ANTI-TUMOUR ACTIVITY OF ICI 11863-NEW POTENT LUTEINIZING-HORMONE-RELEASING HORMONE AGONIST

Experiments were undertaken with DMB A-induced mammary tumours of the rat to determine the anti-tumour properties of a new and potent luteinizing hormone-releasing hormone (LH-RH) agonist, [D-Ser(But)6Azgly10]-LH-RH (ICI 118630). Tumours were classified according to their oestrogen-receptor (ER) content. Twice daily i.m. injections of either 5 µg or 0.5 µg ICI 118630 in saline were as effective as ovariectomy or tamoxifen therapy in causing the regression of ER+ DMB A-induced mammary tumours. ER mammary tumours showed a more equivocal overall response to ICI 118630, some tumours progressing, others regressing. About one-third of the ER+ tumours disappeared in the 20-day treatment period. Those tumours which did regrow after the cessation of treatment proved to be hormone-dependent. In addition to the inhibitory effects of the LH-RH agonist on pre-existing tumours, ICI 118630 also reduced the total number of new tumours formed during and after treatment. © 1979, The British Empire Cancer Campaign for Research. All rights reserved.