Repeated anti-CEA-radioimmunotherapy (RAIT) with 131iodine-labetuzumab after resection of colorectal liver metastases (CLM): Long-term results of a prospective phase II study.

719 Background: Previously, single anti-CEA-radioimmunotherapy (RAIT) with 131iodine(I)-labetuzumab after complete (R0) resection of CEA-positive CLM was well tolerated and improved overall survival (OS) compared to a control group without RAIT. In this phase II study, we examined safety, feasibility, and long-term efficacy of repeated RAIT in the same setting. Methods: After R0-resection of CEA-positive CLM, 63 pts (42 m, 21 f; median age, 64.5 yrs) with synchronous (n=33) or metachronous (n=30) CLM received RAIT with 40-50 mCi/m2 per dose. 45 pts were intermediate/high risk for early metastatic relapse according to the Fong score. Restaging with CT/MRI and FDG-PET was performed prior to each RAIT. Pts with persistent elevated serum CEA-levels or inconclusive lesions during post-operative restaging received RAIT, but were classified as “non-adjuvant.” Toxicity was classified according to NCI-CTC v2.0. Time to progression (TTP), OS and cancer-specific survival (CSS) were calculated. The median follow-up w...