Transthyretin deposition in the eye in the era of effective therapy for hereditary ATTRV30M amyloidosis

RNA Interference and Neuromuscular Diseases: A Focus on Hereditary Transthyretin Amyloidosis

Neuromuscular diseases are severe disorders affecting the peripheral nervous system, usually driving to death in a limited time. Many new drugs, through RNA-interference technology, are revolutionizing the prognosis and quality of life for these patients. Nevertheless, given the increased life expectancy, some new issues and phenotypes are expected to be revealed. In the transthyretin-mediated hereditary amyloidosis (ATTR-v, "v" for "variant"), the RNA interference was demonstrated to effectively reduce the hepatic synthesis of transthyretin, with a significant increase in disease progression in terms of polyneuropathy and cardiomyopathy. The increased life expectancy could promote the involvement of organs where the extra-hepatic transthyretin is deposited, such as the brain and eye, which are probably not targeted by the available treatments. All these issues are discussed in this editorial.

Ophthalmological involvement in wild-type transthyretin amyloidosis: A multimodal imaging study

BACKGROUND AND AIMS

Ophthalmological abnormalities have been reported in hereditary transthyretin-related amyloidosis (ATTRv, v for variant) but not in wild-type transthyretin-related amyloidosis (ATTRwt).

METHODS

Patients with ATTRwt, ATTRv, and light chain amyloidosis (AL) and healthy subjects (controls) underwent complete eye examination, including optical coherence tomography (OCT), OCT angiography (OCTA), and in vivo corneal confocal microscopy (CCM).

RESULTS

Seventeen ATTRwt, nine ATTRv, two ATTRv carriers, and seven AL patients were enrolled. Compared with other groups, ATTRwt patients had 10 letters lower visual acuity and a higher prevalence of glaucoma, cataract, and retinal pigment epithelium alterations. In the whole group of patients, especially in ATTRwt, we observed (1) a reduced corneal nerve fiber length and more tortuous stromal nerves at CCM, (2) a reduced macular volume and peripapillary nerve fiber layer thickness at OCT, and (3) impairment of peripapillary and macular vascularization at OCTA.

INTERPRETATION

Ophthalmological abnormalities are common in ATTRwt, significantly impairing visual acuity. Noninvasive imaging modalities allow for the identification of small nerve fibers and small vessel damage, which may represent further warning signs for early diagnosis of ATTRwt.

Hereditary transthyretin amyloid neuropathies: advances in pathophysiology, biomarkers, and treatment

Hereditary transthyretin (TTR) amyloid polyneuropathy is an autosomal dominant life-threatening disorder. TTR is produced mainly by the liver but also by the choroid plexus and retinal pigment epithelium. Detailed clinical characterisation, identification of clinical red flags for misdiagnosis, and use of biomarkers enable early diagnosis and treatment. In addition to liver transplantation and TTR stabilisers, three other disease-modifying therapies have regulatory approval: one antisense oligonucleotide (inotersen) and two small interfering RNAs (siRNAs; patisiran and vutrisiran). The siRNAs have been shown to stop progression of neuropathy and improve patients' quality of life. As none of the disease-modifying therapies can cross the blood-brain barrier, TTR deposition in the CNS, which can cause stroke and cognitive impairment, remains an important unaddressed issue. CRISPR-Cas9-based one-time TTR editing therapy is being investigated in a phase 1 clinical study. Identification of the earliest stages of pathogenesis in TTR variant carriers is a major challenge that needs addressing for optimal management.

Ocular findings in patients with acquired ATTRv amyloidosis following domino liver transplantation

PURPOSE

To investigate the presence of amyloidosis-related ocular findings in patients who received domino liver transplantation from ATTRv amyloidosis donors.

METHODS

We reviewed the ocular findings in patients who had previously undergone domino liver transplantation and received ophthalmologic examinations between January 2009 and March 2023. The presence of amyloidosis-related ocular findings was retrospectively assessed by two ophthalmologists.

RESULTS

During the study period, a total of 7 patients with 14 eyes were examined. All patients were considered as acquired ATTRv amyloidosis. The mean age at the final visit was 64.6±8.4 years (52-75 years), and the mean time since domino liver transplantation was 167.6±76.2 months (69-257 months). The two evaluators' assessments for amyloidosis-related ocular findings were completely identical. No amyloid fibril deposition was observed in the pupil, lens, or vitreous. Five patients (10 eyes) had a Schirmer test result of 5mm or less than 5 mm, and four patients with a total of 8 eyes underwent fluorescein angiography and indocyanine green angiography, and no evidence of retinal amyloid angiopathy was found on fluorescein angiography. However, three patients with 6 eyes showed choroidal amyloid angiopathy on indocyanine green angiography.

CONCLUSION

While cases of choroidal amyloid angiopathy were observed, serious amyloidosis-related ocular complications such as vitreous opacity or secondary glaucoma did not occur even in the long term after domino liver transplantation.

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.

Long-term surgical results of trabeculectomy for secondary glaucoma in Val30Met hereditary transthyretin amyloidosis

This study reports the long-term results of trabeculectomy (LEC) for secondary glaucoma in hereditary transthyretin (ATTRv) amyloidosis patients and its correlation with prior vitrectomy. A retrospective case series was conducted involving 31 consecutive eyes of 20 ATTRv amyloidosis patients who underwent LEC between 2007 and 2020. The mean follow-up period was 73.2 ± 37.0 months (range: 20-181 months). Postoperative intraocular pressures (IOPs) were evaluated based on the following criteria: (a) IOP between 6 and 21 mmHg without additional glaucoma surgeries, except for laser suture lysis, (b) IOP between 6 and 15 mmHg without additional glaucoma surgeries, except for laser suture lysis, and (c) IOP between 6 and 21 mmHg without additional glaucoma surgeries, except for needling and laser suture lysis. Kaplan-Meier analysis revealed survival rates after LEC of 0.52 at 36 months, 0.42 at 60 months, and 0.25 at 84 months under criterion (a); 0.49 at 36 months, 0.27 at 60 months, and 0.11 at 84 months under criterion (b); and 0.76 at 36 months, 0.71 at 60 months, and 0.65 at 84 months under criterion (c). Eyes with a history of small gauge transconjunctival vitrectomy (SGTV) exhibited a tendency towards lower survival rates, although no statistically significant difference was observed (log-rank test; p = 0.193 under criterion (a) and p = 0.0553 under criterion (b)). Our findings suggest that LEC and additional needling procedures can provide some control over IOP; however, the overall postoperative outcomes of LEC for ATTRv amyloidosis remain unsatisfactory, even in the era of SGTV with reduced conjunctival scarring.

OPHTHALMOLOGIC INVOLVEMENT IN PATIENTS WITH HEREDITARY TRANSTHYRETIN AMYLOIDOSIS

PURPOSE

The aim of this study was to determine the ophthalmologic involvement in patients with hereditary transthyretin amyloidosis and its correlation with the mutations described in the literature.

METHODS

Cross-sectional, noninterventional study. Fifty-two eyes of 26 consecutive patients diagnosed with hereditary transthyretin amyloidosis who visited the Puerta de Hierro-Majadahonda University Hospital from September 2019 to March 2022. All patients underwent complete ophthalmologic examination and multimodal imaging. Cardiologic, neurologic, digestive, and renal examinations were also recorded.

RESULTS

Eighteen eyes of the total (34.61%) showed amyloid-related ocular involvement, vitreous amyloid deposits being the most common ocular manifestation (18/52). Statistically significant differences were found for the presence of vitreous amyloid deposits ( P < 0.01), crystalline amyloid deposits ( P < 0.05), parenchymal amyloid deposits ( P < 0.01), and vascular alterations ( P < 0.01) when comparing affected and unaffected eyes. Moreover, affected eyes showed worse best-corrected visual acuity ( P < 0.01).

CONCLUSION

Ocular manifestations are present in a substantial number of patients with ATTR that could potentially lead to devastating consequences to patients' best-corrected visual acuity and quality of life. Therefore, it is important to emphasize the importance of multidisciplinary management and ophthalmologic assessment, follow-up and surgical treatment when necessary. To the best of our knowledge, this represents the largest series in Spain of amyloidosis' ophthalmologic involvement.

Drug and Gene Therapy for Treating Variant Transthyretin Amyloidosis (ATTRv) Neuropathy

Variant Transthyretin Amyloidosis (ATTRv) neuropathy is an adult-onset, autosomal dominant, lethal, multisystemic disease due to the deposition of mutated transthyretin (TTR) in various organs, commonly involving the peripheral nerves and the heart. Circulating TTR tetramers are unstable due to the presence of mutated TTR and dissociate into monomers, which misfold and form amyloid fibrils. Although there are more than 140 mutations in the TTR gene, the p.Val50Met mutation is by far the commonest. In the typical, early-onset cases, it presents with a small sensory fibre and autonomic, length-dependent, axonal neuropathy, while in late-onset cases, it presents with a lengthdependent sensorimotor axonal neuropathy involving all fibre sizes. Treatment is now available and includes TTR stabilizers, TTR amyloid removal as well as gene silencing, while gene editing therapies are on the way. Its timely diagnosis is of paramount importance for a better prognosis.

Leptomeningeal Disease Secondary to Thr60Ala Transthyretin Amyloidosis: Case Report and Review of the Literature

A 31-year-old woman with transthyretin (TTR) amyloidosis secondary to a Thr60Ala mutation developed recurrent stroke-like episodes with fluctuating mental status. Evaluation for stroke and seizures was unrevealing. She was found to have leptomeningeal contrast enhancement on magnetic resonance imaging, which was confirmed to be CNS TTR amyloidosis on histopathology following brain and dura biopsy. While leptomeningeal disease has rarely been known to be associated with TTR amyloidosis, this is the first documented case of leptomeningeal disease secondary to a Thr60Ala mutation in the TTR gene. A literature review of TTR amyloidosis is presented with special focus on the treatment of leptomeningeal TTR amyloidosis.

Does Patisiran Reduce Ocular Transthyretin Synthesis? A Pilot Study of Two Cases

BACKGROUND

Variant transthyretin-mediated amyloidosis (ATTR-v) is a well-characterized disease affecting the neurologic and cardiovascular systems. Patisiran has been approved for neurologic involvement as it reduces hepatic synthesis of transthyretin (TTR). Eye involvement is a lateonset feature increasing the risk of glaucoma and cataracts in patients.

AIMS

The aim of this case series was to assess whether patisiran can effectively reduce TTR synthesis in such a barrier-protected organ as the eye.

METHODS

Two patisiran-treated ATTR-v patients underwent serum and aqueous humor sampling to measure TTR levels detected by SDS-PAGE and immunoblotting. Serum samples were compared to healthy control (HC), whereas aqueous humor samples were compared to non-amyloidotic subjects affected by cataracts and glaucoma.

RESULTS

Serum TTR levels representative of hepatic synthesis were sharply lower in treated patients if compared to the HC (-87.5% and -93.75%, respectively). Aqueous humor TTR levels showed mild-tono reduction in treated patients compared to non-amyloidotic subjects with cataracts (-34.9% and +8.1%, respectively) and glaucoma (-41.1% and -2.1%).

CONCLUSION

Patisiran does not seem to be as effective in inhibiting ocular TTR synthesis as it is in inhibiting hepatic synthesis. Re-engineering the envelope could allow the drug to target RPE cells thus avoiding any ocular involvement.

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.

Application of optical coherence tomography angiography to assess systemic severity in patients with hereditary transthyretin amyloidosis

Hereditary transthyretin amyloidosis is an autosomal dominant form of amyloidosis caused by an abnormality in transthyretin, with various ocular manifestations. Among these, ocular amyloid angiopathy has attracted attention because of its direct link to visual impairment and its correlation with systemic severity. We hypothesized that optical coherence tomography angiographic parameters would be useful biomarkers of amyloidosis systemic severity and investigated their correlation with the systemic severity score. The primary outcome was the correlation between the systemic severity score and choriocapillaris flow deficit percentage. Secondary outcomes were the correlations between the systemic severity score and retinal optical coherence tomography angiographic parameters, including foveal avascular zone size and circularity and superficial/deep/total retinal perfusion and vessel densities. The choroidal and retinal vasculature was quantified in 36 eyes from 36 patients (age, 51.8±12.1 years; disease duration, 13.4±6.2 years). Ten eyes had a history of vitrectomy for vitreous opacity. Choriocapillaris flow deficit percentage was not significantly correlated with the systemic severity score (Spearman’s rank correlation: r = 2.96×10⁻², p = 0.863). Similarly, foveal avascular zone size and circularity, and superficial/deep/total retinal perfusion and vessel densities were not significantly correlated with the systemic severity score. These results may indicate that optical coherence tomography angiographic parameters are not sufficient to predict amyloidosis severity.

Monitoring the Patient with Retinal Angiopathy Associated with Hereditary Transthyretin Amyloidosis: Current Perspectives

Retinal angiopathy associated with hereditary transthyretin amyloidosis (ATTRv), if untreated, may lead to irreversible vision loss. Our purpose was to systematically review the clinical and imaging features of retinal angiopathy associated with ATTRv and assemble a monitoring approach for these patients. All types of original research studies reporting clinical and imaging findings on retinal angiopathy associated with ATTRv were included. The most common clinical findings were tortuous retinal vessels, microaneurysms, retinal hemorrhages, sheathing of retinal vessels, whitish amyloid deposits along retinal arteries, obliteration of retinal vessels, vitreous hemorrhage, retinal and iris neovascularization. The most relevant imaging findings were hyperautofluorescence of perivessel amyloid deposits; delayed arterial filling, vascular leakage, and retinal ischemia on fluorescein angiography; late hypercyanescence along the choroidal arteries on indocyanine green angiography; perivascular hyperreflective material, needle-shaped deposits on the retinal surface and macular edema on optical coherence tomography (OCT) and attenuated retinal vascular network on OCT-angiography. ATTRv patients should be strictly followed to detect and treat retinal angiopathy, avoiding complications. Both panretinal photocoagulation and intravitreal anti-vascular endothelial growth factor have been used to treat retinal angiopathy in ATTRv. In an individual that presents with retinal angiopathy of unknown etiology, ATTRv should be considered as in the differential diagnosis, even out of the initial core countries. The prognostic value of subclinical findings, namely in OCT-A, is not yet established.

Specific postoperative complications of vitrectomy in hereditary transthyretin amyloidosis

INTRODUCTION

Vitrectomy may improve visual acuity of hereditary transthyretin amyloidosis (ATTRv) patients presenting with vitreous opacities but is associated with severe complications. The objective of this study is to report visual outcomes, early and late complications of a series of ATTRv patients who underwent vitrectomy in the French ATTRv reference center.

METHODS

This retrospective, single-center study, included all ATTRv patients who underwent vitrectomy between 2002 and 2017. Data were collected on pre and postoperative best corrected visual acuity (BCVA) and early and late postoperative complications.

RESULTS

A total of 21 eyes from 15 patients were included. The mean postoperative follow-up was 40 ± 20 months (6-160 months). BCVA increased from 0.7 ± 0.4 LogMAR preoperatively to 0.3 ± 0.4 LogMAR (p = 0.003) at last postoperative visit. During follow-up, all initially glaucomatous eyes worsened, with three eyes (37%) requiring filtering surgery and two eyes (25%) had further vision loss. Among non-glaucomatous patients, four eyes (31%) developed glaucoma with two requiring trabeculectomy and one eye (8%) had further vision loss. Three eyes (three patients) presented with complications of amyloid angiopathy. Three eyes (three patients) experienced recurrence of vitreous deposits requiring surgical revision.

CONCLUSION

Due to the potential complications, vitrectomy in ATTRv requires specific perioperative management and life-long postoperative monitoring.

Subclinical retinal angiopathy associated with hereditary transthyretin amyloidosis - assessed with optical coherence tomography angiography

BACKGROUND

Retinal angiopathy is a known ocular manifestation of hereditary transthyretin amyloidosis (ATTRv). Optical coherence tomography angiography (OCT-A) is a recent noninvasive imaging technique, used in other retinal vascular diseases. Our purpose was to analyse subclinical changes in retinal vessels, with OCT-A, in patients with ATTRv amyloidosis.

METHODS

Observational cross-sectional study in Centro Hospitalar e Universitário do Porto in the cohort of patients with genetic diagnosis of ATTRv. Patients were included if they had just one eye with scalloped iris (the other eye without scalloped iris), postulating eyes were at different stages, in the same patient. Patients were excluded if they had other manifestations of ocular ATTRv amyloidosis, namely clinical retinal angiopathy and/or vitreous opacities. The group of eyes with scalloped iris were compared with eyes without scalloped iris, using paired tests. Values are shown as Δ = mean difference between groups; p = p-value, d = Cohen's d for effect size measurement.

RESULTS

Twenty-four patients (24 eyes in each group) were included. Mean age was 46.5 ± 5.0 years. Eyes with scalloped iris showed attenuated retinal vascular network: larger foveal avascular zone (FAZ) area (Δ = +0.02 mm², p = 0.002, d = 0.70); decreased foveal vascular density (Δ = -3.57%, p = 0.001, d = -0.75); superficial (Δ = -1.50%, p = 0.049, d = -0.43) and deep (Δ = -2.53%, p = 0.023, d = -0.50) plexus vascular density. Acircularity index was superior in scalloped iris eyes (Δ = 0.04, p = 0.004, d = -0.65), representing an abnormal FAZ morphology.

CONCLUSION

Scalloped iris in ATTRv eyes are associated with a more advanced subclinical retinal angiopathy, than eyes without scalloped iris. Our results identify for the first time and in vivo, early changes in retinal vessels in ATTRv amyloidosis. Henceforward, OCT-A may play a role in the evaluation of ATTRv patients oculopathy and the effectiveness of future eye targeting treatments.

Deposits on Retinal Surface Seen on OCT in Ocular Amyloidosis

PURPOSE

To investigate the tomographic features in patients with hereditary amyloidosis transthyretin (hATTR).

DESIGN

Retrospective case series and analysis of B-scan OCT images.

PARTICIPANTS

A total of 120 patients (240 eyes) diagnosed with hATTR.

METHODS

We performed a retrospective review of the treatment history and retrospective analysis of the OCT images of patients with hATTR. The parameters analyzed were the age at which the last OCT was performed, presence of ocular amyloidosis, history of pars plana vitrectomy (PPV), systemic treatment, and genetic mutations. Two independent evaluators evaluated the OCT images for characteristic needle-shaped pattern deposits on the retinal surface, and a third evaluator resolved any differences in their evaluations.

MAIN OUTCOME MEASURES

The frequency of characteristic needle-shaped deposits on the retinal surface seen on OCT.

RESULTS

The mean age at the time of the last OCT was 56.5 ± 14.9 years. Ninety-nine patients had gene encoding transthyretin (TTR) with the Val30Met mutation, and 21 patients had other mutations. Of 240 eyes, 128 had signs of ocular amyloidosis. Fifty of 73 eyes (68.5%) with a history of PPV for vitreous opacities exhibited characteristic deposits on OCT. Four of 31 eyes with vitreous opacity but without a history of PPV showed deposits on the retinal surface. No eyes without a history of vitreous opacities revealed the characteristic needle-shaped deposits.

CONCLUSIONS

Characteristic needle-shaped deposits on the retinal surface seen on OCT are significant because they are seen in most of the vitrectomized eyes presenting with ocular amyloidosis.

Recommendations for pre-symptomatic genetic testing for hereditary transthyretin amyloidosis in the era of effective therapy: a multicenter Italian consensus

Hereditary transthyretin amyloidosis (ATTRv, v for variant) is a late-onset, autosomal dominant disease caused by progressive extracellular deposition of transthyretin amyloid fibrils, leading to organ damage and death. For other late-onset fatal diseases, as Huntington’s disease, protocols for pre-symptomatic genetic testing (PST) are available since decades. For ATTRv, limited experience has been reported to date, mostly gathered before the availability of approved therapies. We aimed at developing recommendations for a safe and feasible PST protocol in ATTRv in the era of emerging treatments, taking also into account Italian patients’ characteristics and healthcare system rules. After an initial survey on ongoing approaches to PST for ATTRv in Italy, two roundtable meetings were attended by 24 experts from 16 Italian centers involved in the diagnosis and care of this disease. Minimal requirements for PST offer and potential critical issues were highlighted. By November 2019, 457 families affected by ATTRv with 209 molecularly confirmed pre-symptomatic carriers were counted. The median age at PST was 41.3 years of age, regardless of the specific mutation. Half of the Italian centers had a multidisciplinary team, including a neurologist, an internist, a cardiologist, a medical geneticist and a psychologist, although in most cases not all the specialists were available in the same center. A variable number of visits was performed at each site. Experts agreed that PST should be offered only in the context of genetic counselling to at risk individuals aged 18 or older. Advertised commercial options for DNA testing should be avoided. The protocol should consist of several steps, including a preliminary clinical examination, a pre-test information session, an interval time, the genetic test and a post-test session with the disclosure of the test results, in the context of an experienced multidisciplinary team. Recommendations for best timing were also defined. Protocols for PST in the context of ATTRv can be refined to offer at risk individuals the best chance for early diagnosis and timely treatment start, while respecting autonomous decisions and promoting safe psychological adjustment to the genetic result.