Experimental evidence for the existence of the passive antitumor defense system formed by the synergistic action of certain small substances of the circulatory system.

In AIDS, only a few types of tumors (mainly Kaposi's sarcoma and non-Hodgkin's lymphoma) increase in incidence despite global abnormalities in the immune system. In addition, the reason for the higher incidence of these tumors is not immunosuppression but other agents. This shows that the immune system has no absolute role in the prevention of tumors. Consequently, the fact that tumors do not develop in the majority of the population during their lifetime, indicates the existence of other defense system(s). We demonstrated previously that a mixture of 16 substances (selected experimentally out of 89 compounds of the circulatory system using the synergistic tumor cell-killing effect as criteria) had a cytotoxic effect (inducing apoptosis) in vitro and in vivo on tumor cell lines, but not on normal cells in vitro or animals. In our hypothesis these substances (L-tryptophan, L-tyrosine, L-methionine, L(-)malate, L-ascorbate, L-arginine, L-phenylalanine, L-histidine, 2-deoxy-D-ribose, d-biotin, pyridoxine, adenine, riboflavin, D(+)-mannose, orotate, and hippurate) are the active agents of a passive antitumor defense system (PADS). On the basis of the results, a tablet and a cream were developed, and an infusion is in preclinical phase. In this study we demonstrate that the above-mentioned substances can kill tumor cells when the experimental protocols, concentrations, and cell numbers are chosen to be comparable to the physiological conditions that exist in the living system when these substances fight against arising cancer cells. The results of our experiments demonstrate that the PADS really works in the human body.