Serum free light chain analysis: persisting limitations with new kids on the block.

OBJECTIVES: Serum free light chain (sFLC) measurements have inherent analytical limitations impacting sFLC clinical interpretation. We evaluated analytical and diagnostic performance of three polyclonal sFLC assays on four analytical platforms. METHODS: sFLC concentration was measured using Diazyme FLC assays (Diazyme) on cobas c501/c503 analyzer (Roche); Freelite assays (The Binding Site) on Optilite analyzer (The Binding Site) and cobas c501 analyzer and Sebia FLC ELISA assays (Sebia) on AP22 ELITE analyzer (DAS). Imprecision, linearity, method comparison vs. Freelite/Optilite, antigen excess detection and reference value verification were assessed. Diagnostic performance was compared on 120 serum samples and on follow-up samples of five patients with κ and λ monoclonal gammopathy. RESULTS: Method comparison showed excellent correlation with Freelite/Optilite method for all assays. A large proportional negative bias was shown for both Sebia κ and λ ELISA and a significant positive proportional bias for λ in the low (<10 mg/L) Freelite/cobas c501 method. Clinically relevant underestimation of κ sFLC levels due to antigen excess was shown for 7% of each Diazyme/cobas application and for 11 and 32.1% of λ sFLC assay of respectively Diazyme/cobas and Sebia/AP22. sFLC reference values revealed application specific. Cohen's κ values were (very) good for κ sFLC but only moderate to good for λ sFLC. In 4/10 follow-up patients, significant differences in clinical interpretation between sFLC assays were noticed. CONCLUSIONS: Important analytical limitations remain for all sFLC applications. Differences in reference values and diagnostic performance hamper interchangeability of sFLC assays. Assay specific sFLC decision guidelines are warranted.

The Road to Personalized Myeloma Medicine: Patient-specific Single-domain Antibodies for Anti-idiotypic Radionuclide Therapy.

To this day, multiple myeloma remains an incurable cancer. For many patients, recurrence is unavoidably a result of lacking treatment options in the minimal residual disease stage. This is due to residual and treatment-resistant myeloma cells that can cause disease relapse. However, patient-specific membrane-expressed paraproteins could hold the key to target these residual cells responsible for disease recurrence. Here, we describe the therapeutic potential of radiolabeled, anti-idiotypic camelid single-domain antibody fragments (sdAbs) as tumor-restrictive vehicles against a membrane-bound paraprotein in the syngeneic mouse 5T33 myeloma model and analogously assess the feasibility of sdAb-based personalized medicine for patients with multiple myeloma. Llamas were immunized using extracts containing paraprotein from either murine or human sera, and selective sdAbs were retrieved using competitive phage display selections of immune libraries. An anti-5T33 idiotype sdAb was selected for targeted radionuclide therapy with the ß--particle emitter 177Lu and the α-particle emitter 225Ac. sdAb-based radionuclide therapy in syngeneic mice with a low 5T33 myeloma lesion load significantly delayed tumor progression. In five of seven patients with newly diagnosed myeloma, membrane expression of the paraprotein was confirmed. Starting from serum-isolated paraprotein, for two of three selected patients anti-idiotype sdAbs were successfully generated.

Validation of a PCR-Based Next-Generation Sequencing Approach for the Detection and Quantification of Minimal Residual Disease in Acute Lymphoblastic Leukemia and Multiple Myeloma Using gBlocks as Calibrators.

Detection of minimal residual disease (MRD) to guide therapy has been a standard practice in treatment of childhood acute lymphoblastic leukemia (ALL) for decades. In multiple myeloma (MM), a clear correlation is found between absence of MRD and longer survival. Quantitative allele-specific oligonucleotide (qASO)-PCR is the standard molecular method for MRD detection in these hematologic malignant tumors. However, this technique has some drawbacks that can be overcome by next-generation sequencing (NGS). In this study, NGS is validated as an alternative method for qASO-PCR for MRD detection in both ALL and MM. MRD results obtained by NGS and qASO-PCR were compared in 59 and 39 bone marrow samples of 33 and 14 patients with ALL and MM, respectively. Our results indicate that the use of gBlocks as calibrators makes the NGS approach a powerful tool to quantify MRD. With an input of 400 ng of DNA (corresponding to approximately 7 × 104 cells), a limit of detection of 0.01% can be achieved. The specificity of the NGS-MRD technique was 100%, and a correlation with qASO-PCR for quantifiable MRD results of 0.93 and 0.91 was found in ALL and MM, respectively. Especially for MM, the higher applicability (100%) of the NGS-MRD protocol, compared with qASO-PCR (57%), was clearly demonstrated. These results demonstrate that NGS is an even better alternative to qASO-PCR.

The Transfer of Sphingomyelinase Contributes to Drug Resistance in Multiple Myeloma.

Multiple myeloma (MM) is well-known for the development of drug resistance, leading to relapse. Therefore, finding novel treatment strategies remains necessary. By performing a lipidomics assay on MM patient plasma, we aimed to identify new targets. We observed a dysregulation in the sphingolipid metabolism, with the upregulation of several ceramides and downregulation of sphingomyelin. This imbalance suggests an increase in sphingomyelinase, the enzyme responsible for hydrolyzing sphingomyelin into ceramide. We confirmed the upregulation of acid sphingomyelinase (ASM) in primary MM cells. Furthermore, we observed an increase in ASM expression in MM cell lines treated with melphalan or bortezomib, as well as in their exosomes. Exosomes high in ASM content were able to transfer the drug-resistant phenotype to chemosensitive cells, hereby suggesting a tumor-protective role for ASM. Finally, inhibition of ASM by amitriptyline improved drug sensitivity in MM cell lines and primary MM cells. In summary, this study is the first to analyze differences in plasma lipid composition of MM patients and match the observed differences to an upregulation of ASM. Moreover, we demonstrate that amitriptyline is able to inhibit ASM and increase sensitivity to anti-myeloma drugs. This study, therefore, provides a rational to include ASM-targeting-drugs in combination strategies in myeloma patients.

Daratumumab and dexamethasone is safe and effective for triple refractory myeloma patients: final results of the IFM 2014-04 (Etoile du Nord) trial.

Single agent daratumumab has shown clinical activity in relapsed, refractory multiple myeloma (RRMM). The Intergroupe Francophone du Myélome 2014-04 trial was designed to further investigate daratumumab in combination with dexamethasone in triple RRMM patients. Patients received daratumumab infusions in combination with weekly dexamethasone until disease progression or unacceptable toxicity. Fifty-seven patients were included in the trial and evaluable for response. The overall response rate and the clinical benefit rate were 33% (n = 19) and 48% (n = 27), respectively. Five (8·8%) patients achieved a very good partial response or better. The median time to response was 4 weeks. For responding patients, the median progression-free survival was 6·6 months, compared to 3·7 months (3·0-5·5) for those with a minimal or stable disease. The median overall survival (OS) for all patients was 16·7 months (11·2-24·0). For responding patients, the median OS was 23·23 months, whereas that of patients with progressive disease was 2·97 months. The incidence of infusion-related reactions was 37%; all cases were manageable and did not lead to dose reduction or permanent treatment discontinuation. These data demonstrate that treatment with daratumumab and dexamethasone results in a meaningful long-term benefit with an acceptable safety profile for patients with triple RRMM.

Myeloid-derived suppressor cells induce multiple myeloma cell survival by activating the AMPK pathway.

Multiple Myeloma (MM) is an incurable malignancy of terminally differentiated plasma cells, which are predominantly localized in the bone marrow. Myeloid-derived suppressor cells (MDSC) are described to promote MM progression by immunosuppression and induction of angiogenesis. However, their direct role in drug resistance and tumor survival is still unknown. In this study, we performed co-culture experiments of myeloma cells with 5TMM derived MDSC in vitro, leading to increased survival and proliferation of MM cells. Co-culture experiments resulted in MDSC-induced AMPK phosphorylation in MM cells, which was associated with an increase in the anti-apoptotic factors MCL-1 and BCL-2, and the autophagy-marker LC3II. In addition, 5TMM cells inoculated in mice showed a clear upregulation of AMPK phosphorylation in vivo. Targeting the AMPK pathway by Compound C resulted in apoptosis of human myeloma cell lines, primary MM cells and 5TMM cells. Importantly, we observed that the tumor-promoting effect of MDSC was partially mediated by AMPK activation. In conclusion, our data clearly demonstrate that MDSC directly increase the survival of MM cells, partially through AMPK activation, identifying this pathway as a new target in the treatment of MM patients.

Child-onset thrombotic thrombocytopenic purpura caused by p.R498C and p.G259PfsX133 mutations in ADAMTS13.

INTRODUCTION: Patients suffering from congenital thrombotic thrombocytopenic purpura (cTTP) have a deficiency in ADAMTS13 due to mutations in their ADAMTS13 gene. OBJECTIVE: The aim of this study was to determine ADAMTS13 parameters (activity, antigen, and mutations), to investigate if the propositus suffered from child-onset cTTP, and to study the in vitro effect of the ADAMTS13 mutations. METHODS: ADAMTS13 activity and antigen were determined using the FRETS VWF73 assay and ELISA and ADAMTS13 mutations via sequencing of the exons. Mutant proteins were expressed in Chinese hamster ovary cells, and their expression was studied using fluorescence microscopy and ELISA. Molecular modeling was used to evaluate the effect of the mutations on ADAMTS13 structure and stability. RESULTS: The propositus was diagnosed with cTTP at the age of 20. ADAMTS13 activity was below 10%, and 2 compound heterozygous mutations, the p.R498C point and the p.G259PfsX133 frameshift mutation, were identified. Expression of ADAMTS13 mutants revealed that the p.R498C and the p.G259PfsX133 mutation cause secretion and translation defects in vitro, respectively. Molecular modeling showed that the R498 intra-domain interactions are lacking in the p.R498C mutant, resulting in protein instability. CONCLUSION: The ADAMTS13 mutations result in a severe ADAMTS13 deficiency explaining the patient's phenotype.

Impact of lenalidomide maintenance on the immune environment of multiple myeloma patients with low tumor burden after autologous stem cell transplantation.

Lenalidomide is a potent anti-myeloma drug with immunomodulatory properties. It is increasingly used in a low-dose maintenance setting to prolong remission duration after standard treatment. Data on the in vivo effects of lenalidomide are scarce and sometimes different from the well-described in vitro effects. We therefore evaluated the numerical, phenotypical and functional impact of lenalidomide maintenance on several immune cell types in a cohort of seventeen homogeneously treated myeloma patients achieving a low residual myeloma burden after a bortezomib based-induction followed by autologous stem cell transplantation. Lenalidomide maintenance: 1) increased the fraction of naïve CD8+ T cells and several memory T-cell subsets, 2) reduced the numbers of terminal effector CD8+ T cells, 3) resulted in a higher expression of co-stimulatory molecules on resting T cells and of the inhibitory checkpoint molecules LAG-3 on CD4+ T cells and TIM-3 on CD4+ and CD8+ T cells, 4) reduced the number of TIGIT+ CD8+ T cells, 5) increased the number of regulatory T cells with a phenotype associated with strong suppressive capacity. Purified CD8+ T cells showed increased and more polyfunctional recall viral responses. However, PBMC responses were not enhanced during lenalidomide maintenance and CD4+ T-cell responses specific for the myeloma-associated antigen MAGE-C1 even tended to become lower. We conclude that lenalidomide maintenance after autologous stem cell transplantation has complex pleotropic effects on the immune environment. Immune interventions such as anti-myeloma vaccination should include measures to tackle an expanded inhibitory Treg compartment.

Extracellular S100A9 Protein in Bone Marrow Supports Multiple Myeloma Survival by Stimulating Angiogenesis and Cytokine Secretion.

Dysregulated expression of S100 protein family members is associated with cancer proliferation, invasion, angiogenesis, and inflammation. S100A9 induces myeloid-derived suppressor cell (MDSC) accumulation and activity. MDSCs, immunosuppressive cells that contribute to tumor immune escape, are the main producers of S100A9. In this study, we evaluated the role of extracellular S100A9 and the therapeutic relevance of S100A9 inhibition in multiple myeloma (MM), using the immunocompetent murine 5T33MM model. We demonstrated the presence of S100A9 and its receptor TLR4 in both monocytic and granulocytic MDSCs in human and mouse samples. We showed that S100A9 acted as a chemoattractant for MM cells and induced MDSCs to express and secrete inflammatory and pro-myeloma cytokines, including TNFα, IL6, and IL10. Blocking S100A9 interactions in vivo with the small molecule ABR-238901 did not directly affect MDSC accumulation but did reduce IL6 and IL10 cytokine expression by MDSC. ABR-238901 treatment in vivo reduced angiogenesis but had only minor effects on tumor load as single agent (6% reduction). However, ABR-238901 treatment in combination with bortezomib resulted in an increased reduction in tumor load compared with single treatments (50% relative reduction compared with bortezomib alone). Our data suggest that extracellular S100A9 promotes MM and that inhibition of S100A9 may have therapeutic benefit. Cancer Immunol Res; 5(10); 839-46. ©2017 AACR.

Bone Marrow Metastases from a 1p/19q Co-deleted Oligodendroglioma - A Case Report.

BACKGROUND: Metastasis of oligodendroglioma outside of the central nervous system (CNS) is a very rare event. CASE: We describe in detail the clinical story of a 50-year-old woman diagnosed with profound pancytopenia and signs of extramedullary hematopoiesis caused by diffuse bone marrow replacement by a metastatic oligodendroglioma. RESULTS: Upon development of pancytopenia, a diagnostic bone marrow examination revealed the presence of metastatic oligodendroglial cells. No others sites of malignant dissemination were found outside the CNS. Despite best supportive care, the patient died three weeks after diagnosis of myelophthisis. CONCLUSION: Extracranial metastases from CNS oligodendroglioma are a very rare event but can be the cause of bone marrow failure.

An unexpected complication of chronic myelomonocytic leukemia: severe renal failure due to malignant tubulo-interstitial cell infiltration.

Acute renal failure may complicate the course of a hematologic malignancy but is a highly unusual finding in patients with chronic myelomonocytic leukemia. Kidney biopsy is rarely performed in this setting, and the pathologic substrate underlying kidney injury is not well identified. We present a case of a biopsy-proven acute tubulo-interstitial nephritis due to massive infiltration of neoplastic myelomonocytic cells. Since the leukemic process involving the kidney may respond favorably to treatment, a renal biopsy should be considered in any patient presenting with unexplained severe or evolving kidney disease.

Inhibiting the anaphase promoting complex/cyclosome induces a metaphase arrest and cell death in multiple myeloma cells.

The anaphase promoting complex/cyclosome (APC/C) is an ubiquitin ligase involved in cell cycle. During the metaphase-anaphase transition the APC/C is activated by Cdc20. The aim of this study is to elucidate the importance and therapeutic potential of APC/C and its co-activator Cdc20 in multiple myeloma (MM). Gene expression analysis revealed that Cdc20 was expressed at higher levels in gene expression-based high-risk MM patients. Moreover, high Cdc20 expression correlated with poor prognosis. Treatment of human myeloma cell lines with proTAME, an APC/C inhibitor, resulted in an accumulation of APC/CCdc20 substrate cyclin B1 and an accumulation of cells in metaphase. Moreover we observed a significant dose-dependent decrease in viability and increase in apoptosis in MM cells upon proTAME treatment. The induction of apoptosis was accompanied with caspase 3, 8, 9 and PARP cleavage. A similar metaphase arrest and induction of apoptosis were obtained with specific knockdown of Cdc20. In addition, we demonstrated the accumulation of Bim was partially responsible for the observed cell death. Combining proTAME with another APC/C inhibitor apcin or the alkylating agent melphalan resulted in enhanced anti-MM activity. This study suggests that the APC/C and its co-activator Cdc20 could be a new and promising target especially in high-risk MM patients.

The IGF-1 receptor inhibitor picropodophyllin potentiates the anti-myeloma activity of a BH3-mimetic.

The ABT-analogous 737, 263 and 199 are BH3 mimetics showing potent anti-myeloma (MM) activity, but only on defined molecular subgroups of MM patients presenting a Bcl-2high/Mcl-1low profile. IGF-1 is a major survival factor in MM regulating the expression of Bcl-2 proteins and might therefore be a resistance factor to these ABT-analogous. We first show that IGF-1 protected human MM cell lines (HMCLs) against ABT-737. Concurrently, the IGF-1 receptor inhibitor picropodophyllin (PPP) synergistically sensitized HMCL, primary human MM and murine 5T33MM cells to ABT-737 and ABT-199 by further decreasing cell viability and enhancing apoptosis. Knockdown of Bcl-2 by shRNA protected MM cells to ABT-737, while Mcl-1 shRNA sensitized the cells. PPP overcame the Bcl-2 dependency of ABT-737, but failed to completely overcome the protective effect of Mcl-1. In vivo, co-treatment of 5T33MM bearing mice significantly decreased tumor burden and prolonged overall survival both in a prophylactic and therapeutic setting. Interestingly, proteasome inhibitor resistant CD138- 5T33MM cells were more sensitive to ABT-737, whereas PPP alone targeted the CD138+ cells more effectively. After co-treatment, both subpopulations were targeted equally. Together, the combination of an IGF-1R inhibitor and an ABT-analogue displays synergistic anti-myeloma activity providing the rational for further (pre)clinical testing.

Immunomodulatory drugs improve the immune environment for dendritic cell-based immunotherapy in multiple myeloma patients after autologous stem cell transplantation.

Multiple myeloma (MM) is characterized by a malignant proliferation of plasma cells in the bone marrow with associated organ damage. Although the prognosis of MM has improved recently, the disease remains incurable for the large majority of patients. The eradication of residual disease in the bone marrow is a main target on the road toward cure. Immune cells play a role in the control of cancer and can be tools to attack residual MM cells. However, the myeloma-associated immune deficiency is a major hurdle to immunotherapy. We evaluated ex vivo the effects of low doses of the immunomodulatory drugs (IMiDs) lenalidomide and pomalidomide on several immune cell types from MM patients after autologous stem cell transplantation and with low tumor burden. We observed that these drugs increased CD4(+) and CD8(+) T-cell proliferation and cytokine production, enhanced the lytic capacity of cytotoxic T lymphocytes and reduced the suppressive effects of regulatory T cells on CD8(+) T-cell responses. In addition, we found that functional dendritic cells (DCs) can be generated from mononuclear cells from MM patients. The presence of IMiDs improved the quality of antigen-specific T cells induced or expanded by these DCs as evidenced by a higher degree of T-cell polyfunctionality. Our results provide a rationale for the design of early phase clinical studies to assess the efficacy of DC-based immunotherapy in combination with posttransplant maintenance treatment with IMiDs in MM.

Preclinical evaluation of invariant natural killer T cells in the 5T33 multiple myeloma model.

Immunomodulators have been used in recent years to reactivate host anti-tumor immunity in several hematological malignancies. This report describes the effect of activating natural killer T (NKT) cells by α-Galactosylceramide (α-GalCer) in the 5T33MM model of multiple myeloma (MM). NKT cells are T lymphocytes, co-expressing T and NK receptors, while invariant NKT cells (iNKTs) also express a unique semi-invariant TCR α-chain. We followed iNKT numbers during the development of the disease in both 5T33MM mice and MM patients and found that their numbers dropped dramatically at the end stage of the disease, leading to a loss of total IFN-γ secretion. We furthermore observed that α-GalCer treatment significantly increased the survival of 5T33MM diseased mice. Taken together, our data demonstrate for the first time the possibility of using a preclinical murine MM model to study the effects of α-GalCer and show promising results of α-GalCer treatment in a low tumor burden setting.

miR-146a inhibits cell growth, cell migration and induces apoptosis in non-small cell lung cancer cells.

Aberrant expression of microRNA-146a (miR-146a) has been reported to be involved in the development and progression of various types of cancers. However, its role in non-small cell lung cancer (NSCLC) has not been elucidated. The aim of this study was to investigate the contribution of miR-146a to various aspects of the malignant phenotype of human NSCLCs. In functional experiments, miR-146a suppressed cell growth, induced cellular apoptosis and inhibited EGFR downstream signaling in five NSCLC cell lines (H358, H1650, H1975, HCC827 and H292). miR-146a also inhibited the migratory capacity of these NSCLC cells. On the other hand, miR-146a enhanced the inhibition of cell proliferation by drugs targeting EGFR, including both TKIs (gefitinib, erlotinib, and afatinib) and a monoclonal antibody (cetuximab). These effects were independent of the EGFR mutation status (wild type, sensitizing mutation or resistance mutation), but were less potent compared to the effects of siRNA targeting of EGFR. Our results suggest that these effects of miR-146a are due to its targeting of EGFR and NF-κB signaling. We also found, in clinical formalin fixed paraffin embedded (FFPE) lung cancer samples, that low expression of miR-146a was correlated with advanced clinical TNM stages and distant metastasis in NSCLC (P<0.05). The patients with high miR-146a expression in their tumors showed longer progression-free survival (25.6 weeks in miR-146a high patients vs. 4.8 weeks in miR-146a low patients, P<0.05). miR-146a is therefore a strong candidate prognostic biomarker in NSCLC. Thus inducing miR-146a might be a therapeutic strategy for NSCLC.