SARS-CoV-2 Neutralizing Antibodies Kinetics Postvaccination in Cancer Patients under Treatment with Immune Checkpoint Inhibition

SIMPLE SUMMARY: Solid tumor patients under active anticancer treatment are peculiarly affected by COVID-19 infection, given not only its ominous outcomes but also the need of disruptions of their rather strict therapeutic scheme. Thus, they have been globally prioritized for both primary and booster vaccinations. The existing data with respect to the seroconversion rate of neutralizing antibodies (NAbs) among them, after vaccination, remain nevertheless obscure. Therefore, we prospectively evaluated the long-term humoral immunity dynamics for up to one month after the third dose in patients with solid malignancies receiving immunotherapy. Further research is required to assess the incremental benefit of booster doses and to optimize the vaccination schedule across different types of cancer and diverse systemic therapies. ABSTRACT: Considering that COVID-19 could adversely affect cancer patients, several countries have prioritized this highly susceptible population for vaccination. Thus, rapidly generating evidence on the efficacy of SARS-CoV-2 vaccination in the subset of patients with cancer under active therapy is of paramount importance. From this perspective, we launched the present prospective observational study to comprehensively address the longitudinal dynamics of immunogenicity of both messenger RNA (mRNA) and viral vector-based vaccines in 85 patients treated with immune checkpoint inhibitors (ICIs) for a broad range of solid tumors. Despite the relatively poor humoral responses following the priming vaccine inoculum, the seroconversion rates significantly increased after the second dose. Waning vaccine-based immunity was observed over the following six months, yet the administration of a third booster dose remarkably optimized antibody responses. Larger cohort studies providing real-world data with regard to vaccines effectiveness and durability of their protection among cancer patients receiving immunotherapy are an increasing priority.