The PanaMa trial aimed to compare the efficacy of 5-fluorouracil and folinic acid (FU/FA)±panitumumab maintenance in untreated RAS wild-type metastatic colorectal cancer (mCRC) patients. In this final phase 2 trial analysis, adult mCRC patients responding to six cycles of FU/FA, oxaliplatin and panitumumab were randomized (1:1, open-label) to maintenance of either FU/FA+panitumumab or FU/FA alone. The primary endpoint was superiority of progression-free survival of maintenance (PFS; time from random assignment to progression/death) in favour of FU/FA+panitumumab. Secondary endpoints included PFS of re-induction (PFS re-ind.), time to failure of strategy (TFS) and overall survival (OS). The trial is registered with ClinicalTrials.gov (NCT01991873). In 248 patients of the Full Analysis Set recruited between May 2014 and February 2021, with a median observation of 64.0 (range 12.5-86.3) months and 59.7 (range 3.7-97.3) months in the treatment arms, 230 events for PFS (92.7%) and 196 events for OS (79.0%) were recorded. Adding panitumumab to FU/FA resulted in significantly longer PFS (8.8 versus 5.8 months, HR=0.73 (95% CI 0.56-0.94), P=0.015), shorter PFS re-ind. (4.1 versus 7.4 months, HR=1.93 (95% CI 1.33-2.82), P<0.001), comparable TFS (17.1 versus 15.7 months, HR=0.98 (95% CI 0.68-1.42), P=0.92) and numerically longer OS (29.9 versus 24.7 months, HR=0.85 (95% CI 0.64-1.12), P=0.24). The most frequent adverse event (AE) grade ≥3 was rash (FU/FA+panitumumab: n=15, 12.0%, FU/FA: n=17, 6.9%). 141 patients (37.3%) experienced at least one serious AE One treatment-related death occurred (neutropenic sepsis, FU/FA). Panitumumab plus FU/FA might be considered a standard of care maintenance regimen since a potential re-induction therapy with panitumumab cannot be guaranteed at the time of maintenance treatment decision. Amgen.
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