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

Description

This protocol provides instructions and guidance for collecting and processing samples for coagulation testing, performing a population-based 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 PhenX Hemophilia Inhibitor Research Working Group (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.

Availability

Available

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Protocol

Emicizumab Therapy: Population-based 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 Funk 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 and processed plasma can be stored at -20^o C for 2 weeks and should be transferred to < -70^o 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. The WG notes that there may be a number of different assays and instruments that are appropriate to perform the chromogenic substrate assay. ]]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: Population-based Pharmacokinetic Study

The WG recommends that investigators follow parameters outlined by the International Society on Thrombosis and Haemostasis Subcommittee on Factor VIII, Factor VIII and Rare Coagulation Disorders (Iorio et al., 2017). These parameters include taking two to three measurements at least 12 hours apart in the after a routine dose of the extended half-life product (i.e., no washout period and no standardized dose) at the following timepoints:

4-8 hours after infusion;
16-28 hours after infusion; and
40-60 hours after infusion.

In addition, investigators should take a sample 60-84 hours after infusion.

Extended Half-life Factor VIII Products: Population-based Pharmacokinetics Model

Investigators should use a "robust" population pharmacokinetics model, such as WAPPS-Hemo or PKFit.

Personnel and Training Required

Phlebotomist

Equipment Needs

Laboratory with the ability to perform the chromogenic substrate assay with bovine reagents.

Requirements

Requirement Category	Required
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

Lifestage

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

Standard	Name	ID	Source

Derived Variables

None

Process and Review

Not applicable.

Protocol Name from Source

Medical and Scientific Advisory Committee (MASAC) of the National Hemophilia Foundation (NHF), 2017

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.

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.

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. 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

911502

Variables

Export Variables

Variable Name	Variable ID	Variable Description	dbGaP Mapping
PX911502_Factor_Eight_Emicizumab_Population_Extended_Pharmacokinetic_Study
	PX911502040100	Were the parameters outlined by the more International Society on Thrombosis and Haemostasis Subcommittee on Factor VIII, Factor VIII and Rare Coagulation Disorders (Iorio et al., 2017) followed? show less	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Pharmacokinetic_Study_After_Infusion_Hours_12
	PX911502040400	Was Factor VIII activity tested 12-28 hour more after infusion? show less	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Pharmacokinetic_Study_After_Infusion_Hours_4
	PX911502040300	Was Factor VIII activity tested 4-8 hour more after infusion? show less	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Pharmacokinetic_Study_After_Infusion_Hours_40
	PX911502040500	Was Factor VIII activity tested 40-60 hour more after infusion? show less	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Pharmacokinetic_Study_Infusion_Baseline
	PX911502040200	Was Factor VIII activity tested before more infusion (baseline)? show less	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Pharmacokinetic_Study_Interpretation_Results
	PX911502050000	Was a robust population pharmacokinetics more model, such as WAPPS-Hemo or PKFit, used? show less	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Collection
	PX911502010100	Were the sample collection procedures more outlined in Lippi et al. (2012) followed? show less	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Collection_Blood_Draw
	PX911502010400	Was the order of blood draw recorded?	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Collection_Nonhemolyzed
	PX911502010300	Were nonhemolyzed samples collected?	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Collection_Tubes
	PX911502010500	Were collection tubes filled and mixed as more outlined in Lippi et al. (2012)? show less	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Collection_Tubes_Discard
	PX911502011000	Was a discard tube drawn?	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Collection_Tubes_Filled
	PX911502010700	Were the tubes filled within 11% of the fill line?	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Collection_Tubes_Second
	PX911502010800	Was a second tube collected?	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Collection_Tubes_Winged
	PX911502010900	Was a winged butterfly collection system used?	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Collection_Venipuncture
	PX911502010600	Was blood collected by direct venipuncture more into 3.2% sodium citrate tubes? show less	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Collection_Venous_Statsis
	PX911502010200	Were steps taken to prevent prolonged venous more stasis? show less	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Processing
	PX911502020100	Were the sample collection and processing more procedures outlined in Adcock Funk et al. (2012) followed? show less	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Processing_Agitation
	PX911502020500	Were samples agitated during transportation?	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Processing_Assayed
	PX911502021000	Were samples assayed within 4 hours of collection?	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Processing_Centrifuge_Validated
	PX911502021100	Was the centrifuge validated so that process more results in less than 10,000 platelets/microliter show less	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Processing_Deep_Freeze
	PX911502021300	Was the sample transferred to <= -70 C, more including shipment? show less	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Processing_Frozen
	PX911502021200	Was the sample frozen immediately and stored more at -20 C for at most 2 weeks? show less	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Processing_Platelet_Poor_Plasma
	PX911502020900	Were samples processed to platelet poor more plasma (PPP) within 1 hour of collection? show less	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Processing_Refrigerated
	PX911502020300	Were samples refrigerated or stored on ice more or in an ice bath? show less	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Processing_Sodium_Citrate
	PX911502020200	Did unprocessed or processed sodium citrate more samples remain capped and at room temperature until testing? show less	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Processing_Storage_Plasma
	PX911502020800	Were samples stored as plasma processed by more centrifugation and aliquoting into a second tube? show less	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Processing_Storage_Unprocessed
	PX911502020600	Were samples stored as unprocessed sodium more citrate whole blood samples? show less	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Processing_Storage_Whole_Blood
	PX911502020700	Were samples stored as whole blood samples more centrifuged and maintained in sodium citrate tubes? show less	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Sample_Processing_Transportation
	PX911502020400	Were samples transported vertically?	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Therapy_Bethesda_Assay_Nijmegen_Modification_Chromogenic_Substrate_Assay
	PX911502030100	Were any changes made in the protocol over more the course of the study? show less	N/A
PX911502_Factor_Eight_Emicizumab_Population_Extended_Therapy_Bethesda_Assay_Nijmegen_Modification_Chromogenic_Substrate_Assay_Record
	PX911502030201	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

Measure Name

Response to Factor VIII Infusion in the Presence of Emicizumab - Population 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 the population-based pharmacokinetic study (i.e., initial recovery and half-life) can be used to guide prophylactic dosage of standard and extended half-life Factor VIII products in hemophiliacs who do not have FVIII inhibitors.

Keywords

Hemophilia inhibitors, Factor VIII, FVIII, hemophilia A, pharmacokinetic study, population pharmacokinetic study, popPK, prophylaxis, recovery, half-life

Measure Protocols

Protocol ID	Protocol Name
911501	Emicizumab Therapy: Population-based Pharmacokinetic Study of Standard Half-life Factor VIII Products: Chromogenic Substrate Assay with Bovine Reagents
911502	Emicizumab Therapy: Population-based Pharmacokinetic Study of Extended Half-life Factor VIII Products: Chromogenic Substrate Assay with Bovine Reagents

Publications

There are no publications listed for this protocol.