ABSTRACT
Background: Vaccination plays a major role in controlling SARS-CoV2 infection but faces the issue of short-term protection. Beyond the generation of Abs, induction of memory CD8+T cells with stem cell-like (Tscm) properties is essential for long-term immunity to viruses. We have designed a sub-unit CD40.CoV-2 vaccine which targets Spike (S) and nucleocapsid (N) regions from SARS-CoV-2 to antigen presenting cells with comparable immunogenicity and protective effect than mRNA BNT162b2 (Pfizer-BioNTech) in preclinical models (Coleon S. EBioMed 2022). We hypothesized that CD40.CoV2 vaccine will elicit CD8+ Tscm cells. Method(s): CD40.CoV2 vaccine is a fully humanized mAb fused to RBD (aa 318-541) and N (aa 276-411). Humanized (hu) NSG mice (HIS-mice) (n=6/ group) received: i) CD40.CoV2 (10 mug equal to 1.3 mug of RBD, i.p.) +/- poly-ICLC (TLR3 agonist;50mug) or ii) BNT162b2 (1mug, i.m.);iii) IgG4.CoV2 (10mug, i.p.) as non-CD40-targeting control. Phenotype and function of splenic S and N-specific T cells were assessed at W5. Result(s): The CD40.CoV2 vaccine +/- poly-CLC induced significant S and N-specific Th1 huCD4+, cytokines-secreting huCD8+ T cells and RBD-specific IgG-switched huB cells as compared to mock injections and non-targeted IgG4.CoV2. CD40.CoV-2 vaccine +/- adjuvant induced higher frequencies of huCD8+ Tscm (CD95+ CD45RA+ CD62L+ ;median, (IQR) 22.4% (12.3-27.4) and 23% (20.7-29.1) +/- adjuvant, respectively) and central memory (TCM;CD45RA- CD62L+) CD8+ T cells (2.7% (2.3-6.2) and 5.1% (3.8-7.8) +/- adjuvant, respectively). In contrast, BNT162b2 induced predominantly effector memory (TEM, CD45RA- CD62L- ;median, (IQR) 63.1% (47.3-72.3)) but not Tscm (1.6% (0.9-6.6)) (figure). CD40.CoV-2 induced huCD8+ Tscm cells exhibit ;i) a higher proliferation index than TCM and TEM;ii) a functional profile secreting TNF and IFNgamma after restimulation with RBD or N peptides;cardinal features of Tscm cells. Conclusion(s): The CD40.SARS.CoV2, but not BNT162b2 vaccine, stimulates selective enrichment in S-and N-specific CD8+ Tscm cells that support longlasting anti-viral immunity. CD40.CoV2 sub-unit is under clinical development as a booster vaccine aimed to maintain durable anti-viral T and humoral responses. (Figure Presented).
ABSTRACT
Background & Aim: Cytokine Release Syndrome (CRS) and Immune effector Cell-Associated Neurotoxicity Syndrome (ICANS) are related side effects of immunotherapies seen in up to 76% of patients treated with CAR-T and 48% of those treated with BiTEs. In up to 27% of the patients, these syndromes may lead to severe consequences. Current treatments for severe CRS are ineffective in >30% of the cases and can worsen ICANS prognosis, calling for novel treatments, especially in light of the expanding use of immunotherapies. Despite their obvious potential, mesenchymal cell (MSC) therapies were seldom investigated in this context. In the present study, Bonus BioGroup has set to assess the potential for treating CRS with MesenCure™, our allogeneic MSC platform, professionalized to enhance the cells’ potency and shown safe and effective in severe COVID patients. Methods, Results & Conclusion: A highly translational and validated CRS model was established in humanized NSG mice bearing human PBMCs, B-cell lymphoma, and CAR-T cells. CAR-T introduction significantly increased the serum levels of proinflammatory cytokines in model animals, indicative of CRS (Fig. 1A). Two IV MesenCure injections were well-tolerated in this model (Fig. 1B) and did not obstruct the CAR-Ts’ ability to inhibit tumor growth by 89% (Fig. 1C, p<0.0001). Remarkably, significant reductions in all proinflammatory cytokines tested (excluding IL-6) were measured in model animals treated with MesenCure, substantiating its potential to treat CRS (Fig. 1A). Interestingly, the magnitudes of these reductions resembled those observed in 50 severe COVID patients treated with MesenCure. MesenCure’s robust immunomodulatory capacity was further demonstrated in vitro by its ability to inhibit the proliferation of activated CD4 T cells with an IC50 of 6k MSC/200k PBMCs, twice more effectively than non-professionalized MSCs. Comparable results were also obtained with CD8 T cells. Similarly, MesenCure inhibited neutrophils’ ROS production by up to 80% within an hour following activation (IC50 19k MSC/200k neutrophils). These effects are likely mediated, in part, by IDO, whose RNA levels were found to be 6.8-fold higher in MesenCure cells than in non-professionalized MSCs (p<0.05), two hours after activation with IFNγ. Moreover, IDO inhibition by 1-MT (1 mM) reduced MesenCure’s (Figure Presented) Fig. 1 (A) The levels of serum proinflammatory cytokines measured in tumor-bearing NSG mice after CRS induction by injection of human PBMCs/CAR-Ts (or saline control) and MesenCure treatment (or saline control). Experimental groups’ designation: Control – not injected with PBMCs/CAR-Ts and not treated by MesenCure;CAR-T – CRS model animals, injected with PBMCs/CAR-Ts but not treated with MesenCure;MesenCure – treated with MesenCure but not injected with PBMCs/CARTs;and CAR-T + MesenCure – CRS model animals treated with MesenCure. (B) Relative change in body weight from the day of tumor induction (Day 0) and (C) IVIS analysis of tumor burden (dorsal aspect) in the above four experimental groups. Statistical significance indicators: ns – not significant, * p<0.05, *** p<0.001, **** p<0.0001. Statistical tests: Holm-Šídák’s multiple comparisons test (A) and two- sided t-test (C). ability to inhibit T cells’ proliferation by 73%. In conclusion, we provide the first evidence for the potential of MSCs and MesenCure, in particular, for treating immunotherapy-related CRS.
ABSTRACT
Background: Following natural infection or vaccination, the generation of stem cell-like memory T (Tscm) cells is essential for long-term protective immunity to the virus. Tscm cells have the capacity for self-renewal and multipotency. In SARS-CoV2 infection, the emergence of CD8+ Tscm cells is correlated with the number of symptom-free days. The development of a COVID-19 vaccine able to generate CD8+ Tscm cells is of the utmost importance since the emergence of SARS-CoV2 variants of concerns requires maintaining strong and long-lasting immune responses, 2) as an efficient alternative in immunocompromised people who have difficulties raising humoral immune responses. Methods: We have developed a new Dendritic Cell-based vaccine composed of a humanized αCD40 monoclonal antibody fused to the RBD protein in its C-terminal Fc-domains and three T cell epitopes spanning sequences from S and N proteins in its light chains (αCD40-CoV2). Previous studies have shown that this platform elicited durable and robust T-and B-cell responses and is currently in phase I clinical development in HIV. We tested the capacity of two injections of the vaccine (10υg, i.p) given with or without poly(IC) (50υg, i.p) at 3 weeks apart to i) elicit human (hu) B-, and huT-cell responses in NSG mice reconstituted with a Human Immune System (HIS mice), ii) protect against SARS-CoV2 infection in the hCD40xK18hACE2 transgenic mice. Results: We performed AIM assays and intracellular staining on spleen cells of HIS mice stimulated with overlapping peptide pools spanning the sequences of vaccine antigens. We found that both non-adjuvanted and adjuvanted vaccine efficiently induced SARS-CoV2-specific Th1 huCD4+ and huCD8+ T cells in all vaccinees compared to mock animals. SARS-CoV2-specific huCD4+ T cells were polyfunctional. We confirmed the presence of RBD-specific huCD8+ T cells in the vaccinated animals using HLA-I tetramers. A significant proportion of the multimer+ huCD8+ T cells were Tscm (CD45RA+ CD62L+ CD95+) cells in both vaccinated groups. Besides, we detected significant amounts of spike-IgG+ switched huB cells in all vaccinees. In SARS-CoV2 challenge experiments, we further showed that both vaccination settings significantly protected animals with a survival rate of 100%. Conclusion: We demonstrate that the targeting of SARS-CoV-2 epitopes to CD40 induces significant B and T cells with a long-term memory phenotype in HIS mice and the ability of the vaccine to ensure complete protection against SARS-CoV2 infection.
ABSTRACT
Correct interpretation of tumor progression data, including the influence of host biology, in mouse models of breast cancer requires models and conditions that faithfully recapitulate human disease and human host status. Our previous attempts to investigate the effects of social isolation have proven inconclusive due to premature mortality in tumor-bearing animals. Those studies were completed in standard temperature (ST), which commonly is 70-72°F (21-22°C) for in vivo murine research based on laboratory animal care and use guidelines. Previous work from the Repasky lab (Kokulus, 2013), which we have validated (Gaymon, 2020), demonstrates that ST housing results in chronic cold stress and immune suppression mediated by an increase in norepinrephrine (NE) levels, leading to increased tumor aggressiveness. Based on these findings, we investigated the effects of social isolation on BALB/cJ-4T1-luc and C57BL/6J/E0771 tumor progression and metastasis in thermoneutral housing conditions (84-85°F). Mice were first acclimatized to thermoneutral temperature and/or isolation for two weeks in cages that were unilaterally draped to provide physical and visual isolation. In BALB/cJ mice, 4T1-luc tumors were significantly larger in isolated mice compared to group-housed (GH) mice at day 18 (p<.0001). Statistically larger tumors were observed in isolated mice compared to GH mice through day 24 and final tumor masses were Salso significantly different (p=.004). Spleen masses were not statistically different. In C57BL/6J mice, E0771 tumors were significantly larger in isolates at Day 25 (p=.002). Final tumor masses were statistically (p=.002) different while no difference in spleen sizes were observed. Data on metastasis will be presented at the meeting. We hypothesized that social isolation may perturb immune function and next investigated the growth of 4T1-luc xenograft tumors in NSG mice. 4T1-luc/NSG tumor progression and metastasis data will also be presented at the meeting. We conclude that syngeneic breast tumor growth in immunocompetent BALB/cJ and C57BL/6J mice demonstrates that social isolation is a bona fide stress with sufficient influence to exacerbate breast cancer growth. These data are potentially clinically important due the known relationship of social support to survivorship outcomes in patients and the high-risk of depression and isolation in patients following breast cancer diagnosis. The data may provide additional insight into possible effects of COVID-19 isolation on breast cancer progression.