Elliptinium, norcantharidin and tetrachlordecaoxide in combined chemo-immunotherapy prolong the survival of Friend-virus-infected mice.

Abstract

The association of several drugs with different target specificities has long been proven to be more efficient than one single agent in the treatment of cancer. This strategy might also be of benefit in the cure of retrovirus-induced diseases. The effectiveness of several drug combinations was evaluated on DBA/2 mice injected with Friend leukaemia virus (FLV). Elliptinium (ELP), a known chemotherapeutic agent with possible antiviral activity, was given in association with norcantharidin (NCTD) (shown previously to increase the cytotoxic potential of human lymphocytes) and/or in association with tetrachlordecaoxide (TCDO), which augments both humoral and cellular immune responses. ELP alone at a dose of 0.2 mg/kg in long-term treatment significantly increased the survival of mice infected by FLV. When ELP, TCDO (2 micrograms/kg) and NCTD (2 mg/kg) were given together, the survival time was prolonged 1.6 times and 2 times as compared to the group treated by ELP alone or to non-treated controls, respectively. Moreover, the combined treatment gave more effective inhibition of hepatomegaly than ELP alone, suggesting that this protocol might have an organ-specific effect and might suppress the leukaemogenesis induced by FLV in some erythropoietic organs. These results indicate that a chemotherapeutic agent (ELP) associated with two immunomodulatory substances (NCTD and TCDO) is more effective than chemotherapy alone in controlling retroviral infection and in the prolongation of survival. These data taken together suggest that the role of the two immunomodulatory agents might be to suppress the retroviral infection synergistically with ELP and enhance immune functions. Possible modes of action are discussed and are under investigation.