Dendritic Cell/Tumor Fusion Vaccine(Beth Israel Deaconess Medical Center)

Background: Chimeric antigen receptor (CAR) T-cell therapy is practical in treating cancers of hematopoietic origin, but of that in solid tumors compromises efficacy for the loss of the antigen recognized by the CAR. However, dendritic cell (DC)/tumor fusion vaccines present a spectrum of known or unknown tumor antigens to stimulate T cell expansion and enhanced T cell response. Developing a new strategy of enhanced nanobody-based CAR-T (Nb-CAR-T) cells antitumor activity by DC/tumor fusion vaccines stimulation would provide guidance for more effective CAR-T cell therapies. Methods: Considering the therapeutic potential of nanobody (Nb), we first screened EGFRvIII Nb, then constructed and verified the function of EGFRvIII Nb-CAR-T cells in vitro and in vivo. We further combined DC/tumor fusion vaccines to boost EGFRvIII Nb-CAR-T cells antitumor effect, which was evaluated in vitro Nb-CAR-T cell function and in the tumor-bearing xenograft mouse models. Results: We had for the first time successfully selected EGFRvIII Nb for the generation of the novel EGFRvIII Nb-CAR-T cells. Importantly, our results suggested that DC/tumor fusion vaccines stimulate Nb-CAR-T cells response not only in improving T cell proliferation, T cell activation, cytokine secretion and tumor-specific cytotoxicity in vitro, but also significantly reducing tumor burden, prolonging survival and improving Nb-CAR-T cells infiltration. Conclusions: We have innovatively shown that DC/tumor fusion vaccines significantly enhance the efficacy of Nb-CAR-T cells against solid tumors. This new strategy has provided a promising therapeutic platform for promoting the clinical treatment of CAR-T cells therapy.

Vaccination with fusions of dendritic cells (DCs) and mucin-1 (MUC1)-positive tumor cells (FC/MUC1) induces MUC1-specific antitumor immunity. However, little is known about the function of Cluster of Differentiation (CD)4 T-cells primed with FC/MUC1 in MUC1 transgenic (MUC1.Tg) mice.

CD4 T-cells primed with FC/MUC1 were analyzed by flow cytometry. Antitumor immunity by adoptive transfer of primed CD4 T-cells in Rag2(-/-) mice was assessed.

The effector and memory T-cells generated with FC/MUC1 were crucial to maintenance of long-term antitumor immunity. MUC1-8-mer peptide SAPDTRPA presented by FC/MUC1 was recognized by CD4 and CD8 T-cells. A subset of primed CD4 T-cells possessed cytotoxicity to lyse major histocompatibility complex (MHC) class I and MUC1 positive tumor cells. Interestingly, adoptive transfer of primed CD4 T-cells prevented lung metastasis in Rag2(-/-) mice.

CD4 T-cells primed by FC/MUC1 play direct role in antitumor immunity.