Combined treatment with the PARP inhibitor and CTLA-4 antibody induces protective immunity. Peritoneal cells (A) and splenocytes (B) were retrieved on days 7, 14, and 21 from combination therapy— treated mice, and from long-term survivors on day 90, and restimulated ex vivo with PMA and ionomycin for analysis by flow cytometry for intracellular IFNγ production by CD4+ and CD8+ T cells. * , P < 0.05; ** , P < 0.025, Tukey multiple comparisons test. C, adoptive transfer of CD8+ T cells from long-term survivors protects recipients from tumor development. CD8+ T cells were isolated by MACS-negative selection from long-term combination therapy survivors, pooled, and 2×105 cells were adoptively transferred to recipient mice 12 hours prior to challenge with 2×105 BRCA- tumor cells. Mice were monitored for survival (n 1/4 5/group) log-rank (Mantel–Cox) test.