Julian D. Gillmore

Amyloid load and clinical outcome in AA amyloidosis in relation to circulating concentration of serum amyloid A protein.

BACKGROUND Reactive systemic (AA, secondary) amyloidosis occurs in chronic inflammatory diseases, and most patients present with nephropathy. The amyloid fibrils are derived from the circulating acute-phase reactant serum amyloid A protein (SAA), but the relation between production of fibril precursor protein, amyloid load, and clinical outcome in AA and other types of amyloidosis is unclear. METHODS We studied amyloidotic organ function and survival prospectively for 12-117 months in 80 patients with systemic AA amyloidosis in whom serum SAA concentration was measured monthly and visceral amyloid deposits were assessed annually by serum amyloid P component scintigraphy. Underlying inflammatory diseases were treated as vigorously as possible. FINDINGS Amyloid deposits regressed in 25 of 42 patients whose median SAA values were within the reference range (<10 mg/L) throughout follow-up, and amyloidotic organ function stabilised or improved in 39 of these cases. Outcome varied substantially among patients whose median SAA concentration exceeded 10 mg/L, but amyloid load increased and organ function deteriorated in most of those whose SAA was persistently above 50 mg/L. Estimated survival at 10 years was 90% in patients whose median SAA was under 10 mg/L, and 40% among those whose median SAA exceeded this value (p=0.0009). INTERPRETATION Although isolated amyloid fibrils are stable in vitro, AA amyloid deposits exist in a state of dynamic turnover, and outcome is favourable in AA amyloidosis when the SAA concentration is maintained below 10 mg/L. The potential for amyloid to regress and for the function of amyloidotic organs to recover support therapeutic strategies to decrease the supply of amyloid fibril precursor proteins in amyloidosis generally.

Outcome in systemic AL amyloidosis in relation to changes in concentration of circulating free immunoglobulin light chains following chemotherapy.

Summary. Monoclonal immunoglobulin light chains are deposited as amyloid fibrils in systemic AL (primary) amyloidosis, but the underlying plasma cell dyscrasias are often difficult to detect or unquantifiable. The relationships between circulating monoclonal light chains, amyloid load and clinical outcome, and the relative efficacies of chemotherapy regimens aimed at suppressing monoclonal immunoglobulin production, have not been determined. Circulating free immunoglobulin light chain (FLC) concentration was measured with a sensitive nephelometric immunoassay in 262 patients with AL amyloidosis, and followed serially in 137 patients who received either high‐dose chemotherapy or one of two intermediate‐dose cytotoxic regimens. Amyloid load was quantified by serum amyloid P component scintigraphy. A monoclonal excess of FLC was identified at diagnosis in 98% of patients. Among 86 patients whose abnormal FLC concentration fell by more than 50% following chemotherapy, 5‐year survival was 88% compared with only 39% among those whose FLC did not fall by half (P < 0·0001). Amyloid deposits regressed in 58 patients. The magnitude and duration of the FLC responses to intermediate‐ and high‐dose chemotherapy regimens were similar. The FLC assay enabled the circulating fibril precursor protein in AL amyloidosis to be quantified and monitored in most patients. Reduction of the amyloidogenic FLC by more than 50% was associated with substantial survival benefit, regardless of the type of chemotherapy used. Clinical improvement following chemotherapy in AL amyloidosis is delayed, but treatment strategies can be guided by their early effect on serum FLC concentration.

Antibodies to human serum amyloid P component eliminate visceral amyloid deposits

Accumulation of amyloid fibrils in the viscera and connective tissues causes systemic amyloidosis, which is responsible for about one in a thousand deaths in developed countries. Localized amyloid can also have serious consequences; for example, cerebral amyloid angiopathy is an important cause of haemorrhagic stroke. The clinical presentations of amyloidosis are extremely diverse and the diagnosis is rarely made before significant organ damage is present. There is therefore a major unmet need for therapy that safely promotes the clearance of established amyloid deposits. Over 20 different amyloid fibril proteins are responsible for different forms of clinically significant amyloidosis and treatments that substantially reduce the abundance of the respective amyloid fibril precursor proteins can arrest amyloid accumulation. Unfortunately, control of fibril-protein production is not possible in some forms of amyloidosis and in others it is often slow and hazardous. There is no therapy that directly targets amyloid deposits for enhanced clearance. However, all amyloid deposits contain the normal, non-fibrillar plasma glycoprotein, serum amyloid P component (SAP). Here we show that administration of anti-human-SAP antibodies to mice with amyloid deposits containing human SAP triggers a potent, complement-dependent, macrophage-derived giant cell reaction that swiftly removes massive visceral amyloid deposits without adverse effects. Anti-SAP-antibody treatment is clinically feasible because circulating human SAP can be depleted in patients by the bis-d-proline compound CPHPC, thereby enabling injected anti-SAP antibodies to reach residual SAP in the amyloid deposits. The unprecedented capacity of this novel combined therapy to eliminate amyloid deposits should be applicable to all forms of systemic and local amyloidosis.

Bortezomib With or Without Dexamethasone in Primary Systemic (Light Chain) Amyloidosis

PURPOSE To assess the efficacy and tolerability of bortezomib with or without dexamethasone and to define prognostic factors for patients with primary systemic light chain (AL) amyloidosis treated with bortezomib or both. PATIENTS AND METHODS Ninety-four patients from three centers were analyzed: 19% received the combination as first-line treatment, 81% had a median of two previous therapies, and 69% had refractory disease, while most patients had symptomatic heart involvement or elevated serum N-terminal pro-brain natriuretic peptide (NT-proBNP). Results A hematologic response was achieved in 71% within a median of 52 days, including 25% complete responses (CRs). Previously untreated patients had a 47% CR rate. Age 65 years or younger (P = .043) and twice weekly administration of bortezomib (P = .041) were associated with higher response rates. A cardiac response was documented in 29% of patients, in most as sustained improvement of functional class and less often as a decrease in wall thickness. Hematologic responses were associated with a cardiac response and NT-proBNP reduction. After a median follow-up of 12 months, 29% of patients had organ progression and 27% had hematologic progression. Median survival has not been reached and the 1-year survival rate is 76%. Baseline NT-proBNP was independently associated with survival (P = .001), while in a landmark analysis, survival was associated with NT-proBNP reduction of > or = 30% (P = .006) and achievement of hematologic response (P = .001). Toxicity was manageable and mostly consisted of neuropathy, orthostasis, peripheral edema, and constipation or diarrhea. CONCLUSION Bortezomib with or without dexamethasone is active in AL amyloidosis and induces rapid responses and high rates of hematologic and organ responses. Serial measurement of cardiac biomarkers is a powerful predictor of outcome.

Nonbiopsy Diagnosis of Cardiac Transthyretin Amyloidosis

Background— Cardiac transthyretin (ATTR) amyloidosis is a progressive and fatal cardiomyopathy for which several promising therapies are in development. The diagnosis is frequently delayed or missed because of the limited specificity of echocardiography and the traditional requirement for histological confirmation. It has long been recognized that technetium-labeled bone scintigraphy tracers can localize to myocardial amyloid deposits, and use of this imaging modality for the diagnosis of cardiac ATTR amyloidosis has lately been revisited. We conducted a multicenter study to ascertain the diagnostic value of bone scintigraphy in this disease. Methods and Results— Results of bone scintigraphy and biochemical investigations were analyzed from 1217 patients with suspected cardiac amyloidosis referred for evaluation in specialist centers. Of 857 patients with histologically proven amyloid (374 with endomyocardial biopsies) and 360 patients subsequently confirmed to have nonamyloid cardiomyopathies, myocardial radiotracer uptake on bone scintigraphy was >99% sensitive and 86% specific for cardiac ATTR amyloid, with false positives almost exclusively from uptake in patients with cardiac AL amyloidosis. Importantly, the combined findings of grade 2 or 3 myocardial radiotracer uptake on bone scintigraphy and the absence of a monoclonal protein in serum or urine had a specificity and positive predictive value for cardiac ATTR amyloidosis of 100% (positive predictive value confidence interval, 98.0–100). Conclusions— Bone scintigraphy enables the diagnosis of cardiac ATTR amyloidosis to be made reliably without the need for histology in patients who do not have a monoclonal gammopathy. We propose noninvasive diagnostic criteria for cardiac ATTR amyloidosis that are applicable to the majority of patients with this disease.

Amyloidosis and the respiratory tract

Amyloidosis is a generic term for a heterogeneous group of disorders associated with deposition of protein in an abnormal fibrillar form.1 The diverse spectrum of amyloid related diseases is now recognised to include Alzheimer’s disease, type II diabetes, and the transmissible spongiform encephalopathies. Amyloidosis can be hereditary or acquired, localised or systemic, and potentially lethal or merely an incidental finding. Amyloid deposits consist mainly of protein fibrils, the varying peptide subunits of which constitute the basis for its classification (table1).2 Despite much heterogeneity among their respective precursor proteins, all amyloid fibrils have a remarkably similar adopted ultrastructure and share many physicochemical properties attributable to their acquired rich β-sheet content.3Certain glycosaminoglycans (GAGs) are invariably associated with the fibrils and, in addition, all amyloid deposits contain the normal plasma protein serum amyloid P component (SAP). The specific binding interaction between SAP and all amyloid fibrils is the basis for our development of radiolabelled SAP as a diagnostic nuclear medicine tracer.4 5 View this table: Table 1 Classification of the more common types of amyloid and amyloidosis There have been many recent advances in amyloidosis including elucidation of the structure and properties of amyloid fibrils, the role of GAGs and SAP, and substantial improvements in clinical diagnosis and management. Although a specific generic treatment for the disease is not yet available, compelling evidence that amyloid deposits frequently regress when the supply of the respective fibril precursor protein is reduced has encouraged a much more positive approach to patient care.5 Amyloidosis is a disorder of protein folding which breaks the traditional dogma that amino acid sequence is the sole determinant of a protein’s tertiary form. Amyloid fibril proteins can evidently exist as two radically different stable structures—a normal soluble form and the highly abnormal fibril conformation. The pathogenesis of amyloidosis thus …

AMYLOIDOSIS: A REVIEW OF RECENT DIAGNOSTIC AND THERAPEUTIC DEVELOPMENTS

Amyloid deposition is associated with a diverse range of disorders that includes Alzheimers disease, type II diabetes mellitus and dialysis arthropathy. Although less common, systemic AA and AL amyloidosis remain important because effective treatments have increasingly become available.

Native T1 Mapping in Transthyretin Amyloidosis

OBJECTIVES The aims of the study were to explore the ability of native myocardial T1 mapping by cardiac magnetic resonance to: 1) detect cardiac involvement in patients with transthyretin amyloidosis (ATTR amyloidosis); 2) track the cardiac amyloid burden; and 3) detect early disease. BACKGROUND ATTR amyloidosis is an underdiagnosed cause of heart failure, with no truly quantitative test. In cardiac immunoglobulin light-chain amyloidosis (AL amyloidosis), T1 has high diagnostic accuracy and tracks disease. Here, the diagnostic role of native T1 mapping in the other key type of cardiac amyloid, ATTR amyloidosis, is assessed. METHODS A total of 3 groups were studied: ATTR amyloid patients (n = 85; 70 males, age 73 ± 10 years); healthy individuals with transthyretin mutations in whom standard cardiac investigations were normal (n = 8; 3 males, age 47 ± 6 years); and AL amyloid patients (n = 79; 55 males, age 62 ± 10 years). These were compared with 52 healthy volunteers and 46 patients with hypertrophic cardiomyopathy (HCM). All underwent T1 mapping (shortened modified look-locker inversion recovery); ATTR patients and mutation carriers also underwent cardiac 3,3-diphosphono-1,2-propanodicarboxylicacid (DPD) scintigraphy. RESULTS T1 was elevated in ATTR patients compared with HCM and normal subjects (1,097 ± 43 ms vs. 1,026 ± 64 ms vs. 967 ± 34 ms, respectively; both p < 0.0001). In established cardiac ATTR amyloidosis, T1 elevation was not as high as in AL amyloidosis (AL 1,130 ± 68 ms; p = 0.01). Diagnostic performance was similar for AL and ATTR amyloid (vs. HCM: AL area under the curve 0.84 [95% confidence interval: 0.76 to 0.92]; ATTR area under the curve 0.85 [95% confidence interval: 0.77 to 0.92]; p < 0.0001). T1 tracked cardiac amyloid burden as determined semiquantitatively by DPD scintigraphy (p < 0.0001). T1 was not elevated in mutation carriers (952 ± 35 ms) but was in isolated DPD grade 1 (n = 9, 1,037 ± 60 ms; p = 0.001). CONCLUSIONS Native myocardial T1 mapping detects cardiac ATTR amyloid with similar diagnostic performance and disease tracking to AL amyloid, but with lower maximal T1 elevation, and appears to be an early disease marker.

Cyclophosphamide, bortezomib, and dexamethasone therapy in AL amyloidosis is associated with high clonal response rates and prolonged progression-free survival

Bortezomib has shown great promise in the treatment of amyloid light-chain (AL) amyloidosis. We present our experience of 43 patients with AL amyloidosis who received cyclophosphamide, bortezomib, and dexamethasone (CVD) upfront or at relapse. Of these, 74% had cardiac involvement and 46% were Mayo Cardiac Stage III. The overall hematologic response rate was 81.4%, including complete response (CR) in 41.9% and very good partial response with >90% decrease in difference between involved/uninvolved light chain (VGPR-dFLC) in 51.4%. Patients treated upfront had higher rates of CR (65.0%) and VGPR-dFLC (66.7%). The estimated 2-year progression-free survival was 66.5% for patients treated upfront and 41.4% for relapsed patients. Those attaining a CR or VGPR-dFLC had a significantly better progression-free survival (P=.002 and P=.026, respectively). The estimated 2-year overall survival was 97.7% (94.4% in Mayo Stage III patients). CVD is a highly effective regimen producing durable responses in AL amyloidosis; the deep clonal responses may overcome poor prognosis in advanced-stage disease.

Bleeding symptoms and coagulation abnormalities in 337 patients with AL-amyloidosis.

Haemorrhage is a frequent manifestation of amyloidosis. We performed a retrospective clinical analysis of 337 patients with systemic immunoglobulin light‐chain (AL)‐amyloidosis, in whom whole‐body serum amyloid P component (SAP) scintigraphy and a clotting screen had been performed. Abnormal bleeding was noted in 94 cases (28%), and the coagulation screen was abnormal in 172 cases (51%). The most common abnormalities were prolongation of the thrombin time (TT; 108 cases, 32%) and the prothrombin time (PT; 82 cases, 24%). In multivariate analysis, a prolonged PT was the only coagulation abnormality associated with abnormal bleeding (P = 0·0012), but this was independent of the whole‐body amyloid load. Prolongation of the TT was associated with hepatic amyloid infiltration (P < 0·00001), with proteinuria (P < 0·001) and low serum albumin (P < 0·00001). In 154 patients who were studied further, subnormal factor X activity (FX:C) was found in 22 cases (14%). In cases with subnormal FX:C, the corresponding factor X antigen (FX:Ag) measurements were consistently higher (median FX:Ag/FX:C 2·5, range 0·81–9·25, n = 16) than cases with normal FX:C (median FX:Ag/FX:C 0·96, range 0·65–1·29, n = 28, P < 0·0001). No evidence was found of an FX inhibitor. Of the 48/154 (31%) cases with a prolonged TT, the reptilase time was also prolonged in 38/48 cases (79%). These data show that haemorrhage and abnormal coagulation are common in AL‐amyloidosis and are multifactorial in origin. We provide evidence suggesting that hepatic amyloid infiltration and nephrotic syndrome are determinants of the TT. In most patients, prolongation of the PT was explained by reduction in FX:C, but this was not wholly explained by a reduction in FX:Ag.