Efficacy of FOLFIRI3 (irinotecan 100mg/m2 D1,D3 combined with LV5FU) or other irinotecan-based regimens in oxaliplatin-pretreated metastatic colorectal cancer in the OPTIMOX1 study

4059 Background: In metastatic colorectal cancers initially treated with FOLFOX, irinotecan is commonly used as second line. We investigated in an unselected population which irinotecan-based regimen had the best antitumoral activity. Methods: As the choice of the second line therapy was given to the investigators, without any inclusion criterion, various second line regimens were prospectively registered in the phase III OPTIMOX1 study (front-line FOLFOX4 or 7). Simultaneous use of EGFR inhibitors was excluded. Patient’s characteristics (Age, performance status (PS), LDH, ALP and CEA levels before the first line of chemotherapy), first line regimen (FOLFOX4 or 7, oxaliplatin reintroduction, PFS achieved in first line) and type of irinotecan-based regimen were tested for an association with second-line progression-free survival (PFS) and tumor control. Results: Among the 620 patients enrolled in the OPTIMOX1 study, 343 received an irinotecan-based second-line chemotherapy: FOLFIRI-3 (n=101, irinotecan 100...