[Combination chemotherapy with bleomycin ointment and lysozyme ointment against mouse WHT squamous cell carcinoma]

The antitumor effect of bleomycin (BLM) ointment in combination with lysozyme (LY) ointment was investigated. Nine-week-old male and female WHT/Ht mice were implanted with a graft of WHT squamous cell carcinoma into the subcutis of back, and the skin covering the developed solid tumor was resected 7 days after implantation. Thereafter, the mice were administered twice daily for 7 days with each of the following: 220 mg of 0.25% BLM ointment, 2.5% LY ointment, and a 1:1 mixture of 0.5% BLM ointment plus 5% LY ointment. BLM ointment and the combination of BLM ointment and LY ointment were effective with an inhibition rate of 79.3 and 89.7%, respectively. The inhibition rates of these groups showed a statistically significant increase over that of control group. Further, the rate of the combination group displayed a statistically significant increase over that of the BLM ointment group. Formation of crusta on the solid tumor was markedly inhibited in the groups applied LY ointment and the combination of LY ointment and BLM ointment. LY was ineffective against cultured cells of WHT squamous cell carcinoma and did not potentiate the antitumor activity of BLM in combination. These results suggest that potentiation of the antitumor effect of BLM ointment in combination with LY ointment is due to inhibition of crusta formation by LY resulting in an increased permeation of BLM into tumor tissue.