A Cancer Research (UK) randomized phase II study of idoxifene in patients with locally advanced/metastatic breast cancer resistant to tamoxifen

Johnston, S. et al. (2004) A Cancer Research (UK) randomized phase II study of idoxifene in patients with locally advanced/metastatic breast cancer resistant to tamoxifen. Cancer Chemotherapy and Pharmacology, 53(4), pp. 341-348. (doi: 10.1007/s00280-003-0733-6)

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Idoxifene is a novel selective oestrogen receptor modulator (SERM) which had greater binding affinity for the oestrogen receptor (ER) and reduced agonist activity compared with tamoxifen in preclinical studies. In a randomized phase II trial in 56 postmenopausal patients with progressive locally advanced/metastatic breast cancer we assessed whether idoxifene showed evidence of activity compared with an increased 40 mg/day dose of tamoxifen in patients who had previously demonstrated resistance to the standard 20 mg/day dose of tamoxifen. Of 47 patients eligible for response (25 idoxifene, 22 tamoxifen), two partial responses and two disease stabilizations (SD) for >6 months were seen with idoxifene (overall clinical benefit rate 16%, 95% CI 4.5-36.1%). The median duration of clinical benefit was 9.8 months. In contrast, no objective responses were seen with the increased 40 mg/day dose of tamoxifen, although two patients had SD for 7 and 14 months (clinical benefit rate 9%, 95% CI 1.1-29.2%). Idoxifene was well tolerated and the reported possible drug-related toxicities were similar in frequency to those with tamoxifen (hot flushes 13% vs 15%, mild nausea 20% vs 15%). Endocrine and lipid analysis in both groups showed a similar significant fall in serum follicle-stimulating hormone and luteinizing hormone after 4 weeks, together with a significant rise in sex hormone binding globulin levels and 11% reduction in serum cholesterol levels. In conclusion, while idoxifene was associated with only modest evidence of clinical activity in patients with tamoxifen-resistant breast cancer, its toxicity profile and effects on endocrine/lipid parameters were similar to those of tamoxifen.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Evans, Professor Jeff
Authors: Johnston, S., Gumbrell, L., Evans, T., Coleman, R., Smith, I., Twelves, C., Soukop, M., Rea, D., Earl, H., Howell, A., Jones, A., Canney, P., Powles, T., Haynes, B., Nutley, B., Grimshaw, R., Jarman, M., Halbert, G., Brampton, M., Haviland, J., Dowsett, M., and Coombes, R.
College/School:College of Medical Veterinary and Life Sciences > School of Cancer Sciences
Journal Name:Cancer Chemotherapy and Pharmacology

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