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Protocol - Emicizumab Therapy: Individual Pharmacokinetic Study of Extended Half-life Factor VIII Products: Chromogenic Substrate Assay with Bovine Reagents

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Description:

This protocol provides instructions and guidance for collecting and processing samples for coagulation testing, performing an individual pharmacokinetic study using the chromogenic substrate assay, and interpreting pharmacokinetic results in response to infusion of extended half-life Factor VIII products. Because there are many comparable assays for performing the chromogenic assay, the protocol also provides basic guidelines to aid comparability among different studies.

Specific Instructions:

The PhenX Hemophilia Inhibitor Research Working Group (WG) notes that these measures are intended for use in observational and interventional trials but are not sufficient to define hemophilia phenotypes when used in isolation.

The WG recommends that when measuring inhibitor recovery in non-severe patients, endogenous factor should be measured by the same assay that was optimized prior to inhibitor development.

The WG recommends that Factor VIII and IX assays, either by one-stage clotting factor or chromogenic substrate methodology, should be performed by a laboratory that is College American Pathologists (CAP) accredited or Clinical Laboratory Improvement Amendments of 1998 (CLIA) certified. For multi-center clinical trials, the use of a central laboratory is strongly encouraged.

Emicizumab is a bispecific antibody that mimics the cofactor function of activated factor VIII (FVIIIa) by bridging activated factor IX (FIXa) and factor X (FX). Factor VIII (FVIII) levels and inhibitors can be measured in the presence of emicizumab using chromogenic assays with bovine reagents. One-stage clot-based assays cannot be used for determination of FVIII levels and FVIII inhibitors in the presence of emicizumab because results will show artifactually elevated FVIII levels. For more information see the Medical and Scientific Advisory Committee (MASAC) of the National Hemophilia Foundations MASAC Update on the Approval and Availability of the New Treatment: Emicizumab (Hemlibra), for Persons with Hemophilia A with Inhibitors to Factor VIII: Interim Guidance on Acute Bleed Management and Use of Laboratory Assays (https://www.hemophilia.org/sites/default/files/MASAC-Update-on-the-Approval-and-Availability-of-the-New-Treatment.pdf).

The WG notes the activity of FVIII extended half-life products in plasma determined by the chromogenic clotting factor assay can vary according to the reagents and instrumentation used (Kitchen et al., 2017). Investigators should select an assay that aligns with the one used to determine the potency of the product. Additionally, investigators should record the make and manufacturer of equipment, the repeatability and coefficients of variation for the assay, and the reagents used.

The WG expects that a pharmacokinetic study of standard and extended half-life FVIII products in the presence of emicizumab will primarily be used to guide prophylaxis for surgery and for episodic prophylaxis around peak activity.

The WG recommends that investigators wait at least 6 months from the patients last dose of emicizumab before using assays with regular (non-bovine) reagents.

Additionally, the WG notes that in the HAVEN 2 study, one patient developed an antibody to emicizumab which was associated with increased bleeding, decreased chromogenic factor VIII activity, and a prolonged activated partial thromboplastin time (aPTT).

If a washout is not performed, comparison of pharmacokinetic data between studies should be conducted under steady-state conditions. Steady-state is defined as a patient-specific condition during which a pharmacokinetic assessment remains valid over a clinically useful period of time. Examples of non-steady state conditions include:

  • Bleeding state
  • Peri- and immediate post-surgical states in which patients are receiving continuous or regular high (non-routine prophylactic) doses of FVIII
  • Immune tolerance induction during which inhibiter titers are in flux
  • Children in whom age- and weight-based clearance is still developing toward adult physiologic states.
Protocol:

Emicizumab Therapy: Individual Pharmacokinetic Study of Extended Half-life Factor VIII Products: Chromogenic Substrate Assay with Bovine Reagents

Sample Collection

The PhenX Hemophilia Inhibitors Working Group (WG) recommends that investigators follow the sample collection procedures outlined in Lippi et al. (2012) to ensure quality specimens for coagulation testing. These recommendations include basic criteria for venipuncture (e.g., proper patient identification, use of correct techniques, appropriate devices and needles) as well as additional guidance for critical parameters which can affect the outcome of clot-based tests. These critical parameters include prevention of prolonged venous stasis, collection of nonhemolyzed samples, order of blood draw, and appropriate filling and mixing of collection tubes.

Additionally, the WG highlights that blood should be collected by direct venipuncture into 3.2% sodium citrate tubes and filled within 11% of fill line. A second tube should be collected. A discard tube should be drawn if using a winged butterfly collection system.

Sample Processing

The WG recommends that investigators follow the sample collection procedures outlined in Adcock Fuck et al. (2012). The procedures include that:

  • unprocessed or processed sodium citrate samples remain capped and at room temperature until testing,
  • samples should not be refrigerated or stored on ice or in an ice bath,
  • samples should be transported vertically, and
  • processed samples should not be agitated during transportation to avoid remixing of components.

Additionally, samples can be transported and stored as:

  • unprocessed sodium citrate whole blood samples,
  • whole blood samples centrifuged and maintained in sodium citrate tubes, or
  • plasma processed by centrifugation and aliquoted into a second tube.

Ideally, whole blood samples should be processed to platelet poor plasma (PPP) within 1 hour of collection and assayed within 4 hours of collection.

If centrifuging samples, the centrifuge should be validated so that post-centrifuged samples contain less than 10,000 platelets/microliter. Centrifuged samples should be frozen and can be stored at -20o C for 2 weeks. Samples should be transferred to < -70o C for longer storage, including shipment.

Emicizumab Therapy: Chromogenic Substrate Assay with Bovine Reagents for Determining Factor VIII Activity in Plasma

In patients being treated with emicizumab, Factor VIII inhibitors can only be measured using a chromogenic assay with bovine reagents. Investigators should select an assay that aligns with the one used to determine the potency of the product. Once an assay is chosen for a particular study, the WG recommends that no changes in the protocol be made over the course of the study. Because results can vary with the instrumentation and reagents, the WG recommends that the investigator record the make and manufacturer of equipment, the repeatability and coefficients of variation for the assay, and the reagents used. Use of a central laboratory for multi-center clinical trials is strongly encouraged.

Extended Half-life Factor VIII Products: Individual Pharmacokinetic Study

Prior to pharmacokinetic evaluations, participants should undergo a treatment-free washout period lasting longer than five half-lives. Samples should be taken before infusion (baseline), 10-15 minutes after infusion, and then up to eight other timepoints that cover 2.5 half-lives of the extended half-life FVIII products. The WG notes that the list of timepoints necessary for the pharmacokinetic study to cover 2.5 half-lives will depend on the specific extended half-life FVIII product being used and can be identified in relevant pre-licensure studies. Investigators should report which timepoints were used.

Extended Half-life Factor VIII Products: Interpretation of Individual Pharmacokinetic Study Results

The half-life of extended half-life FVIII products is highly variable and the level at which an inhibitor is suggested has not been established.

Protocol Name from Source:

N/A; see source.

Availability:

Publicly available

Personnel and Training Required

Phlebotomist

Equipment Needs
Laboratory with the ability to perform the chromogenic substrate assay with bovine reagents.
Requirements
Requirement CategoryRequired
Major equipment No
Specialized training No
Specialized requirements for biospecimen collection Yes
Average time of greater than 15 minutes in an unaffected individual Yes
Mode of Administration

Bioassay

Life Stage:

Toddler, Child, Adolescent, Adult

Participants:

Any age

Selection Rationale

The PhenX Hemophilia Inhibitors Working Group selected the recommendations from Lippi et al. (2012) and Adcock Funk et al. (2012) as the best standardized methodology for collecting and processing samples for coagulation testing. The International Society on Thrombosis and Haemostasis (Lee et al., 2001) provides standard timepoints for consistent implementation of the pharmacokinetic study.

Language

English

Standards
StandardNameIDSource
Common Data Elements (CDE) Individual Pharmacokinetic Study Coagulation Factor VIII Extended Half Life Chromogenic Substrate Clotting Factor Assay 6712203 CDE Browser
Derived Variables

The results of this protocol can be combined with the results of Emicizumab Therapy: Determination of Factor VIII Inhibitors Using the Bethesda Assay with Nijmegen Modification: Chromogenic Substrate Assay with Bovine Reagents to document:

Presence of an Inhibitor

The presence of an inhibitor is indicated by one or more of the following:

  • lack of clinical response (cessation of bleeding) to factor infusion for treatment of bleeding;
  • less than expected (< 66%) recovery of Factor VIII level immediately after infusion (Response to Factor VIII Infusion in the Presence of Emicizumab - Individual Pharmacokinetic Study);
  • positive inhibitor titer (Quantitative Measure of Factor VIII Inhibitor Activity in the Presence of Emicizumab);
  • Reduced FVIII half-life below 6 hours.

Evolution of an Inhibitor

Inhibitor evolution is indicated by:

  • change in inhibitor titer over time (Quantitative Measure of Factor VIII Inhibitor Activity in the Presence of Emicizumab), with or without immune tolerance induction;
  • change in clinical response (i.e., bleeding) to FVIII infusion;
  • change in FVIII activity after factor infusion (Response to Factor VIII Infusion in the Presence of Emicizumab - Individual Pharmacokinetic Study).

Resolution of an Inhibitor

Inhibitor resolution is indicated by the following:

  • for patients receiving immune tolerance therapy for eradication of an FVIII inhibitor, success is defined as a negative inhibitor titer (Quantitative Measure of Factor VIII Inhibitor Activity in the Presence of Emicizumab) and a normal recovery (>= 66% of expected) and half-life >= 6 hours of infused FVIII concentrate (Response to Factor VIII Infusion in the Presence of Emicizumab - Individual Pharmacokinetic Study).

Persistence of an Inhibitor

A persistent inhibitor is indicated by a decreased response to FVIII concentrate infusion (Response to Factor VIII Infusion in the Presence of Emicizumab - Individual Pharmacokinetic Study) with or without a persistently positive inhibitor titer (Quantitative Measure of Factor VIII Inhibitor Activity in the Presence of Emicizumab).

Blanchette, V. S., Key, N. S., Ljung, L. R., Manco-Johnson, M. J., van den Berg, H. M., & Srivastava, A.; Subcommittee on Factor VIII, Factor IX and Rare Coagulation Disorders of the Scientific and Standardization Committee of the International Society on Thrombosis and Hemostasis. (2014). Definitions in hemophilia: Communication from the SSC of the ISTH. Journal of Thrombosis and Haemostasis, 12(11), 1935-1939.

Process and Review

Not applicable.

Source

Adcock Funk, D. M., Lippi, G., & Favaloro, E. J. (2012). Quality standards for sample processing, transportation, and storage in hemostasis testing. Seminars in Thrombosis and Hemostasis, 38(6), 576-585.

Lippi, G., Salvagno, G. L., Montagnana, M., Lima-Oliveira, G., Guidi, G. C., & Favaloro, E. J. (2012). Quality standards for sample collection in coagulation testing. Seminars in Thrombosis and Hemostasis, 38(6), 565-575.

Medical and Scientific Advisory Committee (MASAC) of the National Hemophilia Foundation (NHF). (2017). MASAC update on the approval and availability of the new treatment: Emicizumab (hemlibra), for persons with hemophilia A with inhibitors to factor VIII: Interim guidance on acute bleed management and use of laboratory assays. https://www.hemophilia.org/sites/default/files/MASAC-Update-on-the-Approval-and-Availability-of-the-New-Treatment.pdf

General References

Blanchette, V. S., Key, N. S., Ljung, L. R., Manco-Johnson, M. J., van den Berg, H. M., & Srivastava, A.; Subcommittee on Factor VIII, Factor VIII and Rare Coagulation Disorders of the Scientific and Standardization Committee of the International Society on Thrombosis and Hemostasis. (2014). Definitions in hemophilia: Communication from the SSC of the ISTH. Journal of Thrombosis and Haemostasis, 12(11), 1935-1939.

Hay, C. R., & DiMichele, D. M.; International Immune Tolerance Study. (2012). The principal results of the International Immune Tolerance Study: A randomized dose comparison. Blood, 119(6), 1335-1344.

Iorio, A., Edginton, A.N., Blanchette, V., Blatny, J., Boban, A., Cnossen, M., Collins, P., Croteau, S.E., Fischer, K., Hart, D.P., Ito, S., Korth-Bradley, J., Lethagen, S., Lillicrap, D., Makris, M., Matht, R., Morfini, M., Neufeld, E.J., Spears, J. (2018). Performing and interpreting individual pharmacokinetic profiles in patients with Hemophilia A or B: Rationale and general considerations. Research and Practice in Thrombosis and Haemostasis, 2(3), 535-548.

Kitchen, S., Kershaw, G., & Tiefenbacher, S. (2016). Recombinant to modified factor VIII and factor VIII Chromogenic and one-stage assays issues. Haemophilia, 22(Suppl. 5), 72-77.

Kitchen, S., Tiefenbacher, S., & Gosselin, R. (2017). Factor activity assays for monitoring extended half-life FVIII and factor IX replacement therapies. Seminars in Thrombosis and Haemostasis, 43(3), 331-337.

Lee, M., Morfini, M., Schulman, S., & Ingerslev, J.; Factor VIII/Factor VIII Scientific and Standardization Committee of the International Society for Thrombosis and Haemostasis. (2001). Scientific and Standardization Committee communication. The design and analysis of pharmacokinetic studies of coagulation factors. https://www.isth.org/members/group_content_view.asp?group=100348&id=159244. Retrieved August 30, 2018.

Mahlangu, J., Oldenburg, J., Paz-Priel, I., Negrier, C., Niggli, M., Mancuso, M. E., Schmitt, C., Jimnez-Yuste, V., Kempton, C., Dhalluin, C., Callaghan, M. U., Bujan, W., Shima, M., Adamkewicz, J. I., Asikanius, E., Levy, G. G., & Kruse-Jarres, R. (2018). Emicizumab prophylaxis in patients who have hemophilia A without inhibitors. New England Journal of Medicine, 379(9), 811-822.

Morfini, M., Lee, M., Messori, A. and the Factor VIII/Factor IX Scientific and Standardization Committee of the International Society for Thrombosis and Haemostasis. (1991). The design and analysis of half-life and recovery studies for factor VIII and factor IX. Thrombosis and Haemostasis, 66(3), 384-386.

Oldenburg, J., Mahlangu, J. N., Kim, B., Schmitt, C., Callaghan, M. U., Young, G., Santagostino, E., Kruse-Jarres, R., Negrier, C., Kessler, C., Valente, N., Asikanius, E., Levy, G. G., Windyga, J., & Shima, M. (2017). Emicizumab prophylaxis in hemophilia A with inhibitors. The New England Journal of Medicine, 377(9), 809-818.

Peyvandi, F., Oldenburg, J., & Friedman, K. D. (2006). A critical appraisal of one-stage and chromogenic assays of factor VIII activity. Journal of Thrombosis and Haemostasis, 14(2), 248-261.

Shima, M., Hanabusa, H., Taki, M., Matsushita, T., Sato, T., Fukutake, K., Fukazawa, N., Yoneyama, K., Yoshida, H., & Nogami, K. (2016). Factor VIII-mimetic function of humanized bispecific antibody in hemophilia A. New England Journal of Medicine, 374(21), 2044-2053.

Protocol ID:

911402

Variables:
Export Variables
Variable NameVariable IDVariable DescriptionVersiondbGaP Mapping
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Pharmacokinetic_Study_After_Infusion_Hours_1 PX911402040500 Was Factor VIII activity tested 1 hour after more
infusion? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Pharmacokinetic_Study_After_Infusion_Hours_24 PX911402040900 Was Factor VIII activity tested 24 hours more
after infusion? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Pharmacokinetic_Study_After_Infusion_Hours_28 PX911402041000 Was Factor VIII activity tested 28 hours more
after infusion? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Pharmacokinetic_Study_After_Infusion_Hours_3 PX911402040600 Was Factor VIII activity tested 3 hours more
after infusion? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Pharmacokinetic_Study_After_Infusion_Hours_32 PX911402041100 Was Factor VIII activity tested 32 hours more
after infusion? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Pharmacokinetic_Study_After_Infusion_Hours_6 PX911402040700 Was Factor VIII activity tested 6 hours more
after infusion? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Pharmacokinetic_Study_After_Infusion_Hours_9 PX911402040800 Was Factor VIII activity tested 9 hours more
after infusion? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Pharmacokinetic_Study_After_Infusion_Minutes_10 PX911402040300 Was Factor VIII activity tested 10-15 more
minutes after infusion? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Pharmacokinetic_Study_After_Infusion_Minutes_30 PX911402040400 Was Factor VIII activity tested 30 minutes more
after infusion? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Pharmacokinetic_Study_Infusion_Baseline PX911402040200 Was Factor VIII activity tested before more
infusion (baseline)? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Pharmacokinetic_Study_Interpretation_Results PX911402050000 Was the Factor VIII half-life (t) less than more
6 hours? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Pharmacokinetic_Study_Washout PX911402040100 Have partipants undergone a treatment-free more
washout period lasting longer than five half-lives? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Collection PX911402010100 Were the sample collection procedures more
outlined in Lippi et al. (2012) followed? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Collection_Blood_Draw PX911402010400 Was the order of blood draw recorded? N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Collection_Nonhemolyzed PX911402010300 Were nonhemolyzed samples collected? N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Collection_Tubes PX911402010500 Were collection tubes filled and mixed as more
outlined in Lippi et al. (2012)? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Collection_Tubes_Discard PX911402011000 Was a discard tube drawn? N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Collection_Tubes_Filled PX911402010700 Were the tubes filled within 11% of the fill line? N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Collection_Tubes_Second PX911402010800 Was a second tube collected? N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Collection_Tubes_Winged PX911402010900 Was a winged butterfly collection system used? N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Collection_Venipuncture PX911402010600 Was blood collected by direct venipuncture more
into 3.2% sodium citrate tubes? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Collection_Venous_Statsis PX911402010200 Were steps taken to prevent prolonged venous more
stasis? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Processing PX911402020100 Were the sample collection and processing more
procedures outlined in Adcock Funk et al. (2012) followed? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Processing_Agitation PX911402020500 Were samples agitated during transportation? N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Processing_Assayed PX911402021000 Were samples assayed within 4 hours of collection? N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Processing_Centrifuge_Validated PX911402021100 Was the centrifuge validated so that process more
results in less than 10,000 platelets/microliter show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Processing_Deep_Freeze PX911402021300 Was the sample transferred to <= -70 C, more
including shipment? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Processing_Frozen PX911402021200 Was the sample frozen immediately and stored more
at -20 C for at most 2 weeks? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Processing_Platelet_Poor_Plasma PX911402020900 Were samples processed to platelet poor more
plasma (PPP) within 1 hour of collection? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Processing_Refrigerated PX911402020300 Were samples refrigerated or stored on ice more
or in an ice bath? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Processing_Sodium_Citrate PX911402020200 Did unprocessed or processed sodium citrate more
samples remain capped and at room temperature until testing? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Processing_Storage_Plasma PX911402020800 Were samples stored as plasma processed by more
centrifugation and aliquoting into a second tube? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Processing_Storage_Unprocessed PX911402020600 Were samples stored as unprocessed sodium more
citrate whole blood samples? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Processing_Storage_Whole_Blood PX911402020700 Were samples stored as whole blood samples more
centrifuged and maintained in sodium citrate tubes? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Sample_Processing_Transportation PX911402020400 Were samples transported vertically? N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Therapy_Bethesda_Assay_Nijmegen_Modification_Chromogenic_Substrate_Assay PX911402030100 Were any changes made in the protocol over more
the course of the study? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Therapy_Bethesda_Assay_Nijmegen_Modification_Chromogenic_Substrate_Assay_Clinical_Trial PX911402030202 Is this study a part of multi-center more
clinical trials? show less
N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Therapy_Bethesda_Assay_Nijmegen_Modification_Chromogenic_Substrate_Assay_Clinical_Trial_Laboratory PX911402030300 Is a central laboratory being used? N/A
PX911402_Factor_Eight_Emicizumab_Individual_Extended_Therapy_Bethesda_Assay_Nijmegen_Modification_Chromogenic_Substrate_Assay_Record PX911402030201 Were the make and manufacturer of equipment, more
repeatability and coefficients of variation for the assay, and the reagents used recorded? show less
N/A
Hemophilia Inhibitor Research
Measure Name:

Response to Factor VIII Infusion in the Presence of Emicizumab - Individual Pharmacokinetic Study

Release Date:

May 7, 2019

Definition

A series of plasma Factor VIII activity determinations in blood samples are obtained immediately prior to, and at timepoints after, infusion of FVIII concentrate.

Purpose

The results of an individual pharmacokinetic study (i.e., initial recovery and half-life) of infused Factor VIII concentrate can characterize an individual’s response to a new drug or can confirm the success of immune tolerance induction (ITI).

Keywords

Hemophilia inhibitors, Factor VIII, FVIII, hemophilia A, inhibitors, pharmacokinetic study, immune tolerance induction, prophylaxis, recovery, half-life