Current laboratory practices in the diagnosis and management of haemophilia

Transcription

1 Current laboratory practices in the diagnosis and management of haemophilia Marc Jacquemin University of Leuven BSTH 2013

2 Detection of severe haemophilia A

3 Validation of the FVIII assay for the detection of severe hemophilia A (FVIII < 1%) No specific guidelines about measuring FVIII 1% Is there any problem with the detection of FVIII <1%?

4 Plasma of a pa*ent with a Factor VIII level <1% number of laboratories factor VIII (%) ECAT ECAT

5 Plasma of a pa*ent with a Factor VIII level <1% number of laboratories 20% of labs: FVIII < 1% => severe hemophilia A factor VIII (%) ECAT ECAT

6 Plasma of a pa*ent with a Factor VIII level <1% number of laboratories 20% of labs: FVIII < 1% => severe hemophilia A 75% of labs: FVIII = 1% factor VIII (%) ECAT ECAT

7 Plasma of a pa*ent with a Factor VIII level <1% number of laboratories 20% of labs: FVIII < 1% => severe hemophilia A 75% of labs: FVIII 1% 5% of labs: FVIII 2% => moderate hemophilia A factor VIII (%) ECAT ECAT

8 Plasma of a pa*ent with a Factor VIII level <2% number of laboratories factor VIII (%) ECAT

9 Plasma of a pa*ent with a Factor VIII level <2% number of laboratories 75% of labs: FVIII 1% => moderate hemophilia A factor VIII (%) ECAT

10 Plasma of a pa*ent with a Factor VIII level <2% number of laboratories 75% of labs: FVIII 1% => mild hemophilia A 25% of labs: FVIII < 1% => severe hemophilia A factor VIII (%) ECAT

11 Validation of the FVIII assay for the detection of severe hemophilia A (FVIII < 1%) no specific guidelines commercial FVIII-deficient plasma (immunodepleted)? plasma from severe haemophilia A patients with known inversion or deletion of the FVIII gene?

12 Gene*c analyses can o=en but not always confirm a diagnosis of severe haemophilia

13 Detection of mild/moderate haemophilia A

14 Detection of mild/moderate haemophilia A - repeated measurements (stress, inflamma*on) - lower FVIII and VWF levels in blood group O

15 Muta*ons impairing the stability of ac*vated FVIII

16 Na*ve and thrombin- ac*vated FVIII Na*ve FVIII B! FVIIIa A1! * A2! A3! * * A1! A2! A3! C1! C1! C2! C2! * Thrombin cleavage site

17 Activated Factor VIII as cofactor of Factor IXa Factor VIIIa Factor IXa * A1! A2! * A3!* Factor X Factor Xa C2! * Phospholipids Haemostasis X by Factor VIII

18 Accelerated dissociation of A2 inactivates FVIIIa Factor VIIIa * A1! A2! C2! * * * A3! Ser289 Ala284 Arg534 Arg698 His1954 Tyr1979 * A1! A2! * * A3! Factor IXa C2! *

19 FVIII one- stage assay (APTT- based) HK / PK test sample (FVIII) + FVIII- deficient plasma XII XIIa + non physiological surface (glass, silica, kaolin) XI XIa + phospholipids + Ca ++ VIII IX VIIIa IXa V X Va Xa Prothrombin Thrombin Fibrinogen Fibrin

20 FVIII one- stage assay (APTT- based) HK / PK test sample (FVIII) + FVIII- deficient plasma XII XIIa + non physiological surface (glass, silica, kaolin) VIII XI V IX VIIIa XIa does NOT detect X Va IXa muta*ons impairing FVIIIa stability Prothrombin Xa Thrombin + phospholipids + Ca ++ Fibrinogen Fibrin

21 FVIII chromogenic assay test sample (FVIII) + bovine FIXa, FX, + a livle thrombin + phospholipids thrombin VIII VIIIa IXa incubawon period + Ca ++ X Xa incubawon period + chromogenic substrate for FXa substrate color incubawon period

22 FVIII chromogenic assay test sample (FVIII) + bovine FIXa, FX, + a livle thrombin + phosphoplipids thrombin VIII VIIIa IXa incubawon period + Ca FVIII ++ X incubawon period sensi*ve to muta*ons + chromogenic substrate for FXa impairing FVIIIa stability substrate FVIIIa incubawon period ifviiia

23 Muta*ons reducing FVIII binding to VWF

24 FVIII is bound to vwf in plasma vwf FVIII A1 A3 C1 C2 D D3

25 Muta*ons reducing FVIII binding to vwf result in mild/ moderate hemophilia A FVIII A2 Ile2098 Ser2119 Asn2129 Arg2150 Pro2153 A1 A1 C1 C2 A3 Tyr1680 Trp2229 Gln2246 Del2201

26 Muta*ons reducing vwf binding to FVIII are responsible for VWD type 2N A1 C1 C2 A3 R760 R763 R782 G785 E787 C788 T791 T795 M800 C804 P812 R816 H817 R854 C858 D879 R924 Q1053 Q1060 C1099 E1078 C1225 D D3 vwf

27 Detection of VWD type 2 N low FVIII (similar to mild/moderate haemophilia A) no mutation in FVIII gene reduced FVIII binding to VWF in ELISA also in women! A1 FVIII vwf implications for: - treatment - genetic counseling

28 Monitoring

29 Monitoring Plasma derived FVIII concentrates: no specific guidelines Recombinant FVIII: product specific guidelines!

30 FVIII assays available for the monitoring

31 FVIII one- stage assay (APTT- based) HK / PK test sample (FVIII) + FVIII- deficient plasma XII XIIa + non physiological surface (glass, silica, kaolin) XI XIa + phospholipids + Ca ++ VIII IX VIIIa IXa V X Va Xa Prothrombin Thrombin Fibrinogen Fibrin

32 FVIII chromogenic assay test sample (FVIII) + bovine FIXa, FX, + a livle thrombin + phospholipids thrombin VIII VIIIa IXa incubawon period + Ca ++ X Xa incubawon period + chromogenic substrate for FXa substrate color incubawon period

33 Measurement FVIII:C in plasma- derived FVIII concentrates FVIII:C dependent on the type of assay Kirkwood et al. Br J Haematol 1978; 40: 333 Dawson et al. Haemostasis 1989; 19: 131

34 Measurement of recombinant FVIII FVIII:C dependent on the type of assay

35 Measurement of recombinant FVIII FVIII:C dependent on the type of assay Will the real FVIII please stand up! Lusher JM, et al. Blood 1995; 86 suppl 1 abstract 755. Lusher JM, et al. Haemophilia 1998; 4: 641. Lee CA et al. Thromb Haemost 1999; 82: Hubbard AR, et al. Br J Haematol 2002; 117:

36 rfviii levels measured with one stage and chromogenic FVIII assays in patients samples sample one-stage assay calibrated with plasma chromogenic assay calibrated with plasma difference (%) difference (%): 100 x (one stage chromogenic)/chromogenic Haemophilia 2013

37 rfviii levels measured with one stage and chromogenic FVIII assays in patients samples Full length rfviii Kogenate R (n = 5) -29 ± 12 Advate R (n = 3) -35 ± 9 Helixate R (n = 5) -28 ± 15 B-domain deleted FVIII Refacto-AF R (n = 8) -35 ± 14 normal plasma (n = 2) -2 ± 7 difference (%) mean ± SD (%) Haemophilia 2013

38 rfviii levels measured with one stage and chromogenic FVIII assays in patients samples Full length rfviii Kogenate R (n = 5) -29 ± 12 Advate R (n = 3) -35 ± 9 Helixate R (n = 5) -28 ± 15 B-domain deleted FVIII Refacto-AF R (n = 8) -35 ± 14 normal plasma (n = 2) -2 ± 7 difference (%) mean ± SD (%)! Reagent effect Haemophilia 2013

39 Strategy to monitor rfviii in patients samples with the one-stage FVIII assay No product-specific standard to calibrate the assay Advate Helixate Kogenate Like versus like Refacto-AF: Refacto-AF Laboratory Standard

40 Strategy to monitor rfviii in patients samples with the one-stage FVIII assay No product-specific standard to calibrate the assay Advate Helixate Kogenate Like versus like Refacto-AF: Refacto-AF Laboratory Standard

41 Strategy to monitor rfviii in patients samples with the one-stage FVIII assay No product-specific standard to calibrate the assay Advate Helixate Kogenate Like versus like Refacto-AF: Refacto-AF Laboratory Standard New rfviii and rfix with prolonged half-life?

42 Difficulties inherent to the use of multiple standards: multiple calibration curves CSLI guidelines: calibration every run

43 Difficulties inherent to the use of multiple standards: multiple calibration curves CSLI guidelines: calibration every run! assays with stored calibration curves [Lattes Haemophilia 2011; 17: 139] [Nougier Blood Coag Fibrinol 2011; 22: 151]

44 Difficulties inherent to the use of multiple standards: multiple calibration curves CSLI guidelines: calibration every run! assays with stored calibration curves [Lattes Haemophilia 2011; 17: 139] [Nougier Blood Coag Fibrinol 2011; 22: 151] calibration curve with each new batch [Mackie I. IJLH 2012 Britisch Committee for Standards in Haematology]

45 Calibration with normal plasma is stable over prolonged period of time 90 Coagulation time (Sec) plasma pool mean ± SD of 4 calibration curves carried out on different days FVIII:C (%)

46 Interpretation of monitoring data type of assay calibration of the assay (normal plasma or like versus like )

47 Detection of inhibitor Bethesda test Nijmegen modification of the Bethesda test Kasper et al., Thromb Diathes Haemorrh 1975 B. Verbruggen et al., Thromb Haemost 1995 B. Verbruggen et al. Thromb Haemost 2001 B. Verbruggen et al. Thromb Haemost 2002

48 Conclusions identification of patients with severe hemophilia A requires a strict control of the available commercial methods. attention must be given to the identification of mild/ moderate haemophilia A patients with discrepant one stage/two stage FVIII assays. efficient interactions between clinici and clinical biologists are critical for the monitoring of treatment with FVIII concentrates

49 Acknowledgments Mathieu Cauchie Jelle Toelen Kathelijne Peerlinck University of Leuven