CoVac-1 and T-Cell Responses in Patients With B-Cell Deficiencies

The following article features coverage from the American Association for Cancer Research (AACR) 2022 meeting. Click here to read more of Hematology Advisor‘s conference coverage.

In a recent study of patients with B-cell deficiencies, a new SARS-CoV-2 vaccine called CoVac-1 induced T-cell immune responses in most patients. The results of this study were presented at the AACR Annual Meeting 2022 by Claudia Tandler of University Hospital Tübingen in Tübingen, Germany, and colleagues.¹

SARS-CoV-2 vaccines have been associated with strong immune responses in most recipients, but people who are immunocompromised have experienced lower efficacy with approved vaccines.² This includes patients receiving treatments that diminish B-cell populations, who, with reduced humoral immunity, are at greater risk of developing severe COVID-19. Improving T-cell response is a potential approach to optimizing vaccine efficacy for such patients.^1,2

CoVac-1 is a peptide-based vaccine, and it was developed from 6 different SARS-CoV-2 antigens. These 6 epitopes, according to the researchers, have frequently been recognized by T cells in patients with COVID-19.¹ The researchers indicated CoVac-1 may induce broader immunity through T-cell responses than is seen with existing messenger RNA (mRNA)-based or adenoviral vector-based vaccines that are directed toward the virus’s spike protein. ²

“To our knowledge, CoVac-1 is currently the only peptide-based vaccine candidate specifically developed and evaluated for immunocompromised patients,” senior study author Juliane Walz, MD, said in a press release associated with the research group’s presentation.²

A prior first-in-human trial (ClinicalTrials.gov Identifier: NCT04546841) demonstrated safety and T-cell responses with CoVac-1 in healthy adults. The current analysis presented by Tandler and colleagues included interim safety and immunogenicity results from a phase 1/2 trial (ClinicalTrials.gov Identifier: NCT04954469) in patients with congenital or acquired B-cell deficiencies. Most patients had leukemia or lymphoma.¹

The majority of patients in this study (64%) had received approved vaccines against SARS-CoV-2 but had not developed humoral immune responses with them.^1,2 The researchers reported that in this study CoVac-1 was associated with a positive safety and tolerability profile that was similar to what was seen with healthy adults.¹

On day 28 following CoVac-1 vaccination, 93% of patients showed CoVac-1-specific T-cell responses. Most individuals (71%) in this study had also shown responses on day 14. T-cell responses associated with CoVac-1 were reportedly similar to those seen in healthy volunteers with SARS-CoV-2 infection or the use of approved vaccines. Multifunctional T-helper 1 CD4+ T cells were noted to mediate T-cell responses in this study.¹

The research team considered the study’s findings to support consideration of CoVac-1 as a potential vaccine candidate for immunocompromised patients, such as those with cancer or an immunoglobulin deficiency.¹ The researchers are preparing for a phase 3 trial with a larger population of immunocompromised patients, according to the press release.²

Read more of Hematology Advisor’s coverage of AACR 2022 by visiting the conference page.

References

1. Tandler C, Heitmann JS, Marconato M, et al. Interim safety and immunogenicity results of a phase I trial evaluating the multi-peptide COVID-19 vaccine candidate CoVac-1 for induction of SARS-CoV-2 T cell immunity in cancer patients with disease- or treatment-related immunoglobulin deficiency. Presented at AACR 2022; April 8-13, 2022. Abstract CT258.
2. Novel COVID-19 vaccine may provide protection for cancer patients with B-cell deficiencies. News release. AACR; April 12, 2022.