Bone Marrow Microenvironment Interplay and Current Clinical Practice in Multiple Myeloma: A Review of the Balkan Myeloma Study Group

What happens to regulatory T cells in multiple myeloma

Abnormal tumor microenvironment and immune escape in multiple myeloma (MM) are associated with regulatory T cells (Tregs), which play an important role in maintaining self-tolerance and regulating the overall immune response to infection or tumor cells. In patients with MM, there are abnormalities in the number, function and distribution of Tregs, and these abnormalities may be related to the disease stage, risk grade and prognosis of patients. During the treatment, Tregs have different responses to various treatment regiments, thus affecting the therapeutic effect of MM. It is also possible to predict the therapeutic response by observing the changes of Tregs. In addition to the above, we reviewed the application of Tregs in the treatment of MM. In conclusion, there is still much room for research on the mechanism and application of Tregs in MM.

Pomalidomide enhances the maturation of dendritic cells derived from healthy donors and multiple myeloma patients

Objective: To explore the effect of pomalidomide on the maturation of monocyte-derived dendritic cells (moDCs) from healthy donors (HDs) and multiple myeloma (MM) patients. Methods: MoDCs were generated by the incubation of monocytes from peripheral blood mononuclear cells (PBMCs) for 7 days in a medium consisting of 800 U/ml granulocyte-macrophage colony stimulating factor (GM-CSF), 500 U/ml interleukin-4 (IL-4), RPMI 1,640 medium, 5% human serum, 100 U/ml penicillin and 0.1 mg/ml streptomycin. Meanwhile, the incubation system was administrated with 10 µM pomalidomide or 1 × PBS as the control group. On the eighth day, cells were harvested and analyzed by flow cytometry. The CD80⁺CD86⁺ cell population in total cells was gated as moDCs in the FACS analyzing system. After that, the expression of CD40 and HLA-DR on moDCs was analyzed. Meanwhile, the supernatant from the incubation system was evaluated for the secretion of cytokines interleukin-12 (IL-12), tumor necrosis factor-α (TNF-α), and macrophage inflammatory protein 1α (MIP-1α) by enzyme-linked immunosorbent assay (ELISA). Results: When analyzing all the HD-moDCs together (n = 15), pomalidomide significantly increased the mean fluorescence intensity (MFI) of CD40 expression and HLA-DR expression on moDCs compared with the control group (p = 0.003, p = 0.040). Meanwhile, the proportion of CD40⁺ moDCs and HLA-DR⁺ moDCs in total moDCs was significantly higher in the pomalidomide group than in the control group (p = 0.008, p = 0.032). When analyzing all MM patient-moDCs together (n = 11), pomalidomide significantly increased the MFI of CD40 expression and HLA-DR expression on moDCs compared with the control group (p = 0.047, p = 0.006). Meanwhile, the proportion of HLA-DR⁺ moDCs in total DCs was significantly higher in the pomalidomide group than in the control group (p < 0.001). Moreover, HD-moDCs (n = 8) treated with pomalidomide secreted 192% IL-12, 110% TNF-α, and 112% MIP-1α of the untreated moDCs (p = 0.020, p = 0.006, p = 0.055). However, when analyzing MM patient-moDCs (n = 10) together, the secretion of IL-12, TNF-α and MIP-1α from moDCs showed no significant difference between the pomalidomide group and the control group (p = 0.458, p = 0.377, p = 0.248). Conclusion: In vitro, 10 µM pomalidomide enhances the maturation of moDCs derived from both HDs and MM patients. Pomalidomide shows potential to be applied as a DC adjuvant for DC-based immunotherapy, such as the DC vaccine and DC cell therapy in MM.

Solitary Extramedullary Plasmacytoma of the Larynx and Secondary Laryngeal Involvement in Plasma Cell Myeloma: Single-Centre Retrospective Analysis and Systematic Literature Review

The involvement of the larynx in plasma cell myeloma (PCM) may manifest as solitary extramedullary plasmacytoma of the larynx (sEMP-L) or as infiltration of the larynx during newly diagnosed or relapsed systemic disease with bone marrow involvement (plasma cell myeloma with laryngeal involvement, PCM-L). To increase knowledge about these rare conditions, we performed a retrospective analysis along with a comprehensive literature review of cases of sEMP-L or PCM-L. Six patients (two sEMP-L and four PCM-L) were identified in our tertiary laryngological centre from 2009 to 2021, constituting 0.88% of all malignant laryngeal tumours. The literature search yielded 187 cases, including 152 sEMP-L and 35 sPCM-L. A comparison of baseline characteristics between sEMP-L and PCM-L performed in the combined cohort of cases from literature review and retrospective analysis revealed that patients with sEMP-L were younger (56 vs. 64 years, p ≤ 0.001) and presented less commonly with thyroid or cricoid cartilage involvement (2.2% vs. 30.8%, p ≤ 0.001). The prognosis of sEMP-L was better than PCM-L (overall survival 86% vs. 55% at 5 years, p = 0.002). Analysis of potential factors that could influence progression-free survival (PFS) in the group of sEMP-L revealed that male sex and cartilage involvement negatively affected PFS in univariate analyses, while only cartilage involvement retained statistical significance in multivariate analysis (HR = 19.94, p = 0.024). In conclusion, PCM with laryngeal involvement is sporadic. Secondary involvement of the larynx during PCM might be more common than sEMP-L and is associated with worse survival. The involvement of cartilage adversely influences the outcome of sEMP-L.

Regulatory T-Cells and Multiple Myeloma: Implications in Tumor Immune Biology and Treatment

Multiple myeloma (MM) is associated with both cellular and humoral immune deficiencies and, despite significant advances in treatment, remains an incurable disease. Regulatory T-cells (Tregs) represent a critical subset of CD4 T-cells, characterized by CD4 + CD25+ Forkhead box P3+ (FoxP3+) phenotype, able to control peripheral tolerance and responses to foreign and tumor antigens. Tregs are elevated in various types of cancer, including hematological malignancies; in MM, data regarding Tregs function and numbers and their correlation with survival parameters are controversial. Advances in cancer biology have shown that the tumor microenvironment plays an important role in tumor progression. In MM, the highly immunosuppressive nature of the bone marrow microenvironment has been significantly elucidated in the past decade and it is now well acknowledged that targeting only the tumor clone may not be able to cure MM. Tregs within the tumor microenvironment might play a significant role in the suppression of antitumor immune responses against cancer cells and are considered to predict poor outcome in cancer patients; nonetheless the exact prognostic significance of this cell subpopulation in malignancies is still a matter of debate. In this review, we discuss the role of Tregs as an essential cell population of the MM immune microenvironment.

Myeloma multiplex treatment and overall survival

The Multiple myeloma (MM) is a plasma cell malignancy in which monoclonal plasma cells proliferate in bone marrow, resulting in an overabundance of monoclonal paraprotein (M protein), destruction of bone, and displacement of other hematopoietic cell lines. This retrospective-prospective study was conducted at the University Clinic for Hematology in Skopje, North Macedonia, in the period between January 2009 and December 2019. Patients younger than 65 years, without comorbidities, fit for autologous peripheral blood stem cell transplantation (PBSCT), were treated with Cyclophosphamide-Thalidomide-Dexamethasone (CyThalDex) protocol divided into two daily doses which were maintained until complete remission. Patients over 65 years of age, unfit for more aggressive treatment options like peripheral blood stem cells (PBSCT) with comorbidities and renal failure, were treated with Melphalan-Prednisone-Thalidomide (MPT) protocol. The third group of patients was treated without new immunomodulators such as thalidomide, but instead a salvage therapy was given consisted of chemotherapy and corticosteroids. The use of thalidomide can lead to more undesirable effects such as deep vein thrombosis and renal neuropathy. The results obtained in our study showed no high percentage of these effects. However, a better survival rate was registered along with a longer period without progression of the underlying disease (PFS). Moreover, a higher percentage of complete remission (CR) was achieved and a very good partial response (VGPR) in general. Myeloma multiplex is still incurable disease with pattern of regression and remission followed by multiple relapses rising from the residual myeloma cells, but in the future still many unsolved questions has to be answered. Keywords: myeloma multiplex, autologous stem cell transplantation, thalidomide