Cancer Immunotherapy : Oncolytic viruses and CAR-T cells
Abstract: Various forms of cancer immunotherapy have developed rapidly with improved survival and quality of life for cancer patients. Cancer immunotherapy aims to educate the patient’s immune system to eliminate cancer cells, including immune checkpoint inhibitors (ICIs), adoptive cell transfer (mostly T cells), oncolytic viruses (OVs) and cancer vaccines. Especially ICIs have induced durable responses in patients with many different types of cancers. Chimeric antigen receptor (CAR)-T cell therapy has shown good efficacy in treating hematologic malignancies. However, there is still a significant number of patients that do not benefit from these treatments due to immune evasion. Strategies to modify cancer immunotherapies with immunomodulating agent needs to be investigated to maximize the effect of immunotherapy. Helicobacter pylori Neutrophil Activating Protein (HP-NAP) could be used as an immunomodulating agent to recruit, activate and mature immune cells, such as dendritic cells (DCs), monocytes and neutrophils, and also induce T helper type 1 (Th1)-polarized response. In this thesis, we examined to arm oncolytic virus or CAR-T cells with HP-NAP.Papers I and II investigate oncolytic viruses. In paper I, we investigated wild-type Adenovirus (Ad), Semliki forest virus (SFV) and Vaccinia virus (VV), for their ability to mediate lysis of tumor cells, which was found to be associated with the release of danger-associated molecular patterns (DAMPs) and subsequently triggered phagocytosis and maturation of DCs. However, only SFV-infected tumor cells triggered significant Th1-cytokine release by DCs and induced antigen-specific T cell activation, while VV induced immunosuppressive responses. In Paper II, we armed VV and SFV with the tumor-associated antigen GD2 and HP-NAP. We found that arming these OVs with HP-NAP resulted in distinct anti-tumor immune response and therapeutic benefit. VV-GD2m-NAP showed significantly increased therapeutic efficacy compared to VV-GD2m, associated with elevated antiGD2 antibody production. In contrast, there was no additive antitumor effect for SFV-GD2m-NAP compared with SFV-GD2m. Due to intrinsic properties of OVs, engineering OVs with immunomodulating agents needs careful consideration. Engineering SFV or similar viruses, which is very immunogenic, should focus on improving oncolysis, de-bulking tumor and release of tumor-associated antigens, while for VV or similar viruses, with immunosuppressive properties, the focus can be on arming the virus with immune modulators to improve anti-tumor immune response. Papers III and IV investigate CAR-T cells. In paper III, CAR-T cells were engineered to inducible secrete HP-NAP upon antigen recognition (CAR(NAP)-Ts). CAR(NAP)-Ts successfully reduced tumor growth and prolonged survival of mice in several solid tumor models with epitope spreading and initiated endogenous anti-tumor immune responses. Secreted HP-NAP created an immunologically hot tumor microenvironment with enhanced infiltration of immune cells (DCs, neutrophils, macrophages, and cytotoxic natural killer cells). In paper IV, we developed CAR T cells targeting CD20 (rituCD20CAR T cells). We found that rituCD20CAR T cells could efficiently kill CD20-positive lymphoma cell lines (U2932, Karpas422, DB, U698, Raji, Daudi) as well as primary mantle cell CD20-positive lymphoma (CD20+ MCL) cells accompanying with IFNγ secretion. Both rituCD20CAR and NAP-armed rituCD20CAR(NAP) T-cell treatment delayed tumor growth and prolonged mice survival in the murine lymphoma A20-hCD20 model. In summary, combing OVs and CAR-T cells with the immunomodulating agent HP-NAP is a promising way of maximizing the benefit of immunotherapy to combat cancers.
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