Anti-idiotypic antibody and recombinant antigen vaccines in colorectal cancer patients

The colorectal carcinoma (CRC)-associated GA733 antigen (also known as CO17 -1A, KS1-4, KSA or EpCAM) has been the target of a phase II/III randomized trial of passive immunotherapy with monoclonal antibody CO17-1A and phase I active immunotherapy trials with polyclonal anti-idiotypic antibodies mimi cking the CO17-1A or GA733 epitope on the antigen. The CO17-1A antigen was molecularly cloned and the extracellular domain expressed in baculovirus (B V) GA733-2E. Whereas, anti-idiotypic antibody mimics a single epitope on th e antigen, BV CA733-2E expresses multiple potentially immunogenic epitopes. In animals, the immunogenicity of BV GA733-2E in aluminum hydroxide was su perior to that of anti-idiotype in the same adjuvant. Here, we compared the immunogenicity of anti-idiotypic antibody and GA733-2E antigen in CRC pati ents. These studies indicate that the antigen is superior to the anti-idiot ype antibody in inducing humoral and cellular immunity in CRC patients. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.