Antiproliferative efficacy of the somatostatin analogue TT-232 in human melanoma cells and tumours

Background: TT-232, a somatostatin analogue, induces apoptosis in various tumours. The aim of our study was to characterise its effect on human melanoma cells and tumours. Materials and Methods: Proliferation of seven melanoma cell lines was tested in vitro with the methylene blue test. D10 and 205 cells were also implanted into CB17-scid mice which received 30-150-750 μg/kg/day of TT-232 or saline. Animals with 205 cells received twice-daily subcutaneous injections whereas animals with D10 cells were treated with osmotic mini-pumps. In addition, TT-232 metabolites were generated with tissue homogenates and tested in vitro. Results: TT-232 strongly inhibited proliferation of all cell lines in vitro and tumour growth in vivo. Two out of 8 animals (30-150 μg/kg) in the 205 model and one out of 8(150 μg/kg) in the D10 model became completely tumour-free at the 11 th and 9 th day of treatment, respectively. TT-232 was degraded only by liver homogenate whilst its metabolite had no antiproliferative effect in vitro. Conclusions: TT-232 is a promising drug candidate for melanoma.