Figure 4.

SAHA and Reolysin Combinatorial Therapy-Mediated Anti-Tumor Efficacy in a Murine Head and Neck Cancer Syngeneic Model

Immunocompetent C57BL/6 male mice (n = 10) bearing subcutaneous syngeneic MTE squamous tumors (treatment started at 150 mm³) were treated with DMSO, SAHA (50 mg/kg via intraperitoneal injection on days 1, 3, 5, 8, and 10), Reolysin (Reo) (2.5 × 10⁸ PFU via intratumoral injection on days 0, 3, and 10), or SAHA plus Reolysin combinatorial therapy. Mice were observed for tumor growth and euthanized when tumor burden reached removal criteria as per our Institutional Animal Care and Use Committee (IACUC) protocol. (A) Tumor volume growth was assessed over time for each mouse in every treatment group. **p < 0.0001 (difference between combination-treated mice and all other treatment groups; left panel). Kaplan-Meir plots of mice bearing subcutaneous MTE tumors treated with SAHA, reovirus, or the combination as indicated (the treatment schema is indicated below the plot). *p < 0.01 (combination treatment differences compared to each individual treatment group). All survival studies were performed in duplicate. (B) Representative macrophage- (CD68) and T cell (CD8)-stained tumors at time of death when tumors reached ∼1,500 mm³ at a magnification of ×400. (C) In a separate experiment, splenocytes from mice treated with reovirus, HDACis, or both were cultured with tumor cells and tumor cell killing was evaluated by live and dead cell staining. Data shown are representative histograms from the flow cytometric analysis of day 7 splenocytes following 48-hr ex vivo co-culture with MTE tumor cells at a ratio of 4:1, respectively. The right panel is the quantification of killing (n = 3 mice/group). *p < 0.01 (combination treatment differences compared to each individual treatment group). Murine studies were performed in duplicate.