Babies born to mothers who received nipocalimab during pregnancies at high risk of severe hemolytic disease of the fetus and newborn (HDFN) showed no signs of impaired growth through six months or of delayed development or reduced quality of life through the age of 2.
These results come from a recently published extended report of the phase 2 UNITY trial studying nipocalimab, which is owned by Johnson & Johnson. Completing the full treatment course was linked to lower levels of harmful antibodiesAntibody A protein made by the immune system that recognizes and attacks foreign substances, such as bacteria, or in HDFN, fetal red blood cells carrying incompatible antigens. in the baby’s cord blood and milder disease after birth.
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This report offers the first detailed look at the infants’ health, adding to earlier findings that nipocalimab prevented or delayed fetal anemiaAnemia A condition that occurs when the body doesn’t have enough healthy red blood cells to carry oxygen to its tissues. In HDFN, anemia occurs when maternal antibodies destroy fetal red blood cells. without lasting harm to babies’ immune systems.
HDFN develops when a pregnant person’s immune system makes antibodies against a protein on the baby’s red blood cells, such as RhD or Kell. These antibodies cross the placenta and destroy the baby’s red blood cells, which can cause severe anemia. When severe anemia appears before 24 weeks of pregnancy, known as early-onset severe HDFN, the risk of serious complications and death rises. Both the anemia and intrauterine transfusions (IUTIntrauterine transfusion A procedure that delivers donor red blood cells to the fetus through the umbilical vein to treat severe anemia caused by HDFN.) complications (blood transfusions given to the fetus in the womb), contribute to this risk.
Read more about HDFN symptoms and risks
Nipocalimab, a lab-made antibodyAntibody A protein made by the immune system that recognizes and attacks foreign substances, such as bacteria, or in HDFN, fetal red blood cells carrying incompatible antigens., blocks FcRn, a receptor that carries antibodies across the placenta, to limit how many harmful antibodies reach the baby. The drug is approved for generalized myasthenia gravis and, in August, it was approved for warm autoimmune hemolytic anemia in the U.S.
The trial enrolled 13 pregnant participants who had a previous pregnancy affected by early-onset severe HDFN. They received weekly intravenous nipocalimab from week 14 to week 35 of pregnancy. Twelve pregnancies resulted in live births, and one ended in fetal loss due to IUT complications.
Seven infants were born to mothers who completed treatment without needing IUTs. Six of them needed no transfusions after birth, and one needed a single transfusion. Those with cord blood testing had low antibody levels at birth. In contrast, all five infants whose mothers stopped nipocalimab early and needed IUTs required at least one transfusion after birth, and some needed up to seven. Their cord blood antibody levels were far higher.
Eleven of 12 infants received phototherapyPhototherapy A treatment that uses special blue light to help newborns break down bilirubin and prevent kernicterus., a light treatment, to prevent or treat hyperbilirubinemiaHyperbilirubinemia A common cause of jaundice, this refers to higher than normal bilirubin levels in the blood. (high levels of bilirubinBilirubin A yellow substance produced when red blood cells break down. High bilirubin levels in newborns with HDFN can cause jaundice or, in severe cases, brain damage., a yellow substance from broken-down red blood cells). Only one infant, who had received an IUT, required an exchange transfusion, which replaces the baby’s blood to clear antibodies and bilirubin.
All but two infants grew within expected ranges through 6 months. Development also stayed on track, with average caregiver-reported scores in the normal range at 6, 12 and 24 months. By age 2, quality-of-life scores were favorable.
The study was small, had no comparison group and relied on caregiver reports of development, limitations the phase 3 AZALEA trial aims to address with a larger, placebo-controlled design and clinician-led developmental testing.
