FU/FA maintenance therapy with or without panitumumab (pmab) in RAS wild-type metastatic colorectal cancer (mCRC) (PanaMa, AIO KRK 0212): Updated efficacy analyses.

3506 Background: The randomized open-label phase II PanaMa trial compared FU/FA with or without pmab maintenance after mFOLFOX6+pmab induction for RAS wild-type mCRC. Updated efficacy results of the Full Analysis Set are presented. Methods: Median progression-free survival (PFS), overall survival (OS), PFS of re-induction (PFS re-ind.), time to failure of strategy (TFS), and objective response rates (ORR) were compared by log-rank test / Cox regression and Fisher’s exact test. Results: PFS was significantly (8.8 vs. 5.8 months, HR=0.73 (95%CI 0.56 – 0.94), P=0.015) and OS numerically longer (29.9 vs. 24.7 months, HR=0.85 (95%CI 0.64 – 1.12), P=0.24). PFS re-ind. was significantly shorter after pmab maintenance (4.1 vs. 7.4 months, HR=1.93 (95%CI 1.33 – 2.82), P<0.001). TFS was comparable (17.1 vs. 15.7 months, HR=0.98 (95%CI 0.68 – 1.42), P=0.92). Molecular subgroups are displayed in Table 1. ORR of FU/FA+pmab was comparable to FU/FA during induction (74.4% vs. 76.4%, P=0.77), higher during maintenance (40.8% vs. 29.3%, P=0.06), but lower at re-induction (8.0% vs. 35.9%, P<0.001). Conclusions: PFS remained improved by the addition of pmab to FU/FA maintenance therapy, while OS was not significantly longer. Re-induction of pmab+mFOLFOX6 did not provide benefit following pmab maintenance regarding PFS. Clinical trial information: NCT01991873 . [Table: see text]