Successful treatment of severe passenger lymphocyte syndrome with efgartigimod synergy

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. The model for end-stage liver disease (MELD) score was 15 at presentation. The patient developed hepatic artery thrombosis after an orthotopic liver transplant and was relisted for transplant with a MELD score of 40. The patient received a hepatitis C virus antibody positive, hepatitis C virus nucleic amplification test positive donor liver on postoperative day (POD) 7 after first transplant. On POD 7 after the second transplant, the patient developed profound thrombocytopenia refractory to platelet infusion. They were found to have serum antibody to HPA-1a based upon serum platelet alloantibody testing. The donor was later found to be negative for HPA-1a by genetic testing. However, the patient's native platelets were HPA-1a positive. The patient was diagnosed with PLS. Results: The patient's treatment course included 57 units of platelets transfused, emergency splenectomy, rituximab, plasma exchange, intravenous immunoglobulin (IVIG), eltrombopag, romiplostim, and efgartigimod. Discussion: The synergistic effect of efgartigimod with eltrombopag and romiplostim most likely resolved the patient's thrombocytopenia. This case represents a novel use of efgartigimod in the treatment of passenger lymphocyte syndrome following liver transplant.