Investigation a novel vaccine combination composed HER2/Neu antigen and a saponin adjuvant against HER2 positive breast cancer
Project no. 422 · Status: Kapanmış · 2016
Summary
HER2 positive breast cancer cases covers more than %20 of total breast cancer cases in the World. Current cancer therapeutics are not powerful enough to destroy this tremendous disease. Apart from not curing totally, they also have many side effects. Because of all that reason, current cancer research studies were directed towards immunotherapeutics. Immunotherapy is basically using hosts immune system to fight with cancer cells. In this thesis, a novel combination immunotherapy composed of HER2/Neu based vaccination together with saponin adjuvant (QS-21) was investigated against HER2 positive breast cancer. For this purpose, various combinations including dendritic cells loaded with HER2/Neu antigen, addition of anti-PD-L1 mAb and usage of chemotherapeutic agent doxorubicin was added to the combination groups to further support the vaccine formulation. The combination immunotherapy formulated in this thesis project was aiming to boost host immune response against tumor cells as well as blocking immune evasion of the target tumor cells. Two main experiments were set up in this study. In the first study, the effect of active and passive immunotheraoy combination was investigated on 6-8 weeks old Balb/c mice that was subcutaneously injected 1.5 x 106 cells/ml HER2 expressing 4T1 cells were used on day 0 to form a xenograft model of breast cancer. Vaccination protocol was started at day 1, and mice were injected two times total once in a week. Anti-PD-L1 mAb was given to the mice on days 4 and 9. In the second experimental set up, active and passive immunizations were further supported by doxorubicin. The effect of triple combination immunotherapy was investigated on 6-8 weeks old Balb/c mice that was subcutaneously injected 5 x 106 cells/ml HER2 expressing 4T1 cells on day 0 of the experiment. Vaccination protocol was started at day 1, and mice were injected once in a week, two times. Anti-PD-L1 mAb was given to the mice on days 4 and 9. Doxorubicin was given to the mice at 5mg/ml concentration at days 5 and 10. At the end of the study, tumor dimensions were measured and mice were sacrificed to collect serum, spleen tissues, and tumors for further evaluation of the vaccine efficiency. LDH assay, Flow cytometric measurement of CD8, CD3 and IFN-? levels, ELISA for determining the antibody titer and IHC studies were performed for analyzing the immune response rates in different combinations. In the first study, DC+HER2/Neu+QS-21+anti-PD-L1 combination group demonstrated the best effect in terms of both tumor dimensions, tumor specific cytotoxicity with 35-40% cell lysis, anti-HER2 antibody titer as well as highest stimulation of CD8+ T cells and IFN-??secretion. IHC data further supported the local and internal populations of CD4+ and CD8+ T cells in the tumor niche. It also demonstrated that, DC+HER2/Neu+QS-21+anti-PD-L1 vaccine combination showed the least metastatic and tumorigenic potential among other vaccine formulations. In the second study, Doxsorubisin+DC+HER2/Neu+QS-21+anti-PD-L1 combination group demonstrated the best effect in terms of both tumor dimensions, tumor specific cytotoxicity with 45-50% cell lysis, anti-HER2 antibody titer as well as highest stimulation of CD8+ T cells and IFN-? secretion. IHC data further supported the local and internal populations of CD4+ and CD8+ T cells in the tumor niche. It also demonstrated that, DC+HER2/Neu+QS-21+anti-PD-L1 vaccine combination showed the least tumorigenic potential among other vaccine formulations. In this study, active and passive immunotherapeutics were used for the first time together with a chemotherapeutic agent. The results obtained from the study are very promising and we believe that this study would highlight the importance of combination immunotherapies especially the triple combination groups against cancer.