Cell-free production of scFv fusion proteins: an efficient approach for personalized lymphoma vaccines

The unique immunoglobulin (Ig) idiotype on the surface of each B-cell lymphoma represents an ideal tumor-specific antigen for use as a therapeutic vaccine. We have used an Escherichia coli-based, cell-free protein-expression system to produce a vaccine within hours of cloning the Ig genes from a B-cell tumor. We demonstrated that a fusion protein consisting of an idiotypic single chain Fv antibody fragment (scFv) linked to a cytokine (GM-CSF) or to an immunostimulatory peptide was an effective lymphoma vaccine. These vaccines elicited humoral immune responses against the native Ig protein displayed on the surface of a tumor and protected mice against tumor challenge with efficacy equal to that of the conventional Ig produced in a mammalian cell and chemically coupled to keyhole limpet hemocyanin. The cell-free E coli system offers a platform for rapidly generating individualized vaccines, thereby allowing much more efficient application in the clinic.