Antisense DNA directed against C-myc oncogene blocks tumor growth in normal mice. The first clinical trials of oligonucleotide therapeutics have demonstrated antisense efficacy in patients against follicular lymphoma, chronic myelogenous leukemia, cytomegalovirus and Crohn's disease. The central hypothesis of this application is that second and third generation derivatives of ant-c-myc DNAs will display greater systemic potency than phosphorothioates in animal models of c-myc- dependent lymphomas and other myc dependent malignancies. Previous work under this grant has demonstrated efficacy of a variety of DNA derivatives, against a variety of c-myc mRNA targets, in malignant cells growing in culture and in murine hosts. Over the next five years, these successes will be translated into lead compounds. 1. More sensitive c-myc mRNA targets will be identified. Radio-labeled c-myc mRNA targets will be hybridized to overlapping antisense DNA oligomers immobilized on polypropylene chips. To test the hybridization results, the antisense efficacy of a series of overlapping anti-c-myc oligomers will be measured in cultured lymphoma cells. 2. The potency of anti-c-myc DNAs will be increased. For the best sequences identified in 1., anti-c-myc DNA chimeras will be synthesized with terminal phosphorothioates and central methylphosphonates, or 2'-O-methyl residues. Peptide nucleic acid derivatives will also be prepared, with cyclic peptide ligands designed for receptor specific cellular uptake. For each lead compound, sequence specificity and mechanism will be tested with 1-4 mismatches. Aptameric effects will be screened. 3. The pharmacodynamics of anti-c-myc DNAs will be optimized. (a) Tumor cells from Eu-myc lymphoma cells, transplanted into the immuno-compatible parental strain, will be treated with the most potent anti-c-myc DNA derivatives above. Tumor size, mRNA, and antigen levels will be studied as a function of dose and schedule. (b) Intraperitoneal, subcutaneous, subcutaneous depot, and oral administration will be compared. (c) The most potent anti-c-myc DNAs will be tested for adjuvant therapy of residual disease, by allowing transplanted lymphoma cells to establish for varying times prior to initiation of therapy. 4. The safety of anti-c-myc DNAs will be evaluated. (a) Administration, distribution, metabolism, and excretion of new anti-c-myc derivatives will be compared to elucidate variation of potency with route. (b) Body weight, splenomegaly, cytokines, complement, liver enzymes and complete blood count will be compared to identify the anti-c-myc derivative with the greatest therapeutic ration. 5. The breadth of spectrum of anti-c-myc DNAs will be determined. Candidate sequences will be tested for efficacy against xenografts of human (a) ST486 Burkitt's lymphoma cells (b) U937 erythroleukemia cells (c) BT474 breast cancer cells (d) COLO320 colon cancer cells and (e) A549 lung cancer cells. The efficacy and potency of combination therapy will be evaluated. Anti-c-myc DNA's will be tested in combination or alteratively with (a) immunostimulatory DNAs or (b) anti- proliferative compounds. The lead compounds resulting from these studies will then be translated to a separate collaborative application for a Phase I/II clinical trial.
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