1. LISA N BOGGIO, MS, MD
RUSH UNIVERSITY
MEDICAL CENTER
Inhibitors in Congenital
Hemophilia

2. Faculty Disclosure
 CSL Behring – Advisory Board, Investigator
 Novo Nordisk – Investigator
 Baxter – Advisory Board, Investigator
 Bayer – Investigator
 Biogen-Idec - Investigator

3. Educational Objectives
 Identify patients at risk for developing factor VIII
(FVIII) and factor IX (FIX) inhibitors
 Evaluate treatment options for the management of
acute bleeding episodes in patients with inhibitors
 Discuss therapeutic options for the prevention of
bleeding in the surgical and nonsurgical setting

4. Introduction
 Congenital bleeding disorder
 X-linked
 Deficiency of FVIII or factor IX
 80%-85% FVIII deficiency (hemophilia A)
 60% is severe hemophilia
 15% moderate
 25% mild

5. Recurrent Joint Bleeding
©2009 Rush University Medical Center.
Right Left

6. Inhibitors
 Occur in up to 30% of patients with severe (<1%
FVIII) hemophilia A
 0.9%-7% of those with mild to moderate hemophilia A
 3% of those with hemophilia B
 Do not increase mortality, but bleeding more
difficult to control
 Uncontrollable hemorrhage, devastating joint disease and
disability

7. What Is an Inhibitor?
 Antibody to FVIII molecule
 IgG4 subclass
 Does not fix complement
 No immune complex disease
 Measured in Bethesda units (BU)
 Normal, <0.6 BU
 Low-responding inhibitor, 0.6-5 BU
 Transient or persistent
 High-responding inhibitor, >5 BU
 Anamnestic response

8. Mechanisms of FVIII Inhibitor Action
Scandella D. Vox Sang. 1999;77 (suppl 1):17-20.
FX
interaction
A2A3
FIXa Interactions
C1
C2
Phospholipid
interaction
FVIIIa
A1

9. Bethesda Unit
Kasper CK et al. Thromb Diath Haemorrh. 1975;34:869-872.
BU per mL Plasma
1 BU = amount of inhibitor that
inactivates half of FVIII
in incubation mixture
ResidualFVIII(%ofcontrol)
100
75
50
25
10
0 0.4 1 2

10. Genetics of FVIII Inhibitors
Schwaab R et al. Thromb Haemost.
1995;74:1402-1406.
 Certain molecular abnormalities are highly
associated with inhibitor development
 Large deletions (69% risk)
 Stop mutation (35% risk)
 Inversion of intron 22 (39% risk)
 Absence of protein may be associated with inhibitor
development

11. Inhibitor Prevalence in Hemophilia A
Oldenburg J, Pavlova A. Haemophilia.2006;12 (suppl 6):15-22.
Multidomain
88%
Large
deletions
41%
Intron 22/1
inversions
21%/17%
Single
domain
25%
Light chain
40%
Nonsense
31%
Heavy chain
40%
Non–A-Run
21%
Small
deletions
16%
Splice site
17%
A-Run
3%
C1-C2
Missense
Non–C1-C2
10%
5%
3%
100
75
50
25
0
InhibitorPrevalence(%)

12. Incidence of Inhibitors
Lusher JM et al. N Engl J Med. 1993;328:453-459. Bray G. Ann Hematol. 1994;68(suppl 3):S29-S34.
 FVIII: 15%-30%
 Less pure products may produce lower titer inhibitor
 Intermediate purity, 20%
 Monoclonal products, 16%
 Recombinant products, 24%
 25%: transient inhibitor
 30%: low-responding inhibitor
 45%: high-responding inhibitor

13. Onset of Bleeding and Inhibitors in Patients
With Severe Hemophilia
Pollmann H et al. Eur J Pediatr. 1999;158(suppl 3):S166-S170.
<5 BU
>5 BU
100
80
60
40
20
0
Patients(%)
FVIII Exposure (days)
0 50 100 150 200 250
%WithBleeding
100
80
60
40
20
0
Age (years)
0 1 2 3 4 5
Bleeding
All patientsJoint
Other
White GC II et al. Am J Hematol. 1982;13:335-342.

14. Inhibitor Development
Lusher JM et al. N Engl J Med. 1993;328:453-459; Bray G. Ann Hematol. 1994;(suppl 3):S29-S34; McMillan CW et al. Blood.
1988;71:344-348.
 Inhibitors usually develop in young patients
 Median, 20 months for pure products
 Present later in life for less pure product
 2% incidence for previously treated adults
 Inhibitor development occurs in severe hemophilia
(<2% FVIII activity)
 Mild-moderate (2.5% incidence)
 Inhibitors develop early after exposure: median, 9
doses

15. Treatment-Related Risk Factors for Inhibitor
Gouw SC et al. Blood. 2007;109:4648-4654.
 CANAL: Retrospective cohort study in 366 patients with
severe hemophilia A
 Age at first exposure
 Incidence ↓ from 41% in patients treated within first month of
age to 18% in patients first treated after 18 months
 Association largely disappeared after adjustment for treatment
intensity
 ↑ risk associated with surgical procedures and peak
treatments
 60% lower risk in patients on prophylactic vs on-demand
treatment

16. Risk Factors for Inhibitor Development
Viel KR et al. N Engl J Med. 2009;360:1618-1627; Ragni MV et al. Haemophilia. 2009;15:1074-1082.
• Mismatched recombinant FVIII replacement therapy
may be a risk factor for inhibitor development in
black patients
• In a prevalent case-control study of 950 patients
with hemophilia A enrolled in the Hemophilia
Inhibitor Study (HIS), the following are risk factors
for inhibitor development
– High intensity product exposure
– CNS bleeding
– African-American race
– Lack of missense mutations

17. Treatment Modalities
 Control Bleeding
 High dose factor replacement
 Porcine factor VIII
 Bypassing agents
 Prothrombin complex concentrates
 Recombinant factor VIIa
 Eradicate inhibitor
 Immune tolerance induction

18. Control Bleeding
 High dose factor
 Only helpful for low titer inhibitors
 Bypassing products
 Porcine factor VIII
 Activated prothrombin complex concentrate (aPCC)
 Recombinant factor VIIa (rFVIIa)

19. Porcine Factor VIII
Morrison et al. Blood 1993: 1513
 Not currently available
 Can follow factor VIII activity
 Complications: inhibitor, thrombocytopenia, DIC
 Study of 64 patients with acquired inhibitor
 Bleeding control
 Excellent 26
 Good 24
 Fair or poor 14
 Average dose 90 U/kg q12 hours

20. Activated Prothrombin Concentrates
Sjamsoedin LJ et al. N Engl J Med. 1981;305:717-721; Hilgartner MW et al. Blood. 1983;61:36-40.
• More effective than prothrombin concentrates (PCC)
• Dose: 50-75 U/kg, every 12 hours as needed for
bleeding resolution
• 36% of patients respond to a single dose of aPCC 50
U/kg within 12 hours
• Doses >200 U/kg/d associated with increased risk
for thrombosis
• Complications more prevalent than with PCC
– Especially disseminated intravascular coagulation
– Rare complications: MI, PE, DVT, allergic reactions

21. Recombinant Factor VIIa
Young G et al. Haemophilia. 2008;14:287-294; Kavakli K et al. Thromb Haemost. 2006;95:600-605.
 Mechanism of action: activation of FIX and FX
 Thrombin generation (amount and rate) essential
 Conventional dosing: 90 µg/kg every two hours until
hemostasis achieved
 Recent studies demonstrated that 270 μg/kg
single dose similar to 90 μg/kg x 3
 Gradually increase dosing interval as patient improves

22. Recombinant FVIIa Dosing
Key NS et al. Thromb Haemost. 1998;80:912-918; Lusher JM. Blood Coag Fibrinolysis. 2000;11 (suppl 1):S45-S49.
 Package insert: dose, 90-120 µg/kg
 Clinical studies indicate that an average of 2.2 doses
are needed to control a bleed at these doses
 Earlier treatment results in better outcome
 23% of patients respond to a single dose of rFVIIa 90
µg/kg within 3 hours

23. aPCC vs rFVIIa
Astermark J et al. Blood. 2007;109:546-551; Young G et al. Haemophilia. 2008;14:287-294.
 Each alone is effective in about 70%-90% of bleeds
 Two prospective studies compared aPCC and rFVIIa
head to head
 FENOC study (investigator-initiated sponsored by Baxter)1
 F7Haem-2068 (industry-initiated sponsored by Novo
Nordisk)2

24. FENOC Study
FENOC = FEIBA NovoSevenComparative .Astermark J et al. Blood. 2007;109:546-551.
• Randomized, open-label study comparing single
dose of aPCC 75-100 U/kg vs 2 doses of rFVIIa 90-
120 µg/kg
• Primary end points
– Hemostatic efficacy
– Pain
• Results
– aPCC and rFVIIa appear to exhibit a similar effect on joint
bleeds
– Statistical criterion of equivalence not met

25. FENOC Study: Efficacy Outcomes
 No statistically significant differences in the distribution of
outcomes by treatment at any time point
 Primary endpoint of equivalence not met
Astermark J et al. Blood. 2007;109:546-551.
Frequency
50
40
30
20
10
0
4836
Effective
Poorly effective
Not effective
Partially effective
aPCC
Hour
Treatment
2 6 12 24 2 6 12 24 36 48
rFVIIa

26. F7Haem-2068: Study Design
The rFVIIa doses were blinded and placebo-controlled.
First bleed
T0 T+3h T+6h
27 patients
with
hemophilia
+ inhibitors
rFVIIa
270 μg/kg
Placebo
Placebo
rFVIIa
90 μg/kg
rFVIIa
90 μg/kg
rFVIIa
90 μg/kg
aPCC
75 U/kg
rFVIIa
270 μg/kg
Placebo
Placebo
rFVIIa
90 μg/kg
rFVIIa
90 μg/kg
rFVIIa
90 μg/kg
aPCC
75 U/kg
rFVIIa
270 μg/kg
Placebo
Placebo
rFVIIa
90 μg/kg
rFVIIa
90 μg/kg
rFVIIa
90 μg/kg
aPCC
75 U/kg
Second bleed
T0 T+3h T+6h
Third bleed
T0 T+3h T+6h
Young G et al. Haemophilia. 2008;14:287-294.

27. F7Haem-2068: Hemostasis Achieved
Key et al, 92%; Kavakli et al, 90.5%; Young G et al. Haemophilia. 2008;14:287-294.
91.7 90.9
0
20
40
60
80
100
PatientsNotNeedingRescue
Medicationat9h(%)
22/24
rFVIIa
270 μg/kg
single dose
rFVIIa
3 x 90 μg/kg
multiple doses
20/22
aPCC
75 U/kg
63.6
14/22
*P = 0.032
P = 0.069

28. F7Haem-2068: Summary
Young G et al. Haemophilia. 2008;14:287-294.
 A significant reduction in the use of rescue
medications occurred in the single-dose rFVIIa 270-
μg/kg group compared with aPCC
 A trend to significance was also noted in the
multiple-dose rFVIIa arm vs aPCC
 This may be biased by the study design

29. Prophylaxis for Patients With Inhibitors
 Potential benefits
 Reduce incidence of bleeding
 Allow for more normal quality of life
 Resolve target joint
 Prevent joint damage
 Improve overall functioning prior to major surgery

30. rFVIIa Prophylaxis Study:
Konkle BA et al. J Thromb Haemost. 2007;5:1904-1913.
Preprophylaxis
Period
Postprophylaxis
Period
Prophylaxis
Period
MeanNo.ofBleedsperMonth
7
6
5
4
3
2
1
0
90 µg/kg
270 µg/kg
*
+35%; +22%
*** ***
– 45%; –59%
** ***
– 27%; –50%
Bracketed data are the estimated changes (%) in no. of bleeds/month (defined as 28 days) for
the 90 µg/kg and 270 µg/kg rFVIIa treatment groups during the prophylaxis or postprophylaxis
period as compared with the preprophylaxis period, and during the prophylaxis period as
compared with the postprophylaxis period. ***P≤0.001; **P≤0.01; *P≤0.05.

31. rFVIIa Prophylaxis Quality of Life
Hoots WK et al. Haemophilia. 2008;14:466-475
80
60
40
20
0
%PatientsWithNoProblems
Mobility
Screening Preprophylaxis End of
Prophylaxis
End of
Postprophylaxis
EQ-5D dimension
Anxiety
Self-care
Pain
Unusual activities

32. aPCC Prophylaxis Case Series
Joint ROM Bleeding
Author Year N Unit/Wk Better No Δ Worse Reduction
Valentino 2009 6 700 NR NR NR 100%
Leissinger 2007 5 225 1 4 0 78%
Ohga 2007 1 150 NR NR NR 100%
DiMichele 2006
1
4
245 3 8 2 53%
Siegmund 2005 1 210 1 0 0 NR
Hilgartner 2003 7 375 2 NR 7 NR

33. aPCC Prophylaxis: Efficacy
DiMichele D, Négrier C. Haemophilia. 2006;12:352-362.
Excellent/GoodEfficacy(%)
Pre-/Intraoperative Postoperative
0
10
20
30
40
50
60
70
80
90
100

34. Eradicate Inhibitor
CTX = cyclophosphamide; IVIg = intravenous immunoglobulin; EACA = epsilon aminocaproic acid.
Regimen FVIII Other
Bonn 100-150 IU/kg bid aPCC prn
Los Angeles 50 IU/kg/d Steroids
Malmö Keep FVIII >0.40 CTX, IVIg, EACA
van Creveld 25 IU/kg alternate days
Oxford On demand
Immune Tolerance Induction (ITI)

35. Defining Outcome With ITI
International consensus
• Undetectable inhibitor titer <0.6 BU
– By Bethesda or Nijmegen assay
and
• Normalized FVIII pharmacokinetics
– Plasma FVIII recovery >66% of expected
and
– Half-life >6 h after 72-hour FVIII exposure-free period

36. Evidence-Based Approach to ITI
ITI failure
• Failure to attain the definition of success within 33
months of uninterrupted ITI
• Failure to demonstrate a progressive 20% reduction
in inhibitor titer over each successive
6-month period of uninterrupted ITI, beginning 3
months after initiation to allow for expected
anamnesis

37. Factor IX Inhibitors in Hemophilia B
DiMichele D. Br J Haematol. 2007;138:305-315.
42
 Occur in 3% of patients
 Approximately 80% are high-responding
 Frequent occurrence of allergic/anaphylactic
reactions prior to or simultaneously with the onset of
inhibitors
 Antibodies to FIX protein
 IgG4 and IgG1 subclasses

38. Hemophilia B: Genetics
Belvini D et al. Haematologica. 2005;90:635-642.
43
• Type of mutations: missense (69.5%), nonsense
(14.4%), small deletions (6.4%), splice site
(5.9%), large deletions (2.5%), promoter mutations
(1.3%)
• Correlation with disease severity
– Deletions, nonsense mutations: severe hemophilia B (HB)
– Missense mutations: mild HB (88%), moderate HB
(90%), severe HB (59%)
• Mutation type and risk for inhibitor development
– Inhibitors in 4.7% with severe HB
– Large deletions, nonsense mutations, frameshift

39. ISTH-SSC International FIX Inhibitor Registry
44
 Focus on patients with FIX inhibitor-related
complications (severe allergic or anaphylactic
reactions)
 Median age at inhibitor detection: 19.5 months (9-
156)
 Median exposure days to FIX replacement therapy:
11 days (2-180)
 Mean peak inhibitor titer: 30 BU (1-1156)

40. Success Rate of ITI Regimens for FVIII Inhibitors
International and North American ITI Studies; reported at Bonn, August 1997.
International
North
American Combined
Success 114 (69%) 93 (72%) 207 (70%)
Failure 51 (31%) 37 (28%) 88 (30%)

41. Prognostic Factors for ITI Host Factors
IL = interleukin; TNF = tumor necrosis factor-alpha. DiMichele D. J Thromb Haemost. 2007;5(suppl1):143-150.
• No single host-related variable has been shown to be
specific and sufficient for predicting anti-FVIII
antibody development
– Hemophilia severity
– FVIII gene mutation (null mutations)
– Ethnicity
– Family history
– IL-10 (odds ratio, 4.4) and TNF polymorphism

42. F8 Gene Mutations and ITI Outcome
Rocino A et al. Haematologica. 2006;91:558-561.
 Successful ITI
 12/17 (70%) of patients with intron 22 inversion
 5/7 (75%) of patients with other null mutations
 Null mutations did not affect chance of achieving
successful ITI

43. Coppola A et al. J Thromb Haemost. 2009;7:1809-1815.

44. ITI Success and F8 Mutation
Coppola A et al. J Thromb Haemost. 2009;7:1809-1815.
Low risk
High risk
20
40
60
80
100
CumulativeITISuccessRate(%)
0
0 5 10 15 20
Time (months)
403025 35

45. Prognostic Factors for ITI
DiMichele D. J Thromb Haemost. 2007;5(suppl 1):143-150.
 Pre-ITI titer
 Historical peak titer
 Dose of FVIII concentrate
 FVIII product type
 Immune modulation
 Supportive care
 Bypass therapy bleeding prophylaxis

46. Influence of Inhibitor Titer
DiMichele D. J Thromb Haemost. 2007;5(suppl 1):143-150.

47. International ITI Study: Results
Hay and DiMichele. Blood. 2012; 119: 1335

48. Time to Tolerance
Hay and DiMichele. Blood. 2012; 119: 1533
Intent to Treat
Group
Responding
Group

49. ITI Milestones By Treatment Arm
Hay and DiMichele. Blood. 2012; 119: 1533
n LD n HD p
Phase 1: start of ITI to
negative titer
29 9.2
(4.9-17.0)
31 4.6
(2.8-13.8)
.017
Phase 2: negative titer to
first normal recovery
27 13.6
(8.7-19.0)
23 6.9
(3.5-12.0)
.001
Phase 3: normal recovery to
tolerance
24 15.5
(10.8-22.0)
22 10.6
(6.3-20.5)
.096

50. Work Still Needs To Be Done
 Role of gene haplotypes in inhibitor development
 Rates of inhibitor development in PUPs with plasma-
derived factor (SIPPET)
 Inhibitor rates with long-acting factors