Our objective is to combine receptor-binding epitopes with synthetic water-soluble polymer-adriamycin (ADR) conjugates to produce polymer therapeutics recognizable by a subset of lymphocytes. This will yield new potent drugs effective to treat lymphomas. Leukemia, lymphoma, and myeloma will kill an estimated 59,000 persons m the U.S. this year. Leukemia and lymphomas are the leading fatal cancers in young women and young men under 35. It appears that new approaches for the treatment of these diseases are needed. Clinical trials in the last 25 years have demonstrated that high-dose chemotherapy can result in improved response and overall survival rates for patients with various malignant diseases. The fact that clinical data with N-(2- hydroxypropyl)methacrylamide (HPMA) copolymer - adriamycin (ADR) conjugates demonstrated a 3 to 4 times higher maximum tolerated dose of ADR than free ADR seems to indicate that the use of polymer therapeutics is one of the ways to proceed. The EDPGFFNVE nonapeptide (NP) was recognized as the CD21 (CR2) binding epitope of the Epstein-Barr virus (EBV) gp350/220 envelope glycoprotein, which mediates the virus attachment to immunocompetent cells. Attachment of the NP via a tetrapeptide (GFLG) side-chain to HPMA copolymers resulted in a tridecapeptide epitope (GFLGEDPGFFNVE) and in a modified biorecognition by B and T cells. This strongly suggested the possibility to manipulate the structure of epitopes with the aim to produce targetable drug delivery systems suitable for the treatment of lymphomas. A new approach to the design of targetable polymeric anticancer drugs, based on the combination of molecular biology with traditional sciences, is proposed. Plasmids encoding specific protein structures containing epitopes recognizable by immunocompetent cells will be designed and expressed in E. coli. The purified proteins, antiparallel coiled-coil stem loop (AP-CCSL) structures, will contain recognizable epitopes in the loop. When self-assembled on a solid substrate the epitopes will be displayed at the solid-liquid interface in an organized manner. The unique design of the DNA sequence encoding the AP-CCSL will incorporate restriction sites permitting an easy replacement of epitope encoding sequences. The interaction of exposed epitopes with immunocompetent cells, determination of the relationship between the sequence and/or secondary structure of epitopes and biorecognition, and binding studies in the presence of monoclonal antibodies specific for particular receptors will be performed. These studies will result in the identification of optimal receptor-epitope pairs for B and/or T cells. The identified sequence(s) will be used to synthesize HPMA copolymer- ADR conjugates containing oligopeptide epitopes as lymphocyte recognition sites. The relationship between the structure of these conjugates and their biological activity in vitro on selected B and T cells will be performed. A CB17 scid mouse model which produces a disseminated disease analogous to that seen in humans will be used to evaluate the biological activity of the conjugates in vivo. The results of the proposed studies will provide a new method to treat human lymphomas.
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