Vaccine-induced CD8 T cells are redirected with peptide-MHC class I-IgG antibody fusion proteins to eliminate tumor cells in vivo

Redirector of Vaccine-induced Effector Responses (RoVER) for specific killing of cellular targets

BACKGROUND

In individuals with malignancy or HIV-1 infection, antigen-specific cytotoxic T lymphocytes (CTLs) often display an exhausted phenotype with impaired capacity to eliminate the disease. Existing cell-based immunotherapy strategies are often limited by the requirement for adoptive transfer of CTLs. We have developed an immunotherapy technology in which potent CTL responses are generated in vivo by vaccination and redirected to eliminate target cells using a bispecific Redirector of Vaccine-induced Effector Responses (RoVER).

METHODS

Following Yellow fever (YF) 17D vaccination of 51 healthy volunteers (NCT04083430), single-epitope YF-specific CTL responses were quantified by tetramer staining and multi-parameter flow cytometry. RoVER-mediated redirection of YF-specific CTLs to kill antigen-expressing Raji-Env cells, autologous CD19+ B cells or CD4+ T cells infected in vitro with a full-length HIV-1-eGFP was assessed in cell killing assays. Moreover, secreted IFN-γ, granzyme B, and TNF-α were analyzed by mesoscale multiplex assays.

FINDINGS

YF-17D vaccination induced strong epitope-specific CTL responses in the study participants. In cell killing assays, RoVER-mediated redirection of YF-specific CTLs to autologous CD19+ B cells or HIV-1-infected CD4+ cells resulted in 58% and 53% killing at effector to target ratio 1:1, respectively.

INTERPRETATION

We have developed an immunotherapy technology in which epitope-specific CTLs induced by vaccination can be redirected to kill antigen-expressing target cells by RoVER linking. The RoVER technology is highly specific and can be adapted to recognize various cell surface antigens. Importantly, this technology obviates the need for adoptive transfer of CTLs.

FUNDING

This work was funded by the Novo Nordisk Foundation (Hallas Møller NNF10OC0054577).

Applications of Anti-Cytomegalovirus T Cells for Cancer (Immuno)Therapy

Infection with cytomegalovirus (CMV) is highly prevalent in the general population and largely controlled by CD8pos T cells. Intriguingly, anti-CMV T cells accumulate over time to extraordinarily high numbers, are frequently present as tumor-resident 'bystander' T cells, and remain functional in cancer patients. Consequently, various strategies for redirecting anti-CMV CD8pos T cells to eliminate cancer cells are currently being developed. Here, we provide an overview of these strategies including immunogenic CMV peptide-loading onto endogenous HLA complexes on cancer cells and the use of tumor-directed fusion proteins containing a preassembled CMV peptide/HLA-I complex. Additionally, we discuss conveying the advantageous characteristics of anti-CMV T cells in adoptive cell therapy. Utilization of anti-CMV CD8pos T cells to generate CAR T cells promotes their in vivo persistence and expansion due to appropriate co-stimulation through the endogenous (CMV-)TCR signaling complex. Designing TCR-engineered T cells is more challenging, as the artificial and endogenous TCR compete for expression. Moreover, the use of expanded/reactivated anti-CMV T cells to target CMV peptide-expressing glioblastomas is discussed. This review highlights the most important findings and compares the benefits, disadvantages, and challenges of each strategy. Finally, we discuss how anti-CMV T cell therapies can be further improved to enhance treatment efficacy.

Nanovaccine Displaying Immunodominant T Cell Epitopes of Fibroblast Activation Protein Is Effective Against Desmoplastic Tumors

Cancer-associated fibroblasts (CAFs), which are dominant cell types in the tumor microenvironment (TME), support tumor growth by secreting cytokines and forming an extracellular matrix (ECM) that hampers the penetration of chemical and biological therapeutics within the tumor and thereby limits their therapeutic efficacy. Here, we report a cancer nanovaccine targeting fibroblast activation protein α (FAP)-expressing CAFs as a potential pan-tumor vaccine. We predicted immunodominant FAP-specific epitope peptides in silico and selected two candidate peptides after in vitro and in vivo screening for immunogenicity and antitumor efficacy. Next, we developed a nanoparticle-based vaccine that displays the two selected epitope peptides on the surface of lipid nanoparticles encapsulating CpG adjuvant (FAP_PEP-SLNPs). Immunization with one of two FAP_PEP-SLNP nanovaccines led to considerable growth inhibition of various tumors, including desmoplastic tumors, by depleting FAP⁺ CAFs and thereby reducing ECM production in the TME while causing little appreciable adverse effects. Furthermore, when combined with a chemotherapeutic drug, the FAP_PEP-SLNP nanovaccine increased drug accumulation and resulted in a synergistic antitumor efficacy far better than that of each corresponding monotherapy. These findings suggest that our FAP_PEP-SLNP nanovaccine has potential for use as an "off-the-shelf" pan-tumor vaccine applicable to a variety of tumors and may be a suitable platform for use in various combination therapies.

Antibody-mediated delivery of a viral MHC-I epitope into the cytosol of target tumor cells repurposes virus-specific CD8+ T cells for cancer immunotherapy

Background

Redirecting pre-existing virus-specific cytotoxic CD8⁺ T lymphocytes (CTLs) to tumors by simulating a viral infection of the tumor cells has great potential for cancer immunotherapy. However, this strategy is limited by lack of amenable method for viral antigen delivery into the cytosol of target tumors. Here, we addressed the limit by developing a CD8⁺T cell epitope-delivering antibody, termed a TEDbody, which was engineered to deliver a viral MHC-I epitope peptide into the cytosol of target tumor cells by fusion with a tumor-specific cytosol-penetrating antibody.

Methods

To direct human cytomegalovirus (CMV)-specific CTLs against tumors, we designed a series of TEDbodies carrying various CMV pp65 antigen-derived peptides. CMV-specific CTLs from blood of CMV-seropositive healthy donors were expanded for use in in vitro and in vivo experiments. Comprehensive cellular assays were performed to determine the presentation mechanism of TEDbody-mediated CMV peptide-MHC-I complex (CMV-pMHCI) on the surface of target tumor cells and the recognition and lysis by CMV-specific CTLs. In vivo CMV-pMHCI presentation and antitumor efficacy of TEDbody were evaluated in immunodeficient mice bearing human tumors.

Results

TEDbody delivered the fused epitope peptides into target tumor cells to be intracellularly processed and surface displayed in the form of CMV-pMHCI, leading to disguise target tumor cells as virally infected cells for recognition and lysis by CMV-specific CTLs. When systemically injected into tumor-bearing immunodeficient mice, TEDbody efficiently marked tumor cells with CMV-pMHCI to augment the proliferation and cytotoxic property of tumor-infiltrated CMV-specific CTLs, resulting in significant inhibition of the in vivo tumor growth by redirecting adoptively transferred CMV-specific CTLs. Further, combination of TEDbody with anti-OX40 agonistic antibody substantially enhanced the in vivo antitumor activity.

Conclusion

Our study offers an effective technology for MHC-I antigen cytosolic delivery. TEDbody may thus have utility as a therapeutic cancer vaccine to redirect pre-existing anti-viral CTLs arising from previously exposed viral infections to attack tumors.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12943-022-01574-0.