Preoperative chemoradiotherapy for advanced lower rectal cancer using SOX+Bev regimen.

Abstract

708 Background: We have performed preoperative CRT for advanced lower rectal cancer patients using S-1 or UFT. To improve response rate, we are performing phase 2 trial of preoperative CRT using S-1/ Oxaliplatin /Bevacizumab (SOX+Bev) regimen. In this study, we show the results of the trial and the promising predictive factor. Methods: Twenty-five patients (SOX+Bev) and 59 patients (S-1 or UFT) were included in this study. S-1(80mg/m2), UFT(300mg/m2) were administered orally every day on radiation therapy, and S-1(80mg/m2,Oxaliplatin(40-60mg/m2),Bevacizumab(5mg/kg) were administered in SOX+Bev group. Total dose of radiation was 40Gy with four field technique. As a predictive factor, we measured miR-223 with real-time PCR using pre CRT biopsy specimens. Results: Clinical response by RECIST were as follows: SOX+Bev group: CR/PR/SD/PD = 1/21/3/0, S-1/UFT group: CR/PR/SD/PD = 1/32/26/0. Clinical response rate were 88% in SOX+Bev group, higher than 56.0% in S-1/UFT group. Pathological response grade were as follows: SOX+Bev group: 1a/1b/2/3 = 5/4/10/6,S-1/UFT group :1a/1b/2/3 = 13/16/27/3. Pathological response rate was 64% in SOX+Bev group, 51% in S-1/UFT group and there was no significant difference. The pCR rate was 24% in SOX+Bev group, significantly higher than 5% in S-1/UFT group (p < 0.05)B In S-1 group, miR-223 in responder group tended to be higher than non-responder group (p = 0.06). And in SOX+Bev group, miR-223 in Grade 3 group(8.89±9.41) was significantly higher than other group (3.19±4.64) (p = 0.05). Conclusions: Preoperative CRT with SOX+Bev regimen can improve response rate and bring high pCR rate. miR-223 may be promising predictive factor and useful to perform order made therapy. Clinical trial information: 13267.