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The Glanzmann’s Thrombasthenia Registry (GTR): Safety of Platelet Therapy in Patients with Glanzmann’s Thrombasthenia, with a Focus on Changes in alloimmunization Status

1Departments of Medicine, Pediatrics and Oncology, University of Calgary, Calgary, Alberta, Canada, 2Southern Alberta Rare Blood and Bleeding Disorders Comprehensive Care Program, Foothills Medical Centre, Calgary, Alberta, Canada, 3Centre de Référence de l’Hémophilie et des Maladies Hémoragiques Constitutionnelles, Hôpital Bicêtre, AP-HP, Université Paris Saclay, Le Kremlin-Bicêtre, France, 4Biostatistics & Programming GD GBS, Novo Nordisk Service Centre India Private Ltd, Bangalore, India, 5Institute for Laboratory Medicine, Blood Coagulation and Transfusion Medicine (LBT), Düsseldorf, Germany, 6Department of Hemostasis, Hemotherapy and Transfusion Medicine, Heinrich Heine University Medical Centre, Düsseldorf, Germany, 7Department of Clinical Medicine and Surgery, Regional Reference Center for Coagulation Disorders, Federico II University, Naples, Italy

Abstract Number: PB0893

Meeting: ISTH 2021 Congress

Theme: Platelet Disorders, von Willebrand Disease and Thrombotic Microangiopathies » Platelet Function Disorders, Hereditary

Background: Glanzmann’s Thrombasthenia (GT) is a rare, inherited, autosomal-recessive platelet disorder resulting in defective glycoprotein (GP) IIb–IIIa. Treatment outcome and platelet transfusion safety data are limited due to the rarity of GT. The international, prospective, observational GT registry (GTR; NCT01476423), which assessed the effectiveness and safety of recombinant activated factor FVII (rFVIIa) in GT, recorded treatment data including rFVIIa and platelet transfusion from 218 patients (10 May 2007–16 December 2011). Data presented here do not affect the GTR primary analysis results.

Aims: Describe GTR sub-analysis results evaluating platelet-based therapy safety in GT patients.

Methods: This sub-analysis identified GTR patients with a recorded change in anti-platelet antibody and platelet refractoriness status (alloimmunization) following treatment including rFVIIa, platelets and antifibrinolytics alone or in combination, and adverse events (AEs) following platelet-based therapies. No statistical comparisons were conducted.

Results: 34/218 (16%) patients had ≥1 instance of platelet refractoriness. Platelet antibodies were reported in 65/218 (30%) patients. Alloimmunization status change was recorded in 5/218 patients (Table 1). One patient experienced an antibody status change. Four patients experienced a platelet-refractoriness status change: one in whom rFVIIa-based treatments were recorded as only partially effective, and another with GPIIb-IIIa antibodies. In the 5 patients, platelet-based regimens were used in the majority of admissions, regardless of the presence/absence of antibodies/refractoriness. The majority of admission records were incomplete (Table 1). In 581 admissions, there were 24 AEs in 10 patients who received platelets alone, platelets and other hemostatics or other hemostatics alone; one AE was serious (generalized hives) (Table 2).

Patient Sex Age at admission Previous treatments Antibody status Platelet refractory status Treatment administered Effectiveness to stop bleeding
1  M  47
 56
 57		 Single donor platelets, HLA  HLA –
 HLA +
 HLA +		  NA
 NA
 NA		  N7POH
 P
 POH		  Effective
 NA
 NA
2  M  2
 2
 2
 3
 3		 Standard platelets, Single donor platelets  NA
 NA
 NA
 NA
 GPIIb/IIIa +		  Negative
 Negative
 Positive
 Positive
 Positive		  N7OH
 N7POH
 N7OH
 N7OH
 N7OH		  Effective
 Effective
 Effective
 Effective
 Effective
3  M  3.3
 3.3
 3.8
 7.1
 8.5
 8.6
 9
 9
 10
 10
 10
 10
 10.3
 11
 11		 Standard platelets, RBCs, antifibrinolytic  NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA		  Negative
 Negative
 Negative
 Negative
 Negative
 Negative
 Positive
 Positive
 Positive
 Positive
 Positive
 Positive
 NA
 NA
 NA		  POH
 P
 OH
 P
 P
 N7
 N7OH
 N7POH
 N7POH
 N7
 N7OH
 N7
 NA
 NA
 NA		  NA
 NA
 NA
 NA
 NA
 Effective
 NA
 NA
 Partially effective
 Partially effective
 Partially effective
 Partially effective
 Partially effective
 Partially effective
 Effective
4  M  0.9
 1
 1		 Standard platelets, RBCs  NA
 NA
 NA		  Negative
 Negative
 Positive		  OH
 POH
 POH		  NA
 NA
 NA
5  F*  5
 5
 5
 5
 6
 6
 6
 6
 6
 6
 6
 6
 6
 6
 6
 6
 6
 6
 6
 6
 6
 7
 7
 7
 7
 7
 7
 7
 7
 8
 8
 8
 8
 8
 8
 8
 8
 8
 8
 8
 8
 8
 8
 8
 8
 8
 8
 8
 8
 8
 8
 8
 8
 8
 8		 Standard platelets, RBCs, NovoSeven®  NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA		  Positive
 NA
 NA
 NA
 NA
 Positive
 Positive
 Positive
 Positive
 Positive
 Positive
 Positive
 Positive
 Positive
 Positive
 Positive
 Positive
 Positive
 Positive
 Positive
 Positive
 Positive
 Positive
 Positive
 Positive
 Positive
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 Positive
 NA
 Positive
 Positive
 NA
 Positive
 NA
 Positive
 Positive
 Positive
 NA
 NA
 NA
 Negative
 Positive
 Negative
 Negative
 Negative		  POH
 NA
 NA
 NA
 NA
 POH
 POH
 POH
 P
 POH
 POH
 POH
 N7POH
 POH
 POH
 POH
 POH
 POH
 POH
 POH
 POH
 POH
 POH
 POH
 POH
 POH
 OH
 POH
 POH
 POH
 POH
 P
 P
 P
 NA
 NA
 NA
 P
 NA
 POH
 POH
 NA
 P
 POH
 OH
 POH
 POH
 NA
 OH
 NA
 P
 POH
 POH
 POH
 POH		  NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
 NA
*Patient was not pregnant.
GPIIb/IIIa, glycoprotein IIb/IIIa; GPIIb/IIIa +, GPIIb/IIIa positive; GTR, Glanzmann’s Thrombasthenia Registry; HLA, human leukocyte antigen; HLA –, HLA negative; HLA +, HLA positive; N7, NovoSeven®; N7OH, NovoSeven® and other hemostatic treatment; N7POH, NovoSeven®, platelets and other hemostatic treatment; NA, not available; OH, other hemostatic treatment (mostly antifibrinolytics); P, platelets; POH; platelets and other hemostatic treatment; RBCs, red blood cells; rFVIIa, recombinant activated factor VII (NovoSeven®)

Demographics of GTR patients with a recorded change in anti-platelet antibody and platelet refractoriness status (alloimmunization) following treatment including rFVIIa, platelets and antifibrinolytics alone or in combination

  Number of patients Number of admissions Number of adverse events
  152 581  
Adverse events, n 10* 16 24
  Serious adverse events, n 1 1 1†
  Non-serious adverse events, n 10 15 23
*One patient experienced non-serious adverse events and a serious adverse event resulting in a total of 10 patients reporting adverse events.
 †Generalized hives; treatment related to a bleeding episode.
 GTR, Glanzmann’s Thrombasthenia Registry; rFVIIa, recombinant activated factor VII (NovoSeven®)

Adverse events occurring during admissions of patients in the GTR who were not treated with rFVIIa either for a bleeding episode or for treatment related to surgery.

Conclusions: Platelet transfusions may lead to AEs and treatment failure due to platelet refractoriness. However, in GT patients, routine platelet antibody testing is often not available due to the specialized nature of testing.

To cite this abstract in AMA style:

Poon M-, d’Oiron R, Baby S, B Zotz R, Di Minno G. The Glanzmann’s Thrombasthenia Registry (GTR): Safety of Platelet Therapy in Patients with Glanzmann’s Thrombasthenia, with a Focus on Changes in alloimmunization Status [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/the-glanzmanns-thrombasthenia-registry-gtr-safety-of-platelet-therapy-in-patients-with-glanzmanns-thrombasthenia-with-a-focus-on-changes-in-alloimmunization-status/. Accessed August 9, 2022.

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