A major challenge for inducing antitumor immune responses with native or 
modified tumor/self-Ags in tumor-bearing hosts relates to achieving efficient 
uptake and processing by dendritic cells (DCs) to activate immune effector cells 
and limit the generation of regulatory T cell activity. We analyzed the ability 
of therapeutic DC vaccines expressing a CD166 cross-reactive mimotope of the GD2 
ganglioside, 47-LDA, to selectively expand adoptively transferred, 
tumor-specific T cells in NXS2 neuroblastoma tumor-bearing syngeneic mice. 
Before the adoptive cell transfer and DC vaccination, the tumor-bearing mice 
were lymphodepleted by nonmyeloablative total body irradiation or a 
myeloablative regimen that required bone marrow transplantation. The 47-LDA 
mimotope was presented to DCs either as a linear polypeptide in conjunction with 
universal Th epitopes or as a fusion protein with the murine IgG2a Fc fragment 
(47-LDA-Fcgamma2a) to deliver the antigenic cassette to the activating Fcgamma 
receptors. We demonstrate that immunization of adoptively transferred T cells in 
tumor-bearing mice with the 47-LDA mimotope expressed in the context of the 
activating Fc fusion protein induced higher levels of antitumor immune responses 
and protection than the 47-LDA polypeptide-DC vaccine. The antitumor efficacy of 
the therapeutic 47-LDA-Fcgamma2a-DC vaccine was comparable to that achieved by a 
virotherapy-associated cancer vaccine using a recombinant oncolytic vaccinia 
virus expressing the 47-LDA-Fcgamma2a fusion protein. The latter treatment, 
however, did not require total body irradiation or adoptive cell transfer and 
resulted in induction of antitumor immune responses in the setting of 
established tolerance, paving the way for testing novel anticancer treatment 
strategies.