Role of the Immune Response in Disease Progression and Therapy in Multiple Myeloma

The clinical regimens and cell membrane camouflaged nanodrug delivery systems in hematologic malignancies treatment

Hematologic malignancies (HMs), also referred to as hematological or blood cancers, pose significant threats to patients as they impact the blood, bone marrow, and lymphatic system. Despite significant clinical strategies using chemotherapy, radiotherapy, stem cell transplantation, targeted molecular therapy, or immunotherapy, the five-year overall survival of patients with HMs is still low. Fortunately, recent studies demonstrate that the nanodrug delivery system holds the potential to address these challenges and foster effective anti-HMs with precise treatment. In particular, cell membrane camouflaged nanodrug offers enhanced drug targeting, reduced toxicity and side effects, and/or improved immune response to HMs. This review firstly introduces the merits and demerits of clinical strategies in HMs treatment, and then summarizes the types, advantages, and disadvantages of current nanocarriers helping drug delivery in HMs treatment. Furthermore, the types, functions, and mechanisms of cell membrane fragments that help nanodrugs specifically targeted to and accumulate in HM lesions are introduced in detail. Finally, suggestions are given about their clinical translation and future designs on the surface of nanodrugs with multiple functions to improve therapeutic efficiency for cancers.

Improving NK cell function in multiple myeloma with NKTR-255, a novel polymer-conjugated human IL-15

Multiple myeloma (MM) is characterized by an immunosuppressive microenvironment that enables tumor development. One of the mechanisms of immune evasion used by MM cells is the inhibition of natural killer (NK) cell effector functions; thus, the restoration of NK cell antitumor activity represents a key goal to increase tumor cell recognition, avoid tumor escape and potentially enhancing the effect of other drugs. In this study, we evaluated the ability of the investigational medicine NKTR-255, an IL-15 receptor agonist, to engage the IL-15 pathway and stimulate NK cells against MM cells. We observed that incubation with NKTR-255 was able to tilt the balance toward an activated phenotype in NK cells isolated from peripheral blood mononuclear cells of patients with MM, with increased expression of activating receptors on the surface of treated NK cells. This resulted in an enhanced degranulation, cytokine release, and anti-tumor cytotoxicity when the NK cells were exposed to both MM cell lines and primary MM cells. We further evaluated the in vivo effect of NKTR-255 in fully humanized immunocompetent mice subcutaneously engrafted with H929 MM cells. Compared with placebo, weekly injection of the mice with NKTR-255 increased the number of circulating NK cells in peripheral blood and delayed tumor growth. Finally, we observed that combination of NKTR-255 with the anti-CD38 antibody, daratumumab, was effective against MM cells in vitro and in vivo. Taken together, our data suggest a significant impact of NKTR-255 in inducing NK cell function against MM cells with important translational implications.

Gene polymorphisms of interleukin 10 (− 819 C/T and − 1082 G/A) in women with ovarian cancer

Background

Ovarian cancer (OC) is the leading cause of death associated with gynecologic cancer. IL-10 plays an important role in tumorigenesis. We investigated IL-10 gene polymorphisms in OC patients. The current case–control study screened forty-eight women with OC and forty-eight healthy women who did not have OC. The genotyping of SNPs (− 1082 G > A; rs1800896 and − 819 C > T; rs1800871) of the IL-10 gene was done by tetra primers sequence-specific primer polymerase chain reaction (SSP-PCR) technique. The plasma levels of IL-10 were measured using an enzyme-linked immunosorbent assay (ELISA).

Results

For IL-10 (− 1082 G/A) polymorphism, the G (wild allele) was significantly associated with increasing the risk of OC (OR = 2.054 with CI = 1.154–3.657; P < 0.05), while the A (variant allele) and AA genotype was significantly associated with decreasing the risk of OC (OR = 0.487 with CI = 0.273–0.867; P < 0.05) and (OR = 0.15; 95% CI = 0.04–0.63; P < 0.05), respectively. For IL-10 (− 819C/T) polymorphisms, the T allele (variant allele) and (TT, CT genotypes) were significantly associated with increasing the risk of OC (OR = 2.800 with 95% CI = 1.577–5.037; P < 0.05), (OR = 18.33 with 95% CI = 3.46–97.20; P < 0.001), and (OR = 9.44 with 95% CI = 2.52–35.40; P < 0.001), respectively, while the C (wild allele) was significantly associated with decreasing the risk of OC (OR = 0.357 with 95% CI = 0.199–0.642; P < 0.05). The haplotype analysis for (− 1082 G > A and − 819 C > T shows the GT haplotype was significantly associated with increasing the risk of OC (OR = 50.09 with CI = 6.34–395.92; P < 0.001). OC was substantially correlated with IL-10 level (r = 0.457; p < 0.001). There is no linkage disequilibrium (LD) between IL 10 − 1082 G/A and IL 10 − 819 C/T (D′ = 0.1315, r2 = 0.016; P = NS). A statistically significant positive relationship existed between IL-10 and CA125 and ALT (P < 0.05). IL-10 and albumin showed a strong negative association (P < 0.05), whereas the correlation of IL10 plasma level with BUN, AST, T. Bil., TLC, PLT, Cr., and HB has not any significant value (P > 0.05).

Conclusions

Overall, this study supports an association of IL-10 (− 1082 G/A and − 819C/T) polymorphisms with the risk of ovarian cancer.

Preclinical evidence of a direct pro-survival role of arginine deprivation in multiple myeloma

Multiple myeloma grows by establishing multiple interactions with bone marrow cells. These include expansion of myeloid-derived suppressor cells, which drive immunoevasion via mechanisms that include arginase-1-driven depletion of L-arginine, thus indirectly promoting myeloma cell survival and tumor progression. The peculiar biology of malignant plasma cells postulates that arginine depletion may benefit their fitness also directly, e.g., by engaging the integrated stress response, or by stimulating autophagy through mTORC1 inhibition. We thus investigated the direct impact of arginine deprivation on myeloma cells and challenged its pathophysiological relevance in vitro and in vivo. First, we found that partial arginine depletion spared proliferation of human multiple myeloma cells at concentrations that arrest human T cells. Next, we asked if arginine shortage activates putative adaptive pathways in myeloma cells. Low arginine failed to activate the integrated stress response, as indicated by unmodified phosphorylation of the eukaryotic initiation factor 2α, but sizably inhibited mTORC1, as revealed by reduced phosphorylation of ribosomal protein S6. Notably, depressed mTORC1 activity was not sufficient to increase autophagy, as assessed by the lysosomal digestion rate of the autophagosome-associated protein, LC3-II. Rather, it stimulated mTORC2, resulting in increased phosphatidylinositol-3 kinase-dependent AKT phosphorylation and activity, leading to heightened inhibitory phosphorylation of the pro-apoptotic BAD protein. We then tested whether arginine depletion-activated AKT may protect malignant plasma cells from cell death. Indeed, culturing myeloma cells in low arginine medium significantly reduced the apoptotic effect of the first-in-class proteasome inhibitor, bortezomib, an outcome prevented by pharmacological inhibition of AKT phosphorylation. Finally, we challenged the relevance of the identified circuit in vivo. To gauge the pathophysiologic relevance of low arginine to myeloma growth independently of immunoevasion, we xenotransplanted human myeloma cells subcutaneously into T cell-deficient Rag2^–/–γc^–/– recipient mice and treated palpable tumor-bearing mice with the clinical-grade arginase inhibitor CB1158. Arginase inhibition significantly raised serum arginine concentration, reduced tumor growth by caliper assessment, and decreased intra-tumor AKT phosphorylation in vivo. Altogether, our results reveal a novel direct pro-survival effect of arginine deprivation on myeloma cells, with potential therapeutic implications.

Recovery of polyclonal immunoglobulins during treatment in patients ineligible for autologous stem-cell transplantation is a prognostic marker of longer progression-free survival and overall survival

Immunoparesis is the suppression of normal polyclonal immunoglobulins and is present in most patients with newly diagnosed multiple myeloma (MM). The association of immunoparesis at diagnosis, and particularly its recovery along with treatment, with survival in patients ineligible for autologous stem-cell transplantation (ASCT) has not been well established. This retrospective study evaluated the impact of immunoparesis in 431 patients diagnosed with MM, ineligible for ASCT, with a median overall survival of 36 months [95% confidence interval (CI): 31-40]. Immunoparesis was present in 81.2% of patients at diagnosis and was associated with a trend to a worse overall response rate (ORR: 84.8% vs. 74.9%; OR 1.88 (95% CI: 0.97-3.63), shorter progression-free survival (PFS) [22.0 vs. 18.2 months; hazard ratio (HR) 0.775; 95%CI: 0.590-1.018; p = 0.066], and overall survival (OS) (45.9 vs. 34.2 months; HR 0.746; 95% CI: 0.551-1.010; p = 0.057). Twenty-four per cent of patients who had immunoparesis at diagnosis recovered polyclonal immunoglobulins in the follow-up period. Interestingly, these patients had a better ORR (96.3% vs. 68.2%; OR 12.29 (95% CI: 3.77-40.06), PFS (HR 0.703; 95CI%: 0.526-0.941; p = 0.018) and OS (HR 0.678; 95 CI%: 0.503-0.913; p = 0.011) than patients who did not recover it. In summary, restoring a healthy immune system along with first-line treatment in patients with MM, not receiving ASCT, is associated with better outcomes.

RAGE is a potential biomarker implicated in immune infiltrates and cellular senescence in lung adenocarcinoma

Background

Receptor for Advanced Glycation End‐products (RAGE) is an oncogene abnormally expressed in various cancers. However, the clinical value of RAGE and the biological role of RAGE in lung cancer have not been fully investigated.

Methods

We compared the RAGE expression using several public databases. The relationship between RAGE expression and clinicopathological variables was assessed. The R software package was used to carry out enrichment analyses of RAGE co‐expression and gene set enrichment analysis (GSEA). Additionally, we used the TIMER database to assess the association between immune infiltration and RAGE expression. The correlation between RAGE expression and senescence biomarkers in lung adenocarcinoma was analyzed using the TCGA database.

Results

Our findings indicated that the expression of RAGE was downregulated in lung adenocarcinoma, and down‐regulation of RAGE was related to poor overall survival and disease‐free survival. Functional enrichment analysis indicated that RAGE co‐expression genes were mainly associated with neutrophil activation involved in immune response, neutrophil degranulation, and regulation of leukocyte‐mediated immunity. Correlation analysis revealed that RAGE expression was closely related to the purity of the tumor and immune infiltration. GSEA indicated that the RAGE‐related differential genes were mainly enriched in senescence‐related pathways. Besides, the RAGE expression was significantly associated with senescence‐related genes.

Conclusion

Down‐regulation of RAGE expression was associated with poor prognosis, as well as defective immune infiltration and cellular senescence in lung adenocarcinoma.

Involvement of Alarmins in the Pathogenesis and Progression of Multiple Myeloma

OBJECTIVE

Multiple Myeloma (MM) is a haematological disease resulting from the neoplastic transformation of plasma cells. The uncontrolled growth of plasma cells in the bone marrow and the delivery of several cytokines causes bone erosion that often does not regress, even in the event of disease remission. MM is characterised by a multi-step evolutionary path, which starts with an early asymptomatic stage defined as monoclonal gammopathy of undetermined significance (MGUS) evolving to overt disease.

DATA SOURCES AND STUDY SELECTION

We have selected scientific publications on the specific topics "alarmis, MGUS, and MM", drawing from PubMed. The keywords we used were alarmines, MGUS, MM, and immune system.

RESULTS

The analysis confirms the pivotal role of molecules such as high-mobility group box-1, heat shock proteins, and S100 proteins in the induction of neoangiogenesis, which represents a milestone in the negative evolution of MM as well as other haematological and non-haematological tumours.

CONCLUSIONS

Modulation of the host immune system and the inhibition of neoangiogenesis may represent the therapeutic target for the treatment of MM that is capable of promoting better survival and reducing the risk of RRMM.

The Impact of Induction Regimes on Immune Responses in Patients with Multiple Myeloma

Current standard frontline therapy for newly diagnosed patients with multiple myeloma (NDMM) involves induction therapy, autologous stem cell transplantation (ASCT), and maintenance therapy. Major efforts are underway to understand the biological and the clinical impacts of each stage of the treatment protocols on overall survival statistics. The most routinely used drugs in the pre-ASCT "induction" regime have different mechanisms of action and are employed either as monotherapies or in various combinations. Aside from their direct effects on cancer cell mortality, these drugs are also known to have varying effects on immune cell functionality. The question remains as to how induction therapy impacts post-ASCT immune reconstitution and anti-tumor immune responses. This review provides an update on the known immune effects of melphalan, dexamethasone, lenalidomide, and bortezomib commonly used in the induction phase of MM therapy. By analyzing the actions of each individual drug on the immune system, we suggest it might be possible to leverage their effects to rationally devise more effective induction regimes. Given the genetic heterogeneity between myeloma patients, it may also be possible to identify subgroups of patients for whom particular induction drug combinations would be more appropriate.

Immunomodulation by durvalumab and pomalidomide in patients with relapsed/refractory multiple myeloma

This study sought to understand how the programmed death ligand 1 (PD-L1) inhibitor durvalumab and the immunomodulatory agent pomalidomide regulate immune cell activation and function in patients with relapsed/refractory (RR) multiple myeloma (MM). Immunologic changes in peripheral blood and bone marrow of patients treated with durvalumab as monotherapy or in combination with pomalidomide with/without dexamethasone were characterized by assessing subsets of immune cells and gene signatures to understand the immunomodulatory effect of the treatment. Soluble PD-L1 levels were elevated at screening in patients with RRMM but did not correlate with response to durvalumab combination therapy. Immune cell subsets were increased in peripheral blood during treatment with durvalumab and pomalidomide, and combination therapy induced significant gene expression changes in the MM tumor microenvironment versus durvalumab alone. Estimation of cell populations based on RNA sequencing data revealed increased monocytes, neutrophils, and natural killer cells with the combination therapy, but not with durvalumab alone. Additionally, multiplex immunofluorescence of bone marrow demonstrated that immune populations were different in responders versus nonresponders to durvalumab plus pomalidomide with dexamethasone therapy. Overall, durvalumab effectively blocked soluble PD-L1; however, durvalumab monotherapy was not associated with immunologic changes, which were observed with combination therapy.

Anti-BCMA CAR T administration in a relapsed and refractory multiple myeloma patient after COVID-19 infection: a case report

BACKGROUND

Very little is known about the risk that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral infection poses to cancer patients, many of whom are immune compromised causing them to be more susceptible to a host of infections. As a precautionary measure, many clinical studies halted enrollment during the initial surge of the global Novel Coronavirus Disease (COVID-19) pandemic. In this case report, we detail the successful treatment of a relapsed and refractory multiple myeloma (MM) patient treated with an anti-B cell maturation antigen (BCMA) chimeric antigen receptor (CAR) T cell therapy immediately following clinical recovery from COVID-19.

CASE PRESENTATION

The 57 year old Caucasian male patient had a 4-year history of MM and was considered penta-refractory upon presentation for CAR T cell therapy. He had a history of immunosuppression and received one dose of lymphodepleting chemotherapy (LDC) the day prior to COVID-19 diagnosis; this patient was able to mount a substantial immune response against the SARS-CoV-2 virus, and antiviral antibodies remain detectable 2 months after receiving anti-BCMA CAR T cell therapy. The recent SARS-CoV-2 infection in this patient did not exacerbate CAR T-associated cytokine release syndrome (CRS) and conversely the CAR T cell therapy did not result in COVID-19-related complications. One month after CAR T cell infusion, the patient was assessed to have an unconfirmed partial response per International Myeloma Working Group (IMWG) criteria.

CONCLUSION

Our case adds important context around treatment choice for MM patients in the era of COVID-19 and whether CAR T therapy can be administered to patients who have recovered from COVID-19. As the COVID-19 global pandemic continues, the decision of whether to proceed with CAR T cell therapy will require extensive discussion weighing the potential risks and benefits of therapy. This case suggests that it is possible to successfully complete anti-BCMA CAR T cell therapy after recovery from COVID-19. CRB-402 study registered 6 September 2017 at clinicaltrials.gov (NCT03274219).

Case Report: B Lymphocyte Disorders Under COVID-19 Inflammatory Pressure

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infects humans through the angiotensin converting enzyme-2 (ACE-2) receptor expressed on many cells, including lymphocytes. In Covid-19 patients IL-6 is overexpressed, and hyperactivated plasmacytoid lymphocytes are detected in peripheral blood film. We hypothesize that, due to the unpredictable interaction between the new virus and the B cell lineage of infected patients, a cascade of out of control events can ensue, capable of determining unexpected pathologic disorders involving such lineage. Here we report two cases of autoimmune hemolytic anemia (AIHA) and two cases of B-cell hematological malignancies developed or reactivated during acute SARS-CoV-2 infection. The temporal relationship of the events may suggest a potential causal relationship between SARS-CoV-2 infection and the hematopoietic disorders. We suggest that special attention should be paid to COVID-19 patients with underlining B cell lineage disorders.

HDP-101, an Anti-BCMA Antibody-Drug Conjugate, Safely Delivers Amanitin to Induce Cell Death in Proliferating and Resting Multiple Myeloma Cells

Despite major treatment advances in recent years, patients with multiple myeloma inevitably relapse. The RNA polymerase II complex has been identified as a promising therapeutic target in both proliferating and dormant cancer cells. Alpha-amanitin, a toxin so far without clinical application due to high liver toxicity, specifically inhibits this complex. Here, we describe the development of HDP-101, an anti-B-cell maturation antigen (BCMA) antibody conjugated with an amanitin derivative. HDP-101 displayed high efficacy against both proliferating and resting myeloma cells in vitro, sparing BCMA-negative cells. In subcutaneous and disseminated murine xenograft models, HDP-101 induced tumor regression at low doses, including durable complete remissions after a single intravenous dose. In cynomolgus monkeys, HDP-101 was well tolerated with a promising therapeutic index. In conclusion, HDP-101 safely and selectively delivers amanitin to myeloma cells and provides a novel therapeutic approach to overcome drug resistance in this disease.

Evaluation of SARS-CoV-2 Serological Testing in Patients with Multiple Myeloma and Other Hematologic Malignancies on Monoclonal Antibody Therapies

Background: Patients with hematological malignancies (HM), including multiple myeloma (MM), frequently suffer from immune deficiency-associated infectious complications because of both the disease and the treatment. Alarming results from China and the UK confirm the vulnerability of HM patients to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection-driven coronavirus disease 2019 (COVID-19). Given that the immunoassay interference from the endogenous monoclonal immunoglobulin (M paraprotein) and treatment antibodies continually challenges the MM management, it is critical to evaluate the SARS-CoV-2 serology tests for suspected interference/cross-reactivity. Methods: We compared the degree of interference in three SARS-CoV-2 serology assay platforms in HM patients with and without COVID-19 and on various therapeutic monoclonal antibody (t-mAb) treatments. Further, we confirmed the cross-reactivity in pooled samples from normal and COVID-19 + samples spiked with respective antibodies in vitro. Results: None of the 93 HM patient samples with or without t-MAbs showed cross-reactivity on any of the three serology platforms tested. Conclusions: The tested three serologic assays for SARS-CoV-2 are specific and do not have cross-reactivity with M-components or t-MAbs indicating that they can be used safely in oncology practice and in research exploring the immunologic response to COVID-19 in patients with HM.

A tertiary center experience of multiple myeloma patients with COVID-19: lessons learned and the path forward

BACKGROUND

The COVID-19 pandemic, caused by SARS-CoV-2 virus, has resulted in over 100,000 deaths in the USA. Our institution has treated over 2000 COVID-19 patients during the pandemic in New York City. The pandemic directly impacted cancer patients and the organization of cancer care. Mount Sinai Hospital has a large and diverse multiple myeloma (MM) population. Herein, we report the characteristics of COVID-19 infection and serological response in MM patients in a large tertiary care institution in New York.

METHODS

We performed a retrospective study on a cohort of 58 patients with a plasma-cell disorder (54 MM, 4 smoldering MM) who developed COVID-19 between March 1, 2020, and April 30, 2020. We report epidemiological, clinical, and laboratory characteristics including the persistence of viral detection by polymerase chain reaction (PCR) and anti-SARS-CoV-2 antibody testing, treatments initiated, and outcomes.

RESULTS

Of the 58 patients diagnosed with COVID-19, 36 were hospitalized and 22 were managed at home. The median age was 67 years; 52% of patients were male and 63% were non-White. Hypertension (64%), hyperlipidemia (62%), obesity (37%), diabetes mellitus (28%), chronic kidney disease (24%), and lung disease (21%) were the most common comorbidities. In the total cohort, 14 patients (24%) died. Older age (> 70 years), male sex, cardiovascular risk, and patients not in complete remission (CR) or stringent CR were significantly (p < 0.05) associated with hospitalization. Among hospitalized patients, laboratory findings demonstrated elevation of traditional inflammatory markers (CRP, ferritin, D-dimer) and a significant (p < 0.05) association between elevated inflammatory markers, severe hypogammaglobulinemia, non-White race, and mortality. Ninety-six percent (22/23) of patients developed antibodies to SARS-CoV-2 at a median of 32 days after initial diagnosis. The median time to PCR negativity was 43 (range 19-68) days from initial positive PCR.

CONCLUSIONS

Drug exposure and MM disease status at the time of contracting COVID-19 had no bearing on mortality. Mounting a severe inflammatory response to SARS-CoV-2 and severe hypogammaglobulinemia was associated with higher mortality. The majority of patients mounted an antibody response to SARS-CoV-2. These findings pave a path to the identification of vulnerable MM patients who need early intervention to improve outcomes in future outbreaks of COVID-19.

A tertiary center experience of multiple myeloma patients with COVID-19: lessons learned and the path forward

BACKGROUND

The COVID-19 pandemic, caused by SARS-CoV-2 virus, has resulted in over 100,000 deaths in the United States. Our institution has treated over 2,000 COVID-19 patients during the pandemic in New York City. The pandemic directly impacted cancer patients and the organization of cancer care. Mount Sinai Hospital has a large and diverse multiple myeloma (MM) population. Herein, we report the characteristics of COVID-19 infection and serological response in MM patients in a large tertiary care institution in New York.

METHODS

We performed a retrospective study on a cohort of 58 patients with a plasma-cell disorder (54 MM, 4 smoldering MM) who developed COVID-19 between March 1, 2020 and April 30, 2020. We report epidemiological, clinical and laboratory characteristics including persistence of viral detection by polymerase chain reaction (PCR) and anti-SARS-CoV-2 antibody testing, treatments initiated, and outcomes.

RESULTS

Of the 58 patients diagnosed with COVID-19, 36 were hospitalized and 22 were managed at home. The median age was 67 years; 52% of patients were male and 63% were non-white. Hypertension (64%), hyperlipidemia (62%), obesity (37%), diabetes mellitus (28%), chronic kidney disease (24%) and lung disease (21%) were the most common comorbidities. In the total cohort, 14 patients (24%) died. Older age (>70 years), male sex, cardiovascular risk, and patients not in complete remission (CR) or stringent CR were significantly (p<0.05) associated with hospitalization. Among hospitalized patients, laboratory findings demonstrated elevation of traditional inflammatory markers (CRP, ferritin, D-dimer) and a significant (p<0.05) association between elevated inflammatory markers, severe hypogammaglobulinemia, non-white race, and mortality. Ninety-six percent (22/23) of patients developed antibodies to SARS-CoV-2 at a median of 32 days after initial diagnosis. Median time to PCR negativity was 43 (range 19-68) days from initial positive PCR.

CONCLUSIONS

Drug exposure and MM disease status at the time of contracting COVID-19 had no bearing on mortality. Mounting a severe inflammatory response to SARS-CoV-2 and severe hypogammaglobulinemia were associated with higher mortality. The majority of patients mounted an antibody response to SARS-CoV-2. These findings pave a path to identification of vulnerable MM patients who need early intervention to improve outcome in future outbreaks of COVID-19.

Runx2 Deficiency in Osteoblasts Promotes Myeloma Progression by Altering the Bone Microenvironment at New Bone Sites

Multiple myeloma is a plasma cell malignancy that thrives in the bone marrow (BM), with frequent progression to new local and distant bone sites. Our previous studies demonstrated that multiple myeloma cells at primary sites secrete soluble factors and suppress osteoblastogenesis via the inhibition of Runt-related transcription factor 2 (Runx2) in pre- and immature osteoblasts (OB) in new bone sites, prior to the arrival of metastatic tumor cells. However, it is unknown whether OB-Runx2 suppression in new bone sites feeds back to promote multiple myeloma dissemination to and progression in these areas. Hence, we developed a syngeneic mouse model of multiple myeloma in which Runx2 is specifically deleted in the immature OBs of C57BL6/KaLwRij mice (OB-Runx2-/- mice) to study the effect of OB-Runx2 deficiency on multiple myeloma progression in new bone sites. In vivo studies with this model demonstrated that OB-Runx2 deficiency attracts multiple myeloma cells and promotes multiple myeloma tumor growth in bone. Mechanistic studies further revealed that OB-Runx2 deficiency induces an immunosuppressive microenvironment in BM that is marked by an increase in the concentration and activation of myeloid-derived suppressor cells (MDSC) and the suppression and exhaustion of cytotoxic CD8+ T cells. In contrast, MDSC depletion by either gemcitabine or 5-fluorouracil treatment in OB-Runx2-/- mice prevented these effects and inhibited multiple myeloma tumor growth in BM. These novel discoveries demonstrate that OB-Runx2 deficiency in new bone sites promotes multiple myeloma dissemination and progression by increasing metastatic cytokines and MDSCs in BM and inhibiting BM immunity. Importantly, MDSC depletion can block multiple myeloma progression promoted by OB-Runx2 deficiency.Significance: This study demonstrates that Runx2 deficiency in immature osteoblasts at distant bone sites attracts myeloma cells and allows myeloma progression in new bone sites via OB-secreted metastatic cytokines and MDSC-mediated suppression of bone marrow immunity.

Therapeutic targets in myeloma bone disease

Multiple myeloma (MM) is the second most common haematological malignancy and is characterized by a clonal proliferation of neoplastic plasma cells within the bone marrow. MM is the most frequent cancer involving the skeleton, causing osteolytic lesions, bone pain and pathological fractures that dramatically decrease MM patients' quality of life and survival. MM bone disease (MBD) results from uncoupling of bone remodelling in which excessive bone resorption is not compensated by new bone formation, due to a persistent suppression of osteoblast activity. Current management of MBD includes antiresorptive agents, bisphosphonates and denosumab, that are only partially effective due to their inability to repair the existing lesions. Thus, research into agents that prevent bone destruction and more importantly repair existing lesions by inducing new bone formation is essential. This review discusses the mechanisms regulating the uncoupled bone remodelling in MM and summarizes current advances in the treatment of MBD. LINKED ARTICLES: This article is part of a themed issue on The molecular pharmacology of bone and cancer-related bone diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.9/issuetoc.

Use of carbon monoxide breath test to assess red blood cell lifespan in newly diagnosed multiple myeloma patients

To clarify the role of red blood cell (RBC) lifespan in anemia of multiple myeloma (MM), RBC lifespan was detected in 40 newly diagnosed MM patients by measuring exhaled endogenous carbon monoxide concentration. Mean RBC lifespan was significantly reduced in MM patients (63 ± 23 d) than healthy controls (116 ± 17 d). RBC lifespan in MM patients without anemia (78 ± 21 d) was also significantly lower than for healthy controls. RBC lifespan in MM patients with anemia (52 ± 18 d) was significantly lower than those without. Besides, RBC lifespan in MM patients with renal insufficiency (50 ± 16 d) was lower than those without (66 ± 23 d). RBC lifespan was significantly negatively correlated with % reticulocytes, erythropoietin concentration, % clonal plasma cells, β2-microglobulin (MG) level, and creatinine level. Receiver operator characteristics curve was used to determine a cut-off point (61 d) to predict effect of RBC lifespan on chemotherapy. Overall response rates were significantly higher in MM patients with RBC lifespan ≥61 d than those <61 d. In conclusion, RBC lifespan of MM patients is reduced, and severely shortened RBC lifespan may be involved in the occurrence of anemia in MM patients. The chemotherapeutic effect of MM patients can be predicted by RBC lifespan.