Abstract 2311: Adenovirus-transduced allogeneic dendritic cells for cancer immunotherapy

Abstract

Abstract Immunotherapy is currently being established as standard treatment for cancer. Immune checkpoint blockade antibodies can cure a large proportion of patients with refractory melanoma and lung cancer, and adoptive transfer of patient-derived CD19 chimeric antigen receptor (CAR) T cells results in complete remission in a majority of patient with refractory leukemia. Cancer vaccines based on patient-derived dendritic cells (DC) modified ex vivo to present tumor antigens are promising for cancer treatment especially when combined with immune checkpoint blockade antibodies. Ex vivo-modified DCs are however poor in migrating to secondary lymphoid organs after re-administration. In reality, it is more likely endogenous DC that endocytos the injected DC, mature and then migrate to lymph nodes where they present peptide fragments of tumor antigen to T cells together with required co-stimulation. Herein, we present a new strategy utilizing adenovirus (Ad)-transduced allogeneic DCs (alloDCs) as immunostimulatory adjuvant to induce both innate and adaptive immune response. Ad/alloDC can be prepared, tested and made ready for release in advance and quickly be prepared for injection in cancer patients upon request, thereby minimizing GMP-processing and handling of cells. Besides encoding tumor antigens, adenovirus also provides stimulatory danger signals for DC activation. We show that Ad/alloDCs secret a panel of proinflammatory cytokines and chemokines including IL-12 and CXCL10 at high levels in a sustainable fashion. We also show that Ad/alloDC recruit and activate neutrophils and NKs to the site of injection. Ad/alloDC can also recruit and interact with allo-reactive T cells to create a proinflammatory milieu, which further recruit and activate endogenous DCs. We verified that endogenous DCs activated in situ by an Ad/alloDC injection migrate to draining lymph node, where they present the engulfed tumor antigen to T cells. We show that these migratory endogenous DCs facilitate T cell activation and proliferation. Moreover, when injected intratumorally, Ad/alloDCs modulate the immunosuppressive environment by reducing the ratio of monocytic to granulocytic myeloid-derived suppressor cells (MDSC). To evaluate the therapeutic efficacy, we use B16 melanoma tumor-bearing C57Bl/6 mice injected with adenovirus-transduced DCs from Balb/c origin to obtain an allogeneic reaction. We show that Ad/alloDC treatment could significantly delay tumor growth and prolong survival of tumor-bearing mice. Citation Format: Magnus Essand, Grammatiki Fotaki, Chuan Jin, Mohanraj Ramachandran, Jing Ma, Alex Karlsson-Parra, Di Yu. Adenovirus-transduced allogeneic dendritic cells for cancer immunotherapy. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2311.