Influenza Vaccination Strategy for Patients With Hematologic Malignancy

Overview

This randomized controlled trial evaluates and compares the immunogenicity of three different influenza vaccine formulations: high-dose trivalent (HD-IIV3), MF59-adjuvanted quadrivalent (aIIV4), and standard-dose trivalent (SD-IIV3) vaccines. The study population consists of patients with hematologic malignancies, including those undergoing autologous stem cell transplantation or CAR-T cell therapy. The primary goal is to identify which vaccine strategy elicits the most robust antibody and T cell-mediated immune responses in this severely immunocompromised population

Patients with hematologic malignancies face a 3-10 times higher risk of influenza infection and a 5-20 times greater rate of severe complications compared to the general population, owing to disease- and treatment-related immunosuppression. Although high-dose and adjuvanted influenza vaccines have been proposed to overcome suboptimal vaccine responses in this population, robust comparative evidence remains lacking - particularly following recent clinical trials which did not demonstrate superiority of adjuvanted vaccine over standard-dose vaccine in terms of antibody response. Critically, T cell-mediated immune responses, which may serve as an independent correlate of protection especially in B cell-depleted patients (e.g., post-CAR-T therapy), have not been comprehensively evaluated in prior trials. This randomized controlled trial aims to compare the immunogenicity of three influenza vaccine formulations - high-dose trivalent inactivated vaccine (HD-IIV3; Efluelda), MF59-adjuvanted quadrivalent inactivated vaccine (aIIV4; Fluad Quadrivalent), and standard-dose trivalent inactivated vaccine (SD-IIV3) - in patients with hematologic malignancies including lymphoma, leukemia, plasma cell disorders, and those undergoing autologous stem cell transplantation or CAR-T cell therapy. Immunogenicity will be assessed by both antibody responses (HAI-based GMT, seroconversion, seroprotection) and cellular immune responses (polyfunctional CD4+ and cytotoxic CD8+ T cells via IFN-γ/TNF-α/IL-2 intracellular cytokine staining of PBMCs) at baseline, Day 28, Day 180, and Day 365.