Since the discovery of tumor-associated antigens (TAAs), researchers have tried 
to develop immune-based anti-cancer therapies. Thanks to their specificity, 
monoclonal antibodies (mAbs) offer the major advantage to induce fewer side 
effects than those caused by non-specific conventional treatments (e.g., 
chemotherapy, radiotherapy). Passive immunotherapy by means of mAbs or cytokines 
has proved efficacy in oncology and validated the use of immune-based agents as 
part of anti-cancer treatment options. The next step was to try to induce an 
active immune protection aiming to boost own's host immune defense against TAAs. 
Cancer vaccines are thus developed to specifically induce active immune 
protection targeting only tumor cells while preserving normal tissues from a 
non-specific toxicity. But, as most of TAAs are self antigens, an immune 
tolerance against them exists representing a barrier to effective vaccination 
against these oncoproteins. One promising approach to break this immune 
tolerance consists in the use of anti-idiotypic (anti-Id) mAbs, so called Ab2, 
as antigen surrogates. This vaccination strategy allows also immunization 
against non-proteic antigens (such as carbohydrates). In some clinical studies, 
anti-Id cancer vaccines indeed induced efficient humoral and/or cellular immune 
responses associated with clinical benefit. This review article will focus on 
recent achievements of anti-Id mAbs use as cancer vaccines in solid tumors.