Comparison of the hematologic toxicity of 7-N-(p-hydroxyphenyl),-mitomycin C and mitomycin C.

7-N-(p-Hydroxyphenyl)-mitomycin C (M-83), a new analog of mitomycin C (MMC) with equivalent or greater antitumor potencies against various experimental tumors, was investigated to determine its hematologic toxicity in mice. M-83 showed a significantly lower toxicity than MMC with respect to myelosuppression and leukopenia when compared at equivalent effective doses. In M-83-treated mice, the damage to the bone marrow was much milder at the nadir point and the recovery from myelosuppression to the normal level was faster as compared with that in the case of MMC. As a result, the number of white blood cells in the peripheral blood of the M-83-treated groups was considerably greater than that in the MMC-treated ones. These findings suggest that M-83 may be effective in clinical use.