cemadotin and Breast-Neoplasms

LU 103793 is a synthetic analogue of Dolastatin 15 that inhibits tubulin polymerisation. The aim of this study was to evaluate the efficacy and tolerability of LU 103793 in patients with metastatic breast cancer who had been previously treated with two lines of chemotherapy for advanced disease. Patients received LU 103793 at a dose of 2.5 mg/m(2)/day over 5 min for 5 consecutive days every 3 weeks. Thirty-four patients were enrolled and 23 patients were eligible for the evaluation of efficacy. Eleven patients experienced grade 4 neutropenia. Other related grade 3/4 adverse events included asthenia (three patients), stomatitis (1), myalgia (1) and increase of serum bilirubin (2). The main toxicity was hypertension occurring in seven out of 34 patients. There were no objective responses, 7 patients had stable disease. These results do not support the further evaluation of LU 103793 in metastatic breast cancer patients using this dose and schedule.

Topics: Adult; Aged; Antineoplastic Agents; Breast Neoplasms; Female; Humans; Hypertension; Middle Aged; Neoplasm Metastasis; Oligopeptides

LU103793 (NSC D-669356) is a new synthetic derivative of Dolastatin 15, an antiproliferative compound which was isolated from the mollusk Dolabella auricularia. Like Dolastatin 15, LU103793 is highly cytotoxic in vitro (IC50 = 0.1 nM). To investigate the mechanism of action of LU103793, we used a combination of biochemical and cellular methods. Turbidity assays with bovine brain microtubules demonstrated that LU103793 inhibits microtubule polymerization in a concentration-dependent manner (IC50 = 7 microM). Treatment with this compound also induced depolymerization of preassembled microtubules. Cell cycle analysis of tumor cell lines treated with LU103793 indicated a block in the G2-M phase. At the cellular level, it induced depolymerization of microtubules in interphase cells and development of abnormal spindles and chromosome distribution in mitotic cells. Although these effects are very similar to the cellular alterations caused by vinblastine, LU103793 does not inhibit vinblastine binding to unpolymerized tubulin in vitro. Our results suggest that LU103793 exerts its cytotoxic activity primarily through disruption of microtubule organization.

Topics: Adenocarcinoma; Amino Acid Sequence; Antineoplastic Agents; Breast Neoplasms; Cell Cycle; Cell Division; Chromosomes, Human; Colonic Neoplasms; Drug Interactions; Guanosine Triphosphate; HeLa Cells; Humans; Hydrolysis; Microtubules; Mitosis; Molecular Sequence Data; Neoplasms; Oligopeptides; Tubulin; Tumor Cells, Cultured; Vinblastine