Panitumumab (EGFR mAb) maintenance benefit holds regardless of baseline dNLR in RAS-WT mCRC—dNLR mainly prognostic for OS

Baseline derived neutrophil-to-lymphocyte ratio (dNLR; cut-off 2.2) was assessed post hoc in the PANAMA/AIO KRK0212 randomized Phase 2 trial (NCT01991873) of first-line RAS WT mCRC receiving FU/FA ± panitumumab (EGFR-targeting monoclonal antibody) maintenance after induction FOLFOX+panitumumab. Among 241 patients with baseline counts (dNLR ≤2.2: n=140; >2.2: n=101), dNLR was prognostic for OS from maintenance start (30.8 vs 22.7 months; HR 1.56, 95% CI 1.15–2.12; p=0.004) but not for maintenance PFS (10.1 vs 9.7 months; p=0.25). dNLR did not predict benefit from adding panitumumab to FU/FA during maintenance (interaction p=0.72 for PFS; p=0.294 for OS), with PFS in the expected PANAMA range for FU/FA+panitumumab vs FU/FA alone (~8.8 vs ~5.6 months in dNLR ≤2.2; ~9.7 vs ~5.8 months in dNLR >2.2), but reinduction PFS showed a signal: in dNLR ≤2.2, reinduction PFS was shorter after FU/FA+panitumumab maintenance than after FU/FA maintenance (2.6 vs 7.4 months; interaction p=0.036), raising the possibility of EGFR-pressure biology or treatment-sequencing effects rather than a pure “predictive biomarker” story; key anti-EGFR maintenance toxicities (rash, hypomagnesemia) are not detailed in this abstract and would be needed to weigh sequencing tradeoffs versus the established PANAMA maintenance PFS gain over FU/FA alone.