A major aim of our study was therefore to examine the trAb-induced vaccination effect in combination with CTLA-4 blockade. Importantly, while direct trAb-mediated destruction of tumor cells was only moderately improved by combination with CTLA-4 inhibition, the immunologic memory elicited by the combination treatment was indeed considerably enhanced. The memory induced was associated with an expansion of CD4+ memory cells, whose CD137 expression indicated preceding antigen-specific activation (Figure 5). These phenotypic changes were not seen in the CD8+ T-cell compartment.