(T1230-04-24) Hyaluronic Acid Nanogel Cancer Vaccine: Powerful and Versatile Priming Tool for Combinational T Cell Therapy

Purpose: Monotherapy with adaptive T cell therapy may only show potent but short-term tumor suppressor effects¹⁾. In this study, we demonstrate hyaluronic acid nanogel cancer vaccine could be powerful and versatile priming tool for combinational T cell therapy.

Methods: Fabrication of hyaluronic acid nanogel cancer vaccine (HANG-V). The hyaluronic acid nanogel cancer vaccines were prepared using long peptide antigens and the hyaluronic acid nanogel. The peptides in DMSO were added to the hyaluronic acid nanogel aqueous solution and the mixture was incubated for 24 h at room temperature. After 0.22 mm filtration, the antigen peptide concentration was quantified by reverse phase chromatography analysis. The drug (peptide) contents% and encapsulation efficacy% were calculated. Combination immunotherapy of HANG-V with adoptive T cell transfer against B16F10 melanoma. B16F10 melanoma cells were subcutaneously inoculated into C57BL/6 mice on day 0. The B16F10 tumor-bearing mice were treated with following three conditions. HANG-V group: HANG-V (hyaluronic acid nanogel encapsulating gp100 peptide and CpG) were subcutaneously injected on days 7, 11 and 15. TCR-T group: CD8⁺T cells isolated from Pmel-1/CD90.1 mice were infused on days 8 and 12. HANG-V plus TCR-T group: they were treated with a combination of both. Tumor growth and survival time were monitored. In addition, a comparative experiment with other nanoparticle-based vaccine²⁾ was conducted. The experimental protocol was the same as above except that the vaccine was administered 5 times (days 7, 11, 15, 29 and 36). Expansion of memory CD8⁺ T cells induced by booster vaccination. CMS5a fibrosarcoma cells were subcutaneously inoculated into mice on day 0. The CMS5a tumor-bearing mice were subcutaneously injected with HANG-V (hyaluronic acid nanogel encapsulating mERK2 neoantigen peptide and CpG) on days 7 and 11, and additionally infused with CD8⁺T cells isolated from DUC18/CD90.1 mice, which can recognize mERK2 peptide, on days 8. All the treated mice underwent complete tumor regression by days 30. The complete response-lasting mice were received booster vaccination of HANG-V on days 36 and 39. Before and two days after booster vaccinations, peripheral blood was collected and stained with CD44 and CD62L antibodies. The proportions of effector memory (T_EM) and central memory T cell (T_CM) were monitored.

Results: Fabrication of hyaluronic acid nanogel cancer vaccine (HANG-V). We have developed a hyaluronic acid based nanosized hydrogel (nanogels) to create novel nanomaterials for biomedical applications. The hyaluronic acid derivatives partially hydrophobized by a chemical modification with cholesteryl groups forms physically cross-linked nanogel particles with a diameter of 30~100 nm via self-assembly in water³⁾. The hyaluronic acid nanogel efficiently forms a stable complex with antigenic peptides through hydrophobic interactions. Here, three types of peptides with molecular weights of approximately 5000 Dalton and different pI were used. The facile and simple vaccine formulation processes utilizing hyaluronic acid nanogel achieved high drug contents% and high encapsulation efficiency of about 90% or higher, which means that hyaluronic acid nanogel can formulate drugs versatilely with minimum losses (Figure 1). Combination immunotherapy of HANG-V with adoptive T cell transfer against B16F10 melanoma. B16F10 melanoma is highly metastatic and shows low expression of MHC molecules, low immunogenicity, and low intra-tumoral T cell infiltration. HANG-V encapsulating gp100 long peptide with CpG were administered subcutaneously to B16F10-bearing C57BL/6 mice and infused with CD8⁺ T cells, which recognize gp100 peptides on MHC molecules. B16F10 tumors more than 100 mm² became complete regression, and this anti-tumor efficacy was superior to other nanoparticle-based vaccine. This effect persisted for a long period without recurrence over 100 days, by changing hair color of mice into white. (Figure 2). Expansion of memory CD8⁺ T cells induced by booster vaccination. CMS5a sarcoma of BALB/c mice is known to be refractory to immune checkpoint inhibitor (ICI) therapy. Combinational immunotherapy of HANG-V plus CpG with CD8⁺ T cells led to complete regression and long-term survival in CMS5a-bearing mice. Boost vaccination in completely cured mice on day 36 and 39 improved the ratio of effector memory T cells from about 3% to more than 10%, and the ratio of central memory T cells from about 10% to more than 40%. This result suggests that booster vaccination of HANG-V drives a potent expansion of memory CD8⁺ T cells, thereby preventing tumor recurrence (Figure 3).

Conclusion: We have concluded that hyaluronic acid nanogel has unique characteristics that enable facile and simple fabrication of cancer vaccines, and hyaluronic acid nanogel cancer vaccine strongly enhances efficacy of adaptive TCR-T cell therapy against ICI refractory tumor, resulting in complete regression. Furthermore, we found that boost vaccination drives a potent expansion of memory CD8⁺ T cells, especially central memory T cells. Combination immunotherapy of the hyaluronic acid nanogel cancer vaccine with adoptive T cell therapy could be a breakthrough therapy for difficult-to-treat tumors such as cold tumor and ICI treatment-resistant tumors.

References: 1) J Immunother Cancer 2022 Jun;10(6):e003811
2) ACS Nano. 2014 Sep 23;8(9):9209-18
3) Macromol Biosci. 2012 Apr;12(4):475-83.

Fabrication of hyaluronic acid nanogel cancer vaccine. (A) Schematic illustration of nanogel self-assembly and peptide encapsulation. (B) Encapsulation of antigen peptides.

Combination immunotherapy of HANG-V with adoptive T cell transfer against B16F10 melanoma. (A)Tumor growth and (B) survival rate of each treatment in B16F10. (C) Hair whitening.

Expansion of memory CD8 T cells induced by booster vaccination. (A) Experimental protocol. (B) The proportions of effector memory and central memory CD8 T cells in total CD8 T cells before and after booster vaccinations.