Fig. 4. Anti-tumor efficacy of combination therapy of OVm19t and mCD19-CAR T cells in an immunocompetent murine syngeneic tumor model.
(A) Tumor killing of MC38 tumor cells treated with the indicated MOIs of OVm19t and cocultured with mCD19-CAR T cells or untransduced T cells (Mock) for 24 h. Left: Tumor cell killing was assessed by flow cytometry. Middle: Quantification of percent tumor cells positive for CD19t. Right: Quantification of percent cells positive for vaccinia. (B) Left: Schematic of C57BL/6j mice with subcutaneous MC38 tumors treated with OVm19t and mCD19-CAR T cells. Mice were subcutaneously (s.c.) injected with MC38 cells (5 × 105 cells) on day 0. On days 7 and 9, mice were intratumorally treated (i. t.) with 0 or two doses of 5 × 107 pfu OVm19t per mouse. On day 11, mice were treated by intratumoral injection with either Mock or mCD19-CAR T cells (5 × 106 cells). Tumor volume was measured with calipers. Data for each mouse (n = 9 per group) is shown. Data are from one of two independent experiments. Percent of mice with complete response (curative response) is indicated. (C) Left: Schematic of C57BL/6j mice with intraperitoneal MC38 tumors treated with OVm19t and mCD19-CAR T cells. Mice were injected intraperitoneally (i.p.) MC38 cells expressing firefly luciferase (5 × 105 cells) on day 0. At day 6, mice were i.p. sham injected or were injected with 107 pfu OVm19t per mouse. On day 8, mice were i.p. injected with either Mock T cells or mCD19-CAR murine T cells (5 × 106 cells). n ≥ 6 per group. Right: Tumor growth was measured by non-invasive optical imaging. X indicates mice were euthanized or had died. (D) Average tumor sizes (based on non-invasive imaging) are shown as mean ± SEM. (E) Kaplan-Meier survival curves from the experiment described in C. P value indicates difference between Ovm19t + Mock and OVm19t + CAR as determined by log-rank (Mantel-Cox) test.