Multi-peptide CoVac-1 vaccine induces T-cell immunity in immunoglobulin-deficient cancer patients

In the American Association for Cancer Research (AACR) annual meeting 2022, Dr. Claudia Tandler from the University of Tübingen, Germany, discussed the safety and immunogenicity of a novel multi-peptide vaccine, CoVac-1, for the induction of a (SARS-CoV-2) T-cell immunity in cancer patients with disease- or treatment-related immunoglobulin deficiency.1

The acute immune response following infection with SARS-CoV-2 constitutes CD4+ T-cell response in addition to other T-cell responses, which persists as long-term immunity and protects against the coronavirus disease 2019 (COVID-19), even in the absence of antibody titers that rapidly decline.1 These T-cells are particularly important in patients with leukemia and lymphoma, congenital or acquired immune defects, or organ/hematopoietic transplantation, who lack humoral or antibody-based immune responses.1 As such, patients are at a high risk of COVID-19 infection, and treatment should aim to develop a T-cell activator to induce a high T-cell immunity and protect this population from severe COVID-19 by binding the T cells to target peptides of COVID-19 infected cells.1

Hence, SARS-CoV-2 T-cell epitopes/peptides in COVID-19 human convalescents are identified and lead to the selection of 6 HLA-DR peptides derived from different viral components.1 In a trial, these T-cell activators constituted the CoVac-1 vaccine, administered subcutaneously as a single dose to form a depot at the vaccination site  allowing long-lasting stimulation.1 The safety and efficacy were assessed until day 56, and immunogenicity was measured at baseline on days 7, 14, 28, 56, and after 3 and 6 months.1

The trial consisted of 2 parts – part 1 included 12 healthy adults aged 18-55 years; and part 2 included 24 healthy adults aged 56-80 years.1 Overall, CoVac-1 vaccine showed a favorable safety and tolerability profile with few mild-to-moderate reactions, including expected granuloma local reactions with no inflammatory systemic adverse events.1 The results of immunogenicity showed a 100% T-cell response in participants on day 28, which persisted until month 3.1 In addition, the intensity of T-cell response observed was more potent and consistent across all variants, when compared with the response observed in the COVID-19 convalescents and vaccinated individuals.1

Another phase 1/2 multicentric trial included 54 patients having cancer or congenital B-cell deficiency, with the primary objectives of testing safety and tolerability in the phase 1 study and efficacy in the phase 2 study.1 Most participating patients were previously vaccinated and failed to develop an adequate antibody response.1  Similar to the previous results, the phase 1 trial showed few expected local reactions of granuloma with no inflammatory systemic reactions.1 Moreover, the preliminary results on immunogenicity showed T-cell responses in 86% of participants on day 28 with responses having the desired multifunctional TH1 phenotype.1

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