Multicenter Phase I-II clinical trial~Phase I:~Part I: 14-patients will receive an open-label 500 μl subcutaneous injection via needle and syringe of the study IMP (CoVac-1). 28 days following vaccination of the~1th patient, there will be an interim analysis of safety and immunogenicity and a review by the data safety monitoring board (DSMB) before proceeding to Phase II Definition of sufficient immunogenicity after one dose of vaccination: T cell response to at least one CoVAC-1 vaccine peptide on day28 in ≥80% of study patients, with proven general ability to mount antigen-specific T cell responses (detection of T cell responses to EBV/CMV control peptides) assessed by Interferon gamma (IFN-γ) ELISpot.~The time point (day28) for the assessment of CoVac-1 induced T cell responses was selected based on the results of the ongoing P-pVAC-SARS-CoV-2 study, where CoVac-1-induced SARS-CoV-2 T cell responses were observed in 100% of study subjects at day28.~The threshold of 80% was introduced after considering recent findings about cancer patients with hematological malignancies (comprising patients with B cell or antibody deficiencies) vaccinated with BNT162b2. Here it was observed that only 50% of patients had a BNT162b2-induced T cell response, while this was achieved in 80% of the healthy donors. Thus, the threshold of 80% was chosen, with the aim of providing our study population an immunization comparable to the one achieved in the healthy population vaccinated with the approved vaccines. CoVac-1 induced T cell responses are defined as positive T cell response in Interferon gamm (IFN-γ) ELISPOT assay with spot count at least 2-fold higher than the baseline assay (Visit 1). T cell responses are considered to be positive when the mean spot count per well is at least 3-fold higher than the mean number of spots in the negative control wells (stimulated with a control peptide). Only patients with detectable T cell response to the viral peptide panel ex vivo or after in vitro T cell expansion, and thus general ability to mount an antigen-specific immune response will be considered for the evaluation of sufficient immune responses after one CoVac-1 vaccination. Part II (optional): If there is an insufficient immune response measured by Interferon gamma (IFN-γ) ELISpot in Part I of Phase I on day 28, an additional Part (Part II) of Phase I will start enrollment of 14 subjects receiving two open-label 500 μl subcutaneous injection via needle and syringe of the study IMP (CoVac-1) on day1 and day42.~Phase II (after an amendment to the protocol):~40 subjects will receive an open-label 500 μl subcutaneous injection via needle and syringe of the study IMP (CoVac-1) on d1 and, depending on the data collected in Phase I, a second vaccination on day42 if necessary.
The indication of this study is To evaluate the safety and immunogenicity of a SARSCoV- 2-derived multi-peptide vaccine in combination with the TLR1/2 ligand XS15 in adults with congenital or acquired B-cell/antibody deficiency