Figure 3.

Increases in IFNγ production in response to combined CTLA-4 blockade and PARP inhibition in vivo are sufficient to enhance tumor cell cytotoxicity. Mice were treated as in Supplementary Fig. S1 and euthanized on day 21 followed by retrieval of peritoneal cells (n 1/4 5/group). A total of 5 106 peritoneal cells were restimulated ex vivo with 10 µg/mL of anti-CD3 for 18 hours. Cell-free supernatants were harvested and pooled by treatment group, and levels of IFNγ (A) and TNFα (B) were determined by ELISA. C–E, supernatants were added to BRCA cells at a 4 dilution with DMEM-C in the presence of PARPi at indicated concentrations and cultured 72 hours in the absence (black lines) or presence (red lines) of IFNγ and TNFα neutralizing mAbs (10 µg/mL). C, cells were analyzed for viability by flow cytometry, and values shown are the percentages of dead cells with or without neutralizing antibody treatment. D, overlay of data in C. E, the same as D using BRCAwt cells (T22). *, P < 0.05; **, P < 0.025; ***, P < 0.005; ****, P < 0.0001 by ANOVA and Tukey procedure for multiple comparisons.