ABSTRACT
The ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic and heterologous immunization approaches implemented worldwide for booster doses call for diversified vaccine portfolios. GRAd-COV2 is a gorilla adenovirus-based COVID-19 vaccine candidate encoding prefusion-stabilized spike. The safety and immunogenicity of GRAd-COV2 is evaluated in a dose- and regimen-finding phase 2 trial (COVITAR study, ClinicalTrials.gov: NCT04791423) whereby 917 eligible participants are randomized to receive a single intramuscular GRAd-COV2 administration followed by placebo, or two vaccine injections, or two doses of placebo, spaced over 3 weeks. Here, we report that GRAd-COV2 is well tolerated and induces robust immune responses after a single immunization; a second administration increases binding and neutralizing antibody titers. Potent, variant of concern (VOC) cross-reactive spike-specific T cell response peaks after the first dose and is characterized by high frequencies of CD8s. T cells maintain immediate effector functions and high proliferative potential over time. Thus, GRAd vector is a valuable platform for genetic vaccine development, especially when robust CD8 response is needed.
Subject(s)
COVID-19 , Vaccines , Humans , SARS-CoV-2 , COVID-19 Vaccines , COVID-19/prevention & control , Immunity, CellularABSTRACT
BACKGROUND: Immune checkpoint blockade antibodies (imAbs), such as the anti Cytotoxic T Lymphocyte Antigen-4 (CTLA-4) ipilimumab (IPI) raised overall survival (OS) in metastatic melanoma (MM). Further, long-term OS is a crucial endpoint in MM. Thymosin alpha-1 (Tα1) with dacarbazine (DTIC) showed activity in a phase II trial and a compassionate use program (EAP). We report on long-term follow-up of patients treated with Tα1 to investigate the preconditioning role of Tα1 in imAbs-treated patients. METHODS: Records of patients with melanoma treated with Tα1 within a phase II trial and EAP program were reviewed comparing median OS among patients that sequentially received anti-CTLA-4 imAb and Tα1. Further, the effect of Tα1 on IPI long-term survivor patients was investigated. RESULTS: Among patients treated with Tα1, 21/61 patients received sequentially even anti CTLA-4 imAbs. Median OS at the data cut-off was 57.8 and 7.4 months in patients treated sequentially with anti-CTLA-4 imAbs or not, respectively. Moreover, pretreatment with Tα1 in all (95) IPI-evaluable patients confirmed a significant increase in long-term OS. CONCLUSION: This is the first report on long-term follow-up of Tα1-treated patients. Moreover, an advantage in OS in patients sequentially treated with Tα1 and IPI was seen that suggests a synergistic effect.
