Background: Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a rare bleeding disorder of the fetus/newborn caused by development of maternal alloantibodies against fetal human platelet antigens (HPAs), predominantly HPA-1a. Currently there are no treatments available to prevent maternal alloimmunization to HPAs or FNAIT.
Methods: This proof-of-concept study (EudraCT Number: 2021-005380-49) was designed to assess the ability of subcutaneous (SC) RLYB212, a monoclonal anti-HPA-1a antibody, to eliminate HPA-1a-positive platelets in an antigen challenge model of a 30 mL fetal-maternal hemorrhage. Subjects were randomized to receive a single SC dose of RLYB212 or placebo on day 1 in a single-blinded manner, followed by transfusion of 10 × 10 HPA-1a-positive platelets on day 8.
Results: Four subjects received 0.09 mg SC RLYB212, five received 0.29 mg SC RLYB212, and two received placebo. RLYB212 achieved rapid elimination of HPA-1a-positive platelets in a concentration-dependent manner, with concentrations as low as 3.57 ng/mL meeting the prespecified proof-of-concept criterion of ≥90% reduction in platelet elimination half-life versus placebo. Following HPA-1a-positive platelet transfusion, a rapid decline was observed in the concentration of RLYB212 over a period of 2 to 24 hours, corresponding to the time needed for RLYB212 to bind to ∼10% of HPA-1a on cell surfaces. RLYB212 was well tolerated with no reports of drug-related adverse events.
Conclusion: The data from this study are consistent with preclinical efficacy data and support the potential use of RLYB212 as a prophylactic treatment for FNAIT that prevents maternal HPA-1a alloimmunization during at-risk pregnancies.
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http://dx.doi.org/10.1055/a-2398-9344 | DOI Listing |
CPT Pharmacometrics Syst Pharmacol
November 2024
Certara USA, Radnor, Pennsylvania, USA.
Thromb Haemost
September 2024
Division Clinical Research, Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Frankfurt am Main, Germany.
Transfusion
April 2024
Laboratory Medicine and Pathology, Mayo Clinic, Jacksonville, Florida, USA.
Introduction: This case describes passenger lymphocyte syndrome (PLS) generating human platelet antigen 1a (HPA-1a) alloantibodies against the recipient's platelets after liver transplant. Given the rarity of PLS, especially in liver transplant with HPA-1a alloantibodies, disease course and management options are poorly described.
Methods: The patient had cirrhosis secondary to nonalcoholic steatohepatitis complicated by hepatocellular carcinoma, encephalopathy, and severe ascites.
Lancet Haematol
December 2023
Department of Experimental Immunohematology, Sanquin Research, Amsterdam, Netherlands. Electronic address:
Transfusion
May 2024
Department of Experimental Immunohematology, Sanquin Research, Amsterdam, The Netherlands.
Background: Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a condition during pregnancy, which can lead to thrombocytopenia and a bleeding tendency with intracranial hemorrhage (ICH) being the most concerning complication in the fetus or neonate. An incompatibility between human platelet antigen (HPA)-1a accounts for the majority of FNAIT cases. Binding of HPA-1a-specific alloantibodies to their target on fetal platelets and endothelial cells can induce apoptosis of megakaryocytes, disrupt platelet function, and impair angiogenesis.
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