Disease-Modifying Drugs Extend Survival in Hereditary Transthyretin Amyloid Polyneuropathy.

Hereditary transthyretin (ATTRv) amyloidosis is a rare, fatal systemic disease, associated with polyneuropathy and cardiomyopathy, that is caused by mutant transthyretin (TTR). In addition to liver transplantation, several groundbreaking disease-modifying drugs (DMDs) such as tetrameric TTR stabilizers and TTR gene-silencing therapies have been developed for ATTRv amyloid polyneuropathy. They were based on a working hypothesis of the mechanisms of ATTRv amyloid formation. In this retrospective cohort study, we investigated survival of all 201 consecutive patients with ATTRv amyloidosis in our center. The effects of DMDs on survival improvements were significant not only in early-onset patients but also in late-onset patients. ANN NEUROL 2024;95:230-236.

Treatment of cardiac transthyretin amyloidosis: an update.

Transthyretin (TTR) is a tetrameric protein synthesized mostly by the liver. As a result of gene mutations or as an ageing-related phenomenon, TTR molecules may misfold and deposit in the heart and in other organs as amyloid fibrils. Cardiac involvement in TTR-related amyloidosis (ATTR) manifests typically as left ventricular pseudohypertrophy and/or heart failure with preserved ejection fraction. ATTR is an underdiagnosed disorder as well as a crucial determinant of morbidity and mortality, thus justifying the current quest for a safe and effective treatment. Therapies targeting cardiac damage and its direct consequences may yield limited benefit, mostly related to dyspnoea relief through diuretics. For many years, liver or combined heart and liver transplantation have been the only available treatments for patients with mutations causing ATTR, including those with cardiac involvement. The therapeutic options now include several pharmacological agents that inhibit hepatic synthesis of TTR, stabilize the tetramer, or disrupt fibrils. Following the positive results of a phase 3 trial on tafamidis, and preliminary findings on patisiran and inotersen in patients with ATTR-related neuropathy and cardiac involvement, we provide an update on this rapidly evolving field, together with practical recommendations on the management of cardiac involvement.

Diagnosis of amyloid neuropathy.

Systemic amyloidosis can be hereditary or acquired. The autosomal dominant hereditary transthyretin amyloidosis and the acquired light-chain amyloidosis, the result of a plasma cell dyscrasia, are multisystem disorders with cardiovascular, autonomic and peripheral nerve involvement. There are numerous investigational modalities available to diagnose systemic amyloidosis and to assess the extent of organ involvement, but it is frequently misdiagnosed due to its heterogeneous clinical presentations and misleading investigation findings. An accurate and timely diagnosis of amyloid neuropathy can greatly impact on the outcomes for patients, especially as there will soon be new gene-silencing treatments for hereditary transthyretin amyloidosis.

EGCG remodels mature alpha-synuclein and amyloid-beta fibrils and reduces cellular toxicity.

Protein misfolding and formation of beta-sheet-rich amyloid fibrils or aggregates is related to cellular toxicity and decay in various human disorders including Alzheimer's and Parkinson's disease. Recently, we demonstrated that the polyphenol (-)-epi-gallocatechine gallate (EGCG) inhibits alpha-synuclein and amyloid-beta fibrillogenesis. It associates with natively unfolded polypeptides and promotes the self-assembly of unstructured oligomers of a new type. Whether EGCG disassembles preformed amyloid fibrils, however, remained unclear. Here, we show that EGCG has the ability to convert large, mature alpha-synuclein and amyloid-beta fibrils into smaller, amorphous protein aggregates that are nontoxic to mammalian cells. Mechanistic studies revealed that the compound directly binds to beta-sheet-rich aggregates and mediates the conformational change without their disassembly into monomers or small diffusible oligomers. These findings suggest that EGCG is a potent remodeling agent of mature amyloid fibrils.

Minocycline corrects early, pre-plaque neuroinflammation and inhibits BACE-1 in a transgenic model of Alzheimer's disease-like amyloid pathology.

BACKGROUND: A growing body of evidence indicates that inflammation is one of the earliest neuropathological events in Alzheimer's disease. Accordingly, we have recently shown the occurrence of an early, pro-inflammatory reaction in the hippocampus of young, three-month-old transgenic McGill-Thy1-APP mice in the absence of amyloid plaques but associated with intracellular accumulation of amyloid beta petide oligomers. The role of such a pro-inflammatory process in the progression of the pathology remained to be elucidated. METHODS AND RESULTS: To clarify this we administered minocycline, a tetracyclic derivative with anti-inflammatory and neuroprotective properties, to young, pre-plaque McGill-Thy1-APP mice for one month. The treatment ended at the age of three months, when the mice were still devoid of plaques. Minocycline treatment corrected the up-regulation of inducible nitric oxide synthase and cyclooxygenase-2 observed in young transgenic placebo mice. Furthermore, the down-regulation of inflammatory markers correlated with a reduction in amyloid precursor protein levels and amyloid precursor protein-related products. Beta-site amyloid precursor protein cleaving enzyme 1 activity and levels were found to be up-regulated in transgenic placebo mice, while minocycline treatment restored these levels to normality. The anti-inflammatory and beta-secretase 1 effects could be partly explained by the inhibition of the nuclear factor kappa B pathway. CONCLUSIONS: Our study suggests that the pharmacological modulation of neuroinflammation might represent a promising approach for preventing or delaying the development of Alzheimer's disease neuropathology at its initial, pre-clinical stages. The results open new vistas to the interplay between inflammation and amyloid pathology.

[New elements in the diagnosis and the treatment of primary AL amyloid polyneuropathy and neuropathy due to POEMS syndrome]. / Nouveautés dans le diagnostic et le traitement des neuropathies périphériques liées à l'amylose AL et au syndrome POEMS.

INTRODUCTION: Primary AL amyloid polyneuropathy (AL-PN) and neuropathy due to POEMS syndrome (POEMS-N) are rare, associated with a monoclonal gammopathy (MG) IgGλ or IgAλ at a low rate and systemic manifestations. They are invalidating and life-threatening. STATE OF THE ART: AL-PN usually mimics small fiber length-dependent axonal polyneuropathies, but also multifocal or painful neuropathies, POEMS-N corresponds to a rapid ascending CIDP with MG. To confirm the diagnosis of AL-PN, initial investigations should identify amyloidosis on nerve or accessory salivary glands, to establish the type of amyloid after serum free light-chain (FLC) measurements. For the diagnosis of N-POEMS, diagnosis is based on the presence of four criteria proposed by Dispenzieri. These neuropathies are associated with biomarkers, useful for diagnosis and treatment monitoring: elevated serum level of FLC monoclonal in (AL-PN) or VEGF (N-POEMS). PERSPECTIVES: Early diagnosis of these neuropathies and early treatment using high-dose melphalan associated with an autologous hematopoietic stem cell graft or low monthly doses can improve the clinical manifestations and patient survival. CONCLUSIONS: Systematic search for monoclonal gammopathy by immunofixation and serum free light chains is very useful for the management of progressive peripheral neuropathies of unknown origin.

Primary AL amyloid polyneuropathy successfully treated with high-dose melphalan followed by autologous stem cell transplantation.

We report 2 patients with polyneuropathy associated with amyloid derived from light chains (AL) who were treated successfully with high-dose melphalan followed by autologous peripheral blood stem cell transplantation (HDM/SCT). Neuropathic symptoms improved in conjunction with normalization of serum-free light chains. In addition to amyloid deposits in tissues, an amyloidogenic light chain itself produced by abnormal plasma cells might be harmful to peripheral nerve function, and thus HDM/SCT seems to be a promising therapy for primary AL amyloid polyneuropathy.

The Bioequivalence of Tafamidis 61-mg Free Acid Capsules and Tafamidis Meglumine 4 × 20-mg Capsules in Healthy Volunteers.

Tafamidis, a non-nonsteroidal anti-inflammatory benzoxazole derivative, acts as a transthyretin (TTR) stabilizer to slow progression of TTR amyloidosis (ATTR). Tafamidis meglumine, available as 20-mg capsules, is approved in more than 40 countries worldwide for the treatment of adults with early-stage symptomatic ATTR polyneuropathy. This agent, administered as an 80-mg, once-daily dose (4 × 20-mg capsules), is approved in the United States, Japan, Canada, and Brazil for the treatment of hereditary and wild-type ATTR cardiomyopathy in adults. An alternative single solid oral dosage formulation (tafamidis 61-mg free acid capsules) was developed and introduced for patient convenience (approved in the United States, United Arab Emirates, and European Union). In this single-center, open-label, randomized, 2-period, 2-sequence, crossover, multiple-dose phase 1 study, the rate and extent of absorption were compared between tafamidis 61-mg free acid capsules (test) and tafamidis meglumine 80-mg (4 × 20-mg) capsules (reference) after 7 days of repeated oral dosing under fasted conditions in 30 healthy volunteers. Ratios of adjusted geometric means (90%CI) for the test/reference formulations were 102.3 (98.0-106.8) for area under the concentration-time profile over the dosing interval and 94.1 (89.1-99.4) for the maximum observed concentration, satisfying prespecified bioequivalence acceptance criteria (90%CI, 80-125). Both tafamidis regimens had an acceptable safety/tolerability profile in this population.

An automated microliter-scale high-throughput screening system (MSHTS) for real-time monitoring of protein aggregation using quantum-dot nanoprobes.

Protein aggregation is the principal component of numerous protein misfolding pathologies termed proteinopathies, such as Alzheimer's disease, Parkinson's disease, prion disease, and AA amyloidosis with unmet treatment needs. Protein aggregation inhibitors have great potential for the prevention and treatment of proteinopathies. Here we report the development of an automated real-time microliter-scale high throughput screening (MSHTS) system for amyloid aggregation inhibitors using quantum-dot nanoprobes. Screening 504 crude extracts and 134 low molecular weight aromatic compounds revealed the relationship of amyloid-ß (Aß) aggregation inhibitory activities of plant extracts using a plant-based classification. Within the eudicots, rosids, Geraniales and Myrtales showed higher activity. Screening low molecular weight aromatic compounds demonstrated that the structure of tropolone endows it with potential Aß aggregation inhibitory activity. The activity of the most active tropolone derivative was higher than that of rosmarinic acid. MSHTS also identified three chaperone molecules as tau aggregation inhibitors. These results demonstrate that our automated MSHTS system is a novel and robust tool that can be adapted to a wide range of compounds and aggregation-prone polypeptides.

Treatment of hereditary and acquired forms of transthyretin amyloidosis in the era of personalized medicine: the role of randomized controlled trials.

There have now been randomized controlled trials of four different therapeutics for hereditary amyloid polyneuropathy related to transthyretin (TTR) deposition and one for amyloidotic cardiomyopathy of both genetic and sporadic origin. It is likely that in the next few months those not already approved by either the US Food and Drug Administration (FDA) and/or the European Medicines Authority (EMA) will receive similar approvals for treatment for all or particular groups of patients. This is a far cry from circumstances less than 10 years ago when the only available therapy was gene replacement by liver transplant. The randomized controlled trials have shown that all the treatments (tafamidis, diflunisal, patisiran, and inotersen) are effective in the context of a clinical trial. However, we have very little idea of whether individual patients will respond in an equally positive way to all the drugs or whether there will be some who respond better to one or another or not respond at all, nor do we know whether combinations will be additive or synergistic. We lack validated markers of clinical response. While the small molecule TTR stabilizers increase serum TTR levels, the RNA-based drugs lower serum TTR. In the latter case, it is not clear that the reduction in serum TTR is related to the clinical response in a 1:1 fashion. Pharmaceutical companies have made substantial investments in the development of these agents and will clearly attempt to recoup those investments quickly. It is incumbent upon those of us who care for these patients to develop ways to assess the effects of therapy in the shortest possible time at the lowest possible cost. The better we are able to accomplish this the more likely it is that we will be able to treat the most patients in the most clinically efficient fashion regardless of their economic status. We now have the drugs we just have to figure out who should get them and when.

Influence of baseline neurologic severity on disease progression and the associated disease-modifying effects of tafamidis in patients with transthyretin amyloid polyneuropathy.

BACKGROUND: Emerging evidence suggests that several factors can impact disease progression in transthyretin amyloid polyneuropathy (ATTR-PN). The present analysis used longitudinal data from Val30Met patients participating in the tafamidis (selective TTR stabilizer) clinical development program to evaluate the impact of baseline neurologic severity on disease progression in ATTR-PN. METHODS: A linear mixed-effects model for repeated measures (MMRM) was constructed using tafamidis and placebo data from the intent-to-treat Val30Met population of the original registration study as well as tafamidis data from the two consecutive open-label extension studies. The second extension study is ongoing, but a prospectively-planned interim analysis involving a cleaned and locked database was conducted (cut-off: December 31, 2014). Val30Met patients are presented by treatment groups as those who received tafamidis during the registration and open-label studies (T-T group), or who received placebo during the registration study and were switched to tafamidis in the open-label studies (P-T group). Neurologic functioning was assessed at baseline and subsequent visits using the Neuropathy Impairment Score-Lower Limbs (NIS-LL). The analysis focused on the disease trajectory over the first 18 months of treatment. RESULTS: The T-T (n = 64) and P-T (n = 61) cohorts were predominantly Caucasian and presented with early-stage neurologic disease (mean [standard deviation] baseline NIS-LL values were 8.4 [11.4] and 11.4 [13.5], respectively). The MMRM analysis demonstrated that baseline severity is an independent significant predictor of disease progression in addition to the treatment effect: patients with a lower baseline NIS-LL showed less progression than those with a higher baseline NIS-LL (p < 0.0001). Neurologic progression in the T-T group was less than in the P-T group across all levels of baseline NIS-LL (p = 0.0088), and the degree of separation increased over the 18-month period. Similar results were seen with the NIS-LL muscle weakness subscale. CONCLUSIONS: This analysis of patients with Val30Met ATTR-PN demonstrates that neurologic disease progression strongly depends on baseline neurologic severity and illustrates the disease-modifying effect of tafamidis relative to placebo across a range of baseline levels of neurologic severity and treatment durations. These data also underscore the benefit of early diagnosis and treatment with tafamidis in delaying disease progression in ATTR-PN. TRIAL REGISTRATION: NCT00409175 , NCT00791492 and NCT00925002 registered 08 December 2006, 14 November 2008 (retrospectively registered), and 19 June 2009, respectively.

Refractory Pain Management in Amyloid-Associated Peripheral Neuropathy.

OBJECTIVE: Systemic amyloidosis is a disease that often involves multiple organ systems, including the peripheral nervous system. Patients may present with severe, refractory neuropathic pain; however, the optimal treatment approach for pain for these patients remains unclear. CASE REPORT: A man with severe, refractory neuropathic pain in his bilateral upper and lower extremities and the trunk secondary to amyloid neuropathy is presented. Multiple medication trials, including neuropathic and opioid agents, produced considerable adverse effects and minimal relief. Scrambler therapy, a novel electrical stimulation modality, was used and was associated with substantial short-term but nonsustained benefit. Spinal cord stimulation was considered, but given his diffuse symptoms, it was deemed a less-than-optimal approach. Ultimately, an intrathecal drug delivery system was placed with infusion of hydromorphone, resulting in substantial pain reduction in all involved areas and with an improved adverse effect profile. This intervention resulted in immense improvement in the patient's quality of life, despite progression of his systemic amyloidosis. CONCLUSIONS: Severe pain in the setting of amyloid neuropathy is often difficult to treat. To our knowledge, this represents the first report of Scrambler therapy or an implanted intrathecal drug delivery system used for a patient with refractory amyloidosis-related neuropathic pain, resulting in substantial analgesic benefit and improved quality of life.

Down regulation of a harmful variant protein by replacement of its normal protein.

To compensate for the hypoprotein and hypoalbuminemia of familial amyloidotic polyneuropathy (FAP) patients, 800 ml of fresh frozen plasma (FFP) was intravenously administered and change in total and variant transthyretin (TTR) levels were measured in the plasma. After injection of FFP, total plasma TTR levels were elevated and variant TTR levels decreased from 24 to 48 h, accompanied by an elevation of plasma total protein, albumin levels and TTR levels. To elucidate the mechanism of this phenomenon, a large amount of purified normal TTR from normal human plasma was intravenously injected in mice and FAP patients. By intravenous injection of 3 mg of the purified TTR to C57Black6, the expression of TTR mRNA decreased from 6 to 24 h post injection, and gradually increased up to 48 h post injection. After injecting 400 mg of normal TTR in each of 3 FAP patients, total plasma TTR levels were elevated and variant TTR levels decreased significantly from 24 to 48 h. These results suggested that down regulation of the harmful protein by replacement of its normal form of the protein occurred by this method. This phenomenon should be applied as the basis for one of the useful methods for decreasing the harmful proteins in the circulation.

Oxidative stress and amyloidosis.

From recent findings concerning free radical injury in several types of amyloidosis, it appears that free radical injury is involved either amyloid formation or in post-fibrillar modification. As we show in this review, among the more than 20 different types of amyloidosis, only a few types of amyloidosis present direct evidence of free radical involvement in amyloid formation. However, if we search further for other types of amyloidosis, other important information on free radical injury may be forthcoming. Free radical injury is probably central for the toxic properties of amyloid deposits.

Suppression of transthyretin expression by ribozymes: a possible therapy for familial amyloidotic polyneuropathy.

Familial amyloidotic polyneuropathy type 1 (FAP) is an autosomal-dominantly inherited disorder with systemic deposition of a variant transthyretin (TTR). We attempted to suppress TTR production by ribozyme degradation of TTR mRNA. Hammerhead and hairpin ribozymes cleaved TTR mRNA at specific individual sites in vitro. A ribozyme targeting a variant TTR (E61K) degraded the variant mRNA, but not a wild-type mRNA. These ribozymes also reduced the amounts of TTR mRNA and protein in HepG2 cells and COS-1 cells transfected with TTR-E61K cDNA. Ribozymes might be studied further as a potential treatment for FAP.

[Development of L-threo-DOPS, a norepinephrine precursor amino acid].

threo-Dihydroxyphenylserine (DOPS) is a synthetic amino acid which can be decarboxylated by L-aromatic amino acid decarboxylase to yield natural form of norepinephrine (l-NE), a principal neurotransmitter in both central and peripheral (sympathetic) nervous systems. Like L-Dopa as an agent for dopamine precursor therapy, DOPS was expected to have a potential as an agent for NE precursor therapy. Previous studies carried out by several groups in early 1970s, however, reached a negative conclusion that threo-DOPS was not an effective precursor of NE in the brain because of its low NE-increasing activity and weak pharmacological action. Since the latter half of 1970s, on the contrary, three Japanese research groups have successfully shown the possibility of DOPS as a useful NE-precursor. That is, Tanaka (Kobe Univ.) showed that L-threo-DOPS is the real l-NE precursor among four DOPS-enantiomers, and that it has several pharmacological activities such as a slow-onset and long-lasting pressor effect, an inhibitory effect on harmaline-induced tremor and so on. Hayashi and Suzuki (Osaka Univ.) found through the mobility study on familial amyloid polyneuropatchy (FAP) that the progress of the disease develops NE-deficiency (NE-D), that severe orthostatic hypotention in FAP might be due to NE-D, and that L-DOPS has favorable effects on this symptom. Narabayashi (Juntendo Univ.) found that NE-D develops in patients with advanced Parkinson's disease (PD), that a freezing phenomenon in these patients might be associated with NE-D, and that L-DOPS improves the phenomenon. Based on these findings, the development of L-DOPS for registration had been undertaken by Sumitomo Pharmaceuticals Co., and an approval was given to it in 1989 as an agent for the treatment orthostatic hypotention in FAP or Shy-Drager syndrome and freezing phenomenon in PD. Preclinical and clinical studies done in the R&D confirmed that L-DOPS markedly restored NE-D and improved related-syndrome in the NE-deficient animals/patients, and that its actions were slow-onset, long-lasting and gentle. The R & D of L-DOPS described in this paper includes studies on industrial production, efficacy pharmacology (mode of action), metabolism and clinical trial of this agent.

Smart Soup, a traditional Chinese medicine formula, ameliorates amyloid pathology and related cognitive deficits.

Alzheimer's disease (AD) is a progressive neurodegenerative disease that causes substantial public health care burdens. Intensive efforts have been made to find effective and safe disease-modifying treatment and symptomatic intervention alternatives against AD. Smart Soup (SS), a Chinese medicine formula composed of Rhizoma Acori Tatarinowii (AT), Poria cum Radix Pini (PRP) and Radix Polygalae (RP), is a typical prescription against memory deficits. Here, we assessed the efficacy of SS against AD. Oral administration of SS ameliorated the cognitive impairment of AD transgenic mice, with reduced Aß levels, retarded Aß amyloidosis and reduced Aß-induced gliosis and neuronal loss in the brains of AD mice. Consistently, SS treatment reduced amyloid-related locomotor dysfunctions and premature death of AD transgenic Drosophila. Mechanistic studies showed that RP reduced Aß generation, whereas AT and PRP exerted neuroprotective effects against Aß. Taken together, our study indicates that SS could be effective against AD, providing a practical therapeutic strategy against the disease.

Propranolol restores cognitive deficits and improves amyloid and Tau pathologies in a senescence-accelerated mouse model.

Ageing is associated with a deterioration of cognitive performance and with increased risk of neurodegenerative disorders. Hypertension is the most-prevalent modifiable risk factor for cardiovascular morbidity and mortality worldwide, and clinical data suggest that hypertension is a risk factor for Alzheimer's disease (AD). In the present study we tested whether propranolol, a ß-receptor antagonist commonly used as antihypertensive drug, could ameliorate the cognitive impairments and increases in AD-related markers shown by the senescence-accelerated mouse prone-8 (SAMP8). Propranolol administration (5 mg/kg for 3 weeks) to 6-month-old SAMP8 mice attenuated cognitive memory impairments shown by these mice in the novel object recognition test. In the hippocampus of SAMP8 mice it has been found increases in Aß(42) levels, the principal constituent of amyloid plaques observed in AD, accompanied by both an increased expression of the cleaving enzyme BACE1 and a decreased expression of the degrading enzyme IDE. All these effects were reversed by propranolol treatment. Tau hyperphosphorylation (PHF-1 epitope) shown by SAMP8 mice at this age was also decreased in the hippocampus of propranolol-treated mice, an effect probably related to a decrease in JNK1 expression. Interestingly, propranolol also phosphorylated Akt in SAMP8 mice, which was associated with an increase of glycogen synthase kinase-3ß phosphorylation, contributing therefore to the reductions in Tau hyperphosphorylation. Synaptic pathology in SAMP8 mice, as shown by decreases in synaptophysin and BDNF, was also counteracted by propranolol treatment. Overall, propranolol might be beneficial in age-related brain dysfunction and could be an emerging candidate for the treatment of other neurodegenerative diseases. This article is part of a Special Issue entitled 'Cognitive Enhancers'.

In vivo and in vitro effects of an apolipoprotein e mimetic peptide on amyloid-ß pathology.

BACKGROUND: Apolipoprotein E (ApoE) is the major apolipoprotein present in the high-density lipoprotein-like particles in the central nervous system (CNS). ApoE is involved in various protective functions in CNS including cholesterol transport, anti-inflammatory, and antioxidant effects. An ApoE peptide would be expected to exert protective effects on neuroinflammation. OBJECTIVE: To determine the effects of an ApoE mimetic peptide Ac-hE18A-NH2 on amyloid-ß pathology. METHOD: Using human APP/PS1ΔE9 transgenic mice and in vitro studies, we have evaluated the effect of an ApoE mimetic peptide, Ac-hE18A-NH2, on amyloid plaque deposition and inflammation. RESULTS: Administration of Ac-hE18A-NH2 to APP/PS1ΔE9 mice for 6 weeks (50 µg/mouse, 3 times a week) significantly improved cognition with a concomitant decrease in amyloid plaque deposition and reduced activated microglia and astrocytes, and increased brain ApoE levels. Oligomeric Aß42 (oAß42) and oxidized PAPC (ox-PAPC) inhibited secretion of ApoE in U251 cells, a human astrocyte cell line, and this effect was ameliorated in the presence of peptide Ac-hE18A-NH2. The peptide also increased Aß42 uptake in a cell line of human macrophages. CONCLUSIONS: Peptide Ac-hE18A-NH2 attenuates the effects of oxidative stress on ApoE secretion, inhibits amyloid plaque deposition, and thus could be beneficial in the treatment of Alzheimer's disease.

Tafamidis.

In November 2011, tafamidis (Vyndaqel; Pfizer), a small molecule that inhibits the dissociation of transthyretin tetramers, was granted marketing authorization by the European Commission for the treatment of transthyretin amyloidosis in adult patients with stage 1 symptomatic polyneuropathy to delay peripheral neurological impairment.