Antitumor activity of Virulizin, a novel biological response modifier (BRM) in a panel of human pancreatic cancer and melanoma xenografts

Purpose: To define the anticancer efficacy of Virulizin in vivo as a single agent or in combination with conventional drugs in human pancreatic tumor and melanoma xenografts. Methods: The therapeutic effect of Virulizin was evaluated in a series of human tumor xenografts in athymic nude mice. Results: Virulizin had a high level of antitumor activity against all the pancreatic tumors (BxPC-3, SU 86.86. and Mia-PaCa-2) and melanomas (C8161 and A2058), as indicated by suppression of tumor growth with an optimal T/C value of less than or equal to40% when administered as a single agent. No significant changes in Virulizin antitumor activity were observed when different schedules (3 days/week vs 7 days/week) or routes of administration (i.p. vs i.m.) were used. In combination therapy, Virulizin significantly enhanced the antitumor activity of gemcitabine and 5-fluorouracil against pancreatic tumors and of dacarbazine against metastatic melanomas, as reflected by a further decrease in tumor growth as compared to tumors in animals treated with the conventional drugs alone. Conclusion: These studies suggest that Virulizin effectively inhibits the growth of solid human pancreatic tumors and melanomas in the xenograft model.