Imperial, Robin

AbstractIntroductionThis 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.MethodsThe 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.ResultsThe patient's treatment course included 57 units of platelets transfused, emergency splenectomy, rituximab, plasma exchange, intravenous immunoglobulin (IVIG), eltrombopag, romiplostim, and efgartigimod.DiscussionThe 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.

Abstract Advanced hepatocellular carcinoma (HCC) is responsive to immune checkpoint inhibitors, but there are currently no known biomarkers to predict treatment benefit. Blood TMB (bTMB) estimation via circulating tumor DNA (ctDNA) profiling can provide a convenient means to estimate HCC TMB. Here we provide the first landscape of bTMB in advanced HCC using a commercially available next-generation sequencing assay, show that it is approximately three times as high as matched tissue TMB, and show that bTMB correlates with NAFLD cirrhosis etiology and the presence of genomic alterations in HTERT and TP53. These results lay the foundation for subsequent studies evaluating bTMB as an immune therapy predictive biomarker in HCC.