Complete data from an epidemiologic analysis to find the percentage of women across assorted populations at elevated risk for a pregnancy affected by fetal and neonatal alloimmune thrombocytopenia (FNAIT) will be presented at the Annual Meeting of the American Society of Human Genetics (ASHG) in Denver, CO between Nov. 5-9.
Results presented in this epidemiologic analysis showed that the risk for alloimmunization was highest among women in Caucasian populations. The study is being conducted by Rallybio Corporation in partnership with HealthLumen.
According to Stephen Uden, M.D., Chief Executive Officer of Rallybio, “Data from this analysis provide the first clear evidence of the extent to which ancestries beyond the Caucasian population can carry a higher risk for FNAIT, underscoring the importance of screening all pregnant women for FNAIT risk as part of standard care. This would ensure that all women at higher risk for FNAIT could then be offered prophylactic treatment with RLYB212, if approved.”
RLYB212 currently is being evaluated in a phase 2 trial of pregnant women at high risk for human platelet antigen (HPA)-1a alloimmunization and FNAIT. Treatment with the agent is on track to be initiated in the last quarter of 2024.
Read more about FNAIT causes and risk factors
FNAIT is recognized as a rare, potentially serious disorder of pregnancy in which fetal platelets undergo destruction by maternal alloantibodies. In fact, the clinical implications of the disease, which may be severe, include intracranial hemorrhage. This, in turn, may lead to severe neurologic deficits in the infant and even to death.
Two types of HPA have been recognized—HPA-1a and HPA-1b—both of which are expressed on the surface of platelets. When alloimmunization is reported in a pregnant individual, anti–HPA-1a antibodies that develop in the mother can cross the placenta and subsequently destroy the platelets in the fetus. The destruction of fetal platelets can lead to extremely low platelet counts, which is known as thrombocytopenia. To date, no therapy has been approved for prevention of or prenatal treatment of FNAIT.
Maternal alloantibodies to HLA-1a are responsible for approximately 75% to 80% of all cases of FNAIT. Although the risk for FNAIT has been well described among Caucasians, data among non-Caucasian populations are relatively limited.
FNAIT risk according to ethnicity
Among Caucasian women, the greatest percentage of FNAIT cases were reported in the Ashkenazi Jewish population. Among those in this population, 2.36% of the women were at risk for FNAIT and 0.65% of the women were at high risk for FNAIT.
Among women in other ethnic/racial populations, the proportions at risk for and at high risk for FNAIT among those in Caucasian population groups were as follows:
- Non-Finnish European population: 2.34% and 0.64%, respectively
- Middle Eastern population: 2.25% and 0.62%, respectively
- Amish population: 2.25% and 0.62%, respectively
- White Hispanic population: 2.25% and 0.59%, respectively
- Finnish population: 2.03% and 0.56%, respectively
Further, among women in certain non-Caucasian population groups, the percentages at risk for and at high risk for FNAIT were as follows:
- Caribbean Hispanic population: 1.48% and 0.33%, respectively
- African/African American population: 1.13% and approximately 0.28% , respectively
Of note, women of East Asian, South Asian and Amerindigenous ancestries all were shown to have a lower risk for FNAIT.
“As FNAIT risk in some non-Caucasian populations is comparable to Caucasians, it demonstrates the need for awareness across populations and the need for both broad prenatal FNAIT risk screening and availability of treatment options for all pregnant women,” the authors concluded.
