Immune profiling in patients with monoclonal gammopathy of undetermined significance (MGUS), smoldering multiple myeloma (SMM), and multiple myeloma (MM) provides the framework for developing novel ...immunotherapeutic strategies. Here, we demonstrate decreased CD4
Th cells, increased Treg and G-type MDSC, and upregulation of immune checkpoints on effector/regulatory and CD138
cells in MM patients, compared MGUS/SMM patients or healthy individuals. Among the checkpoints profiled, LAG3 was most highly expressed on proliferating CD4
Th and CD8
Tc cells in MM patients BMMC and PBMC. Treatment with antibody targeting LAG3 significantly enhanced T cells proliferation and activities against MM. XBP1/CD138/CS1-specific CTL generated in vitro displayed anti-MM activity, which was further enhanced following anti-LAG3 treatment, within the antigen-specific memory T cells. Treg and G-type MDSC weakly express LAG3 and were minimally impacted by anti-LAG3. CD138
MM cells express GAL-3, a ligand for LAG3, and anti-GAL-3 treatment increased MM-specific responses, as observed for anti-LAG3. Finally, we demonstrate checkpoint inhibitor treatment evokes non-targeted checkpoints as a cause of resistance and propose combination therapeutic strategies to overcome this resistance. These studies identify and validate blockade of LAG3/GAL-3, alone or in combination with immune strategies including XBP1/CD138/CS1 multipeptide vaccination, to enhance anti-tumor responses and improve patient outcome in MM.
The importance of glutamine (Gln) metabolism in multiple myeloma (MM) cells and its potential role as a therapeutic target are still unknown, although it has been reported that human myeloma cell ...lines (HMCLs) are highly sensitive to Gln depletion. In this study, we found that both HMCLs and primary bone marrow (BM) CD138+ cells produced large amounts of ammonium in the presence of Gln. MM patients have lower BM plasma Gln with higher ammonium and glutamate than patients with indolent monoclonal gammopathies. Interestingly, HMCLs expressed glutaminase (GLS1) and were sensitive to its inhibition, whereas they exhibited negligible expression of glutamine synthetase (GS). High GLS1 and low GS expression were also observed in primary CD138+ cells. Gln-free incubation or treatment with the glutaminolytic enzyme l-asparaginase depleted the cell contents of Gln, glutamate, and the anaplerotic substrate 2-oxoglutarate, inhibiting MM cell growth. Consistent with the dependence of MM cells on extracellular Gln, a gene expression profile analysis, on both proprietary and published datasets, showed an increased expression of the Gln transporters SNAT1, ASCT2, and LAT1 by CD138+ cells across the progression of monoclonal gammopathies. Among these transporters, only ASCT2 inhibition in HMCLs caused a marked decrease in Gln uptake and a significant fall in cell growth. Consistently, stable ASCT2 downregulation by a lentiviral approach inhibited HMCL growth in vitro and in a murine model. In conclusion, MM cells strictly depend on extracellular Gln and show features of Gln addiction. Therefore, the inhibition of Gln uptake is a new attractive therapeutic strategy for MM.
•Myeloma cells produce ammonium in the presence of glutamine, showing high glutaminase and low glutamine synthetase expression.•Myeloma cells show high expression of glutamine transporters and inhibition of ASCT2 transporter hinders myeloma growth.
Multiple myeloma (MM) is characterized by a high capacity to induce alterations in the bone remodeling process. The increase in osteoclastogenesis and the suppression of osteoblast formation are both ...involved in the pathophysiology of the bone lesions in MM. The proteasome inhibitor (PI) bortezomib is the first drug designed and approved for the treatment of MM patients by targeting the proteasome. However, recently novel PIs have been developed to overcome bortezomib resistance. Interestingly, several preclinical data indicate that the proteasome complex is involved in both osteoclast and osteoblast formation. It is also evident that bortezomib either inhibits osteoclast differentiation induced by the receptor activator of nuclear factor kappa B (NF-κB) ligand (RANKL) or stimulates the osteoblast differentiation. Similarly, the new PIs including carfilzomib and ixazomib can inhibit bone resorption and stimulate the osteoblast differentiation. In a clinical setting, PIs restore the abnormal bone remodeling by normalizing the levels of bone turnover markers. In addition, a bone anabolic effect was described in responding MM patients treated with PIs, as demonstrated by the increase in the osteoblast number. This review summarizes the preclinical and clinical evidence on the effects of bortezomib and other new PIs on myeloma bone disease.
Bone disease is the hallmark of multiple myeloma (MM), a hematological malignancy characterized by osteolytic lesions due to a severe uncoupled and unbalanced bone remodeling with pronounced ...osteoblast suppression. Bone metastasis is also a frequent complication of solid tumors including advanced breast or prostate cancer. In the past years, the ubiquitin–proteasome pathway has been proved critical in regulating the balance between bone formation and bone resorption. Proteasome inhibitors (PIs) are a new class of drugs, currently used in the treatment of MM, that affect both tumor cells and bone microenvironment. Particularly, PIs stimulate osteoblast differentiation by human mesenchymal stromal cells and increase bone regeneration in mice. Interestingly, in vitro data indicate that PIs block MM-induced osteoblast and osteocyte cell death by targeting both apoptosis and autophagy. The preclinical data are supported by the following effects observed in MM patients treated with PIs: increase of bone alkaline phosphatase levels, normalization of the markers of bone turnover, and reduction of the skeletal-related events. Moreover, the histomorphometric data indicate that the treatment with bortezomib stimulates osteoblast formation and maintains osteocyte viability in MM patients. This review updates the evidence on the effects of PIs on bone remodeling and on cancer-induced bone disease while focusing on MM bone disease.
C-X3-C motif chemokine ligand 1 (CX3CL1)/fractalkine is a chemokine released after cleavage by two metalloproteases, ADAM metallopeptidase domain 10 (ADAM10) and ADAM metallopeptidase domain 17 ...(ADAM17), involved in inflammation and angiogenesis in the cancer microenvironment. The role of the CX3CL1/ C-X3-C motif chemokine receptor 1(CX3CR1) axis in the multiple myeloma (MM) microenvironment is still unknown. Firstly, we analyzed bone marrow (BM) plasma levels of CX3CL1 in 111 patients with plasma cell disorders including 70 with active MM, 25 with smoldering myeloma (SMM), and 16 with monoclonal gammopathy of undetermined significance (MGUS). We found that BM CX3CL1 levels were significantly increased in MM patients compared to SMM and MGUS and correlated with BM microvessel density. Secondly, we explored the source of CX3CL1 in MM and BM microenvironment cells. Primary CD138⁺ cells did not express CXC3L1 but up-regulated its production by endothelial cells (ECs) through the involvement of tumor necrosis factor alpha (TNFα). Lastly, we demonstrated the presence of CX3CR1 on BM CD14⁺CD16⁺ monocytes of MM patients and on ECs, but not on MM cells. The role of CX3CL1 in MM-induced angiogenesis was finally demonstrated in both in vivo chick embryo chorioallantoic membrane and in vitro angiogenesis assays. Our data indicate that CX3CL1, present at a high level in the BM of MM patients, is a new player of the MM microenvironment involved in MM-induced angiogenesis.
B-cell maturation antigen (BCMA), a member of the tumor necrosis factor receptor superfamily, is universally expressed by normal and neoplastic plasma cells and plays a critical role in the ...proliferation, survival and tumor progression in multiple myeloma (MM). B-cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL) have been recognized as proliferation ligands for BCMA in the bone marrow microenvironment. Soluble BCMA levels in the serum correlates with disease phase and tumor burden and is a predictor of progression-free survival (PFS) and overall survival (OS). Recently, the introduction of new monoclonal antibodies against CD38 (Daratumumab and Isatuximab) and SLAM7 (Elotuzumab) has changed the therapeutic approach to MM, improving the response rate and the time to progression, both in newly diagnosed and refractory/relapsed patients. Among the surface antigens on MM cells, BCMA is a suitable target for the design of new antibody-based strategies. Experimental approaches targeting BCMA are currently being investigated and include antibody-drug conjugates (ADCs), bispecific antibodies (bsAbs) and genetically engineered T-cells with chimeric antigen receptors (CAR). In this review we summarize the more recent findings about BCMA biologic rationale as a therapeutic target and report the updated results of preclinical and clinical studies focused on ADCs and bsAbs targeting BCMA.
Bone marrow monocytes are primarily committed to osteoclast formation. It is, however, unknown whether potential primary alterations are specifically present in bone marrow monocytes from patients ...with multiple myeloma, smoldering myeloma or monoclonal gammopathy of undetermined significance. We analyzed the immunophenotypic and transcriptional profiles of bone marrow CD14
monocytes in a cohort of patients with different types of monoclonal gammopathies to identify alterations involved in myeloma-enhanced osteoclastogenesis. The number of bone marrow CD14
CD16
cells was higher in patients with active myeloma than in those with smoldering myeloma or monoclonal gammopathy of undetermined significance. Interestingly, sorted bone marrow CD14
CD16
cells from myeloma patients were more pro-osteoclastogenic than CD14
CD16-cells in cultures
Moreover, transcriptional analysis demonstrated that bone marrow CD14
cells from patients with multiple myeloma (but neither monoclonal gammopathy of undetermined significance nor smoldering myeloma) significantly upregulated genes involved in osteoclast formation, including
mRNA over-expression by bone marrow CD14
cells was independent of the presence of interleukin-21. Consistently, interleukin-21 production by T cells as well as levels of interleukin-21 in the bone marrow were not significantly different among monoclonal gammopathies. Thereafter, we showed that
over-expression in CD14
cells increased osteoclast formation. Consistently, interleukin-21 receptor signaling inhibition by Janex 1 suppressed osteoclast differentiation from bone marrow CD14
cells of myeloma patients. Our results indicate that bone marrow monocytes from multiple myeloma patients show distinct features compared to those from patients with indolent monoclonal gammopathies, supporting the role of
over-expression by bone marrow CD14
cells in enhanced osteoclast formation.
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