modified body-mass index, and Rasch-built Overall Disability Scale (all at 18 months). TTR reduction with vutrisiran Q3M was non-inferior to within-study patisiran Q3W. Most adverse events were mild or moderate in severity, and consistent with ATTRv amyloidosis natural history. There were no drug-related discontinuations or deaths. CONCLUSIONS: Vutrisiran significantly improved multiple disease-relevant outcomes for ATTRv amyloidosis versus external placebo, with an acceptable safety profile. CLINICALTRIALS.GOV: NCT03759379.

Characteristics of Patients with Hereditary Transthyretin Amyloidosis-Polyneuropathy (ATTRv-PN) in NEURO-TTRansform, an Open-label Phase 3 Study of Eplontersen.

INTRODUCTION: Hereditary transthyretin (ATTRv) amyloidosis is a rare, severe, progressive, debilitating, and ultimately fatal disease caused by systemic deposition of transthyretin (TTR) amyloid fibrils. ATTRv amyloidosis occurs in both males and females. Eplontersen (ION-682884), a ligand-conjugated antisense oligonucleotide designed to degrade hepatic TTR mRNA, is being evaluated for the treatment of ATTRv amyloidosis with polyneuropathy (ATTRv-PN) in the phase 3, international, multicenter, open-label NEURO-TTRansform study (NCT04136184). To describe the study population of this pivotal trial, here we report the baseline characteristics of patients enrolled in the NEURO-TTRansform study. METHODS: Patients eligible for NEURO-TTRansform were 18-82 years old with a diagnosis of ATTRv-PN and Coutinho stage 1 (ambulatory without assistance) or stage 2 (ambulatory with assistance) disease; documented TTR gene variant; signs and symptoms consistent with neuropathy associated with ATTRv; no prior liver transplant; and New York Heart Association (NYHA) functional class I or II. RESULTS: The NEURO-TTRansform study enrolled 168 patients across 15 countries/territories (North America, 15.5%; Europe, 38.1%; South America/Australia/Asia, 46.4%). At baseline, the study cohort had a mean age of 52.8 years, 69.0% of patients were male, and 78.0% of patients were White. The V30M variant was most prevalent (60.1% of patients), and prevalence varied by region. Overall, 56.5% and 17.3% of patients had received previous treatment with tafamidis or diflunisal, respectively. A majority of patients (79.2%) had Coutinho stage 1 disease (unimpaired ambulation) and early (before age 50) disease onset (53.0%). Time from diagnosis to enrollment was 46.6 (57.4) months (mean [standard deviation]). Most patients had a baseline polyneuropathy disability (PND) score of I (40.5%) or II (41.1%), and the mean modified Neuropathy Impairment Score + 7 (mNIS + 7) was 79.0. CONCLUSION: The recruited population in the ongoing NEURO-TTRansform study has global representation characteristic of contemporary clinical practice. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT04136184.

Hereditary transthyretin amyloidosis, also called ATTRv amyloidosis, is a rare and serious disease that is passed down within families. People with ATTRv amyloidosis have a genetic variant that causes their liver to make abnormal versions of the transthyretin protein (also known as "TTR"), which clump together into "clusters" called amyloids. The amyloid clusters build up in various body tissues and organs such as the liver, nerves, heart, and kidney, causing damage that could ultimately lead to death. ATTRv amyloidosis is a progressive disease, meaning that it gets worse over time. Liver transplant has traditionally been the only treatment option. Recently, drugs that target TTR have been approved by the FDA, and potential drugs are being tested in clinical trials. Eplontersen is designed to degrade TTR mRNA in the liver and inhibit the production of TTR protein. NEURO-TTRansform is a global phase 3 study investigating the effectiveness and safety of eplontersen in 168 adults with ATTRv amyloidosis with polyneuropathy (ATTRv-PN), a disease in which amyloid accumulation in peripheral nerves causes multisystem damage and eventually death. This scientific article describes the characteristics of the patients at enrollment, including age, gender, geographic location, and disease-related information, to help improve the understanding of ATTRv-PN. NEURO-TTRansform is an ongoing study, and the results will be published at a later time as prespecified in the analysis plan.

An additive destabilising effect of compound T60I and V122I substitutions in ATTRv amyloidosis.

BACKGROUND: The amyloidogenic transthyretin (TTR) variant, V122I, occurs in 4% of the African American population and frequently presents as a restricted cardiomyopathy. While heterozygosity for TTR V122I predominates, several compound heterozygous cases have been previously described. Herein, we detail features of ATTRv amyloidosis associated with novel compound heterozygous TTR mutation, T60I/V122I and provide evidence supporting the amyloidogenecity of T60I. METHODS: A 63-year-old African American female presented with atrial fibrillation, congestive heart failure, autonomic and peripheral neuropathy. In vitro studies of TTR T60I and V122I were undertaken to compare the biophysical properties of the proteins. RESULTS: Congophilic deposits in a rectal biopsy were immunohistochemically positive for TTR. Serum screening by isoelectric focussing revealed two TTR variants in the absence of wild-type protein. DNA sequencing identified compound heterozygous TTR gene mutations, c.239C > T and c.424G > A. Adipose amyloid deposits were composed of both T60I and V122I. While kinetic stabilities of T60I and V122I variants were similar, distinct thermodynamic stabilities and amyloid growth kinetics were observed. CONCLUSIONS: This report provides clinical and experimental results supporting the amyloidogenic nature of a novel TTR T60I variant. In vitro data indicate that the destabilising effect of individual T60I and V122I variants appears to be additive rather than synergistic.

Impact of baseline polyneuropathy severity on patisiran treatment outcomes in the APOLLO trial.

OBJECTIVE: Assess how baseline polyneuropathy severity impacts response to patisiran regarding neurologic impairment and quality of life (QOL) in patients with hereditary transthyretin-mediated amyloidosis (ATTRv amyloidosis). METHODS: This post hoc analysis grouped patients from the Phase 3 APOLLO study (n = 225) by baseline Neuropathy Impairment Score (NIS) into quartiles: 6-<31; 31-<57; 57-<85.5; 85.5-141.6. Neurologic impairment (modified NIS+7 [mNIS+7], NIS total score), disability (Rasch-built Overall Disability Scale [R-ODS]), gait speed (10-meter walk test [10-MWT]), grip strength, and QOL (Norfolk Quality of Life-Diabetic Neuropathy [Norfolk QOL-DN] questionnaire) were assessed. RESULTS: Across all baseline NIS quartiles, patisiran improved several clinical markers of disease compared with placebo at 18 months. Patients in lower NIS quartiles, treated with patisiran earlier in the disease course, maintained better scores in mNIS+7, NIS total score, R-ODS, 10-MWT, grip strength, and Norfolk QOL-DN versus those in higher NIS quartiles, while placebo-treated patients experienced worsening of all functional measures after 18 months across all quartiles. CONCLUSIONS: Patisiran treatment improved neurologic function and QOL across a wide range of baseline polyneuropathy severities versus placebo. Timing of treatment initiation in patients with ATTRv amyloidosis remains critical for the preservation of function.(ClinicalTrials.gov number, NCT01960348).

Liver-directed drugs for transthyretin-mediated amyloidosis.

Transthyretin-mediated amyloidosis (ATTR) is a rare, under-recognized, progressively debilitating, fatal disease caused by the aggregation and extracellular deposition of amyloid transthyretin (TTR) fibrils in multiple organs and tissues throughout the body. TTR is predominantly synthesized by the liver and normally circulates as a homotetramer, while misfolded monomers aggregate to form amyloid fibrils. One strategy to treat ATTR amyloidosis is to reduce the amount of TTR produced by the liver using drugs that directly target the TTR mRNA or gene. This narrative review focuses on how TTR gene silencing tools act to reduce TTR production, describing strategies for improved targeted delivery of these agents to hepatocytes where TTR is preferentially expressed. Antisense oligonucleotides (ASOs) and small interfering RNAs (siRNAs), termed RNA silencers, cause selective degradation of TTR mRNA, while a TTR gene editing tool reduces TTR expression by introducing nonsense mutations into the TTR gene. Two strategies to facilitate tissue-specific delivery of these nucleic acid-based drugs employ endogenous receptors expressed by hepatocytes. Lipid nanoparticles (LNPs) that recruit apolipoprotein E support low-density lipoprotein receptor-mediated uptake of unconjugated siRNA and are now used for CRISPR gene editing tools. Additionally, conjugating N-acetylgalactosamine (GalNAc) moieties to ASOs or siRNAs facilitates receptor-mediated uptake by the asialoglycoprotein receptor. In summary, ATTR is a progressive disease with various clinical manifestations due to TTR aggregation, deposition, and amyloid formation. Receptor-targeted ligands (eg, GalNAc) and nanoparticle encapsulation (eg, LNPs) are technologies to deliver ASOs, siRNAs, and gene editing tools to hepatocytes, the primary location of TTR synthesis.

Light Chain Testing Abnormalities Among Patients With Transthyretin Amyloid Cardiomyopathy Referred for Technetium-99m Pyrophosphate Imaging.

Clinical algorithms stipulate that transthyretin amyloid cardiomyopathy (ATTR-CM) can be diagnosed noninvasively by technetium-99m pyrophosphate (PYP) imaging when light chain (AL) amyloidosis has been excluded. We sought to define the distribution of light chain abnormalities and final diagnosis of ATTR-CM among patients referred for PYP imaging. We conducted a retrospective cohort study of 378 sequential patients with suspected ATTR-CM, referred for PYP imaging from October 2014 to January 2019. PYP scans were adjudicated as per guidelines. We found that 97 patients (26%) had abnormal plasma cell dyscrasia (PCD) markers, including serum free light chain (FLC) and/or urine/serum immunofixation electrophoresis (IFE). After exclusions for incomplete data or known AL amyloidosis, the final study population with abnormal PCD testing was n = 82. Final adjudication of amyloidosis was determined by multidisciplinary clinical assessment and/or tissue biopsy. The median age of cohort was 75 (68 to 81) years, 88% were men, and 33% were Black. Of the 82 patients, 62 had positive PYP scans (76%) and 20 had negative PYP scans (24%). A total of 64 patients had adjudicated ATTR-CM, confirmed by tissue biopsy in 41 (64%). Of those with confirmed ATTR-CM, 44 (69%) had abnormal FLC ratio between 1.65 and 3.1 and normal IFE. In conclusion, among patients referred for technetium-99m-PYP imaging for suspected ATTR-CM, 26% exhibited abnormalities of PCD markers. An FLC ratio 1.65 to 3.1, with normal IFE was noted in 69% of those with ATTR-CM, suggesting that ATTR-CM can be diagnosed noninvasively without cardiac biopsy in patients with positive PYP scan and similar plasma cell testing results.

Long-term efficacy and safety of inotersen for hereditary transthyretin amyloidosis: NEURO-TTR open-label extension 3-year update.

BACKGROUND: Hereditary transthyretin amyloidosis (hATTR/ATTRv) results from the deposition of misfolded transthyretin (TTR) throughout the body, including peripheral nerves. Inotersen, an antisense oligonucleotide inhibitor of hepatic TTR production, demonstrated a favorable efficacy and safety profile in patients with the polyneuropathy associated with hATTR in the NEURO-TTR (NCT01737398) study. We report longer-term efficacy and safety data for inotersen, with a median treatment exposure of 3 years. METHODS: Patients who satisfactorily completed NEURO-TTR were enrolled in its open-label extension (OLE) study. Efficacy assessments included the modified Neuropathy Impairment Score + 7 (mNIS + 7), Norfolk Quality of Life-Diabetic Neuropathy (Norfolk QoL-DN) questionnaire total score, and the Short Form 36 (SF-36v2) Health Survey Physical Component Summary score. Safety and tolerability were also assessed. Efficacy is reported for patients living in Europe and North America (this cohort completed the study approximately 9 months before the remaining group of patients outside these regions); safety is reported for the full safety dataset, comprising patients living in Europe, North America, and Latin America/Australasia. This study is registered with ClinicalTrials.gov, identifier NCT02175004. RESULTS: In the Europe and North America cohort of the NEURO-TTR study, 113/141 patients (80.1%) completed the study, and 109 patients participated in the OLE study. A total of 70 patients continued to receive inotersen (inotersen-inotersen) and 39 switched from placebo to inotersen (placebo-inotersen). The placebo-inotersen group demonstrated sustained improvement in neurological disease progression as measured by mNIS + 7, compared with predicted worsening based on projection of the NEURO-TTR placebo data (estimated natural history). The inotersen-inotersen group demonstrated sustained benefit, as measured by mNIS + 7, Norfolk QoL-DN, and SF-36v2, compared with estimated natural history as well as compared with the placebo-inotersen group. With a maximum exposure of 6.2 years, inotersen was not associated with any additional safety concerns or increased toxicity in the OLE study. Platelet and renal monitoring were effective in reducing the risk of severe adverse events in the OLE study. CONCLUSION: Inotersen treatment for > 3 years slowed progression of the polyneuropathy associated with hATTR, and no new safety signals were observed.

Predictors of hematologic response and survival with stem cell transplantation in AL amyloidosis: A 25-year longitudinal study.

High-dose melphalan and stem cell transplantation (HDM/SCT) is an effective treatment for selected patients with AL amyloidosis. We report the long-term outcomes of 648 patients with AL amyloidosis treated with HDM/SCT over 25 years. Hematologic CR was achieved by 39% of patients. The median duration of hematologic CR was 12.3 years, and 45% of patients with a hematologic CR had no evidence of a recurrent plasma cell dyscrasia at 15 years after HDM/SCT. With a median follow-up interval of 8 years, the median event-free survival (EFS) and overall survival (OS) were 3.3 and 7.6 years, respectively. Patients with a hematologic CR had a median OS of 15 years, and 30% of these patients survived >20 years. On multivariable analysis, dFLC >180 mg/L and BM plasma cells >10% were independently associated with shorter EFS, whereas BNP >81 pg/mL, troponin I > 0.1 ng/mL, and serum creatinine >2.0 mg/dL were independently associated with shorter OS. We developed a prognostic score for EFS, which incorporated dFLC >180 mg/L and BMPC% >10% as adverse risk factors. Patients with low-risk (0 factors), intermediate-risk (1 factor), and high-risk (2 factors) disease had median EFS estimates of 5.3, 2.8, and 1.0 years, respectively (p < .001). The 100-day treatment-related mortality rate was 3% in the latest treatment period (2012-2021), and the 25-year risk of t-MDS/AML was 3%. We conclude that HDM/SCT induces durable hematologic responses and prolonged survival with improved safety in selected patients with AL amyloidosis.

Guidelines and new directions in the therapy and monitoring of ATTRv amyloidosis.

The recent approval of three drugs for the treatment of amyloid transthyretin (ATTR) amyloidosis, both hereditary and wild-type, has opened a new era in the care of these diseases. ATTR amyloidosis is embedded in its pathophysiology, and the drugs target critical steps of the amyloid cascade. In addition to liver transplant, which removes the pathogenic variants, the introduction of gene silencers has allowed the suppression of both wild type and mutant transthyretin (TTR), thus extending the potential therapeutic range to wild-type cardiac amyloidosis. The kinetic stabilisation of TTR using small molecules has proved to be clinically effective both for amyloid neuropathy and cardiomyopathy. Gene silencers and kinetic stabilizers were recently approved on the basis of the outcome of phase III trials; however, comparative trials have not been performed, making it difficult to draw recommendations. Indications for liver transplantation have narrowed considerably. Here, guidelines for therapy are proposed based on expert consensus, acknowledging that the several drugs currently undergoing clinical trials will probably change in the near future the therapeutic armamentarium and, consequently, the therapeutic strategy. Indications for monitoring disease progression and drug efficacy are also provided for the management of these complexes, but now very treatable, diseases.

A novel substitution of proline (P32L) destabilises ß2-microglobulin inducing hereditary systemic amyloidosis.

BACKGROUND: ß2-microglobulin amyloidosis was first described in the 1980s as a protein deposition disease associated with long-term haemodialysis. More recently, two inherited forms resulting from separate point mutations in the ß2-microglobulin gene have been identified. In this report, we detail a novel ß2M variant, P32L, caused by a unique dinucleotide mutation that is linked to systemic hereditary ß2-microglobulin amyloidosis. METHODS: Three family members from a Portuguese kinship featured cardiomyopathy, requiring organ transplantation in one case, along with soft tissue involvement; other involvements included gastrointestinal, neuropathic and sicca syndrome. In vitro studies with recombinant P32L, P32G, D76N and wild-type ß2-microglobulin were undertaken to compare the biophysical properties of the proteins. RESULTS: The P32L variant was caused by the unique heterozygous dinucleotide mutation c.154_155delinsTT. Amyloid disease featured lowered serum ß2-microglobulin levels with near equal amounts of circulating P32L and wild-type proteins; amyloid deposits were composed exclusively of P32L variant protein. In vitro studies of P32L demonstrated thermodynamic and chemical instability and enhanced susceptibility to proteolysis with rapid formation of pre-fibrillar oligomeric structures by N- and C-terminally truncated species under physiological conditions. CONCLUSIONS: This work provides both clinical and experimental evidence supporting the critical role of P32 residue replacement in ß2M amyloid fibrillogenesis.

Neurological manifestations of hereditary transthyretin amyloidosis: a focus on diagnostic delays.

BACKGROUND: The recent availability of disease-modifying therapies for hereditary transthyretin amyloid (ATTRv) amyloidosis warrants urgency for earlier diagnosis and timely identification of active disease state among genetic carriers. METHODS: We reviewed clinical neurological data of all patients with ATTRv amyloidosis with initial visits at our amyloidosis centre between January 2016 and December 2018. We abstracted the signs and symptoms of neurological manifestations, as well as rates and patterns of diagnostic testing. RESULTS: Of 92 patients with 19 different transthyretin (TTR) mutations, 66 and 36% had symptoms attributed to large-fibre and small-fibre neuropathy, respectively, compared to 75 and 66% with corresponding examination findings. Thirty-six patients with V122I ATTR mutation had asymptomatic polyneuropathy identified on neurological examination, eight without concurrent cardiac disease. Seventy-three percent of patients had symptoms of carpal tunnel syndrome (CTS), while 26% had dysautonomia. The average delays between the onset of symptoms of large fibre neuropathy (LFN) or CTS to ATTRv amyloidosis diagnosis were 2.9 and 6.7 years, respectively. DISCUSSION: Our study found higher rates of polyneuropathy by examination than patient-reported symptoms, especially among those with V122I TTR amyloidosis, signalling asymptomatic polyneuropathy. Our findings suggest the need for routine neurological examinations and other testing for genetic carriers to achieve earlier identification of active disease state.

Diflunisal treatment is associated with improved survival for patients with early stage wild-type transthyretin (ATTR) amyloid cardiomyopathy: the Boston University Amyloidosis Center experience.

BACKGROUND: Diflunisal is a non-steroidal anti-inflammatory drug that stabilises transthyretin (TTR) and reduces neurologic deterioration in patients with polyneuropathy caused by hereditary transthyretin amyloidosis (ATTRv). METHODS: We conducted a retrospective cohort study of patients with wild-type transthyretin cardiac amyloidosis (ATTRwt-CM) treated with diflunisal for at least one year between 2009 and 2016 at the Boston University Amyloidosis Centre. Baseline and one year follow up characteristics were measured, including plasma chemistries and echocardiography. Cox proportional hazards analysis assessed the primary outcome of all-cause mortality. RESULTS: A total of 104 ATTRwt-CM patients were evaluated with 35 patients receiving diflunisal. Patients in the diflunisal group were younger (73.8 vs 76.8 years, p = 0.034), with lower B-type natriuretic peptide (BNP, 335 +/- 67 vs. 520 +/- 296 pg/mL, p = 0.006), similar troponin I (0.1 +/- 0.1 vs 0.2 +/- 0.3 ng/mL, p = 0.09), and better renal function (eGFR 67 +/- 17 vs 53 +/- 18 mL/min/1.73m2, p = 0.0002) at baseline. Over a median follow-up of 3.2 years, 52 deaths occurred. Diflunisal administration was associated with improved survival in unadjusted analysis (HR 0.13, 95% CI 0.05 - 0.36, p < 0.001) that persisted after adjustment for age, baseline BNP, eGFR, troponin I, interventricular septal thickness, and left ventricular ejection fraction (HR 0.18, 95% CI 0.06 - 0.51, p = 0.0006). Over the observation period, no significant changes in BNP, troponin I, interventricular septal thickness or left ventricular ejection fraction were observed with diflunisal treatment. A total of 14 patients (40%) discontinued diflunisal in this study, but only 3 within the first year. Mean eGFR in treated patients was 59 ml/min/1.73m2 at 1 year (change from baseline p = 0.03). CONCLUSION: Diflunisal administration in ATTRwt-CM was associated with improved survival and overall stability in clinical and echocardiographic markers of disease with decrement renal function.