1. aTypical Haemolytic Uremic Syndrome disease overview
Dr. Faisal Alkandari
Consultant Pediatric Nephrologist
Ahmadi Hospital

2. Typical and atypical HUS
HUS is a systemic thrombotic microagniopathy TMA characterised by:1
Microangiopathic haemolytic anaemia
Thrombocytopenia
Renal failure
aHUS, atypical Haemolytic Uraemic Syndrome; HUS, haemolytic uraemic syndrome; TMA, thrombotic microangiopathy
1. Loirat C, Frémeaux-Bacchi V. Orphanet J Rare Dis 2011;6:60;
2. Loirat C et al. Pediatr Nephrol 2008;23: ;
3. Sánchez-Corral P, Melgosa M. Br J Haematol 2010;150:529-42 2

3. Clinical presentation of patients with STEC-HUS is similar to aHUS
Caused by an infection that activates complement
The cause of STEC-HUS is Shiga toxin produced by certain strains of the Escherichia coli bacteria (Shiga toxin-producing E. coli)
Shiga toxin directly activates the complement system as well as interferes with the normal regulation of complement
Shiga toxin damages endothelial cells, leading to platelet activation
Platelet activation and endothelial damage lead to multiple thrombi, inflammation and occlusion of small blood vessels throughout the body: systemic TMA
aHUS, atypical Haemolytic Uraemic Syndrome;
STEC-HUS, Shiga toxin-producing Escherichia coli–haemolytic uraemic syndrome; TMA, thrombotic microangiopathy

4. aTypical HUS aHUS is a lifelong chronic disease
caused by genetic defects in complement regulation that lead to uncontrolled and excessive complement activation2,3
aHUS, atypical Haemolytic Uraemic Syndrome; HUS, haemolytic uraemic syndrome; TMA, thrombotic microangiopathy
1. Loirat C, Frémeaux-Bacchi V. Orphanet J Rare Dis 2011;6:60;
2. Loirat C et al. Pediatr Nephrol 2008;23: ;
3. Sánchez-Corral P, Melgosa M. Br J Haematol 2010;150:529-42 4

5. Complement: always activated
Pathways of additional activation
C3 + water
Microbe
Antibody
Microbe
Alternative pathway
Classical
Lectin
Permanent activation of the complement system
“tick-over”
Complement stimulated by microbes, antibodies, foreign substances
Common infections (common cold, upper respiratory tract infection, gastroenteritis / diarrhoea), pregnancy, surgery, stress, exercise, trauma
Further increase complement activation
Complement is part of the innate immune system and it is fundamentally involved in the main effector mechanisms of antibody-mediated immunity.1
The individual complement reactions develop in a sequential manner, allowing regulation that modulates the intensity of the response and adjusts the effector functions that are generated.2
Complement plays a pivotal role in the activation of pro-inflammatory mediators, the generation of anaphylactic peptides, cytolytic compounds and antimicrobial compounds, the recruitment of effector cells and the induction of effector responses.2
Complement is always activated via the alternative pathway due to the ongoing interaction of C3 and water.
Complement is then further activated by three different pathways, including via the alternative pathway.
Unavoidable common infections and other simple triggers result in further activation of the complement system.
Because the complement system is always active and capable of destructive force, it must be tightly regulated to prevent unwanted damage to our tissues and organs.
References
Walport MJ. N Engl J Med 2001;344:
Zipfel PF, Skerka C. Nat Rev Immunol 2009;9:
Carroll MC. Nat Immunol 2004;5:981-6.
Figueroa JE, Densen P. Clin Microbiol Rev 1991;4:359-95; Walport MJ. N Engl J Med 2001;344: ; SOLIRIS® (eculizumab) [package insert]. Alexion Pharmaceuticals; 2009; Rother RP et al. Nat Biotechnol 2007;25: ; Meyers G et al. Blood 2007;110:Abstract 3683; Hill A et al. Br J Haematol 2010;149:414-25

6. Multiple naturally occurring proteins control complement
Regulate activation of complement
Prevent excessive activation and damage to own cells and organs
Inhibit and control the activation of complement
Integral to the normal functioning of complement
Factor H (CFH) C3
Factor I (CFI)
Factor B (CFB)
MCP (CD46)
Thrombomodulin
CD55, CD59
Several different proteins are involved in the control of the complement system. These proteins are either involved in the regulation or activation of complement.1
Complement regulators:
Complement factor H (CFH) is a plasma protein containing 20 homologous repeats that regulates the alternative complement pathway by competing with complement factor B (CFB) for C3b recognition through its role as a cofactor for complement factor I (CFI) and in enhancing the dissociation of the C3 convertase enzyme.2 CFH has been described as the most important complement regulator.3
CFI is a two-chain serine protease with the catalytic domain located on the light chain.3 The protein is predominantly synthesised by the liver and it regulates all three of the complement pathways by cleaving C3b and C4b in the presence of cofactor proteins.2,3
Membrane cofactor protein (MCP or CD46) is a widely expressed transmembrane glycoprotein that inhibits complement activation on host cells by acting as a membrane-bound cofactor for the cleavage of C3b and C4b facilitated by CFI.3 Intact MCP is also pivotal in preventing C3 activation on glomerular endothelium.2
Thrombomodulin (THBD) is a membrane-bound anticoagulant glycoprotein that facilitates complement inactivation by CFI in the presence of CFH.2 THBD also accelerates the thrombin-mediated activation of protein C, which is involved in the inhibition of further thrombin generation.4 THBD, therefore, plays a pivotal role in suppressing clot formation.
CD55 and CD59 are two widely expressed glycosyl phosphatidylinositol-anchored proteins that may be found on all haematopoietic lineages.5 CD59 is a 19 kDa glycoprotein that interacts directly with the membrane attack complex to prevent lytic pore formation through its role in blocking the aggregation of C9.6 CD55 is a 68 kDa glycoprotein that accelerates the destruction of membrane bound C3 convertase.
Complement activators:
C3 is the pivotal component of the complement system.7 Activation of the classical, lectin and alternative complement pathways cause the cleavage of C3 and the generation of C3b and the anaphylatoxin C3a.
CFB is a zymogen that carries the catalytic site of the alternative pathway convertase C3bBb.3 Upon interaction with C3b, CFB is cleaved into two fragments, Ba and Bb. Ba is released and Bb remains bound to C3b, forming the C3bBb convertase enzyme.
References
Waters AM, Licht C. Pediatr Nephrol 2011;26:41-57.
Noris M, Remuzzi G. N Engl J Med 2009;361:
Hirt-Minkowski P et al. Nephron Clin Pract 2010;114:c
Delvaeye M et al. N Engl J Med 2009;361:
Brodsky RA. Paroxysmal Nocturnal Hemoglobinuria. In: Hematology: Basic Principles and Practice, 4th ed. 2005;
Brodsky RA. Blood Rev Mar;22:65-74.
Frémeaux-Bacchi V et al. Blood 2008;112:
CFH, complement factor H, CFI, complement factor I; MCP, membrane cofactor protein; CFB, complement factor B
Noris M, Remuzzi G. N Engl J Med 2009;361: ; Noris M et al. Clin J Am Soc Nephrol 2010;5:

7. Chronic uncontrolled complement activation leads to devastating consequences in aHUS
Lectin pathway
Classical pathway
Alternative pathway
Immune complex clearance Microbial opsonisation
C5-convertase
C3a C3
C3b
Weak anaphylatoxin
C3 + H2O: always active (chronic)
Amplification
Proximal
Thrombomodulin −
iC3b
Natural inhibitors:
Factor H, I, MCP −
Gain of function Mutations: C3, CFB +
C5a
Potent anaphylatoxin
Chemotaxis
Pro-inflammatory
Leucocyte activation
Endothelial activation
Pro-thrombotic
C5b-9 Membrane attack complex
Cell lysis
Platelet activation C5
C5b C6 C7 C8 C9
Terminal
The alternative complement pathway provides continuous, low-level hydrolysis of C3 activation to produce the anaphylatoxin C3a and an opsonic fragment, C3b, which binds to plasma-exposed surfaces as a prelude to phagocytosis1-3
Generation of C3b also precedes the generation of C3 convertase, which amplifies C3 activation, and C5 convertase, which generates C5a and C5b
C5 activation yields the anaphylatoxin and chemoattractant C5a together with C5b, which initiates assembly of the terminal complement pathway C5b-9 (or membrane attack complex)
On host cells, complement activation is controlled by both membrane-anchored and fluid-phase regulators, favouring the cleavage of C3b to inactive C3b by complement factor I (ie cofactor activity) and dissociating the multicomponent C3 and C5 convertases (ie decay-acceleration activity)
In aHUS patients with loss-of-function mutations in complement regulatory genes (CFH, CFI, MCP and THBD [the thrombomodulin gene]), C3b is not degraded efficiently and forms the C3 and C5 convertases
Similarly, in atypical Haemolytic Uraemic Syndrome patients with gain-of-function mutations in CFB or C3, mutant CFB forms a superconvertase that is resistant to dissociation by complement factor H, while mutant C3b does not bind complement factor H and membrane cofactor protein and is resistant to degradation by complement factor I
References
Hirt-Minkowski P et al. Nephron Clin Pract 2010;114:c219-35
Barbour T et al. Nephrol Dial Transplant 2012;27:
Noris M, Remuzzi G. N Engl J Med 2009;361:
Anaphylaxis
Inflammation
Thrombosis
Consequences
Cell destruction
Inflammation
Thrombosis
Consequences
Zipfel PF et al. Vaccine 2008;26(Suppl 8):I67-74; Figueroa JE, Densen P. Clin Microbiol Rev 1991;4:359-95; Walport MJ. N Engl J Med 2001;344: ; Rother RP et al. Nat Biotechnol 2007;25: ; Meyers G et al. Blood (ASH Annual Meeting Abstracts) 2007;110:abs 3683; Hill A et al. Br J Haematol 2010;149: ; Hillmen P et al. Am J Hematol 2010;85:553-9; Parker C et al. Blood 2005;106: ; Hillmen P et al. N Engl J Med 1995;333:1253-8; Nishimura J et al. Medicine (Baltimore) 2004;83: ; Caprioli J et al. Blood 2006;108: ; Noris M et al. Clin J Am Soc Nephrol 2010;5: ; George JN. Blood 2010;116:4060-9; Loirat C et al. Pediatr Nephrol 2008;23: ; Ståhl AL et al. Blood 2008;111: ; Hosler GA et al. Arch Pathol Lab Med 2003;127;834-9; Ariceta G et al. Pediatr Nephrol 2009;24:687-96
aHUS, atypical Haemolytic Uraemic Syndrome 7

8. Chronic uncontrolled complement activation leads to endothelial and end organ damage
Clinical
consequences
Uncontrolled complement activation on cells
Endothelial cells - Activation
- Swelling and disruption
Platelet consumption
Mechanical haemolysis
Blood clotting
Vessel occlusion
Inflammation
Ischaemia
Systemic multi-organ complications
Red cells
Haemolysis
Platelets - Activation
- Aggregation
Leucocytes
- Activation
In atypical Haemolytic Uraemic Syndrome (aHUS), chronic uncontrolled complement activation causes platelet, endothelial and leucocyte activation1-5
Platelets and leucocytes bind to the endothelial surface, leading to the formation of pro-inflammatory factors
Endothelial swelling and disruption, which allows sub-endothelial accumulation of proteins and cell debris, together with fibrin and platelet-rich thrombi narrow the lumina of arterioles and capillaries
Endothelial damage and thrombosis within the microvasculature create abnormally high shear stress, leading to red cell destruction, with fragmented or distorted erythrocytes evident in blood smears
Exposure of the sub-endothelial extracellular matrix, which lacks endogenous complement regulators, results in tissue damage and destruction
The complement-mediated inflammation, thrombosis and systemic microvascular occlusion result in the clinical features of aHUS; haemolytic anaemia, thrombocytopenia and renal impairment
References
Desch et al. JASN 2007;18:2457–6240
Licht C et al. Blood :4538–4545
Noris M et al. NEJM 2009;361:1676–687
Stahl A et al. Blood 2008;111:5307–5315
Morigi et al. J Immunol 2011
Modified from Desch K et al. J Am Soc Nephrol 2007;18: ; Licht C et al. Blood 2009;114: ; Noris M, Remuzzi G. N Engl J Med 2009;361: ; Ståhl AL et al. Blood 2008;111: ; Morigi M et al. J Immunol 2011;187:172-80

9. Clinical measure of TMA
Decreased platelet count
Thrombus formation consumes platelets
Patient can present with thrombocytopenia
Platelet counts less than normal <150,000 per mm3
Patients can also present with declining platelet counts suggesting ongoing platelet consumption
Giant platelets may be observed in the peripheral smear
Microangiopathic haemolysis
In many cases, patients will present with microangiopathic haemolysis (also historically called MAHA)
Coombs test negative
Decreased haemoglobin
LDH greater than ULN
Low / undetectable haptoglobin concentrations
Schistocytes
Thrombotic microangiopathies (TMAs) are characterised by the presence of thrombocytopenia and haemolytic anaemia caused by the consumption and disruption of platelets and erythrocytes in the microvasculature.1
Thrombocytopenia is defined as:2
a platelet count of <150,000/mm3. In most cases, patients have platelet counts of <60,000/mm3
reduced platelet survival time. This reduced survival time shows that the patient is experiencing enhanced platelet disruption
giant platelets in the peripheral blood smear. When giant platelets occur, this is a sign that patients are experiencing secondary activation of thrombocytopoiesis.
Haemolytic anaemia is defined as:2
haemoglobin concentrations <10 mg/dL. Low haemoglobin concentrations are reported in the majority of cases and many patients have haemoglobin concentrations of <6.5 mg/dL
Iicreased serum lactate dehydrogenase (LDH) concentrations. Patients frequently experience very high LDH levels, which reflects not only haemolysis but also diffuse tissue ischaemia
hyperbilirubinemia (mainly unconjugated), reticulocytosis, circulating free haemoglobin concentrations, and low or undetectable haptoglobin concentrations. These findings are additional non-specific indicators of accelerated red cell disruption and enhanced production
detection of fragmented red blood cells (schistocytes) and a negative Coombs test. Both of these disease characteristics indicate that the patient is experiencing microangiopathic haemolysis.
References
Ruggenenti P et al. Kidney Int 2001;60:
Noris M, et al. In: GeneReviews. The NCBI handbook [internet]. Bethesda (MD): National Library of Medicine (US), NCBI; November [cited 14 Oct 2010]. Available at
Noris M, et al. In: GeneReviews. The NCBI handbook [internet]. Bethesda (MD): National Library of Medicine (US), NCBI; November [cited 14 Oct 2010]. Available at
Noris M, et al. Clin J Am Soc Nephrol 2010;5:
MAHA, microangiopathic haemolytic anaemia; LDH, lactate dehydrogenase; TMA, thrombotic microangiopathy; ULN, upper limit of normal

10. Similarities and differences between aHUS and STEC-HUS

11. Similarities and differences between aHUS and STEC-HUS
aHUS, atypical Haemolytic Uraemic Syndrome; STEC-HUS, Shiga toxin-producing Escherichia coli–haemolytic uraemic syndrome
Similarities and differences between aHUS and STEC-HUS
Factor
aHUS
STEC-HUS
Aetiology
Genetic inability to regulate complement; chronic uncontrolled complement activation1,2
Shiga toxin-producing bacterium, which activates complement 1; causing uncontrolled complement activation lasting weeks to months 3,4
Presentation
Low platelet count, haemolysis, thrombosis in small blood vessels throughout the body involving the brain, kidneys, heart and other organs 1,5
Low platelet count, haemolysis, thrombosis in small blood vessels throughout the body involving the brain, kidneys, heart and other organs 1,5
Age
About half of patients are adults 6,7
In the 2011 German epidemic, 88% were adults, although historically was seen as a paediatric disease 8,9
Diarrhoea
Yes, in 30% 11,12
Yes, commonly
Course
Life-long, chronic, uncontrolled complement activation 2,13
Uncontrolled complement activation lasts weeks to months after disease onset 3,4
Shiga-toxin
Negative 10 OR
Positive with relevant past medical history, family history, severe and prolonged disease course, or subsequent complement mutation
Positive but maintain high clinical suspicion of aHUS 11
1 study found complement genetic mutations in 22% of patients diagnosed with STEC-HUS, highlighting the high need for clinical suspicion of aHUS 11
Noris M et al. Nat Rev Nephrol 2012;8:
Nürnberger J et al. N Engl J Med 2009;360:542-4.
Thurman JM et al. Clin J Am Soc Nephrol 2009;4:
Ståhl AL et al. Blood 2011;117:
Noris M, et al. In: GeneReviews. The NCBI handbook [internet]. Bethesda (MD): National Library of Medicine (US), NCBI; November [cited 14 Oct 2010]. Available at
Caprioli J et al. Blood 2006;108:
Noris M et al. Clin J Am Soc Nephrol 2010;5:
Loirat C et al. Pediatr Nephrol 2008;23:
Frank C et al. N Engl J Med 2011;365:
Loirat C, Frémeaux-Bacchi V. Orphanet J Rare Dis 2011;6:60.
Bitzan M et al. Semin Thromb Hemost 2010;36:
Sellier-Leclerc AL et al. J Am Soc Nephrol 2007;18:
Lapeyraque AL et al. Pediatr Nephrol 2011;26:621-4.

12. Consequences of aHUS

13. aHUS is a genetic, devastating and life-threatening disease
aHUS causes vital organ damage1 and sudden death2
Chronic progressive course with premature mortality1,3,4
33–40% of patients die or progress to end-stage renal disease with the first clinical manifestation1,3
65% of all patients die, require dialysis or have permanent renal damage within the first year after diagnosis despite plasma exchange or plasma infusion3
1.00
0.75
0.50
0.25
0.00 3 6 25
12.5
Cumulative fraction of patients free of events
Follow-up (months)
The systemic thrombotic microangiopathy of atypical Haemolytic Uraemic Syndrome (aHUS) occurs throughout the body, affecting multiple vital organs,1,2 which can cause potentially fatal morbidities.3,4
aHUS is a chronic disease that causes progressive vital organ failure and premature death.5
33–40% of all patients die or progress to end-stage renal disease with the first clinical manifestation.2,6
65% of all patients die, require dialysis or have permanent renal damage within the first year after diagnosis despite plasma exchange or plasma infusion.6
References
Loirat C et al. Pediatr Nephrol 2008;23:
Noris M et al. Clin J Am Soc Nephrol 2010;5:
Sallée M et al. Nephrol Dial Transplant 2010;25:
Langman CB. Poster 0490 presented at the 17th Congress of the European Hematology Association, Amsterdam, The Netherlands, June 2012.
Noris M, Remuzzi G. N Engl J Med 2009;361:
Caprioli J et al. Blood 2006;108:
Modified from Caprioli J et al. Blood CFH mutations only depicted
1. Noris M et al. Clin J Am Soc Nephrol 2010;5: ; 2. Sallée M et al. Nephrol Dial Transplant 2010;25: ;
3. Caprioli J et al. Blood 2006;108: ; 4. Noris M, Remuzzi G. N Engl J Med 2009;361:
aHUS, atypical Haemolytic Uraemic Syndrome 13

14. Systemic, complement-mediated TMA affects multiple vital organs and tissues
Renal
>50% of patients progress to ESRD1
Elevated creatinine2
• Proteinuria3
• Oedema,4 malignant hypertension5
• Decreased eGFR6
Cardiovascular
<43% of patients experience
cardiovascular symptoms3
• Myocardial infarction8
• Hypertension9
• Diffuse vasculopathy6
• Peripheral gangrene10
Gastrointestinal
<30% of patients present with diarrhoea11
• Colitis7
• Nausea / vomiting12
• Pancreatitis12
• Abdominal pain7
• Gastroenteritis3
• Liver necrosis3
CNS
<48% of patients experience neurological symptoms3
• Confusion7
• Stroke7
• Encephalopathy5
• Seizure3
Blood
• Thrombocytopenia1
• Decreased haptoglobin1
• Elevated LDH1
• Decreased haemoglobin1
• Schistocytes1
Several different organs and tissues are affected by atypical Haemolytic Uraemic Syndrome (aHUS)
Renal impairment is a key feature in all patients with aHUS.1 Clinical studies have demonstrated that 50– 70% of patients with aHUS with CFH mutations die or develop end-stage renal disease within a year of onset of the disease2,3
In addition to renal impairment, severe hypertension is commonplace and instances of fatal myocardial infarction have been reported4
Approximately half of patients experience neurological symptoms, and cerebral dysfunction has been observed in patients with severe manifestations of aHUS5,6
The catastrophic consequences of aHUS can also have a significant impact on the lungs and liver. Pulmonary oedema has been reported in patients with complement factor H-associated aHUS, and severe thrombotic liver abnormalities and hepatic encephalopathy have also been observed3,4
Less commonly, ocular involvement7 and necrosis of peripheral extremities have been reported8
Pathological lesions in the adrenal glands have been noted at autopsy9
Patients with aHUS commonly report gastrointestinal symptoms. Despite the fact that bloody diarrhoea is a characteristic indicator for Shiga toxin-producing Escherichia coli-HUS, ~30% of patients with aHUS also report diarrhoeal symptoms.2,10,11 Additionally, in a clinical investigation of 45 individuals with aHUS, 84% of patients reported symptoms of intense abdominal pain and vomiting12
References
Caprioli J et al. Blood 2006;108:
Loirat C, Frémeaux-Bacchi V. Orphanet J Rare Dis 2011;6:60
Noris M et al. Clin J Am Soc Nephrol 2010;5:
Sallée M et al. Nephrol Dial Transplant 2010;25:
Neuhaus TJ et al. Arch Dis Child 1997;76:518-21
Ohanian M et al. Clin Pharmacol Adv App 2011;3:5-12
Larakeb A et al. Pediatr Nephrol 2007;22:
Malina M et al. Pediatr Nephrol 2011;26:
Loirat C et al. Pediatr Nephrol 2008;23:
Zuber J et al. Nat Rev Nephrol 2011;7:23-35
Dragon-Durey MA et al. J Am Soc Nephrol 2005;16:555-63
Dragon-Durey MA et al. J Am Soc Nephrol 2010;21:2180-7
Pulmonary
• Dyspnoea8 • Pulmonary haemorrhage13 • Pulmonary oedema8
Visual
• Ocular occlusion14
1. Caprioli J et al. Blood 2006;108: ; 2. Ariceta G et al. Pediatr Nephrol 2009;24:687-96; 3. Neuhaus TJ et al. Arch Dis Child 1997;76:518-21; 4. Ståhl AL et al. Blood 2008;111: ; 5. Noris M et al. Clin J Am Soc Nephrol 2010;5: ; 6. Loirat C et al. Pediatr Nephrol 2008;23: ; 7. Ohanian M et al. Clin Pharmacol 2011;3:5-12; 8. Sallée M et al. Nephrol Dial Transplant 2010;25: ; 9. Kavanagh D et al. Br Med Bull 2006;77-78:5-22; 10. Malina M et al. Pediatr Nephrol 2013;131:e331-5; 11. Zuber J et al. Nat Rev Nephrol 2011;7:23-35; 12. Dragon-Durey MA et al. J Am Soc Nephrol 2010;21:2180-7; 13. Sellier-Leclerc AL et al. J Am Soc Nephrol 2007;18: ; 14. Larakeb A et al. Pediatr Nephrol 2007;22:
CNS, central nervous system; eGFR, estimated glomerular filtration rate; ESRD, end-stage renal disease; LDH, lactate dehydrogenase; TMA, thrombotic microangiopathy

15. Misconceptions about aHUS

16. Some common misconceptions about aHUS
aHUS is not only a paediatric disease – aHUS affects all ages1
aHUS is not an acute disease – aHUS is a chronic, genetic and lifelong disease1-3
aHUS is not only a renal disease – aHUS is a systemic disease and affects multiple organ systems4
1. Noris M, Remuzzi G. N Engl J Med 2009;361: ; 2. Caprioli J et al. Blood 2006;108: ;
3. Noris M et al. Clin J Am Soc Nephrol 2010;5: ; 4. Langman CB. 17th EHA Congress 2012, abstract 0490; 5. Loirat C et al. Semin Thromb Hemost 2010;36:673-81
aHUS, atypical Haemolytic Uraemic Syndrome

17. Some common misconceptions about aHUS
aHUS diagnosis does not require identifiable genetic mutation – genetic mutations cannot be identified in many patients1
Plasma exchange / plasma infusion has not been proven in well-controlled trials to be safe or effective5
33–40% of patients die or progress to end-stage renal disease with the first clinical manifestation1,2
65% of all patients die, require dialysis or have permanent renal damage within the first year after diagnosis despite plasma exchange or plasma infusion2
1. Noris M, Remuzzi G. N Engl J Med 2009;361: ; 2. Caprioli J et al. Blood 2006;108: ;
3. Noris M et al. Clin J Am Soc Nephrol 2010;5: ; 4. Langman CB. 17th EHA Congress 2012, abstract 0490; 5. Loirat C et al. Semin Thromb Hemost 2010;36:673-81
aHUS, atypical Haemolytic Uraemic Syndrome

18. Is there any treatment available?
How to Manage aHUS
Is there any treatment available?

19. Eculizumab: humanised monoclonal antibody targeted at complement component C51
Human framework regions
No mutations
Germline sequence
FDA approved for treatment
Of aHUS in 2011
Complementarity-determining regions
(murine origin)
CH1
Hinge
Human IgG2 heavy-chain
constant region 1 and hinge
(eliminates Fc receptor binding) CL
Human IgG4 heavy-chain
constant regions 2 and 3
(eliminates complement activation)
Eculizumab (h5G1.1-mAb) is a humanised monoclonal antibody (mAb) derived from the murine anti-human C5 mAb.1
From ~30,000 murine anti-human C5 mAbs screened, m5G1.1 mAb was identified as effectively blocking both terminal complement complex-mediated haemolysis and the generation of C5a.1
To produce eculizumab, m5G1.1 mAb was engineered to reduce immunogenicity and eliminate effector functions.1
Murine complementarity-determining regions were grafted onto human heavy- and light- chain germline antibody framework sequences to minimise immunogenicity.
Human IgG2 and IgG4 heavy-chain sequences were combined to form a hybrid constant region that is unable to bind Fc receptors or activate the complement cascade.
The humanised mAb eculizumab maintained its ability to block the cleavage of C5 during complement activation, as shown by potent inhibition of the generation of C5a- and C5b- 9-mediated human serum haemolytic activity.2
The binding specificity and affinity of eculizumab for human C5 were not compromised by the humanisation process.1
References
Rother RP et al. Nat Biotechnol 2007;25:
Thomas TC et al. Mol Immunol 1996;33:
CH2
CH3
1. Rother RP et al. Nat Biotechnol 2007;25: 19

20. Eculizumab blocks terminal complement complex formation1
Complement cascade1
Eculizumab C3
C3a
Eculizumab binds with high affinity to C51,2
Terminal complement activity is blocked1
Proximal functions of complement remain intact1
Weak anaphylatoxin
Immune complex clearance
Microbial opsonisation
Proximal
C3b C5
C5a
Eculizumab (h5G1.1-mAb) is a humanised monoclonal antibody (mAb) derived from the murine anti-human C5 mAb.1
Eculizumab binds with high affinity to C5, thereby inhibiting its cleavage to C5a and C5b and preventing the formation of the terminal complement complex C5b-9, also known as the membrane attack complex.1,2
Targeted blockade at C5 with eculizumab prevents the deleterious properties of terminal complement activation while preserving the immunoprotective and immunoregulatory functions of proximal complement that are essential for microbial opsonisation, immune complex clearance and weak anaphylatoxin-mediated functions.1
References
Rother R et al. Nat Biotech 2007;25:
Soliris® (eculizumab) Summary of Product Characteristics. Alexion Europe SAS; 2012.
Terminal
C5b
C5b-9
1. Rother RP et al. Nat Biotechnol 2007;25: ;
2. Soliris® (eculizumab) Summary of Product Characteristics. Alexion Europe SAS; 2012 20

21. Experience in Kuwait

22. Case 1 11 yr old Canadian boy
Diagnosed with Ulcerative colitis for 2 years
followed in Amiri Hospital
On Imuran
Was admitted several times to Amiri hospital with bleeding per rectum

23. Case 1 On December 2010 presented with
Coke colored urine, Edema, decrease urine output preceded by bloody diarrhea and fever two weeks PTA.
Investigation revealed impaired renal function, low platelets and Hgb, with fragmented RBC.
Stool was negative

24. Case 1
He later became anuric, hypertensive , generalized edema. Started H.D through femoral line.
Because of ongoing hemolysis, he received multiple blood transfusion.
Imuran was discontinued (Thought to be a cause of TMA)
Plasmapheresis was started
Occasional complications ( pulmonary edema, hypocalcemia, hypotension)
Plasmapheresis was discontinued after one month of treatment and patient was watched carefully.

25. Case 1
Patient was weaned off H.D but remained to have renal impairment.
Parents reluctant to continue plasmapheresis
Few weeks later, routine blood investigations showed recurrence of hemolysis and thrombocytopenia.
Patient was soon back on H.D and plasmapheresis.
Hemolysis stopped but renal function never improved.

26. Watery diarrhea 2-3 x/day for one week PTA Fever X 3 days
Case 2
M A
7 yr
Previously Healthy
Watery diarrhea 2-3 x/day for one week PTA
Fever X 3 days
Repeated vomiting X 3 days
coke colored urine

27. Case 2 Blood Investigations
BUN 12.8
Cr 144
K Na 134
CBC
Hg 11.4
Plt 55
Wbc 11.3
Blood smear: fragmented RBC
Urine R/M
Prt , RBC + 3, Ket 3+
RBC >200
Urine C/S neg
LDH (145 – 345)
Coagulation profile N

28. Case No 1 Course in Hospital
Became oliguric
Rising Urea and Cr
Uremic symptoms
Cental line inserted
Started on H.D ( received two sessions)

29. Case 2 Course in hospital
Received heparin free dialysis in AM
@ 10:30 pm
C/O abdominal and chest pain , looks disoriented
O/E looked very pale, cold peripheries , mottled skin
Peripheral pulses not felt
BP was non recordable
Low O2 sat

30. Case 2
Patient was resuscitated and rushed to PICU
During intubation fresh bleeding from ETT
CXR white lungs
Patient declared Dead. Cause of death was massive pulmonary hemorrhage.

31. Two days later C3 level came back low

32. Case 3 8.5 yo old boy Red urine, fatigue, abdominal pain, vomiting
Hb 5.8, PLT 49
Blood Smear +schistocytes
Urine prt 5 g/L RBC > 200 WBC >200
Creatinine 568 µM, urea 43.9 mM

33. Investigations Na 130, K 4, PO4 2.1 LDH 3897 C4 0.11g/l (0.2- 0.8)
ANA –ve
Stool culture Neg

34. Clinical Course Acute HD femoral line Daily HD & PE
Mild improvement of hemolysis parameters (less PRBC transfusions)

35. Clinical Course Day 4-6, HD not functioning well + oliguria worsening
Day 6, severe Resp distress, desaturation, Resp failure  intubation
Blood from ETT tube ? Pulmonary hemorrhage
PICU: CRRT

36. Course of Treatment
Eculizumab initiated on Day 5 and second dose was given on Day 11and then continued according to the recommended dose and schedule.

40. Patient progress Patient improved clinically and hematologically
Discharged home
Remained hypertensive (Amlodipine) with nephrotic range proteinuria
Biochemical profile continued to improve
Latest Cr 35
Mild proteinuria
Eculizumab discontinued 6 months later (unable to get it)
He remained in remission

41. Case 4 4.5 months old boy Vomiting, fever, dark urine x 1day
Negative consanguinity

42. Case 4 CBC: Hgb 5.1 g/L, WBC 15, PLT 64, retics 7.9%
Smear: +schistocytes
BUN: 28.6 mM, creatinine 164 micromole/L
Normal serum electrolytes, HCO3 16
LDH 2264

43. Case 4 Low C3 0.655, C4 0.18 (borderline low)
Received PRBC & transferred to MKH
Conservative management
Oliguria, melena

44. LDH Level

47. Conclusion aHUS is a devastating disease
Delay in diagnosis and treatment could be due to misconceptions
In Kuwait, Patient presenting with HUS is aHUS until proven otherwise
The earlier you start Eculizumab the better is the outcome
Major drawback of the medication is that it is extremely expensive which affects patient’s management and puts the treating physician in a difficult situation.
Duration of treatment remains an issue to be solved.

48. Thank you