ANTI-IDIOTYPE CYTOKINE FUSION PROTEIN AS TUMOR VACCINE

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As part of our long-term goals to treat cancer patients with anti-idiotypic tumor vaccines we are proposing here to generate "Second Generation Ab2s" for the therapy of breast cancer patients. We have selected as the "First Generation" Ab2, 11D10, which functions as an internal image for a specific epitope of the human milk fat globule (HMFG) and is the therapeutic Ab2 used in Project I. The "Second Generation" Ab2 will be constructed by linkages to key cytokines. Cytokines have been shown to increase the immunogenicity of protein antigens including idiotypes. We will use two cytokines, IL-2 and GM-CSF, to create a chimeric antibody of 11D10, which will contain either of the two cytokines attached to the constant domain (CH3). The variable exon of the H chain gene of 1211D10 will be cloned and sequenced. The VH gene will be incorporated into plasmids which express the constant gene fused to the genes for either IL-2 or GM-CSF. A heavy chain loss mutant of the 11D10 hybridoma cell line will be transfected with these plasmids. Expression of functional cytokines and Ig will be monitored in transfectoma clones and high producing clones will be selected. These chimeric antibodies will be tested in mice and nonhuman primates as anti-idiotype tumor vaccines: 1) the Ab3 titer in animals immunized with the chimeric antibody will be compared to the Ab3 titer in animals immunized with the alum precipitated Ab2 as proposed in Project 1. 2) The Ab1' will also be compared in these groups of animals. We expect to observe a significantly higher Ab3 and Ab1' titer in the chimeric Ab2 immunized group. We also will compare the proliferative response to Ab2 in both groups. If these preclinical studies with chimeric cytokine Ab2s induce superior anti-TAA responses in animals we will initiate a phase I clinical trial in breast cancer patients.