In vivo effects of tumor necrosis factor-α or flavone acetic acid in combination with doxorubicin on multidrug-resistant B16 melanoma

Having observed that tumor necrosis factor (TNF)-alpha and doxorubicin (DXR) produce a synergistic inhibition of melanoma B16 and also of its multidrug resistant (MDR) variant in vitro, we tested whether this interaction would occur in vivo as well. C57BL/6 mice with s.c. tumors were treated with TNF or flavone acetic acid (FAA), a biological response modifier, in simultaneous or sequential combination with DXR. The agents were administered systemically. Overall, the results were negative, apart from a trend towards slight synergy, found in the chemosensitive melanoma, when TNF was given 1 or 2 days before DXR. The effects of FAA and DXR were found to be subadditive or antagonistic. However…