Immune Thrombocytopenia Onset and Relapse During the COVID-19 Pandemic. A Monocenter Study.

Background And Objectives: Several infections and vaccinations can provoke immune thrombocytopenia (ITP) onset or relapse. Information on ITP epidemiology and management during the Covid-19 pandemic is scarce. In a large monocenter ITP cohort, we assessed the incidence and risk factors for: 1) ITP onset/relapse after Covid19 vaccination/infection; 2) Covid19 infection. Methods: Information on the date/type of anti-Covid-19 vaccine, platelet count before and within 30 days from the vaccine, and date/grade of Covid-19 was collected via phone call or during hematological visits. ITP relapse was defined as a drop in PLT count within 30 days from vaccination, compared to PLT count before vaccination that required a rescue therapy OR a dose increase of an ongoing therapy OR a PLT count <30 ×109/L with ≥20% decrease from baseline. Results: Between February 2020 and January 2022, 60 new ITP diagnoses were observed (30% related to Covid-19 infection or vaccination). Younger and older ages were associated with a higher probability of ITP related to Covid19 infection (p=0.02) and vaccination (p=0.04), respectively. Compared to Covid-19-unrelated ITP, Infection- and vaccine-related ITP had lower response rates (p=0.03) and required more prolonged therapy (p=0.04), respectively. Among the 382 patients with known ITP at the pandemic start, 18.1% relapsed; relapse was attributed to Covid-19 infection/vaccine in 52.2%. The risk of relapse was higher in patients with active disease (p<0.001) and previous vaccine-related relapse (p=0.006). Overall, 18.3% of ITP patients acquired Covid19 (severe in 9.9%); risk was higher in unvaccinated patients (p<0.001). Conclusions: All ITP patients should receive ≥1 vaccine dose and laboratory follow-up after vaccination, with a case-by-case evaluation of completion of the vaccine program if vaccine-related ITP onset/relapse and with tempest initiation of antiviral therapy in unvaccinated patients.

Immune thrombotic thrombocytopenic purpura: Personalized therapy using ADAMTS-13 activity and autoantibodies.

Recently, treatment of immune-mediated thrombotic thrombocytopenic purpura (ITTP) has changed with the advent of caplacizumab in clinical practice. The International Working Group (IWG) has recently integrated the ADAMTS-13 activity/autoantibody monitoring in consensus outcome definitions. We report three ITTP cases during the coronavirus disease 2019 pandemic, that received a systematic evaluation of ADAMTS-13 activity and autoantibodies. We describe how the introduction of caplacizumab and ADAMTS-13 monitoring could change the management of ITTP patients and discuss whether therapeutic choices should be based on the clinical response alone. ADAMTS-13 activity/antibodies were assessed every 5 days. Responses were evaluated according to updated IWG outcome definitions. These kinetics, rather than clinical remission, guided the therapy, allowing early and safe caplacizumab discontinuation and sensible administration of rituximab. Caplacizumab was cautiously discontinued after achieving ADAMTS-13 complete remission. These cases illustrate that prospective ADAMTS-13 evaluation and use of updated IWG definitions may improve real-life patients' management in the caplacizumab era.