N-bromoacetyl-β-d-glucosamine tetra-o-acetate and w-bromoacetyl-β-d-galactosamine tetra-o-acetate as chemotherapeutic agents with immunopotentiating effects in ehrlich ascites tumor-bearing mice

N-Bromoacetyl-β-D-glucosamine tetra-O-acetate (NBrAcGIc-TA) and N-bromoacetyl-β-D-galactosamine tetra-O-acetate (NBrAcGal-TA) produced strong in vitro cytotoxicity against both Ehrlich and L1210 leukemia dividing cell lines at μm concentrations. A single administration i.p. at one-half the dose lethal to 10% of the animals of either agent cured 85% of Ehrlich ascites tumor-bearing C57BL/6J × DBN2 (hereafter called B6D2F₁) mice. Animals immunosuppressed by prior X-irradiation could not be cured by these agents. The corresponding chloro and fluoroderivatives and the non-O-acetylated N-haloacetylhexosamines were inactive in vitro and in vivo. No significant effect against L1210 leukemia in vivo was obtained with any of these agents. Cure of immunocompetent mice was associated with strong but incomplete cytotoxicity within 24 hr following drug administration and with a simultaneous increase in peritoneal polymorphonuclear leukocytes. Immunosuppressed mice also showed marked cytotoxic reduction in Ehrlich cell number, but the animals died from resumed tumor growth. Immunocompetent tumor-bearing mice after drug treatment exhibited complete resistance to an additional, normally lethal, challenge with 10⁶ Ehrlich cells within 24 hr after drug treatment and from 1 to 9 weeks after drug-induced cure were completely resistant to 10⁷ Ehrlich cells. Mice treated i.p. with NBrAcGIc-TA or NBrAcGal-TA 24 hr prior to implantation of 10⁶ Ehrlich ascites cells exhibited increased survival time or in some cases complete resistance to this otherwise lethal challenge. NBrAcGal-TA was not immunosuppressive at the dose level that was used in chemotherapy when primary immunoglobulins M and G response to sheep erythrocytes was tested. Ehrlich cells killed in vitro by exposure to NBrAcGIc-TA or NBrAcGal-TA or to other antineoplastic alkylating agents and reimplanted in vivo at a level comparable to that used in the in vivo cured mice failed to generate resistance to rechallenge with viable Ehrlich cells. It appears that NBrAcGIc-TA and NBrAcGal-TA exert anti-Ehrlich tumor activity in vivo by functioning as lipophilic alkylating agents that are cytotoxic to the tumor cells while concurrently enhancing the host response to the tumor.