ANTITUMOR AGENT HAVING HIGH TRANSITION TO CANCER TISSUE

PURPOSE: To obtain an antitumor agent capable of safely taking an antitumor agent in low-density lipoprotein(LDL) in in vivo without using an isolated material of LDL or or a solubilizing agent by binding a steroidal compound to a water-soluble compound and binding the steroidal compound to an antitumor agent. CONSTITUTION: This antitumor agent is obtained by binding (A) a steroidal compound of formula I [A is an amino or OH; B is methyl, carboxyl, etc.; D is H or OH; E is B; G is D; F is a (substituted)3-9C (branched) alkyl, with the proviso that when F has no functional group, at least one of B, D, E and F is A or carboxyl], formula II or formula III to (B) a water-soluble compound such as phosphoric acid, sulfuric acid, succinic acid, maleic acid or methylmalonic acid by ester bond of one OH group of the component A with an acidic functional group or carboxyl of the component B and binding the component A to (C) a carcinostatic agent by urethane bond, acid amino bond or ester bond of OH, carboxyl and amino of the component A with a functional group of the component C.