The present invention relates to a novel diaminedithiol derivative or a pharmaceutically acceptable salt thereof; radiorhenium or radiotechneticum complex thereof; a composition for treating liver cancer comprising the radiorhenium complex and lipiodol; and, a preparative kit of the composition for treating liver cancer.In the composition according to the invention, the diaminedithiol derivative is a novel compound in which long chain alkyl groups were introduced to diaminedithiol, capable of forming a radiorhenium or radiotechnetium complex thereof with an ease and leading to stronger van der Waals bonds with lipiodol. As a result, the complex becomes more stable in a medium, lipiodol, whereby the composition of the invention exhibits a high accumulation rate in liver cancer tissue when injected via hepatic artery, thereby capable of achieving an efficient treatment of liver cancer.

A method of radiolabeling a protein with a radionuclide including contacting the protein with a protected tertiary thiol-containing bifunctional chelating agent that is capable of reacting with the protein at one end of the agent and is capable of complexing with a radionuclide at the other end of the agent, to form a protein-acetyl-t-thiol-containing conjugate. The protein-acetyl-t- thiol-containing conjugate then is deprotected and admixed with a reducing agent for the radionuclide, where the radionuclide is added in a subsequent step, to form a mixture of reducing agent and protein-t-thiol-containing conjugate. This mixture then is reacted with a radionuclide whereby the radionuclide reacts with pendant sulfhydryl groups present on the protein-t-thiol-containing conjugate. Methods of radioimmunotherapy and diagnostic kits suitable for forming a composition to be administered to a human patient also are disclosed.

A method of radiolabeling a protein with a radionuclide including contacting the protein with a protected tertiary thiol-containing bifunctional chelating agent that is capable of reacting with the protein at one end of the agent and is capable of complexing with a radionuclide at the other end of the agent, to form a protein-acetyl-t-thiol-containing conjugate. The protein-acetyl-t-thiol-containing conjugate then is deprotected and admixed with a reducing agent for the radionuclide, where the radionuclide is added in a subsequent step, to form a mixture of reducing agent and protein-t-thiol-containing conjugate. This mixture then is reacted with a radionuclide whereby the radionuclide reacts with pendant sulfhydryl groups present on the protein-t-thiol-containing conjugate. Methods of radioimmunotherapy and diagnostic kits suitable for forming a composition to be administered to a human patient also are disclosed.