Preclinical in vivo activity of a combination gemcitabine/liposomal doxorubicin against cisplatin-resistant human ovarian cancer (A2780/CDDP).

Both gemcitabine and liposomal doxorubicin are antineoplastic drugs with clinical activity in platinum-refractory ovarian cancer. The purpose of this study was to evaluate the antitumor activity of a combination gemcitabine/liposomal doxorubicin administered to athymic mice bearing cisplatin-resistant human ovarian cancer (A2780/CDDP) xenografts. Emphasis was on the use of very low doses of each drug and of different dosing schedules. Data obtained showed that combined treatment with 80 mg/kg gemcitabine and 15 mg/kg liposomal doxorubicin produced a significant enhancement of antitumor activity compared with monotherapy at the same doses of these agents. Noteworthy is the fact that the majority of xenograft-bearing animals receiving the combination therapy demonstrated a complete tumor regression at the end of the study. A similar trend was observed when doses of both drugs were reduced to 20 mg/kg gemcitabine and to 6 mg/kg liposomal doxorubicin. Again, three out of ten mice receiving the combination were tumor free at the end of the study. No significant differences were observed in antitumor activity when comparing the simultaneous vs the consecutive dosing schedule. Remarkably, no additive toxicity was observed in any experimental trials. These data encourage clinical trials to prove the advantages of this combination treatment with respect to the single-agent chemotherapy in platinum-refractory ovarian cancer patients.

Antitumour activity of the silybin-phosphatidylcholine complex, IdB 1016, against human ovarian cancer.

This study aimed to assess, in an in vivo experimental model, the growth inhibitory effects of IdB 1016 (Silipide, a complex of silybin/phosphatidylcholine) when used as a single agent against human ovarian cancer. We also wanted to investigate the mechanism of the antiangiogenic action by assessing Vascular Endothelial Growth Factor (VEGF) levels and by using macroarray technology to evaluate the regulation of a panel of genes involved in angiogenesis. We also aimed to establish the plasma and tumour bioavailability of silybin after repeated administration of IdB 1016. Female nude mice bearing human ovarian cancer xenografts (A2780) received 450 mg/kg/day IdB 1016 daily by oral gavage until the end of the study. At sacrifice, blood and tumour specimens were collected and subsequently processed for the determination of silybin levels, VEGF levels or a gene expression profile. IdB 1016 was significantly active in inhibiting ovarian tumour growth. Treatment with 450 mg/kg/day for a total of 20 administrations produced a tumour weight inhibition (TWI%) of 78% and a Log10 Cell Kill (LCK) of 1.1. Free silybin levels were found to be 7.0+/-5.3 microg/ml and 183.5+/-85.9 ng/g tissue (mean+/-standard deviation (S.D.)) in the plasma and tumour samples, respectively. No significant differences were found in the concentration of human VEGF in xenografts from control and IdB 1016-treated mice. The array analysis suggested the downregulation of the VEGR receptor 3 and the upregulation of angiopoietin-2 as potential mechanisms for the antiangiogenic activity. In conclusion, these findings suggest IdB 1016 is a good candidate, with a relevant clinical potential, for use in the management of recurrent ovarian cancer. A phase II, non-randomised clinical study is now ongoing in our Institute aimed at evaluating the efficacy of daily administrations of IdB 1016 in the serological recurrence of ovarian cancer.