Learn The BasicsFetal and neonatal alloimmune thrombocytopeniaFetal and neonatal alloimmune thrombocytopenia A rare condition in which a mother’s immune system attacks fetal platelets, leading to dangerously low platelet levels before and/or after birth. (FNAITFetal and neonatal alloimmune thrombocytopenia A rare condition in which a mother’s immune system attacks fetal platelets, leading to dangerously low platelet levels before and/or after birth.) is a rare disease in which the immune system of a pregnant woman mistakenly attacks the platelets of her baby.
There is currently no cure for FNAIT, but there are therapies that aim to reduce the risk and effects of FNAIT. Some of these are experimental therapies that are currently being tested in clinical trials.
Intravenous immunoglobulin (IVIG)
IVIGIntravenous immunoglobulin A treatment given to pregnant women with a history of FNAIT or known alloantibodies. IVIG reduces the immune reaction against fetal platelets. is a “gold standard” therapy for pregnancies at risk of FNAIT. In this therapy, immunoglobulin from a donor is given to a pregnant woman at risk of having a baby affected by FNAIT to dampen her immune system.
According to The International Collaboration for Transfusion Medicine Guidelines (ICTMG), IVIG therapy should begin at 12 to 16 weeks of the pregnancy if the woman had a previous baby with FNAIT-associated intracranial hemorrhageBrain bleed Bleeding inside the fetal brain, also known as an intracranial hemorrhage. In FNAIT, it's often caused by severe thrombocytopenia and can lead to long-term disability or death. or bleeding in the brain. It should begin at 20 to 22 weeks is a previous baby was affected by FNAIT but did not have bleeding in the brain.
In some cases, IVIG therapy may also be given to newborn baby with FNAIT to increase their platelet countPlatelet count A measure of how many platelets are in the blood. FNAIT is characterized by severely reduced counts in a fetus or newborn.. However, the effectiveness of this approach is not clear.
Steroids
Steroids, sometimes also called corticosteroids, are anti-inflammatory drugs that can be used to dampen the immune response. These reduce the production of chemicals that cause inflammation thereby reducing damage to the tissues.
They may sometimes be used together with IVIG in high-risk pregnancies. In order to prevent FNAIT in future pregnancies, doctors may start the treatment as early as 12-16 weeks of gestation.
Steroids may also be given to a baby at risk of FNAIT just after birth. But again, the possible benefits of such an approach are not clear.
Nipocalimab
Nipocalimab is an experimental antibody that is currently being tested in clinical trials as a potential therapy for FNAIT, among other conditions.
It is an injection that is given to the mother during pregnancy in an attempt to block a protein called neonatal Fc receptorFc receptor A specialized transport protein. In FNAIT, it carries maternal antiplatelet IgG antibodies across the placenta into the fetus, which destroys the fetus's platelets., which is responsible for transporting immunoglobulin G from the mother to the baby. These are the types of antibodies that cause the baby’s platelets to be destroyed.
Being developed by Johnson & Johnson, the experimental therapy already received Fast-Track Designation from the U.S. Food and Drug Administration to reduce the risk of FNAIT.
If approved, it could benefit pregnant women who are at high risk of having a baby affected by the disease.
Immunoprophylaxis
Another experimental approach that may benefit women at high risk of having a baby affected by FNAIT is immunoprophylaxis.
This therapy includes giving antibodies against the human platelet antigenHuman platelet antigen Proteins found on the surface of platelets. Incompatibility between maternal and fetal human platelet antigens can trigger FNAIT. (HPAHuman platelet antigen Proteins found on the surface of platelets. Incompatibility between maternal and fetal human platelet antigens can trigger FNAIT.)-1a to a pregnant woman in an attempt to prevent FNAIT.
HPA-1a is the protein found on the surface of platelets, which triggers the mother’s immune system in most cases.
The goal of this therapy that these antibodies compete with the antibodies of the mother in recognizing the HPA-1a found on the surface of the baby’s platelets, “masking” them and ensuring the mother’s antibodies cannot attach to them.
This approach has already been tested in clinical trials and has been shown to increase the survival of platelets that have HPA-1a on their surface.
However, more research is needed to identify the right dose and timing of the therapy.
Reviewed by Debjyoti Talukdar, M.D., on September 9, 2024.
