Early Changes in Lymphocyte/Monocyte Ratio on Treatment as a Prognostic Marker to Predict Overall Survival in Patients with Advanced Cancer Treated with Immune Checkpoint Inhibitors

A low absolute lymphocyte/monocyte ratio (LMR) in the peripheral blood is associated with poor prognosis in various cancers; however, its role as a predictive biomarker has not been well defined in the era of treatment with immune checkpoint inhibitors (ICIs). We queried a database of advanced cancer patients treated with at least 1 dose of ICI from 2011 to 2019 to study the association of LMR with overall survival (OS). We calculated LMR at baseline and a median of 21 days after the first cycle of ICI (on-treatment LMR) and considered it low if < 2 and high if ≥ 2. OS was calculated from the initiation of ICI to the date of death or censored at the last follow-up. We identified 1077 patients treated with ICI, including 880 patients with both baseline and on-treatment assessment of LMR. Patients with low baseline LMR had shorter median OS of 8.8 months (95% CI 7.8-10.3) compared to patients with high baseline LMR (19.4 months [95% CI 16.1-21.7], P < 0.0001). Patients with low baseline LMR whose on-treatment LMR increased to high had longer median OS compared to those whose on-treatment LMR remained low (16.8 vs 7.8 months, P < 0.002). Patients with high baseline LMR whose on-treatment LMR remained high had longer median OS compared to patients with low on-treatment LMR (23.9 vs 9.2 months, P < 0.001). In multivariable analysis, high on-treatment LMR was most highly associated with fewer deaths compared to low on-treatment LMR, regardless of baseline LMR. We observed that baseline LMR, as well as change in LMR from baseline after the first cycle of ICI were associated with OS in cancer patients treated with ICI.