Combination therapy of murine tumors with lentinan plus lipopolysaccharide plus cyclophosphamide.

A combination of lentinan and bacterial lipopolysaccharide (LPS), previously reported to have strong antitumor activity against some tumors, was only slightly effective on solid-type MH134 hepatoma and colon 38 adenocarcinoma and was not effective on ascitic L1210 in CDF1 mice. On the other hand, additional combination therapy with cyclophosphamide (CY), that is, lentinan plus LPS plus CY, strongly inhibited the growth of solid-type MH134 and colon 38 adenocarcinoma even when administered from day 12 after tumor inoculation. The antitumor delayed hypersensitivity reaction against MH134 hepatoma, measured by means of the footpad test, was augmented by this combination. The possible role of CY is discussed in relation to the importance of inhibition of immune suppressive mechanisms in this combination therapy.