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Nitrogen mustards: mustard gas used first during WWI. Leukopenia and GI ulceration noted in survivors

Bondage: crosslinking agents. Nitrogen mustards: mustard gas used first during WWI. Leukopenia and GI ulceration noted in survivors. Spontaneous activation of mechlorethamine. Bifunctional crosslinking between G residues in the DNA. Other alkylating agents and intermediates.

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Nitrogen mustards: mustard gas used first during WWI. Leukopenia and GI ulceration noted in survivors

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  1. Bondage: crosslinking agents Nitrogen mustards: mustard gas used first during WWI. Leukopenia and GI ulceration noted in survivors

  2. Spontaneous activation of mechlorethamine

  3. Bifunctional crosslinking between G residues in the DNA

  4. Other alkylating agents and intermediates parent compound reactive intermediate mechlorethamine cyclophosphamide carmustine procarbazine

  5. Cyclophosphamide (Cytoxan) requires P450 activation in liver

  6. Cisplatin: chloro to hydroxyl conversion in cell G H2O G residue in DNA

  7. Vaporization: Bleomycin, radiation

  8. Bleomycin chelates iron/catalyzes formation of hydroxyl radicals

  9. Confusion Actinomycin D

  10. Actinomycin D: -intercalates into the DNA duplex -blocks RNA synthesis and DNA replication

  11. Topoisomerase inhibitors • Topo II inhibitors • doxorubicin (daunorubicin, idarubicin, etoposide) bind to DNA/topo II complex and prevents re-sealing of DNA breaks made by topo II • also act to inhibit DNA and RNA synthesis • etoposide (similar to above) causes DNA strand breaks and cell death • Topo I inhibitors • camptothecins (irinotecan, topotecan) bind the Topo I/DNA complex and prevent religation

  12. Pharmacogenetics

  13. Starvation for substrates • Methotrexate: • inhibitor of human DHFR • 5-fluorouracil: • inhibits thymidylate synthetase and misincorporated into RNA

  14. MTX dTMP FH2 thymidine synthetase 5-FU 5-FdUMP DHFR dUMP FH4 purines purines/amino acids Methotrexate and 5-fluorouracil 5-FU first--> then MTX = antagonism MTX first--> (hrs) then 5-FU = synergism

  15. Starvation for substrates • Methotrexate: • inhibitor of human DHFR • 5-fluorouracil: • inhibits thymidylate synthetase and misincorporated into RNA • 6 thioguanine: • inhibits purine biosynthesis • cytosine arabinoside, difluorodeoxycytidine (gemcitabine): • inhibits DNA polymerase and gets misincorporated • hydroxyurea: • inhibits ribonucleotide reductase and therefore DNA synthesis

  16. Regulation • Hormone therapy: • breast cancer • prostate cancer • ovarian, endometrial cancer

  17. Risk of breast CA in BRCA1/2 carriers • BRCA mutations in about 7% of Caucasian breast CA pts. • BRCAs are tumor suppressor proteins • loss of heterozygosity leads to tumor formation • exercise, normal weight, and child bearing delays onset • other variables (environment?) seem to be speeding onset

  18. BRCA protein function? • BRCA proteins have unique domain structures that bind phosphorylated regulatory proteins • BRCA1 is an E3 ubiquitin ligase that participates in DNA repair and BRCA2 seems to be involved in homologous recombination. Both are required for genomic stability

  19. Position of mutation in BRCA determines risk for breast versus ovarian cancer

  20. Tamoxifen antagonizes estrogen action in breast cancer cells and affects growth factor synthesis • Tamoxifen • IGF-1 • TGFa • plasminogen activator • laminin receptors • TGFb

  21. Emergence of Immunotherapy • Paul Ehrlich (1904) hypothesized that antibodies could be used as ‘magic bullets’ to treat cancer • Köhler and Milstein (1979) described a method to develop antibodies with defined specificity • Rituximab is approved by FDA in 1997 for the treatment of B-cell non-Hodgkin’s lymphoma • Addition of rituximab to standard CHOP chemotherapy provided the first improvement in survival in diffuse large cell lymphoma (2002) in 25 years

  22. Antibodies in Cancer Chemotherapy • Herceptin (trastuzumab) • humanized monoclonal antibody against HER2 (human epidermal growth factor receptor 2) • Avastin (bevacizumab) • humanized monoclonal against VEGF (vascular endothelial growth factor) • Cetuximab • antibody against the EGF receptor

  23. Clinical trial of herceptin

  24. Induction of VEGF and angiogenesis • HIF = hypoxia inducible factor • oxygen dependent proline hydroxylation regulates degradation of HIF- by proteasome • low oxygen leads to increased HIF and induction of VEGF and other genes

  25. Tumor vasculature regrowth after anti-VEGF therapy stopped?

  26. Avastin (bevacizumab) benefits may not persist

  27. Assembly of tubulin into microtubules Vinca alkaloids (vincristine, vinblastine, vindesine) inhibit polymerization Taxol: binds microtubules and prevents depolymer- ization.

  28. Microtubules do more than just help segregate chromosomes at mitosis: for example, they are involved in vesicle transport in neurons.

  29. Gleevec (imatinib) is a specific inhibitor

  30. Imatinib (Gleevec) highly effective in treatment of CML 5000 pts develop CML each year in US 2.1 billion $ for Novartis

  31. Protein kinase inhibitors on the market and in development

  32. Many new drugs targeted to the EGF and VEGFR pathways FDA Avastin Tarceva

  33. Tarceva (erlotinib) is an EGFR tyrosine kinase inhibitor that also promotes regeneration

  34. HDAC inhibitors:promising

  35. Proteasome inhibitor: Bortezomib • small molecule inhibitor of the 26S proteasome • approved by FDA for relapsed multiple myeloma • one-year survival rate was 80 percent among patients taking bortezomib and 66 percent among patients taking dexamethasone

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