Maintenance Strategy With Fluoropyrimidines (Fp) Plus Bevacizumab (Bev), Bev Alone, Or No Treatment, Following A Standard Combination Of Fp, Oxaliplatin (Ox), And Bev As First-Line Treatment For Patients With Metastatic Colorectal Cancer (Mcrc): A Phase Iii Non-Inferiority Trial (Aio Krk 0207).

3503^ Background: The optimal maintenance strategy following combination chemotherapy plus Bev is still controversial. AIO KRK 0207 investigates whether after a 24-week standard induction with F//Ox/Bev, no continuation of therapy or continuation with Bev alone are non-inferior to FP plus Bev. Methods: Pts with mCRC and ‘standard’ eligibility criteria were enrolled. After 24 weeks of induction treatment with FP/Ox/Bev, pts without disease progression were randomized into one of the following arms: A) standard maintenance treatment with FP plus Bev; B) Bev alone; or C) no treatment. At first progression, re-induction of the initial treatment was planned. The primary endpoint was ‘time to failure of strategy’ (TFS), comprising maintenance plusre-induction after first progression. Sample size was calculated (one-sided alpha of 0.0125; power of 80%) to conclude non-inferiority compared with the FP plus Bev arm. Secondary endpoints included time to first progression (PFS1) and overall survival (OS). Results: 840 pts were enrolled, 473 randomized. Median follow-up is 27 months. After induction, 60% of pts had CR/PR, 40% SD. Median PFS1 in arms A, B, C were 6.2, 4.6 and 3.6 months (p< 0.0001; A vs C: HR 2.11, 95% CI 1.63-2.73; A vs B: HR 1.28, 95% CI 0.99-1.65; B vs C: HR 1.56, 95% CI 1.22-1.99), respectively. TFS favored arm A over arm C (HR 1.31, 95% CI 1.01-1.69, p=0.038) but without difference between arms A and B (HR 1.04,95% CI 0.81-1.36, p=0.74). However, upon first progression only 24% in arm A and 47 % in both arms B and C, received re-induction. After 200 documented events, preliminary OS is 23.4 months from randomization, without significant difference between treatment arms (p=0.69). Conclusions: Following 24 weeks of induction, active maintenance with both, FP plus Bev or Bev alone, show prolonged TFS over no treatment. Only a minority of patients received re-induction treatment as planned. With currently limited follow up, the different maintenance strategies had no impact on OS. Clinical trial information: NCT00973609.