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Important discoveries have revealed the molecular basis for the transformation, proliferation, and survival of cancer cells. These advances have revealed new targets for cancer drug design, and have produced agents that inhibit the signaling molecules and pathways responsible for cancer (Figure 10-1) (1). These inhibitors of cancer-associated targets include monoclonal antibodies (mAbs) either alone or coupled with cytotoxic agents or radioisotopes; modified proteins and peptidomimetic molecules; and small-molecular-weight drugs. Still in the development stage are small interfering RNAs (siRNA), antisense oligonucleotides, gene therapy approaches, and ribozymes or DNAzymes. In this chapter we will consider the small molecules that have been approved for clinical use. Monoclonal antibodies and their conjugates will be considered elsewhere (Chapter 15) (see Table 10-1) (2,3,4,5,6,7,8,9).
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