Systemic Amyloidosis: an under- & misdiagnosed disorder

Archrob Khuhapinant, MD, PhD Division of Hematology, Department of Medicine,

Faculty of Medicine, Siriraj Hospital Mahidol University

CASE REPORT Male, 75 years-old. Previous history: myocardial infarction (placement 2 stents). Carpal tunnel surgery. Current history: cardiac congestive failure (dyspnea and oedema) MRI: LV and septum hypertrophy, late gadolinium diffuse myocardial enhancement.

IF(s): IgA-lambda IF(u): negative IgA: 1450 mg/dL FLC: kappa 1,07 mg/dL; lambda 2,05 mg/dL; ratio 0,52 24 h proteins (u): 250 mg Pro-BNP: 6108 pg/dL TnT: 0,02 ng/mL Bone marrow smear: plasma cells 7% Skeletal x-ray survey: absence of lytic lesions

Abdominal fat biopsy: Congo Red negative Heart Biopsy: large congo red + amyloid deposits Immunohistochemistry: AA negative, positive for both FLC kappa and lambda AP Diagnosis: Amyloidosis, probably AL

Proteomic (laser microdisection + mass spectrometry): TTR peptides Dx: senile amyloidosis (TTR wild-type) + MGUS

Amyloidosis: protein misfolding disease

Increased conc. Increased synthesis o Monoclonal LC* o SAA

Reduced clearance o β2-microglobulin

Mutations* o Transthyretin o Apolipoprotein AI o Lysozyme, etc.

Aging (inestability) o Transthyretin wt

Amyloid precursor

Proteolysis Lysosomal enzymes Metalloproteases Matrix components

Amyloid fibrils

Interactions with microenvironment of target organs

GAGs

Oligomers

aggregation of normally soluble proteins into soluble β-sheet fibrils which are deposited in target tissues causing progressive organ dysfunction

Organ dysfunction

SAP

AL72%

AA7%

AApoAI11%

ATTR9%

Other1%

AL Systemic Amyloidosis 10-15 cases/106 people-year

λ 75% k 25%

The most common types of systemic amyloidoses

Type (abbreviation)

Precursor (site of synthesis)

Organs involved

Heart Kidney Liver/GI

PNS/ ANS

Soft Tissue

Immunoglobulin LC amyloidosis (AL)

Monoclonal LC (BM plasma cells) X X X X X

Reactive amyloidosis (AA)

SAA1 (liver) (X) X X XANS

Senile systemic amyloidosis (SSA)

Transthyretin wild type (liver >90%)

X Transthyretin amyloidosis (ATTR)

Variant transthyretin, (liver >90%) X (X) X (X)

Fibrinogen amyloidosis (AFib)

Variant fibrinogen α-chain (liver)

X Apolipoprotein AI amyloidosis (AApoA-1)

Variant Apo A-1 (liver, intestine)

X X X (X)

Clinically is not possible to distinguish between different amyloidosis

74% 65% 24% 20% 15%

X 50%

Carpal tunnel

Clinical picture: related with affected organ(s)

• Rarely pathognomonic (<10%): periorbital ecchymoses, macroglossia…

The most common types of systemic amyloidoses

Type (abbreviation)

Precursor (site of synthesis)

Established Therapy

Immunoglobulin LC amyloidosis (AL)

Monoclonal LC (BM plasma cells)

Chemotherapy ASCT

novel agents Reactive amyloidosis (AA)

SAA1 (liver) Treat underlying diseases

new drug

Senile systemic amyloidosis (SSA)

Transthyretin wild type (liver >90%)

Supportive

Transthyretin amyloidosis (ATTR)

Variant transthyretin, >100 amyloidogenic mutations (liver >90%)

Liver/heart transplantation new drugs

Fibrinogen amyloidosis (AFib)

Variant fibrinogen α-chain (liver)

Organ transplantation

Apolipoprotein AI amyloidosis (AApoA-1)

Variant Apo A-1 (liver, intestine)

Organ transplantation Supportive

Unequivocal identification of amyloid protein is essential for: • appropriate treatment • assess prognosis • genetic counseling (when appropriate)

• Tissue of choice for histological diagnosis in patients with suspected systemic amyloid disease (S: 60%?)

• Available from virtually all patients, innocuous, fast, inexpensive

• Altenative sites: rectum, bone marrow, salivary glands

Fine-needle abdominal fat aspirate

Biopsy of involved organ

Diagnosis relies on demonstration on tissue biopsy of fibrillar deposits which are congophilic and birefringent under polarized light.

• Antibody availability

• Limited sensitivity and specificity: differences between native and misfolded and aggregated protein

• Contamination with serum proteins, charge interaction amyloid-antibody leading to background staining

Limitations of immunohistochemistry

Typing of amyloid deposits

anti-λ antibody

anti-SAA antibody

anti-κ antibody

anti-TTR antibody

Ultrastructural immunohistochemistry

- DNA analysis: hereditary amyloidosis

Typing of amyloid deposits

Theis JD, et al. J Mass Spectrom 2013; 48: 1067-77

Laser microdissection and mass spectrometry-based poteomic analysis of paraffin embedded tissue

Typing of amyloid deposits

Technique Overall (n. 115)

κ clones (n. 30)

λ clones (n. 85)

% positive (95% CI) IFE serum urine serum+urine FLC κ/λ ratio IFE serum + FLC κ/λ IFE serum+urine+FLC κ/λ

80 (72-87) 67 (58-75) 96 (91-98) 88 (68-94) 96 (91-98) 100 (97-100)

60 (42-76) 70 (52-84) 90 (75-97) 97 (85-100) 100 (90-100) 100 (90-100)

87 (79-93) 65 (55-75) 98 (92-100) 82 (69-89) 94 (97-98) 100 (96-100)

IF y FLC in AL amyloidosis

Palladini et al, Clin Chem. 2009;55:499-504.

99mTc DPD gammagraphy

AL ATTR

18F-Florbetapir PET scan

Diagnostic workup of systemic AL amyloidosis

Palladini G, et al. Blood 2016.

Suspicion

Diagnosis

Unequivocal typing

Staging

AL Amyloidosis • Risk stratification (Mayo staging system): pro-BNP

(>1800 pg/L), cTnT (>0,025 ng/mL), FLC-diff (>18 mg/dL)

Kumar R, et al. JCO 2012; 30: 989-95. Kourelis TV, et al. JCO 2013; 31: 4319-24.

Therapeutic approach to systemic AL amyloidosis

Palladini G, et al. Blood 2016.

Low clonal burden, short courses may be enough

Multidisciplinary approach

MDex vs BMDex

• MDEX: HR76% (CR30%); OS: 7 years • Worse results if reduced dexamethasone

• Bortezomib increases and accelerates response but no impact

on survival so far (interim results of RCT-ASH 2014). • Benefit in patients who can’t tolerate high doses of

dexamethasone.

Palladini G, et al. Leukemia 2014; 28: 2311-6. Palladini G, et al. Haematologica 2014; 99: 743-50.

Kastritis E, et al. ASH 2014. Paladini G, et al. ASH 2015.

Doxycycline (100 mg/12 h) in cardiac AL amyloidosis

Wechalekar A, et al. ASH 2015.

Wall JS, et al. PlosOne 2012. Liedtke M, et al. EHA 2015.

Gertz M, et al. J Clin Oncol 2016

NEOD 001

It appears that no patient with amyloidosis should be denied a trial of therapy.

M. Gertz. Blood 2013; 121: 3.301-2