Abstract
Background: The concept of a multimodality therapy in the treatment of soft tissue sarcomas (STS) has been discussed with controversy. Surgical resection with clear margins and radiation therapy remain gold standard in STS therapy. It is still questionable whether a systemic therapy with chemotherapeutics has a positive impact on the overall survival rate especially in early stages of disease, because the therapeutic effect in the treatment of STS is limited by its toxicities and its low responding rates. Treatment options are rare. As a result the search for combination therapies by using low dose approaches is of high importance. Recent studies showed the therapeutic efficiency of a designer host defense-like lytic D,L- amino acid peptide [D]-K 3 H 3 L 9 . Therefore we tested a combination of this peptide with Doxorubicin on two different sarcoma cell lines in vitro and also in a syngeneic immunocompetent murine fibrosarcoma mouse model. Methods: In vitro the human synovial sarcoma cell line SW 982 and the murine fibrosarcoma cell line BFS-1 were exposed to the oncolytic peptide [D]-K 3 H 3 L 9 , to the Anthracycline Doxorubicin and to both agents simultaneously. In vivo the murine fibrosarcoma cell line BFS-1 was injected subcutaneously into the syngeneic mice. When the tumors engrafted the oncolytic designer peptide [D]-K 3 H 3 L 9 , Doxorubicin or a combination of both was administered thrice a week for a three weeks’ follow-up. Results: The combination treatment approach using an oncolytic designer host defense peptide and Doxorubicin inhibited the in vitro sarcoma cell proliferation significantly. The single therapies, either with local intratumoral application of [D]-K 3 H 3 L 9 or with intraperitoneal application of Doxorubicin in the syngeneic mouse model, inhibited at least the tumor progression. The combination of both substances revealed a significant inhibition of tumor growth and weight. Conclusion: The in vivo low dose combination schedule inhibited the tumor growth significantly. Histological analyses of the tumor sections revealed an antiproliferative and antiangiogenic effect. So, these results demonstrate the effectiveness of combined low-dose application forms with designer host defense-like lytic peptides and chemotherapeutics.