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.« Back to ISTH 2021 Congress
ISTH Congress Abstracts - 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/