(T0930-05-27) Viral Mimicry NanoVaccine Boosting B Immunity to Enhance Anti-cancer Efficacy

Purpose: Although B cell vaccines have been successfully used to prevent viral infections (such as SARS-CoV-2, HPV, and many other viruses), B cell vaccines are rarely designed for cancer treatment since the role of B cell immunity in cancer treatment is controversial. However, several recent studies have demonstrated that regardless of the T cell infiltration, high densities of B cells in the tumor are strongly associated with a better clinical response to ICB therapy in various types of cancers. These findings point to the need to develop a new generation of B cell cancer vaccines that promote B cell activation and tumor infiltration, in addition to generating neutralizing antibodies, to boost anticancer immunotherapy.

Methods: In this study, We engineered a virus mimicry nanovaccine (VSMVax) which had an optimal distance between antigen clusters (5–10 nm), and had high local antigen density in each cluster. These unique features are essential to crosslink B cell receptors (BCRs) to elicit extensive early B cell activation and subsequent robust GC responses for antigen specific long-term B cell generation. We also hypothesize that stronger B cell response elicited by VSM may also lead to better B cell access into the tumor microenvironment. To mimic the clustered antigen topography of viruses, we generated nanoparticles with spikes and conjugated HER2 peptides that contained a B cell epitope (SNTAPLQPEQLQ) and CD4+ T helper cell epitope (PESFDGDPA) onto the spikes of VSMVax.

Results: To mimic the virus cluster structure and B cell activation properties, we developed a facile and controllable protocol to engineer a viral antigen cluster topography mimicry nanovaccine (VSMVax) with an optimal distance between antigen clusters, and high local antigen density in each cluster. By crosslink activation imaging, the virus antigen cluster mimicry of VSMVax has a superior ability to crosslink BCRs and induce activation of endogenous B cells, most of which are expected to have low affinity to HER2 peptide. We also monitored the localization of VSMVax in the draining lymph nodes by using confocal (FITC-labeled) and IVIS imaging (Cy5.5-labeled) analysis of sectioned lymph nodes at 24 hours after subcutaneous vaccine administration in tumor-bearing mice with HER2+ breast cancer. The image analysis showed VSMVax penetrated deep inside of lymph node (medullary and B cell zones), while standard nanoparticle INOP vaccine (INOPVax) only localized on the surface of lymph node. The efficiently crosslinking of BCRs to activate B cells within several hours initiates a significant increasing of downstream Tfh cell–supported GC response, which promotes affinity maturation and differentiation into memory B cells and long-lived plasma cells. Thus, we tested the B cell response and GC formation in the lymph nodes 10 days after second booster of immunization. The data showed that VSMVax (6.80%) generated 1.58-fold and 7.5-fold more antigen-specific B cells than the IONPVax (2.66%) and soluble HER2 groups (0.80%), respectively. VSMVax (23.35%) resulted in 1.43-fold and 6.36-fold higher GC response than IONPVax (9.59%) and HER2 (3.17%). For therapeutic efficacy of VSMVax in combination with anti-PD-1 antibody, VSMVax achieved significantly better efficacy than clinical regimens, including anti-PD-1 antibody alone, anti-PD-1 antibody plus anti-HER2 antibody and a clinically tested HER2 T cell cancer vaccine (NeuVax: E75). We also introduced LIGHT, a member of the tumor necrosis factor (TNF) ligand family, into the VSMVax platform to stimulate TLS formulation as TLS may synergy with B cell activation and tumor infiltration. VSMVax (with LIGHT) combined with anti-PD-1 antibody (three vaccination doses) inhibited tumor growth by 96% and achieved long-term cancer remission ( >240 days) with a complete response (CR) rate of 44%.

Conclusion: The role of B cell cancer vaccines is controversial, and T cell cancer vaccines achieve limited efficacy. Here, we designed a virus mimicry B cell nanovaccine (VSMVax) that, when combined with αPD-1, achieved long-term tumor remission by promoting the T follicular helper (Tfh)-dependent B cell response and remodeling tumor immune microenvironment. VSMVax resembled a viral structure with optimal distance between antigen clusters, and optimal local antigen density. VSMVax penetrated deep and accessed the medullary regions of lymph nodes and crosslinked with B cell receptors for early B cell activation. VSMVax increased Tfh-dependent germinal center responses and antigen-specific B cells in lymph nodes. Strikingly, VSMVax promoted tumor immune cell infiltration and remodeled tumor immune microenvironment. VSMVax represents a novel cancer vaccine design that stimulates a unique B cell immunity to achieve long-term cancer remission.

Acknowledgements: This work is partially supported by NIH grants to DS (R01 AI154072) and YLL (R01 DE026728) anda Cancer Center Support Grant(NIH P30 CA046592) for shared resource facility use (Immunology, Advanced Genomics, and Pharmacokinetics shared resources).


Virus-Spike-Mimicry B cell Nanovaccine combined with αPD1 achieve remission in HER2+ breast cancer by promoting Tfh-dependent B cell response in lymph node and tertiary lymphoid structure in tumor. (a) Two stages of lymph node immune responses after vaccination with virus-spiky-mimicry-nanovaccine (VSMVax) for generating robust and long-term B cell immunity, Phase I: Initiation of B cells activation by crosslinking of B cell receptors with high density of epitopes presented in VSMVax; Phase II: germinal center B cells proliferation under the guidance of T follicular helper cells (Tfh). Germinal center B cells will then differentiate into plasma cells for secreting antibody and memory B for long term protection. (b). VSMVax vaccination induce B/T cell infiltration, T cell dependent B cell response and neogenesis of tertiary lymphoid structures in tumor sites for in-situ anti-tumor immune responses.


VSMVax homes to lymph nodes with a unique localization and subsequently induces a robust follicular T helper cell (Tfh)-dependent B cell response. (a, b) Confocal imaging of the VSMVax (a) and IONPVaxlymph node distributions (b) 24 hours after s.c. injection in BALB/c. Scale bar is 200 µm inwhole-lymph-node images and 50 µm inmagnified images. (b) BALB/c mice were vaccinated with control (PBS), HER2 peptide, VSMVax or IONPVax (14.6 nmol antigen and 13.9 nmol 2′3′-cGAMP as adjuvant) at days 0, 7, and 14, and analyzed at day 24. (c) Representative flow cytometry analysis and quantification of Germinal center B cells and Germinal center derived HER2-specific B-cells in lymph nodes using B-cell receptor tetramer staining. Data for quantification are shown as mean ± SD, n = 3. Representative flow cytometry analysis and quantification of GC B cells in lymph nodes. B220+CD3-CD95+ GL-7+ populations were identified as GC B cells. Data for quantification are shown as mean ± SD, n = 4 (c) CyTOF analysis of immune cells from lymph nodes (n=3). SPADE analysis. Node sizes indicate absolute number of cells. Nodes are colored based on the log ratio of the relative number of immune cells in the VSMVax group to that in the HER2 peptide or IONPVax group in the same lymph node. Red indicates a higher relative number of immune cells in the VSMVax group, and blue indicates a lower relative number. Quantification of GC B cells and Tfh cells. CyTOF markers for each immune cell population are shown in Fig. S7. Statistical comparisons were done by one-way ANOVA followed by Tukey’s post hoc pairwise comparison. The asterisks denote statistical significance at * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001.


Fig. 4. VSMVax combined with anti-PD-1 antibody achieves long-term remission of HER2+ breast cancer. (a) Anti cancer efficacy compared with clinical used/investigated medications. (b) Long term Anti-cancer efficacy with different dosing regimens. (c) Anti-cancer efficacy followed clinical dosing regimens.