Osteolytic Bone Disease In Multiple Myeloma Research Articles

CST6 suppresses osteolytic bone disease in multiple myeloma by blocking osteoclast differentiation.

Osteolytic bone disease is a hallmark of multiple myeloma (MM). A significant fraction (~20%) of MM patients do not develop osteolytic lesions (OLs). The molecular basis for the absence of bone disease in MM is not understood. We combined PET-CT and gene expression profiling (GEP) of purified BM CD138+ MM cells from 512 newly diagnosed MM patients to reveal that elevated expression of cystatin M/E (CST6) was significantly associated with the absence of OL in MM. An enzyme-linked immunosorbent assay revealed a strong correlation between CST6 levels in BM serum/plasma and CST6 mRNA expression. Both recombinant CST6 protein and BM serum from patients with high CST6 significantly inhibited the activity of the osteoclast-specific protease cathepsin K and blocked osteoclast differentiation and function. Recombinant CST6 inhibited bone destruction in ex vivo and in vivo myeloma models. Single-cell RNA-Seq showed that CST6 attenuates polarization of monocytes to osteoclast precursors. Furthermore, CST6 protein blocks osteoclast differentiation by suppressing cathepsin-mediated cleavage of NF-κB/p100 and TRAF3 following RANKL stimulation. Secretion by MM cells of CST6, an inhibitor of osteoclast differentiation and function, suppresses osteolytic bone disease in MM and probably other diseases associated with osteoclast-mediated bone loss.

A novel agent SL-401 induces anti-myeloma activity by targeting plasmacytoid dendritic cells, osteoclastogenesis and cancer stem-like cells.

Novel therapies for multiple myeloma (MM) can target mechanism(s) in the host-MM bone marrow (BM) microenvironment mediating MM progression and chemoresistance. Our studies showed increased numbers of tumor-promoting, immunosuppressive and drug-resistant plasmacytoid dendritic cells (pDCs) in the MM BM microenvironment. pDC-MM cell interactions upregulate interleukin-3 (IL-3), which stimulates both pDC survival and MM cell growth. Since IL-3 R is highly expressed on pDCs in the MM BM milieu, we here targeted pDCs using a novel IL-3 R-targeted therapeutic SL-401. In both in vitro and in vivo models of MM in its BM milieu, SL-401 decreases viability of pDCs, blocks pDC-induced MM cell growth, and synergistically enhances anti-MM activity of bortezomib and pomalidomide. Besides promoting pDC survival and MM cell growth, IL-3 also mediates progression of osteolytic bone disease in MM. Osteoclast (OCL) progenitor cells express IL-3 R, and we show that SL-401 abrogates monocyte-derived OCL formation and bone resorption. Finally, we show that SL-401 also decreases the viability of IL-3 R-expressing cancer stem-like cells in MM. Overall, our study provides the preclinical basis for clinical trials of SL-401 to block pDC-induced MM cell growth, inhibit osteoclastogenesis and target MM stem-like cell subpopulations to improve patient outcome in MM.

18F-FDG-PET/CT and Osteolytic Bone Disease in Multiple Myeloma

Introduction: FDG-PET/CT is a promising methodology for staging, prognostication, and response evaluation in multiple myeloma (MM). The number of focal FDG lesions and the intensity of FDG uptake (standard uptake value, SUV) at diagnosis are informative of disease aggressiveness. Osteolytic bone disease is a hallmark of MM. Hypothetically; increased focal metabolic activity will precede, induce and correlate to osteolytic lesions. We aimed to elucidate the association between focal FDG positive lesions and osteolytic bone disease in MM patients.Methods: Twenty-two newly diagnosed MM patients, 16 males and 6 females aged 53-81years, were prospectively enrolled and studied with a standardized baseline FDG-PET/CT at diagnosis. A nuclear medicine and a radiology specialist evaluated the PET and CT parts separately and independently. Focal FDG positive lesions were assessed by dedicated software (ROVER™, ABX, Germany) to yield volume and SUV measures. All osteolytic lesions identified on CT were noted by size and localization.Results: FDG-PET and CT together identified a total of 390 lesions. We found more osteolytic lesions on CT (335) than FDG-positive lesions (169); the concordance between the modalities was 30%. 34% (114/335) of lytic lesions were FDG-positive, whereas ⅔ (114/169) of focal FDG-PET positive lesions were lytic according to CT. We found a significant correlation between higher FDG uptake measured as SUVpeak and osteolytic lesions >10 mm, and focal lesions with high FDG uptake had more pronounced osteolysis than focal lesions with less FDG uptake. Still sparse follow-up data did not allow analysis of the predictive value of focal PET positivity and the risk of development of future osteolysis. More compulsive data will be presented at the meeting.Conclusion: FDG-PET/CT offers dual information including metabolic activity (FDG-avidity) and degree of lytic bone disease (low dose whole body CT) in MM. About ⅔ (221/335) of osteolytic lesions were FDG-negative, whereas ⅔ (114/169) of FDG-positive lesions had a lytic component. DisclosuresPlesner:Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding.

SL-401, a Novel Targeted Therapy Directed to the Interleukin-3 Receptor (IL-3R), Blocks Plasmacytoid Dendritic Cell (pDC)-Triggered Myeloma Cell Growth and Prevents Osteoclastogenesis

Introduction Despite the advent of novel therapies, relapse of multiple myeloma (MM) is common and the disease remains largely incurable. Our previous studies showed that bone marrow (BM) plasmacytoid dendritic cells (pDCs) play a central role in the immune deficiency characteristic of MM; as well as promote MM cell growth, survival, and drug resistance (Chauhan et al., Cancer Cell 2009, 16:309-323). These findings identify an integral role of pDCs in MM pathogenesis and provide the basis for targeting pDC-MM interactions as a novel therapeutic strategy in MM. In this context, we found that pDCs exhibit a high level of interleukin-3 receptor (IL-3Rα) expression, and pDC-MM interactions trigger secretion of interleukin-3 (IL-3), which in turn, induces MM cell growth and pDC survival, and promotes osteolytic bone disease in MM. These findings identified targeting IL-3R expressed on pDCs as a promising novel therapeutic strategy. Additionally, our preliminary data show that a significant number of clonogenic side population cells in MM (MM-SPs) with characteristic stem cell like features express IL-3R. Here we examined the effect of SL-401, a novel targeted therapy directed against IL-3R, on pDC-induced MM cell growth, osteoclast (OCL) formation, and MM-SPs.Methods: Patient MM cells, pDCs, and MNCs were obtained from normal donors or MM patients. Cell growth/viability was analyzed using MTT/WST assays. OCL function and bone resorption were measured using the OsteoAssays and TRAP staining. RPMI-8226 cell line was used to isolate MM-SPs by flow-cytometry based Hoechst 33342 staining. SL-401 is a recombinant protein expressed in E. coli. The hybrid gene is comprised of human IL-3 fused to truncated diphtheria toxin (DT). The IL-3 domain of SL-401, which replaces the binding domain of DT, targets SL-401 to cells that overexpress IL-3R. SL-401 was obtained from Stemline Therapeutics, NY; bortezomib, lenalidomide, pomalidomide, and melphalan were purchased from Selleck chemicals, USA.Results: SL-401 decreased the viability of pDCs even at low concentrations (IC50: 0.83 ng/ml; 14.6 pM, p < 0.001). SL-401 decreased the viability of MM cells at clinically achievable doses, without significantly affecting the viability of normal PBMCs. Co-culture of MM patient-derived pDCs induced proliferation of MM cell lines and patient MM cells; and importantly, SL-401 inhibited pDC-triggered MM cell growth (p < 0.005). Moreover, 3 of 5 samples were obtained from patients whose disease was progressing while on bortezomib, dexamethasone, and lenalidomide therapies. SL-401 blocked pDC-induced growth of dexamethasone-, doxorubicin- or melphalan-resistant MM cells. Combinations of SL-401 with melphalan, bortezomib, lenalidomide, or pomalidomide induced synergistic anti-MM activity (Combination index < 1.0). SL-401 blocked monocyte-derived osteoclast formation in a dose-dependent fashion, as well as restored MM patient BM-derived osteoblast formation. Finally, SL-401 also decreased the viability of IL-3R expressing MM-SPs.Conclusions: Our preclinical study provides the basis for using SL-401 to directly target pDCs and inhibit the pDC-MM interactions, as well as target osteolytic bone disease and clonogenic side populations, in novel therapeutic strategies to enhance MM cytotoxicity, overcome drug-resistance, and improve patient outcome. DisclosuresMacri:Stemline Therapeutics, Inc., New York, NY USA: Employment. Brooks:Stemline Therapeutics: Employment, Equity Ownership. Rowinsky:Stemline Therapeutics: Employment, Equity Ownership. Chauhan:Stemline Therapeutics: Consultancy. Anderson:BMS: Consultancy; Sanofi Aventis: Consultancy; Gilead: Consultancy; Onyx: Consultancy; Millenium: Consultancy; Celgene: Consultancy; Oncopep/Acetylon: Equity Ownership.

Targeting CCR1 for the Treatment of Osteolytic Bone Disease in Multiple Myeloma.

Osteolytic bone disease (OBD) is a frequent complication of multiple myeloma (MM), affecting 70 to 80% of the patients. OBD is characterized by imbalanced bone remodeling, due to decreased osteoblast (OB) number and increased osteoclast (OC) formation and activity. MM cells secrete osteoclastogenic factors, such as receptor activator of nuclear factor kappa B ligand (RANKL) and CCL3. In turn, OC support MM cell proliferation and survival, thus promoting a positive feedback that exacerbates bone resorption. Chemokines modulate osteoclastogenesis and promote MM cell proliferation, in particular CCL3 and its receptor CCR1 play an important role in mediating OBD in MM. MLN3897 (Millennium Pharmaceuticals, Cambridge) is a novel small molecule specific antagonist of human CCR1 (IC50 0.8 nM). It has a favorable toxicity profile in healthy volunteers and is currently undergoing phase II clinical trials in rheumatoid arthritis and multiple sclerosis. Here we evaluate the effects of MLN3897 on OC function and activity, as well as OC-MM cell interactions. Our in vitro data demonstrates a dual mechanism of action for MLN3897: it inhibits osteoclastogenesis and also overcomes the protective effects conferred by OC on MM cells. Our data further shows inhibition of OC formation and function by 40 and 70%, respectively, following MLN3897 treatment. This is mediated via inhibition of the fusion process and is accompanied by downregulation of pERK and c-fos signaling. To analyze its effect on MM cells, we verified CCR1 and CCR5 expression levels on MM1.S (15% and 3.6%) and OPM1 (3.8 and 0.7%). Our data show that OC secrete high levels of CCL3 which triggers MM cell migration; and that MLN3897 abrogates these effects by inhibiting the PI3K/Akt pathway. Moreover, MLN3897 overcomes the proliferative advantage conferred by OC on MM cells, as demonstrated in INA6, MM1.S and MM patient derived primary cells. OC induced MM cell proliferation is mediated by adhesion and cytokine secretion, and MLN3897 abrogates both MM cell-to-OC adhesion and interleukin-6 (IL6) secretion by OC in a co-culture system, thereby resulting in decreased MM cell survival and proliferation. To confirm these in vitro results, in vivo studies in a SCID-hu mouse model are underway. Implanted SCID-Hu INA-6 bearing mice are treated with twice daily oral MLN3897 for 3 weeks. The evaluation of osteolytic lesions and OC, OB and endothelial cell number; and tumor burden will be presented. Our in vitro results therefore show novel biologic sequelae of CCL3 and its inhibition on both osteoclastogenesis and MM cell growth. Our in vivo experiments will further validate the role of CCR1 in a human BM microenvironment-MM model, providing the framework for clinical trials of MLN3897 for the treatment of OBD in MM.

MLN3897, a novel CCR1 inhibitor, impairs osteoclastogenesis and inhibits the interaction of multiple myeloma cells and osteoclasts

AbstractThe interaction between osteoclasts (OCs) and multiple myeloma (MM) cells plays a key role in the pathogenesis of MM-related osteolytic bone disease (OBD). MM cells promote OC formation and, in turn, OCs enhance MM cell proliferation. Chemokines are mediators of MM effects on bone and vice versa; in particular, CCL3 enhances OC formation and promotes MM cell migration and survival. Here, we characterize the effects of MLN3897, a novel specific antagonist of the chemokine receptor CCR1, on both OC formation and OC-MM cell interactions. MLN3897 demonstrates significant impairment of OC formation (by 40%) and function (by 70%), associated with decreased precursor cell multinucleation and down-regulation of c-fos signaling. OCs secrete high levels of CCL3, which triggers MM cell migration; conversely, MLN3897 abrogates its effects by inhibiting Akt signaling. Moreover, MM cell-to-OC adhesion was abrogated by MLN3897, thereby inhibiting MM cell survival and proliferation. Our results therefore show novel biologic sequelae of CCL3 and its inhibition in both osteoclastogenesis and MM cell growth, providing the preclinical rationale for clinical trials of MLN3897 to treat OBD in MM.