Peripheral blood monocyte count is a dynamic prognostic biomarker in multiple myeloma

Abstract

With growing knowledge of multiple myeloma (MM) pathobiology and the introduction of novel therapies, risk stratification continues to evolve. Myeloid-derived suppressor cells and tumor-associated macrophages, derived from peripheral blood monocytes, support malignant plasma cell proliferation in the bone marrow. Since peripheral blood absolute monocyte count (AMC) is thought to could reflect the bone marrow microenvironment, we sought to evaluate the prognostic significance of AMC in MM. We retrospectively analyzed 10,822 patients with newly-diagnosed MM between 2000 and 2019 at Veteran's Administration hospitals. We obtained AMC closest to diagnosis and every 3 months thereafter up to 2.5 years. Patients were stratified into 4 groups: low, normal, elevated, and severely elevated AMC (AMC 0.2, 0.2 to < 0.8, 0.8-1.25 and > 1.25 x103/mm3, respectively). Abnormal AMC at diagnosis was observed in 25.3% of patients and was associated with inferior overall survival (OS). In patients with low, elevated, severely elevated, and normal AMC, At diagnorespectively, sis, median OS at diagnosis was 2.3, 2.7, 3.1, 3.6 years (p < 0.001), and at 2.5 years median OS at 2.5 years was 2.0, 2.6, 3.4, 3.9 years (p < 0.001) in patients with low, elevated, severely elevated, and normal AMC, respectively. Patients with normal AMC at diagnosis who developed an abnormal AMC > 1 year after diagnosis also had inferior OS relative to patients who maintained a normal AMC. Abnormal AMC was also associated with inferior OS independent of validated prognostic markers including the international staging system stage ISS Stage, and high lactate dehydrogenase LDH. Our findings provide novel clues for future prospective studies on the functional role of monocytes in multiple myeloma, which could be a readily available metric for risk stratification.

Monocytes in Tumorigenesis and Tumor Immunotherapy

“…A study highlights the role of peripheral blood absolute monocyte count (AMC) as a potential prognostic marker. In the study, the AMC level of multiple myeloma goes beyond the defined range, indicating inferior overall survival in patients [ 10 ]. Signal regulatory protein α (SIRPα) is a receptor-like transmembrane protein that suppresses both macrophage phagocytic function and inflammatory signaling.…”

Development and validation of an individualized and weighted Myeloma Prognostic Score System (MPSS) in patients with newly diagnosed multiple myeloma

“…13,14 Mass myeloma cells occupying the bone marrow reshape the marrow microenvironment, promoting immunosuppression. 15 Current prognostic models of MM do not incorporate such host-associated predictors like monocyte counts 16 and thrombocytopenia. 2,17,18 In the present study, ISS Stage III, LDH, thrombocytopenia, and number of HRA were integrated into one comprehensive and weighted Myeloma Prognostic Score System (MPSS), capable of stratifying NDMM patients into four risk groups.…”

“…Mass myeloma cells occupying the bone marrow reshape the marrow microenvironment, promoting immunosuppression 15 . Current prognostic models of MM do not incorporate such host‐associated predictors like monocyte counts 16 and thrombocytopenia 2,17,18 …”