Growth suppression of esophageal squamous cell carcinoma induced by heavy carbon-ion beams combined with p53 gene transfer

Heavy carbon-ion beam therapy has revealed several potential advantages over X-rays. Heavy-ion therapy has been applied for various solid tumors including esophageal squamous cell carcinoma (SCC). Although the local control rate in carbon ion radiotherapy for esophageal cancer has revealed better rates than conventional radiotherapy, severe mucosal damage was observed in adjacent normal mucosa. A suitable treatment strategy is required to reduce irradiation dose by introducing combined local therapy. Recently, we initiated clinical p53 gene therapy for esophageal SCC. We herein evaluate the cytotoxic effects of heavy carbon-ion beams combined with p53 gene transfer on human esophageal SCC. We assessed the induction of apoptosis and growth suppression with the use of recombinant adenoviral vector Ad.p53 or heavy carbon-ion beam irradiation or both. Growth suppression was significantly potentiated by combined treatment with heavy carbon-ion beams and Ad.p53 as compared to that treated with either of them alone. Western blot analysis confirmed the expression of both exogenous p53 and p21 proteins after irradiation of Ad.p53 infected cells. Enhanced apoptotic cell death was observed with a terminal deoxynucleotidyl transferase-mediated nick end-labeling assay. These data suggest that heavy carbon-ion beam irradiation combined with Ad.p53 may be a potentially effective therapeutic strategy for locally advanced esophageal SCC

A Phase I/II Clinical Trial of Preoperative Short-Course Carbon-Ion Radiotherapy for Patients With Squamous Cell Carcinoma of the Esophagus

BACKGROUND: Carbon-ion radiotherapy (CIR) has been under development. We report the results of a phase I/II clinical trial of preoperative CIR for esophageal squamous cell carcinoma (ESCC).METHODS: Thirty-one thoracic ESCC patients were enrolled. They were first treated with CIR. The radiation dose was escalated from the initial dose of 28.8 GyE up to 36.8. Four to 8 weeks after CIR followed by clinical evaluation of the therapy, surgery was performed. Thereafter, a pathological evaluation was made.RESULTS: Acute toxicity was not seen except in one case (3.2%), and there were no late toxicities. Throughout the study period, there were no cases of withdrawal due to the effects of preoperative CIR. Twelve out of 31 (38.7%) patients achieved a clinical complete response (CR) and 13 patients (41.9%) achieved a partial response. Twelve out of 31 patients (38.7%) achieved a pathological CR. The overall 1-, 3-, and 5-year survival rates in the stage I cases were 91%, 81%, and 61%, and was 100%, 85%, and 77% for the stage II, and 71%, 43%, and 29% for the stage III cases, respectively.CONCLUSIONS: CIR showed strong local tumor control and is highly effective as a neoadjuvant therapy without severe adverse events