ABSTRACT
Targeted chemotherapy with cytotoxic peptide analogs should be more effective and less toxic for the treatment of various malignancies than conventional systemic chemotherapy. Various cytotoxic drugs are being used as single agents or in combination regimens for the systemic treatment of advanced or metastatic cancers. Biopsies of primary tumors as well as their metastases for measurement of receptors for peptide analogs will greatly facilitate the selection of patients who may benefit from the administration of peptide analogs linked to various cytotoxic radicals. Receptors for peptide hormones such as somatostatin, bombesin/ gastrin-releasing peptide (GRP), and luteinizing hormone releasing hormone are suitable targets for chemotherapy based on cytotoxic conjugates of these peptides. Bombesin/GRP receptors were found on a high percentage of prostate cancer specimens, especially in early stages of the disease, and a 99mTc-labeled analog of bombesin was shown to accumulate in prostate cancers in patients.
