[The sensitivity of experimental tumor systems to ultra low doses of doxorubicin]

Biological effect of doxorubycin in standard (10(-3) mol/l) and ultra low doses (10(-5)-10(-20) mol/l) against some "signal" animal tumor systems--Lewis lung carcinoma, 755 adenocarcinoma, B-16 melanoma, Ehrlich carcinoma and L1210 leukemia was studied. The all models were very sensitive to the action of the drug in standard dose. Solid tumors' growth inhibition by 80-95% as well as increasing in life span of mice with L1210 leukemia by 86% in comparison with control and surviving of animals with Ehrlich carcinoma had been revealed. It had been shown that the drug in the area of ultra low doses occurred the following effects: inhibition of Lewis lung carcinoma growth by 80-95% compared to control after administration of the all tested ultra low doses; increasing of the life span of the animals with Ehrlich carcinoma and L1210 leukemia by 86-123% and 6-23%, correspondingly, upon the action of all tested ultra low doses; inhibition of B-16 melanoma growth by 50 and 70% after administration of the drug in doses 10(-20) mol/l and 10(-5) mol/l, correspondingly as well as deceleration of 755 carcinoma growth by 40% compared to control after action of the drug in the dose 10(-20) mol/l; stimulation of the B-16 melanoma growth by 20% relative to control after 10(-10) mol/l dose injection and enhancement of tumors sizes by 20-60% above control levels as a result of treatment of mice with 755 carcinoma by the drug in such ultra low doses as 10(-5) and 10(-15) mol/l. So, it was found that all tested tumor systems revealed certain sensitivity to the some ultra low doses of the drug. At the same time it was shown that doxorubycin in ultra low doses displayed alternative character of its biological effect, directivity of which varied according with the dose level and tumor strain.