Vaccine 29 (2011) 4690–4697 Contents lists available at ScienceDirect Vaccine j ourna l ho me pag e: www.elsevier.com/locate/vaccine HER-2/neu tolerant and non-tolerant mice for fine assessment of antimetastatic potency of dendritic cell-tumor cell hybrid vaccines Lorena Landuzzi a , Agnese Antognoli b , Giordano Nicoletti a , Stefania Croci b , Arianna Palladini b , Marianna Lucia Ianzano b , Annalisa Murgo b , Valeria Stivani b , Valentina Grosso b , Patrizia Nanni b,c , Carla De Giovanni b,c,∗ , Pier-Luigi Lollini c,d a Laboratory of Experimental Oncology, Rizzoli Orthopedic Institute, Via di Barbiano 1/10, 40136 Bologna, Italy b Cancer Research Section, Department of Experimental Pathology, University of Bologna, Viale Filopanti 22, 40126 Bologna, Italy c Interdepartmental Centre for Cancer Research “Giorgio Prodi”, University of Bologna, via Massarenti 9, 40138 Bologna, Italy d Department of Hematology and Oncologic Sciences, University of Bologna, via Massarenti 9, 40138 Bologna, Italy a r t i c l e i n f o Article history: Received 14 February 2011 Received in revised form 24 March 2011 Accepted 26 April 2011 Available online 11 May 2011 Keywords: HER-2/neu Dendritic cells Cancer vaccines Metastasis Transgenic mice a b s t r a c t Main obstacles to cancer vaccine efficacy are pre-existing antigenic load and immunoescape mechanisms, including tolerance against self tumor-associated antigens. Here we explored the role of tolerance in an antimetastatic vaccine approach based on dendritic cell–tumor cell (DC–TC) hybrids, thanks to the comparison between BALB-neuT mice, transgenic for and tolerant to rat HER-2/neu, with their non- tolerant strain of origin BALB/c. Allogeneic DC–TC hybrid vaccine displayed a high antimetastatic activity in non-tolerant mice, but was far less effective in tolerant mice, even with intensified vaccine schedule. Tolerant BALB-neuT mice revealed a reduced ability to mount polarized Th1 responses. A further attempt to increase the antimetastatic activity by using LPS-matured DC hybrids failed. Allogeneic LPS-matured DC–TC hybrids induced high IFN- levels, but concomitantly also the highest production of IL-4 and IL-10 suggesting activation of mechanisms sustaining regulatory cells able to blunt vaccine efficacy. Our data in tolerant versus non-tolerant hosts suggest that clinical translation of effective DC-based strategies could benefit from more extensive investigations in tolerant transgenic models. © 2011 Elsevier Ltd. All rights reserved. 1. Introduction Dendritic cell (DC)-based vaccines have been extensively inves- tigated as potential cancer vaccines. Many efforts are currently being made to further improve their anti-tumor efficacy and recently a DC-based cancer vaccine has received FDA approval in the United States opening the way to innovative active immunotherapy for cancer [1,2]. DCs are specialized antigen- presenting cells capable to initiate and sustain or alternatively silence immune responses [3]. Key molecules which, when highly expressed, account for the immuno-activating functions are cos- timulatory proteins (CD80 and CD86), class I and class II major histocompatibility complex (MHC) glycoproteins, CD40, and most importantly T and B cells stimulatory and proinflammatory cytokines (IL-1, IL-6 and IL-12) [4]. Thanks to these features, immunostimulatory DC have drawn attention as a useful compo- ∗ Corresponding author at: Cancer Research Section, Department of Experimental Pathology, University of Bologna, Viale Filopanti 22, 40126 Bologna, Italy. Tel.: +39 0512094792; fax: +39 051242169. E-mail address: carla.degiovanni@unibo.it (C. De Giovanni). nent for cancer vaccines [5,6]. DC fused with tumor cells (TCs), more than DC variably loaded with antigenic peptides or apoptotic cells, effectively elicited anti-tumor immunity, both in animal mod- els and in cancer patients [7–11]. DC–TC hybrids should provide costimulatory proteins and cytokines, in addition to a complete array of tumor antigens presented in the context of class I and II MHC molecules. Allogeneic as well as syngeneic DC, or mature as well as immature DC, can induce anti-tumor immunity when fused with autologous tumor cells [12]. Allogeneic response can provide an adjuvant effect able to recruit additional T-cell clones reactive towards tumor antigens [13]. In view of clinical transla- tion, allogeneic vaccines could more easily meet the requirements of standardization and large scale production [14]. Unlike prophylactic vaccines against pathogens that are admin- istered to healthy people as a protection against potential exposure and are directed towards non-self antigens, anti-tumor vaccines administered in cancer patients have to deal with a pre-existing antigenic load and an immunosuppressive environment and, most importantly, have to overcome tolerance against self tumor- associated antigens (self-TAA) [6,15]. Tumor-prone mice transgenic for oncogenes, unlike wild-type mice engrafted with syngeneic TAA-expressing tumor, provide a model which include central 0264-410X/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.vaccine.2011.04.096