title: Immunological mechanisms of intravesical chitosan/interleukin-12 immunotherapy against murine bladder cancer.
abstract: There is a critical unmet clinical need for bladder cancer immunotherapies capable of inducing durable antitumor immunity. We have shown that four intravesical treatments with a simple co-formulation of interleukin-12 and the biopolymer chitosan not only destroy orthotopic bladder tumors, but also promote a potent long-lasting systemic immune response as evidenced through tumor-specificin vitrokilling assays, complete protection from rechallenge, and abscopal antitumor responses at distant non-treated tumors. This study investigates the immunological kinetics underlying these results. We show through depletion studies that CD8+T cells are required for initial tumor rejection, but CD4+T cells protect against rechallenge. We also show that even a single intravesical treatment can eliminate tumors in 50% of mice with 6/9 and 7/8 mice eliminating tumors after three or four treatments respectively. We then performed immunophenotyping studies to analyze shifts in immune cell populations after each treatment within the tumor itself as well as in secondary lymphoid organs. These studies demonstrated an initial infiltration of macrophages and granulocytes followed by increased CD4+and CD8+effector-memory cells. This was coupled with a decreased level of regulatory T cells in peripheral lymph nodes as well as decreased myeloid-derived suppressor cell infiltration in the bladder. Taken together, these data demonstrate the ability of properly delivered interleukin-12-based therapies to engage adaptive immunity within the tumor itself as well as throughout the body and strengthen the case for clinical translation of chitosan/interleukin-12 as an intravesical treatment for bladder cancer.
authors.affiliation: Joint Department of Biomedical Engineering, North Carolina State University and University of North Carolina at Chapel Hill, Raleigh, NC, USA; Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA.
authors.forename: Sean G
authors.initials: SG
authors.lastname: Smith
authors.affiliation: Department of Biomedical Engineering, University of Arkansas , Fayetteville, AR, USA.
authors.forename: John L
authors.identifier: 0000-0001-5726-3205
authors.initials: JL
authors.lastname: Baltz
authors.affiliation: Joint Department of Biomedical Engineering, North Carolina State University and University of North Carolina at Chapel Hill, Raleigh, NC, USA; Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA.
authors.forename: Bhanu Prasanth
authors.initials: BP
authors.lastname: Koppolu
authors.affiliation: Department of Biomedical Engineering, University of Arkansas , Fayetteville, AR, USA.
authors.forename: Sruthi
authors.initials: S
authors.lastname: Ravindranathan
authors.affiliation: Department of Cell and Molecular Biology, University of Arkansas , Fayetteville, AR, USA.
authors.forename: Khue
authors.initials: K
authors.lastname: Nguyen
authors.affiliation: Joint Department of Biomedical Engineering, North Carolina State University and University of North Carolina at Chapel Hill, Raleigh, NC, USA; Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Zaharoff
keywords: BCG; MDSC; TILS; TReg; bladder cancer; chitosan; immunotherapy; interleukin-12; intratumoral; intravesical