The Role of the Bone Marrow Microenvironment in Physical Function and Quality of Life in Patients with Multiple Myeloma After First-Line Treatment with Novel Agents and Autologous Transplantation

Background/Objectives: Multiple myeloma is a malignancy of plasma cells detected in the bone marrow, inducing symptoms like anemia, hypercalcemia, renal problems, and bone fractures in multiple myeloma patients, affecting their quality of life. The bone marrow microenvironment plays a crucial role in the prognosis and progression of the disease. The purpose of this study was to examine the relationship between the percentages of the major cell populations of the bone marrow, including immune cells, and physical function/quality of life in multiple myeloma patients after first-line treatment. Methods: Twenty-one multiple myeloma patients (N = 14 men, N = 7 women) participated in the study after completing first-line treatment. Bone marrow and blood samples were taken one hundred days after transplantation, while physical function (6 min walking test, handgrip test, maximal aerobic power, and isometric strength), health-related quality of life (QLQ-C30), and body composition (DXA) were assessed 2–5 days later. Flow cytometry was used to assess the percentages of plasma cells, mast cells, B cells (total, precursors, naïve, and memory), T cells (total, CD27− and CD27+), NK/NKT cells (total, CD27− and CD27+), eosinophils, monocytes, neutrophils, myeloid progenitors, erythroblasts, and erythroid progenitors, expressed as percentages of total nucleated cells of the bone marrow. Results: The percentage of CD27+ NK/NKT cells was correlated with five parameters of the quality of life questionnaire: physical function (r = 0.78, p = 0.005), role functioning (r = 0.69, p = 0.020), fatigue (r = −0.86, p = 0.000), pain (r = 0.68, p = 0.021), and dyspnea (r = −0.80, p = 0.003). Conclusions: In conclusion, stronger immune surveillance in the bone marrow from CD27+ NK/NKT cells is correlated with better quality of life in multiple myeloma patients.