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.

[BACKGROUND] 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).

[METHODS] 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.

[RESULTS] 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],  < 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,  < 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,  < 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.

[CONCLUSIONS] 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.