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3543 Background: Numerous trials have examined the prognostic and predictive value of the LPT in mCRC, but little is known about the predictive value of LPT on different maintenance strategies. We analyzed progression-free survival (PFS) and overall survival (OS) from start of maintenance according to LPT in patients (pts) from the AIO KRK 0207 trial. Methods: Following a 24-week standard induction 471 pts were randomized to FP/Bev, Bev mono or no treatment with 454 pts being evaluable for PFS. Right sided primary tumors were defined as located in the caecum, ascending colon, transverse colon up to the splenic flexure; left colon was defined as splenic flexure, descending and sigmoid colon and rectum. Results: Data on LPT was available in 414 pts. for PFS (91%). LPT was left sided (LPTl) in 291 (70%) and right-sided (LPTr) in 123 (30%) of pts, respectively (remaining pts: status was either unknown, n = 37 or LPT was located in both regions, n = 3). Median PFS1 was 3.9 months (mos.) for LPTr and 5.3 mos. for LPTl (p = 0.11; HR 1.19, 95%CI 0.96 - 1.48). Analyses on PFS did not demonstrate a major predictive impact of LPT on the efficacy of the three maintenance strategies. The pairwise comparison of treatment arms showed a better PFS for FP/Bev vs no treatment independent from LPT (left: p < 0.0001; HR = 2.39, 95%CI 1.73-3.31; right: p = 0.011; HR 1.78, 95%CI 1.14-2.80). In addition, Bev mono vs no treatment was superior in LPTl (p = 0.0032; HR 1.54, 95%CI 1.15-2.06) with less difference in LPTr (p = 0.17; HR 1.36, 95%CI 0.87-2.14). Analysis for OS (429 evaluable pts) confirmed the strong prognostic impact of LPT (left vs right: 24.0 vs 16.7 months; p < 0.0001; HR = 1.65, 95%CI 1.32 - 2.06), but without major interaction between LPT and maintenance arms. The impact related to RAS mutational status will be reported. Conclusions: The strong prognostic factor of the LPT is confirmed in pts with mCRC undergoing Ox/FP/Bev induction therapy while there seems to be no major predictive impact of LPT on different maintenance strategies. Clinical trial information: EudraCT-Nr: 2008-007974-39.