The antitumor activity of
Ge-132 against a variety of allogeneic and syngeneic murine
ascites tumors was first evaluated. The antitumor effects of
Ge-132 were observed when mice inoculated with Ehrlich
carcinoma (allogeneic) or RL male 1
leukemia (syngeneic) cells were treated orally. However,
Ge-132 had no activity on a
T-cell lymphoma (EL 4, syngeneic) or a
methylcholanthrene-induced
fibrosarcoma (Meth-A, syngeneic). The antitumor effect of
Ge-132 in mice was related to the dose administered as well as the administration schedule. The antitumor activity of
Ge-132 was next studied in mice pretreated with some blockers against immunocompetent cells. The antitumor efficacy of
Ge-132 was not observed when
tumor-bearing mice were treated with
trypan blue and
carrageenan or monoclonal
anti-Thy 1.2 antibody. However, when natural killer cells were eliminated from mice bearing RL male 1 or Ehrlich
ascites tumors by treatment with anti-asialo GM 1 antiserum, the antitumor efficacy of the compound was unchanged. These results suggest that
Ge-132 is effective against certain
ascites tumors regardless of whether the
tumor is syngeneic or allogeneic. Further, its effect might be expressed through host defense mechanisms, including macrophages and/or T lymphocytes.