Persistence of Ad26.COV2.S-associated VITT and specific detection of VITT antibodies

Background: Some COVID-19 vaccinated individuals develop anti-platelet factor 4 (PF4) antibodies that cause thrombocytopenia and thrombosis;a rare syndrome referred to as vaccine-induced immune thrombotic thrombocytopenia (VITT). Currently, information on the characteristics and persistence of anti-PF4 antibodies that cause VITT after Ad26.COV2.S vaccination is limited, and available PF4-polyanion enzyme-linked immunosorbent assays (ELISAs) and functional diagnostic assays fail to differentiate Ad26.COV2.S and ChAdOx1 nCoV-19-associated VITT from similar clinical disorders, namely heparin-induced thrombocytopenia (HIT) and spontaneous HIT. Aim(s): Evaluate the persistence of anti-PF4 antibodies in Ad26. COV2.S-associated VITT and correlate findings with clinical and laboratory variables such as thrombosis and platelet counts. Develop/ investigate laboratory tools that differentiate VITT antibodies from HIT and spontaneous HIT. Method(s): Blood samples from VITT and HIT patient cohorts were tested in antigen-based and functional assays and correlated with clinical and laboratory features. Result(s): While Ad26.COV2.S-associated VITT patients were strongly positive in PF4-polyanion ELISAs;they were frequently negative in the serotonin release assay (4 of 8 tested patients were negative). In contrast, the PF4-dependent p-selectin expression assay (PEA) that uses PF4-treated platelets consistently diagnosed Ad26.COV2.S-associated VITT. Most Ad26.COV2.S-associated VITT antibodies persisted for >5 months in PF4-polyanion ELISAs, while the PEA became negative earlier. Two patients had otherwise unexplained mild persistent thrombocytopenia (140-150,000/ mul) six months after acute presentation. No recurrence of thrombosis was noted. Additionally, a novel un-complexed PF4 ELISA specifically differentiated VITT secondary to Ad26.COV2.S and ChAdOx1 nCoV-19 vaccination, from spontaneous HIT and HIT (Fig 1A-PF4/ polyanion ELISA;Fig 1B-Un-complexed PF4 ELISA;closed black circles-Ad26. COV2.S-associated VITT;closed red circle-ChAdOx1 nCoV-19-associated VITT;***p < 0.001;****p < 0.0001). Its specificity was further confirmed by testing commonly-encountered HIT-suspected patient samples that are PF4/polyanion ELISA-positive but negative in functional assays (1A-1B). Conclusion(s): Ad26.COV2.S-associated VITT antibodies are persistent, and the un-complexed PF4 ELISA appears to be both sensitive and specific for VITT diagnosis.

Outcomes of Patients with Budd-Chiari Syndrome and Factors Predicting the Need for TIPS & Liver Transplantation - a Single-Center Long-Term Experience

Background: Budd-Chiari Syndrome (BCS) is a complex thrombotic disorder caused due to obstruction of hepatic venous outflow involving anywhere from small hepatic venules to the entrance of inferior vena cava into the right atrium. This leads to venous stasis and ischemic injury of hepatic parenchyma and sinusoids, with the risk of liver failure. The prognosis of patients with BCS had improved significantly with long-term anticoagulation and measures like Trans-Jugular-Intrahepatic-Porto-Systemic shunt (TIPS) and liver transplantation. We report the outcomes of patients who follow in our hematology practice and describe the factors predicting the need for TIPS/Liver Transplant. Methods: After appropriate Investigational Review Board permission, we identified patients with a history of BCS following in our thrombosis clinical practice from the year 2010 onwards. We evaluated their laboratory, demographic, anticoagulation data, Model of End-stage Liver Disease (MELD) score, Child-Pugh (CP) score at diagnosis or when earliest available, and other relevant clinical information as outlined. Descriptive statistics with medians, quartiles, frequencies, and percentages are reported. Further, we compared the two categories of patients who needed TIPS/Liver transplants versus those who did not. SAS version 9.4 was used for analysis. For continuous variables, a univariate nonparametric Mann-Whitney test was used. The Fisher's Exact Test was used to associate each variable with the need for TIPS/Liver Transplant. Results: Our study included 23 patients with baseline characteristics, including median age of 36 years (11-59 years), 91% whites, 61% females, 44% smokers, 61% obese(median BMI 29.9 kg/m 2), 6 of 14 women on oral contraceptive pills, 22% with thrombosis history, 17% with stroke history, median hemoglobin 13.4 gm/dL(8.9-20 gm/dL), white blood cell count 9,400/L (3,050-31,500/L), platelet count 294,000/L(14,000-767,000/L), serum creatinine 0.87 mg/L (0.55-2.52 mg/dL), total protein 6.3 gm/dL (5.2-8.8 gm/dL), Bilirubin 2.1 mg/dL(0.1-20.2 mg/dL), Aspartate Aminotransferase (AST) 61 U/L(16-1037 U/L), Alanine Aminotransferase (ALT) 43U/L(18-1694 U/L), MELD score 15 (range 7-38), CP score 9 (5-14), 74% with cirrhosis, 82% with ascites at one point, 57% with myeloproliferative neoplasm (MPN), 4.3% with Paroxysmal Nocturnal Hemoglobinuria (PNH), 17% with Antiphospholipid antibodies positive (APS), 13% had positive antinuclear antibodies, 35% needed TIPS and 44% required liver transplantation. 57% with Janus Kinase (JAK2) V617F mutation (1 patient with a low variant allele frequency of 1%), 1 patient (4.3%) had Calreticulin (CALR) mutation positive MPN, 91% remained on long-term anticoagulation with 40% using warfarin, 35% apixaban, 9% Enoxaparin or Rivaroxaban for long-term anticoagulation, 13% developed heparin-induced thrombocytopenia (HIT). 8.7% had developed BCS after Ad26.COV2.S vaccine to prevent SARS-CoV-2 infection. Excluding the patients with missing variables, 5 of 12 had Protein C deficiency, 3 or 10 had Protein S deficiency, 8 of 20 with Antithrombin (AT) deficiency, 4 of 14 with heterozygous factor V Leiden mutation, 0 of 10 with prothrombin gene mutation, 1 of 13 with hyper-homocysteinemia. 35% had gastrointestinal bleeding though 65% of patients had evidence of varices by endoscopy. When the group needing TIPS/Liver transplant/died is compared to those who did not, they had higher bilirubin, MELD, PC score, AT deficiency, cirrhosis, ascites, and JAK2 mutation (p-value significant: Table 1). With a median follow-up of 90 months, overall survival was not statistically significant between the two groups (Figure 1). Two patients (8.7%) died out of a total of 23. Conclusions: Our data indicate that in patients with BCS, neoplasms (61%), particularly MPN (57%), are very commonly diagnosed. Compared to the historical data in patients with BCS with dismal prognosis (60-80% six-month mortality rate), the overall survival had significantly improved, likely due to supportive measures like TIPS/Liver transplant and long-ter anticoagulation. Outside the established variables like CP and MELD, lower antithrombin activity and positive JAK2 mutation status also predicted a higher TIPS/Liver transplant need. [Formula presented] Disclosures: Bhatt: Partnership for health analytic research, LLC: Consultancy;Abbvie: Consultancy, Research Funding;Jazz: Research Funding;Incyte: Consultancy, Research Funding;Pfizer: Research Funding;Tolero Pharmaceuticals, Inc: Research Funding;National Marrow Donor Program: Research Funding;Abbvie: Consultancy, Research Funding;Genentech: Consultancy;Servier Pharmaceuticals LLC: Consultancy;Rigel: Consultancy. Gundabolu: BioMarin Pharmaceuticals: Consultancy;Blueprint Medicines: Consultancy;Bristol-Myers Squibb Company: Consultancy;Pfizer: Research Funding;Samus Therapeutics: Research Funding.