OBJECTIVETo evaluate the effect of radioimmunotherapy with (188)Re-labeled herceptin in nude mice bearing nasopharyngeal carcinoma expressing HER2/neu proto-oncogene and explore the feasibility of (188)Re-herceptin for use as a chemical therapeutic and radioimmunotherapeutic agent.

METHODSA direct radiolabeling method was used to prepare (188)Re-Herceptin. Thirty-two nude mice bearing nasopharyngeal carcinoma were randomized into 4 groups (n=8) to receive single intravenous injection of (188)Re-Herceptin, intratumoral injection of (188)Re-Herceptin, (188)Re-nmIgG and (188)Re, respectively, all at the equivalent dose of 11.1 MBq (50 microl). Another 5 tumor-bearing mice received only intratumoral injection of 50 microl normal saline to serve as the control group. Two days after the injections, 3 mice were selected from each group (except for the control group) for biodistribution observation, and the rest mice were monitored for 4 consecutive weeks for tumor volume changes. Pathological examination of the tumor tissues was also performed.

RESULTSThe radioactivity uptake in the tumor was significantly greater whereas normal organ uptake significantly lower in the nude mice receiving intratumoral (188)Re-Herceptin injection than in those with intravenous (188)Re-Herceptin injection (11.53%ID/g vs 2.79%ID/g at 48 h). Intratumoral (188)Re-Herceptin injection caused greater inhibition of tumor growth at the 4th week as compared to the intravenous administration.

CONCLUSIONIntratumoral (188)Re-Herceptin administration can significantly inhibit the development of nasopharyngeal carcinoma in mice, and may potentially serve as a new clinical option of regional therapy for treating nasopharyngeal carcinoma overexpressing HER2/neu.