Lymphocyte-to-monocyte ratio (LMR) compared to sidedness of primary tumor to predict outcome of anti-EGFR monotherapy in metastatic colorectal cancer.

Abstract

809 Background: In RAS-wild type metastatic colorectal cancer (mCRC) treatment with cetuximab or panitumumab is the standard of care. Previously, the association between overall survival (OS) and inflamatory biomarkers were reported in several studies in mCRC (NLR, LMR). According to recent observations, primary site location can predict the superior outcome of anti-EGFR agents in first line of treatment. Here we test the relationship between inflamatory biomarkers and sidedness on outcomes of anti-EGFR therapy. Methods: Total 186 consecutive patients treated with panitumumab (n = 106) or cetuximab (n = 80) in monotherapy in third or following lines of palliative treatment were identified via electronic survey of medical records of Maria Sklodowska-Curie Memorial Cancer Center, Poland. All identified patients were treated within the state reimbursment programme with pre-specified inclusion criteria (including ECOG 0-2 mCRC, failure of previous irinotecan, oxaliplatin and fluoropiridine, all RAS-wt tumors) and treatment was administered until RECIST progression. The pretreatment inflamatory biomarkers (NLR, dNLR, LMR, PLR) were obtained for all patients. Results: Median overall survival of the cohort was 31.5 months when calculated from the start of treatment, with no difference for left- and right-sided tumors (31.8 m. vs 29.5 m.; p = 0.58). In third line treatment no difference in PFS between left- and right-sided tumors were observed (p = 0.22; PFSleft 4.82 m. vs PFSright 3.44 m.). No prognostic effect of either biomarker was noted on OS or time to failure of first two lines of treatment. Only a high lymphocyte-to-monocyte ratio (LMR > 2.6) and low derived neutrocyte-to-lymphocyte ratio (dNLR < 3.0) were associated with longer PFS on anti-EGFR treatment (5.5 m. in LMR > 2.6; 2.5 m. in LMR < 2.6; HR 0.53; p = 0.008). Notable, the patients with LMR > 2.6 were more likely to be diagnosed with left sided tumor (p < 0.001; 54% and 15% of left- and right-sided tumors respectively). Conclusions: High limfocyte-to-monocyte ratio may indicate the potential subpopulation of patients which can benefit mostly from anti-EGFR treatment in monotherapy in the refractory setting.