Fetal and Neonatal Alloimmune Thrombocytopenia Clinical Trial
Official title:
An Open-label, Single Centre, Exploratory Trial Investigating the Kinetics of Platelets Transfused to Healthy, Male Subjects
The current phase 0 trial is preceding the phase 1/2 trial of a newly developed drug,
NAITgam, for the prevention of fetal and neonatal alloimmune thrombocytopenia (FNAIT) - a
rare, but potentially very severe bleeding condition in the fetus or newborn. FNAIT may occur
in women whose blood platelets do not express HPA-1a. If the fetus has inherited HPA-1a from
the father, the mother's immune system may be stimulated to produce HPA-1a antibodies if
HPA-1a positive fetal blood platelets enter the maternal circulation during delivery. In a
subsequent pregnancy, such antibodies will cross the placenta and may reduce the number of
HPA-1a positive blood platelets in the fetus, which in turn may result in severe bleeding in
the fetus or newborn.
The phase 1/2 study of NAITgam will examine NAITgam's ability to eliminate HPA-1a positive
blood platelets that has been transfused to healthy male subjects, whose blood platelet do
not express HPA-1a. The ability to quickly eliminate transfused HPA-1a positive platelets is
considered as a surrogate endpoint for NAITgam's ability to prevent formation of antibodies
against HPA-1a after delivery of an HPA-1a positive child.
The current phase 0 trial will examine the survival of blood platelets transfused to healthy
male individuals without subsequent administration of NAITgam. The natural survival of
transfused platelet, as determined in the phase 0 trial, will be compared with the survival
of transfused HPA-1a positive platelets after administration of NAITgam in the phase 1/2
trial. The aim of the phase 0 trial is first, to determine the dose of blood platelet that
should be transfused to the healthy subjects in the phase 1/2 trial; and secondly, to
determine the optimal time point, after transfusion of platelets, for administration of
NAITgam in the phase 1/2 trial.
Eight to 24 healthy male subjects will be included in the phase 0 trial. After transfusion of
platelets, blood samples will be collected at regular intervals to determine the proportion
of transfused blood platelets. Differences between tissue type antigens between donor and
recipient will be used to determine the proportion of transfused platelets. Survival of
transfused platelets will be performed by flow cytometry - a method that can be used to
quantify very small proportions of cells in the blood. Fluorochrome-conjugated monoclonal
antibodies against HLA-A2 and HLA-A9 will be used for flow cytometric identification the
transfused platelets.
n/a
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