Rallybio to Present FNAIT Risk Analysis at ASHG 2024

Rallybio Corporation, a biotechnology firm listed on Nasdaq as RLYB, is advancing its efforts to develop revolutionary treatments for patients afflicted with severe rare diseases. The company has recently announced the presentation of comprehensive data from an epidemiological study at the forthcoming American Society of Human Genetics (ASHG) 2024 Annual Meeting in Denver, Colorado. This analysis aims to quantify the proportion of women across diverse demographics who are at heightened risk of pregnancies impacted by fetal and neonatal alloimmune thrombocytopenia (FNAIT).

Dr. Stephen Uden, the Chief Executive Officer of Rallybio, highlighted the company's ongoing initiatives to increase awareness of FNAIT. He emphasized the significance of understanding the population susceptible to this potentially fatal condition. He noted that the company's Phase 2 trial of RLYB212, targeting pregnant women at risk of HPA-1a alloimmunization and FNAIT, is scheduled to commence in the final quarter of 2024.

The study presents the first substantial evidence that ancestries beyond the Caucasian population are also vulnerable to FNAIT. Dr. Uden stressed the importance of incorporating FNAIT risk screening into standard prenatal care for all pregnant women. Such measures would ensure that those identified as high-risk could receive prophylactic treatment with RLYB212, contingent upon its approval.

The ASHG abstract #7041T outlines the findings of this epidemiological investigation. Women at higher risk for alloimmunization and FNAIT were identified based on their HPA-1a negative and HLA-DRB3*01:01 positive genotype. Allele frequencies were sourced from gnomAD v4 for HPA-1a and the U.S. National Marrow Donor Registry for HLA-DRB3*01:01.

The study revealed that the risk of alloimmunizing is most pronounced in Caucasian populations, with the highest proportions recorded among Ashkenazi Jewish (2.36% and 0.65% at risk and higher risk, respectively), non-Finnish Europeans (2.34% and 0.64%), Middle Eastern (2.25% and 0.62%), Amish (2.25% and 0.62%), White Hispanic (2.25% and 0.59%), and Finnish (2.03% and 0.56%) populations. Additionally, certain non-Caucasian groups also displayed a notable risk, including the Caribbean Hispanic (1.48% and 0.33%) and African/African American populations (1.13% and 0.28%). Women of South Asian, East Asian, and Amerindigenous backgrounds were found to have a lower risk (<1.0% and <0.1%).

Overall, the data indicates that the annual number of pregnancies at higher risk for FNAIT has been significantly underestimated. In North America and major European countries, it is now estimated that over 30,000 pregnancies each year are at elevated risk for FNAIT, representing a 40% increase from previous estimates. This translates into a commercial potential of approximately $1.6 billion.

Rallybio conducted this analysis in collaboration with HealthLumen, an expert in epidemiological modeling of rare genetic diseases. A poster with further details will be available on Rallybio’s website following the conference.

Fetal and Neonatal Alloimmune Thrombocytopenia (FNAIT) is a rare, life-threatening condition that can result in uncontrolled bleeding in fetuses and newborns due to immune incompatibility between the mother and fetus concerning the human platelet antigen 1 (HPA-1). The disease arises when an HPA-1a-negative expectant mother develops antibodies against an HPA-1a-positive fetus, leading to the destruction of fetal platelets. This can cause severely low platelet counts, leading to serious outcomes such as miscarriage, stillbirth, neonatal death, or long-term neurological damage. Currently, there is no approved treatment for preventing or managing FNAIT during pregnancy.

Rallybio, headquartered in New Haven, Connecticut, is committed to developing treatments that address unmet medical needs. The company’s pipeline includes two clinical-stage programs: RLYB212 for preventing FNAIT and RLYB116, which inhibits complement component 5 (C5) for treating various complement dysregulation disorders, along with several preclinical projects.