Human CLEC9A antibodies deliver NY-ESO-1 antigen to CD141⁺ dendritic cells to activate naïve and memory NY-ESO-1-specific CD8⁺ T cells

Abstract

BackgroundDendritic cells (DCs) are crucial for the efficacy of cancer vaccines, but current vaccines do not harness the key cDC1 subtype required for effective CD8+ T-cell-mediated tumor immune responses. Vaccine immunogenicity could be enhanced by specific delivery of immunogenic tumor antigens to CD141+ DCs, the human cDC1 equivalent. CD141+ DCs exclusively express the C-type-lectin-like receptor CLEC9A, which is important for the regulation of CD8+ T cell responses. This study developed a new vaccine that harnesses a human anti-CLEC9A antibody to specifically deliver the immunogenic tumor antigen, NY-ESO-1 (New York esophageal squamous cell carcinoma 1), to human CD141+ DCs. The ability of the CLEC9A-NY-ESO-1 antibody to activate NY-ESO-1-specific naïve and memory CD8+ T cells was examined and compared with a vaccine comprised of a human DEC-205-NY-ESO-1 antibody that targets all human DCs.MethodsHuman anti-CLEC9A, anti-DEC-205 and isotype control IgG4 antibodies were genetically fused to NY-ESO-1 polypeptide. Cross-presentation to NY-ESO-1-epitope-specific CD8+ T cells and reactivity of T cell responses in patients with melanoma were assessed by interferon γ (IFNγ) production following incubation of CD141+ DCs and patient peripheral blood mononuclear cells with targeting antibodies. Humanized mice containing human DC subsets and a repertoire of naïve NY-ESO-1-specific CD8+ T cells were used to investigate naïve T cell priming. T cell effector function was measured by expression of IFNγ, MIP-1β, tumor necrosis factor and CD107a and by lysis of target tumor cells.ResultsCLEC9A-NY-ESO-1 antibodies (Abs) were effective at mediating delivery and cross-presentation of multiple NY-ESO-1 epitopes by CD141+ DCs for activation of NY-ESO-1-specific CD8+ T cells. When benchmarked to NY-ESO-1 conjugated to an untargeted control antibody or to anti-human DEC-205, CLEC9A-NY-ESO-1 was superior at ex vivo reactivation of NY-ESO-1-specific T cell responses in patients with melanoma. Moreover, CLEC9A-NY-ESO-1 induced priming of naïve NY-ESO-1-specific CD8+ T cells with polyclonal effector function and potent tumor killing capacity in vitro.ConclusionsThese data advocate human CLEC9A-NY-ESO-1 Ab as an attractive strategy for specific targeting of CD141+ DCs to enhance tumor immunogenicity in NY-ESO-1-expressing malignancies.

Type 1 conventional dendritic cells and interferons are required for spontaneous CD4+ and CD8+ T‐cell protective responses to breast cancer

“…In future studies, it will be important to determine the precise nature of the protective cDC1 functions induced by STAT1 signalling, and to investigate whether they can be mobilised in preclinical mouse models of progressive triple‐negative breast cancer upon specific chemotherapy 92 or immunotherapy 93 . This should then help further optimising new generation immunotherapeutic strategies aiming at mobilising human cDC1 to treat various cancers 14–17 …”

“…10,11 In human patients suffering from various cancers, several studies have shown that high expression in tumors of genes selectively expressed in cDC1 is of good prognosis, as reviewed in Cancel et al 10 and exemplified for breast cancer in Bottcher et al 12 and Hubert et al 13 Hence, cDC1 represent an attractive target for new generation cancer immunotherapies. 3,10,11,[13][14][15][16][17][18][19][20][21][22] Yet, most of the studies that investigated the antitumor role of cDC1 in vivo used mutant mice whose deficiencies were not affecting exclusively cDC1. Irf8 deficiency in CD11c-expressing cells also affected the differentiation and functions of plasmacytoid dendritic cells 23 and inflammatory cDC2.…”

“…and Hubert et al 13 . Hence, cDC1 represent an attractive target for new generation cancer immunotherapies 3,10,11,13–22 . Yet, most of the studies that investigated the antitumor role of cDC1 in vivo used mutant mice whose deficiencies were not affecting exclusively cDC1.…”

Mimicking Pathogens to Augment the Potency of Liposomal Cancer Vaccines

“…While we discussed that cDC1s, especially in mice but also in humans, appear to be highly relevant in cross-presentation of cell-associated antigen, to the best of our knowledge, liposomal targeting studies specifically directed to cDC1 markers, such as XCR1 and Clec9a, are still lacking. On a side note, cancer vaccine targeting to Clec9a was performed with antigen–antibody conjugates and antibody/antigen/poly (lactic-co-glycolic acid) (PLGA)nanoparticles and resulted in robust induction of antigen-specific T cell responses [ 134 , 135 , 136 ]. In conclusion, active targeting of liposomes by modification of their surface with targeting ligands can markedly increase the potency of vaccination.…”

Will Next-Generation Immunotherapy Overcome the Intrinsic Diversity and Low Immunogenicity of Sarcomas to Improve Clinical Benefit?

“…By exploiting this platform, it has been shown that targeting CD4 and CD8 neo-antigen epitopes to Clec9A + DCs in vivo effectively inhibits the growth of poorly immunogenic tumours [ 122 ]. Masterman et al recently reported another strategy using human CLEC9A antibodies to deliver the NY-ESO-1 antigen to CD141 + DCs [ 123 ]. This study reported superior response of CLEC9A-NY-ESO-1 to activate antigen-specific CD8 + T cells ex vivo in melanoma patients compared to NY-ESO-1 conjugated to DEC-205 antibody or NY-ESO-1 conjugated to control antibody, showcasing the potential of using CLEC9A-NY-ESO-1 antibody to enhance the immune response against NY-ESO-1 positive tumours including sarcomas [ 123 ].…”