Therapeutic effect of an
alkylating agent,
carboquone (CQ:
Esquinon, 1mg/vial Sankyo Co., Tokyo) was investigated with a mouse mammary
tumor MM-46 inherited the MM-
antigen. MM-46
tumor cells (3 X 10(6)) were implanted subcutaneously into the axillary region of syngeneic C3H/He mice and CQ was administered intravenously at a dose of 2 mg/kg by a single injection on day 1, 4, 7 or 10. The experiment was carried out with 10 mice in each group. As a result, treatment of CQ elicited a complete regression effect on MM-46
tumor; the rate of complete regression in the group treated with CQ on day 4 or day 7 was 10/10, but that in control group was 0/10. Administration of CQ after the
tumor inoculation brought about
necrosis of the subcutaneous
tumor, followed by complete regression and only a
scar remained by day 25 at the site of
tumor exclusion. In this experiment no recurrence or
metastasis was observed after
tumor regression. Since the mice which rejected the once developed
tumor were resistant to them on rechallenge with the same amount of MM-46
tumor cells, it was suggested that an immunological response would play an important role in exclusion of the
tumor. The complete regression effect described above has generally been reported on the antitumor pattern of the host-mediated agents such as
polysaccharides of Basidiomycetes, while has hardly on that of the
alkylating agents except
cyclophosphamide. The mechanism of such the regression effect attributed to the activity of CQ is obscure, but these results suggest that this phenomenon may be dependent on the inherent antigenicity of MM-46
tumor.