Fig. 4
Relapsed PDL1 chimeric tumors display significant increases in PDL1 capable tumor cells. a 4 × 105 total cells comprising pure cultures of either B16/F10scramble (WT) or B16/F10PDL1−/− (KO) or a 1:9 mix of WT to KO cells (Mix) were injected SQ into the left flank of syngeneic C57/B6 mice. Seven days post tumor implantation, tumors were treated with IT injection of either saline (Mock: WT n = 10, KO n = 10, Mix n = 10) or 1 × 107 foci forming units of MYXV (MYXV: WT n = 9, KO n = 9, Mix n = 9). Treatment was repeated on days 9 and 11. Response of individual tumors to treatment. Data is displayed as percent tumor area (LxW) compared to tumor area immediately prior to initiation of treatment. The capability of tumor cells to express PDL1 was determined either immediately prior to therapy or at the time of euthanasia following relapse using flow cytometry. Data represents summation of two independent experiments. b Growth of WT or KO cells in vitro. Data represents summation of three independent experiments. c Equal numbers of WT, KO, or a 1:1 mix of each cell type (50% Mix) were plated in replicate wells of a 12 well dish. 12 h prior to harvest, cells were treated with IFNγ to upregulate PDL1 expression. At the indicated time points, cells were then harvested and the expression of PDL1 on the cell surface was analyzed using flow cytometry. Data represents summation of four independent experiments. d 4 × 105 total cells comprising corresponding to a 1:9 mix of WT to KO cells were injected SQ into the left flank of either C57/B6 (black circles) or NOD/Scid (white circles) mice. Tumor makeup was analyzed either pre-treatment (day 8) or after MYXV therapy (day 21). Data represents the summation of two independent experiments. Significance was determined using students T test (*** < 0.01). e and f 4 × 105 total cells comprising corresponding to a 1:9 mix of WT to KO cells were injected SQ into the left flank of C57/B6. A small number of animals were euthanized on day eight to analyze initial tumor makeup. Remaining mice were then separated into two cohorts and given MYXV treatment with either the indicated depleting antibodies (100μg/mouse once/week) or a control IgG (Mock). Tumor makeup was then analyzed following relapse (day 21)