Original Article

Cancer Chemotherapy and Pharmacology

, Volume 52, Issue 2, pp 131-138

Effective combination of ET-743 and doxorubicin in sarcoma: preclinical studies

  • Daniela MecoAffiliated withDivision of Pediatric Oncology, Catholic University of Rome
  • , Tina ColomboAffiliated withDepartment of Oncology, Istituto di Ricerche Farmacologiche "Mario Negri"
  • , Paolo UbezioAffiliated withDepartment of Oncology, Istituto di Ricerche Farmacologiche "Mario Negri"
  • , Massimo ZucchettiAffiliated withDepartment of Oncology, Istituto di Ricerche Farmacologiche "Mario Negri"
  • , Marco ZaffaroniAffiliated withDepartment of Oncology, Istituto di Ricerche Farmacologiche "Mario Negri"
  • , Anna RiccardiAffiliated withDivision of Pediatric Oncology, Catholic University of Rome
  • , Glynn FairclothAffiliated withPharmaMar USA
  • , Jimeno JoseAffiliated withPharma Mar R&D
  • , Maurizio D'IncalciAffiliated withDepartment of Oncology, Istituto di Ricerche Farmacologiche "Mario Negri"

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access

Abstract

Purpose

To investigate the cytotoxic and antitumor effects of the combination of the novel anticancer drug ET-743 and doxorubicin (Dx) and to determine whether any pharmacokinetic interaction occurs in sarcoma-bearing mice.

Methods

The cytotoxicity of each drug and of their combinations was assessed in the rhabdomyosarcoma cell line TE-671 by a clonogenic assay, and isobologram analysis was performed to detect any synergistic, additive or antagonistic effects. The antitumor activities of each drug and of the combinations were also evaluated in nude mice transplanted subcutaneously with human TE-671 rhabdomyosarcoma and in C3H female mice injected intravenously with UV2237 M fibrosarcoma or with the Dx-resistant subline UV2237 M-ADM which overexpresses Pgp. Antitumor activity was evaluated by monitoring the TE-671 tumor volume over time and, in the case of the murine fibrosarcomas, by evaluation of lung deposits at autopsy quantified by determining lung weight. Pharmacokinetic studies were performed in TE-671-bearing mice. ET-743 was determined in plasma by an HPLC-MS method and Dx in plasma and tissue by an HPLC method with fluorescence detection.

Results

The combination of ET-743 and Dx was found to be additive with the average combination index slightly lower than 1 at all survival levels, suggesting weak synergism. In TE-671 tumors in vivo the activity of ET-743 or Dx given alone was marginal, whereas the combination produced a significant antitumor effect. The log cell kill (LCK) values were 0.13 and 0.33 for ET-743 and Dx alone, whereas they ranged from 0.85 to 1.12 for the combination. Giving ET-743 1 h before Dx slightly enhanced the effect (LCK 1.12) compared with giving the drugs simultaneously (LCK 0.85) or in the opposite sequence (LCK 0.92). In UV2237 M fibrosarcoma, both Dx and ET-743 showed an effect in reducing the weight of lung metastases, although the combination of the two drugs was not superior to each drug alone. In UV2237 M-ADM tumors neither of the two drugs was active, whereas the combination, particularly when the two drugs were given simultaneously, produced a significant effect. Plasma levels of ET-743 and Dx were not significantly different when the drugs were given alone or in combination. The concentrations of Dx in tissues including tumor, liver, heart and kidney were found to be the same whether the drug was given alone or in combination with ET-743.

Conclusions

These results indicate that ET-743 and Dx in combination produce an additive effect against human sarcoma cells, reinforcing the idea that they act by a different mechanism of action. In mice no pharmacokinetic interaction between the two drugs was found. The observed activity in UV2237 M-ADM and in human TE-671 sarcoma suggests that the combination of the two drugs could be effective for tumors displaying low sensitivity to each drug given alone. Based on these findings a phase I study on the combination of the two drugs was recently initiated.

Keywords

ET-743 Doxorubicin Combination Sarcoma