ABSTRACT
As solid organ transplant (SOT) recipients receive therapeutic immunosuppression that compromises their immune response to infections and vaccines, they have a high risk of developing severe COVID-19 and an increased risk of COVID-19-related death. The constant immunosuppression may result in reduction of efficiency of immunotherapy. Thus, a therapy is required that enables efficient viral clearance against SARS-CoV-2 whilst simultaneously maintaining immunosuppressive treatment in transplant patients to prevent transplant rejection. Here, we propose adoptive transfer of SARS-CoV-2-specific T-cells rendered resistant to the common immunosuppressant Tacrolimus to optimize performance in immunosuppressed patients. By using a GMP-compatible, vector-free CRISPR-Cas9-based, gene-editing approach, we knocked out the cell-intrinsic adaptor protein FKBP12, which is required for the immunosuppressive function of Tacrolimus, and generated Tacrolimus-resistant SARS-CoV-2-reactive T-cell products (TCPs) from the blood of SARS-CoV-2 convalescent donors. Functional and phenotypical characterization of these products in depth, including single cell CITE- and TCR sequencing analyses, showed that the gene modification did not impact the functional potency of the Tacrolimus-resistant SARS-CoV-2-specific TCPs compared to unmodified SARS-CoV-2-specific TCPs, but confirmed resistance to Tacrolimus and sensitivity to alternative immunosuppressive drugs from the same class (safety switch). Based on the promising results, we aim to clinically validate this approach in transplant recipients. Our strategy has the potential to prevent or ameliorate severe COVID-19 in the SOT setting whilst preventing allogeneic organ rejection. Our platform technology allows targeting of different SARS-CoV-2 variants and other viruses, thus multiplying its potential therapeutic use.
ABSTRACT
Introduction: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused unprecedented public health and economical challenges worldwide. Cellular immunity is known to be crucial for the virus clearance. Recent data demonstrate pre-existing SARS-CoV-2-reactive T cells in samples of healthy blood donors collected before SARS-CoV-2 pandemics. The presence of these potentially protective T cells in SARS-CoV-2 naive population can be explained by cross-reactivity to the endemic common cold coronavirus. Whether such cells are also detectable in immunosuppressed patients is not known so far. Methods: We analysed the presence of SARS-CoV-2-cross-reactive T cell immunity in samples of 10 renal transplant patients (RTX) collected in 2019 before the onset of SARS-CoV-2 pandemics. Samples of 10 non-immunosuppressed/ immune competent SARS-CoV-2 naive patients matched to transplant patients were analysed as controls. T-cell reactivity against Spike-, Nucleocapsid-, and Membrane-SARS-CoV-2 proteins were analysed by multiparameter flow cytometry. Results: 50% of analysed RTX showed CD4 + T-cells reactive against at least one SARS-CoV-2 protein. CD8 + T cells reactive against at least one SARSCoV2 protein were demonstrated in 30% of RTX. Notably, the detected cells were of differentiated memory phenotype producing several Th1 cytokines including IFNg, TNFa, IL-2, as well as Granzyme B. The frequencies and cytokine expression pattern of SARS-CoV-2 reactive T-cells did not differ between transplant and non-transplant cohorts. Conclusion: Despite immunosuppressive treatment and underlined renal disease, transplant patients were able to generate cellular immunity crossreactive to SARS-CoV-2. The magnitude and functionality of the pre-existing immunity was non-inferior compared to the immune competent cohort. Although several pro-inflammatory cytokines were produced by the detected T cells, further studies are required to prove their antiviral protection.