Novel approaches to treatment of double-refractory multiple myeloma

Circadian Clock REV-ERBs Agonist SR9009 Induces Synergistic Antitumor Activity in Multiple Myeloma by Suppressing Glucose-Regulated Protein 78-Dependent Autophagy and Lipogenesis

Background

Proteasome inhibitors, such as bortezomib, have demonstrated efficacy in the therapeutic management of multiple myeloma (MM). However, it is important to note that these inhibitors also elicit endoplasmic reticulum stress, which subsequently triggers the unfolded protein response (UPR) and autophagy, which have been shown to facilitate the survival of tumor cells. The disruption of the circadian clock is considered a characteristic feature of cancer. However, how disrupted circadian clock intertwines with tumor metabolism and drug resistance is not clearly clarified. This work explores the antitumor effectiveness of bortezomib and the circadian clock agonist SR9009, elucidating their impact on glucose-regulated protein 78 (GRP78), the autophagy process, and lipogenesis.

Methods

The antitumor effects of bortezomib and SR9009 were evaluated using human MM cell lines (RPMI8226 and U266) in vitro and in vivo nonobese diabetic/severe combined immunodeficient (NOD/SCID) murine xenograft MM model. The assessment of cell viability was conducted using the cell counting kit-8 (CCK8) method, whereas the measurement of cell proliferation was performed with the inclusion of EdU (5-ethynyl-2'-deoxyuridine). Apoptosis was assessed by flow cytometry. The cells were transduced using adenovirus-tf-LC3, which was labeled with dual fluorescence. Subsequently, confocal imaging was employed to observe and examine the autophagosomes. REV-ERBα knockdown leads to upregulation of ATG5 and BENC1 at the protein level with immunoblot. Changes in the expression levels of GRP78, LC3, stearoyl-CoA desaturase 1 (SCD1), and fatty acid synthase (FASN) were assessed through the utilization of quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting.

Results

Our results showed that both bortezomib and circadian clock REV-ERBs agonist SR9009 decreased MM viability, proliferation rate and induced an apoptotic response in a dose-dependent manner in vitro. However, the two differ greatly in their mechanisms of action. Bortezomib upregulated GRP78 and autophagy LC3, while circadian clock agonist SR9009 inhibited GRP78 and autophagy LC3. Combined SR9009 with bortezomib induced synergistic cytotoxicity against MM cells. REV-ERBα knockdown lead to upregulation of ATG5, BENC1 and significant upregulation of FASN, and SCD1. Mechanically, SR9009 inhibited the core autophagy gene ATG5 and BECN1, and two essential enzymes for de novo lipogenesis FASN and SCD1. SR9009 had synergistic effect with bortezomib and slowed down murine xenograft models of human MM tumor growth in vivo.

Conclusions

Taken together, these results demonstrated that the circadian clock component REV-ERBs agonist SR9009 could inhibit GRP78-induced autophagy and de novo lipogenesis processes and had a synergistic effect with proteasome inhibitors in both in vitro and in vivo models of MM. Our findings shed light on how a disrupted circadian clock interacts with metabolic mechanisms to shape proteasome inhibitor drug resistance and suggest that SR9009 may be able to overcome the inherent drug resistance of proteasome inhibitors.

Che-1/AATF-induced transcriptionally active chromatin promotes cell proliferation in multiple myeloma

Multiple myeloma (MM) is a hematologic malignancy produced by a clonal expansion of plasma cells and characterized by abnormal production and secretion of monoclonal antibodies. This pathology exhibits an enormous heterogeneity resulting not only from genetic alterations but also from several epigenetic dysregulations. Here we provide evidence that Che-1/AATF (Che-1), an interactor of RNA polymerase II, promotes MM proliferation by affecting chromatin structure and sustaining global gene expression. We found that Che-1 depletion leads to a reduction of "active chromatin" by inducing a global decrease of histone acetylation. In this context, Che-1 directly interacts with histones and displaces histone deacetylase class I members from them. Strikingly, transgenic mice expressing human Che-1 in plasma cells develop MM with clinical features resembling those observed in the human disease. Finally, Che-1 downregulation decreases BRD4 chromatin accumulation to further sensitize MM cells to bromodomain and external domain inhibitors. These findings identify Che-1 as a promising target for MM therapy, alone or in combination with bromodomain and external domain inhibitors.

Relapsed refractory multiple myeloma: a comprehensive overview

Most patients with relapsed/refractory multiple myeloma (RRMM) have been treated with drug combinations including a proteasome inhibitor (PI) and/or an immunomodulatory drug (IMiD). The goal of therapy for such patients is therefore to achieve disease control with acceptable toxicity and patient-defined decent quality of life. Physicians face a difficult task not only deciding who to treat, but also when to treat and how to treat, utilizing knowledge of previously administered therapies, patient comorbidities, potential adverse events, and patient wishes to make such a critical decision. New drugs and combination regimens are continuously underway thus broadening the options for therapy and giving way to a more individualized approach for patients with RRMM. The integration of novel agents into the treatment paradigm has shifted the perception of multiple myeloma (MM) from an incurable, fatal disease to a manageable, chronic one. This comprehensive review addresses the results and challenges posed by many of the newer agents for the treatment of RRMM. It attempts to propose a universal strategy for optimal therapy decision-making thus answering three simple fundamental questions-when to treat, how to treat, and how long to treat for.

Deptor transcriptionally regulates endoplasmic reticulum homeostasis in multiple myeloma cells

Multiple myeloma (MM) is a malignant disorder of plasma cells characterized by active production and secretion of monoclonal immunoglobulins (IgG), thus rendering cells prone to endoplasmic reticulum (ER) stress. For this reason, MM cell survival requires to maintain ER homeostasis at basal levels. Deptor is an mTOR binding protein, belonging to the mTORC1 and mTORC2 complexes. It was reported that Deptor is overexpressed in MM cells where it inhibits mTOR kinase activity and promotes cell survival by activating Akt signaling. Here we identify Deptor as a nuclear protein, able to bind DNA and regulate transcription in MM cells. In particular, we found that Deptor plays an important role in the maintenance of the ER network, sustaining the expression of several genes involved in this pathway. In agreement with this, Deptor depletion induces ER stress and synergizes the effect of the proteasome inhibitor bortezomib (Bz) in MM cells. These findings provide important new insights in the ER stress control in MM cells.

New Insights in the Cytogenetic Practice: Karyotypic Chaos, Non-Clonal Chromosomal Alterations and Chromosomal Instability in Human Cancer and Therapy Response

Recently, non-clonal chromosomal alterations previously unappreciated are being proposed to be included in cytogenetic practice. The aim of this inclusion is to obtain a greater understanding of chromosomal instability (CIN) and tumor heterogeneity and their role in cancer evolution and therapy response. Although several genetic assays have allowed the evaluation of the variation in a population of cancer cells, these assays do not provide information at the level of individual cells, therefore limiting the information of the genomic diversity within tumors (heterogeneity). The karyotype is one of the few available cytogenetic techniques that allow us not only to identify the chromosomal alterations present within a single cell, but also allows us to profile both clonal (CCA) and non-clonal chromosomal alterations (NCCAs). A greater understanding of CIN and tumor heterogeneity in cancer could not only improve existing therapeutic regimens but could also be used as targets for the design of new therapeutic approaches. In this review we indicate the importance and significance of karyotypic chaos, NCCAs and CIN in the prognosis of human cancers.

Analysis of Real-World Data on Overall Survival in Multiple Myeloma Patients With ≥3 Prior Lines of Therapy Including a Proteasome Inhibitor (PI) and an Immunomodulatory Drug (IMiD), or Double Refractory to a PI and an IMiD

BACKGROUND

This retrospective study evaluated the treatment patterns in and overall survival (OS) of multiple myeloma (MM) patients who were refractory to a proteasome inhibitor (PI) and an immunomodulatory drug (IMiD) or who had received three or more prior lines of therapy (LOTs) including a PI and an IMiD.

METHODS

Electronic health records in the IMS LifeLink and OPTUM databases were screened for indexing periods of 2000-2014 and 2007-2014, respectively. Patients who were refractory to both a PI and an IMiD (criterion 1) or who received three or more prior LOTs (including a PI and an IMiD) and showed disease progression within 60 days of their most recent regimen (criterion 2) comprised the eligible population. Median OS from time of last LOT was assessed for the full cohort, cohorts meeting criteria 1 and 2, and clinically important subgroups.

RESULTS

Of 3,929 and 3,837 patients with MM diagnoses evaluated in the IMS LifeLink and OPTUM databases, 500 and 162 met the eligibility criteria, respectively. Similar median OS was observed for eligible patients in the IMS LifeLink and OPTUM databases (7.9 vs. 7.9 months; p = .5358). In subgroup analyses of the IMS LifeLink data set, median OS was longer in patients <65 years of age than it was for those ≥65 years at eligibility (9.5 vs 6.7 months; p < .01) and in patients with good or unreported versus poor performance status at last claim (7.8 or 8.8 vs. 2.9 months; p < .0001).

CONCLUSION

The findings of this survival analysis suggest that outcomes for these patients remain poor despite the availability of newer agents.

IMPLICATIONS FOR PRACTICE

This real-world retrospective study of electronic health records examines the survival outcomes of patients with multiple myeloma who are heavily pretreated or highly refractory to currently approved treatments, including recently approved proteasome inhibitors and immunomodulatory drugs. This survival analysis showed that outcomes for these patients remain poor despite the availability of newer agents, with median overall survival of approximately 8 months. These findings highlight a critical need to develop novel therapies for these patients and also serve as a reference point against which emerging agents for heavily pretreated or highly refractory disease may be evaluated.

How I treat high-risk myeloma

The treatment of patients with myeloma has dramatically changed over the past decade due in part to the development of new agents and myeloma-specific targets. Despite these advancements, a group for whom the long-term benefit remains less clear are patients with genetically or clinically defined high-risk myeloma. In order to successfully treat these patients, it is important to first identify these patients, treat them with aggressive combination therapy, and employ the use of aggressive long-term maintenance therapy. Future directions include the use of new immune-based treatments (antibodies or cellular-based therapies) as well as target-driven approaches. Until these treatment approaches are better defined, this review will provide a potential treatment approach for standard- and high-risk myeloma that can be followed using agents and strategies that are currently available with the goal of improving progression-free and overall survival for these patients today.

Double Relapsed and/or Refractory Multiple Myeloma: Clinical Outcomes and Real World Healthcare Costs

Double relapsed and/or refractory multiple myeloma (DRMM), MM that is relapsed and/or refractory to bortezomib and lenalidomide, carries a poor prognosis. The healthcare costs of DRMM have not previously been reported. We analyzed detailed medical resource utilization (MRU) costs, drug costs and outcomes for 39 UK patients receiving standard DRMM therapy. Median OS in this cohort was 5.6 months. The mean cost of DRMM treatment plus MRU until death was £23,472 [range: £1,411-£90,262], split between drug costs £11,191 and other resource use costs £12,281. The cost per assumed quality-adjusted life year (QALY) during DRMM was £66,983. These data provide a standard of care comparison when evaluating the cost-effectiveness of new drugs in DRMM.

Identification of markers that functionally define a quiescent multiple myeloma cell sub-population surviving bortezomib treatment

Background

The mechanisms allowing residual multiple myeloma (MM) cells to persist after bortezomib (Bz) treatment remain unclear. We hypothesized that studying the biology of bortezomib-surviving cells may reveal markers to identify these cells and survival signals to target and kill residual MM cells.

Methods

We used H2B-GFP label retention, biochemical tools and in vitro and in vivo experiments to characterize growth arrest and the unfolded protein responses in quiescent Bz-surviving cells. We also tested the effect of a demethylating agent, 5-Azacytidine, on Bz-induced quiescence and whether inhibiting the chaperone GRP78/BiP (henceforth GRP78) with a specific toxin induced apoptosis in Bz-surviving cells. Finally, we used MM patient samples to test whether GRP78 levels might associate with disease progression. Statistical analysis employed t-test and Mann-Whitney tests at a 95% confidence.

Results

We report that Bz-surviving MM cells in vitro and in vivo enter quiescence characterized by p21^CIP1 upregulation. Bz-surviving MM cells also downregulated CDK6, Ki67 and P-Rb. H2B-GFP label retention showed that Bz-surviving MM cells are either slow-cycling or deeply quiescent. The Bz-induced quiescence was stabilized by low dose (500nM) of 5-azacytidine (Aza) pre-treatment, which also potentiated the initial Bz-induced apoptosis. We also found that expression of GRP78, an unfolded protein response (UPR) survival factor, persisted in MM quiescent cells. Importantly, GRP78 downregulation using a specific SubAB bacterial toxin killed Bz-surviving MM cells. Finally, quantification of Grp78^high/CD138+ MM cells from patients suggested that high levels correlated with progressive disease.

Conclusions

We conclude that Bz-surviving MM cells display a GRP78^HIGH/p21^HIGH/CDK6^LOW/P-Rb^LOW profile, and these markers may identify quiescent MM cells capable of fueling recurrences. We further conclude that Aza + Bz treatment of MM may represent a novel strategy to delay recurrences by enhancing Bz-induced apoptosis and quiescence stability.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1460-1) contains supplementary material, which is available to authorized users.

Mechanisms and clinical applications of chromosomal instability in lymphoid malignancy

Lymphocytes are unique among cells in that they undergo programmed DNA breaks and translocations, but that special property predisposes them to chromosomal instability (CIN), a cardinal feature of neoplastic lymphoid cells that manifests as whole chromosome- or translocation-based aneuploidy. In several lymphoid malignancies translocations may be the defining or diagnostic markers of the diseases. CIN is a cornerstone of the mutational architecture supporting lymphoid neoplasia, though it is perhaps one of the least understood components of malignant transformation in terms of its molecular mechanisms. CIN is associated with prognosis and response to treatment, making it a key area for impacting treatment outcomes and predicting prognoses. Here we will review the types and mechanisms of CIN found in Hodgkin lymphoma, non-Hodgkin lymphoma, multiple myeloma and the lymphoid leukaemias, with emphasis placed on pathogenic mutations affecting DNA recombination, replication and repair; telomere function; and mitotic regulation of spindle attachment, centrosome function, and chromosomal segregation. We will discuss the means by which chromosome-level genetic aberrations may give rise to multiple pathogenic mutations required for carcinogenesis and conclude with a discussion of the clinical applications of CIN and aneuploidy to diagnosis, prognosis and therapy.

Managing multiple myeloma in the over 70s: a review

Multiple myeloma (MM) remains an incurable malignancy. Approximately 37% of patients with plasma cell myeloma are over the age of 75 and the median age of diagnosis is 70. The management approach to over 70s differs from younger patients, as treatment goals may vary and underlying co-morbidities and expected treatment related toxicities have to be taken into account. Individualisation of management is important, aiming to achieve the best response whilst minimising adverse events. A proportion of patients will be unable to tolerate any treatment with palliation being appropriate. Age alone should not be a barrier to treatment however, with some fit patients over the age of 70 potentially benefitting from intensive treatment options including high dose chemotherapy with autologous stem cell rescue. Comprehensive geriatric assessment is indicated in the over 70s; this should be employable in a clinic outpatient setting to make it feasible. Outcomes of this assessment potentially help physicians' choice of therapy. For decades the combination of Melphalan and prednisolone was the standard of care for older MM patients. Over the last ten years, newer drugs and combinations have improved therapeutic options for patients but are yet to demonstrate vast improvement in overall survival in this cohort.

Leveraging the new with the old: providing a framework for the integration of historic microarray studies with next generation sequencing

Next Generation Sequencing (NGS) methods are rapidly providing remarkable advances in our ability to study the molecular profiles of human cancers. However, the scientific discovery offered by NGS also includes challenges concerning the interpretation of large and non-trivial experimental results. This task is potentially further complicated when a multitude of molecular profiling modalities are available, with the goal of a more integrative and comprehensive analysis of the cancer biology.

Microarray transcriptome analyses have resulted in important advances in both the scientific and clinical domains of biomedicine. Importantly, as technology advances, it is critical to leverage what has been gained from historic approaches (e.g., microarrays) with new approaches (NGS). In this regard, necessity dictated a need to utilize and leverage the many years of historical microarray data with new NGS approaches. This is especially important since NGS approaches are now entering clinical medicine. For instance, NGS-based comprehensive analysis of certain cancers has already helped to uncover specific mutations that contribute to the malignant process, identify new therapeutic targets, and improve opportunities for choosing the best treatment for an individual patient.

A suite of custom software tools have been developed to rapidly integrate, explore, discover and validate molecular profiling data from the NGS modalities of Whole Exome Sequencing (WES) and RNA-seq with each other, as well as with historical microarray and salient clinical datasets. Importantly, our approach is independent of any particular type of NGS suite(s) or cancer types. This novel bioinformatic framework is now assisting with the scientific and clinical management of patients with multiple myeloma.

The glutathione synthesis inhibitor buthionine sulfoximine synergistically enhanced melphalan activity against preclinical models of multiple myeloma

Melphalan (L-PAM) has been an integral part of multiple myeloma (MM) treatment as a conditioning regimen before stem cell transplant (SCT). After initial response, most treated patients experience relapse with an aggressive phenotype. Increased glutathione (GSH) in MM may mediate resistance to L-PAM. We demonstrated that the GSH synthesis inhibitor buthionine sulfoximine (BSO) synergistically enhanced L-PAM activity (inducing 2–4 logs of cell kill) against nine MM cell lines (also in the presence of marrow stroma or cytokines) and in seven primary MM samples (combination indices <1.0). In MM cell lines, BSO significantly (P<0.05) depleted GSH, increased L-PAM-induced single-strand DNA breaks, mitochondrial depolarization, caspase cleavage and apoptosis. L-PAM depleted GSH, but GSH rapidly recovered in a L-PAM-resistant MM cell line unless also treated with BSO. Treatment with N-acetylcysteine antagonized BSO+L-PAM cytotoxicity without increasing GSH. In human MM xenografted into beige-nude-xid mice, BSO significantly depleted MM intracellular GSH and significantly increased apoptosis compared with L-PAM alone. BSO+L-PAM achieved complete responses (CRs) in three MM xenograft models including maintained CRs >100 days, and significantly increased the median event-free survival relative to L-PAM alone. Combining BSO with L-PAM warrants clinical testing in advanced MM.

Aseptic necrosis at multiple localisations in a lupus patient with lymphoma

Avascular or aseptic necrosis is a well-defined entity leading to the degradation of cellular elements of the bone. The pathogenesis of osteonecrosis (ON) is still unknown. There are two main types of ON: traumatic or non-traumatic. Several clinical entities could associate with ON, systemic diseases, environmental factors, pregnancy, systemic autoimmune or rheumatic diseases, thrombophilia, corticosteroid therapy, cytotoxic dugs, infections, metabolic and hematologic diseases, etc. Corticosteroids (CS) are still the most frequently used therapeutic options in the early phase and during flares of these diseases. Inflammatory cytokines and antibodies have been described to participate in the pathogenesis of ON. The infiltrative disorders of the bone marrow could also contribute to the development of ON. Hereby, we describe a female patient with NHL followed by SLE in whom ON has developed at least in two localisations. Lupus flare, long-term CS therapy, lymphoma relapse or the presence of antiphospholipid antibodies were excluded. Although the bi-localised ON could be contributed to immunologic factors or trauma, the exact aetiology in this case could not be elucidated.