Antibody-Dependent Cellular Phagocytosis by Macrophages is a Novel Mechanism of Action of Elotuzumab

Elotuzumab, a recently approved antibody for the treatment of multiple myeloma, has been shown to stimulate Fcγ receptor (FcγR)-mediated antibody-dependent cellular cytotoxicity by natural killer (NK) cells toward myeloma cells. The modulatory effects of elotuzumab on other effector cells in the tumor microenvironment, however, has not been fully explored. Antibody-dependent cellular phagocytosis (ADCP) is a mechanism by which macrophages contribute to antitumor potency of monoclonal antibodies. Herein, we studied the NK cell independent effect of elotuzumab on tumor-associated macrophages using a xenograft tumor model deficient in NK and adaptive immune cells. We demonstrate significant antitumor efficacy of single-agent elotuzumab in immunocompromised xenograft models of multiple myeloma, which is in part mediated by Fc-FcγR interaction of elotuzumab with macrophages. Elotuzumab is shown in this study to induce phenotypic activation of macrophages in vivo and mediates ADCP of myeloma cells though a FcγR-dependent manner in vitro Together, these findings propose a novel immune-mediated mechanism by which elotuzumab exerts anti-myeloma activity and helps to provide rationale for combination therapies that can enhance macrophage activity. Mol Cancer Ther; 17(7); 1454-63. ©2018 AACR.

Inhibiting the oncogenic translation program is an effective therapeutic strategy in multiple myeloma

Multiple myeloma (MM) is a frequently incurable hematological cancer in which overactivity of MYC plays a central role, notably through up-regulation of ribosome biogenesis and translation. To better understand the oncogenic program driven by MYC and investigate its potential as a therapeutic target, we screened a chemically diverse small-molecule library for anti-MM activity. The most potent hits identified were rocaglate scaffold inhibitors of translation initiation. Expression profiling of MM cells revealed reversion of the oncogenic MYC-driven transcriptional program by CMLD010509, the most promising rocaglate. Proteome-wide reversion correlated with selective depletion of short-lived proteins that are key to MM growth and survival, most notably MYC, MDM2, CCND1, MAF, and MCL-1. The efficacy of CMLD010509 in mouse models of MM confirmed the therapeutic relevance of these findings in vivo and supports the feasibility of targeting the oncogenic MYC-driven translation program in MM with rocaglates.

Prognostic role of circulating exosomal miRNAs in multiple myeloma

Exosomes, secreted by several cell types, including cancer cells, can be isolated from the peripheral blood and have been shown to be powerful markers of disease progression in cancer. In this study, we examined the prognostic significance of circulating exosomal microRNAs (miRNAs) in multiple myeloma (MM). A cohort of 156 patients with newly diagnosed MM, uniformly treated and followed, was studied. Circulating exosomal miRNAs were isolated and used to perform a small RNA sequencing analysis on 10 samples and a quantitative reverse transcription polymerase chain reaction (qRT-PCR) array on 156 samples. We studied the relationship between miRNA levels and patient outcomes, including progression-free survival (PFS) and overall survival (OS). We identified miRNAs as the most predominant small RNAs present in exosomes isolated from the serum of patients with MM and healthy controls by small RNA sequencing of circulating exosomes. We then analyzed exosomes isolated from serum samples of 156 patients using a qRT-PCR array for 22 miRNAs. Two of these miRNAs, let-7b and miR-18a, were significantly associated with both PFS and OS in the univariate analysis and were still statistically significant after adjusting for the International Staging System and adverse cytogenetics in the multivariate analysis. Our findings support the use of circulating exosomal miRNAs to improve the identification of patients with newly diagnosed MM with poor outcomes. The results require further validation in other independent prospective MM cohorts.

Genomic Aberrations in Multiple Myeloma

Multiple myeloma (MM) is a genetically complex disease. The past few years have seen an evolution in cancer research with the emergence of next-generation sequencing (NGS), enabling high throughput sequencing of tumors-including whole exome, whole genome, RNA, and single-cell sequencing as well as genome-wide association study (GWAS). A few inherited variants have been described, counting for some cases of familial disease. Hierarchically, primary events in MM can be divided into hyperdiploid (HDR) and nonhyperdiploid subtypes. HRD tumors are characterized by trisomy of chromosomes 3, 5, 7, 9, 11, 15, 19, and/or 21. Non-HRD tumors harbor IGH translocations, mainly t(4;14), t(6;14), t(11;14), t(14;16), and t(14;20). Secondary events participate to the tumor progression and consist in secondary translocation involving MYC, copy number variations (CNV) and somatic mutations (such as mutations in KRAS, NRAS, BRAF, P53). Moreover, the dissection of clonal heterogeneity helps to understand the evolution of the disease. The following review provides a comprehensive review of the genomic landscape in MM.

Epigenetics in Multiple Myeloma

Multiple myeloma is characterized by clonal proliferation of plasma cells within the bone marrow resulting in anemia, lytic bone lesions, hypercalcemia, and renal impairment. Despite advanced in our understanding of this complex disease in recent years, it is still considered an incurable malignancy. This is, in part, due to the highly heterogenous genomic and phenotypic nature of the disease, which is to date incompletely understood. It is clear that a deeper level of knowledge of the biological events underlying the development of these diseases is needed to identify new targets and generate effective novel therapies. MicroRNAs (miRNAs), which are single strand, 20-nucleotide, noncoding RNA's, are key regulators of gene expression and have been reported to exert transcriptional control in multiple myeloma. miRNAs are now recognized to play a role in many key areas such as cellular proliferation, differentiation, apoptosis and stress response. Substantial advances have been made in recent years in terms of our understanding of the biological role of miRNAs in a diverse range of hematological and solid malignancues, In multiple myeloma these advances have yielded new information of prognostic and diagnostic relevance which have helped to shed light on epigenetic regulation in this disease.

Monoclonal gammopathy: The good, the bad and the ugly

Monoclonal gammopathy of undetermined significance (MGUS) is a condition characterized by the presence of a monoclonal gammopathy (MG) in which the clonal mass has not reached a predefined state in which the condition is considered malignant. It is a precursor to conditions such as multiple myeloma or lymphoma at a rate of ~1%/year. Thus, from a hematologic standpoint, MGUS is a fairly benign condition. However, it is now recognized that organ damage resulting from just the MG without the need MM or lymphoma can occur. One of the most recognized is nephropathy secondary to monoclonal gammopathy of renal significance (MGRS). Other well-recognized conditions include neuropathies, oculopathies and dermopathies. Some conditions such as autoimmune diseases and coagulopathies are less common and recognized. Finally, systemic involvement of multiple organs is well described in several entities. In all of these conditions, the role of the MG is no longer insignificant. Thus, the term MGUS should be avoided when describing these entities.

The impact of dialysis on the survival of patients with immunoglobulin light chain (AL) amyloidosis undergoing autologous stem cell transplantation

BACKGROUND

Acute renal failure requiring dialysis is associated with high mortality during autologous stem cell transplantation (ASCT). This study examined the association between acute renal failure and mortality in immunoglobulin light chain (AL) amyloidosis during ASCT.

METHODS

Between 1996 and 2010, 408 ASCT patients were evaluated. Data were collected from electronic medical records.

RESULTS

Dialysis was performed on 72 (17.6%) patients. Eight patients started dialysis >30 days prior to ASCT (Group II), 36 started ±30 days after ASCT (Group III) and 28 initiated dialysis >1 month after ASCT (Group IV). Patients who never dialyzed were assigned to Group I. There were no significant age or sex differences. Median overall survival (OS) had not been reached in Groups I and II but was 7.0 months in Group III and 48.5 months in Group IV (P < 0.001). Treatment-related mortality (TRM) was observed in 44.4% of the patients in Group III, 6-fold higher than the next highest group (P < 0.001). The most common causes of TRM were cardiac and sepsis. In the multivariate analysis, only hypoalbuminemia (<2.5 g/dL, P < 0.001) and estimated glomerular filtration rate (eGFR) <40 mL/min/1.73 m(2) (P < 0.001) were independently associated with starting dialysis within 30 days of ASCT.

CONCLUSIONS

The study found significant differences in the OS depending on when the acute renal failure occurred. Patients who required dialysis within 30 days of ASCT had the highest rate of TRM. Screening with serum albumin and eGFR may reduce the risk.

The cancer glycome: carbohydrates as mediators of metastasis

Glycosylation is a frequent post-translational modification which results in the addition of carbohydrate determinants, "glycans", to cell surface proteins and lipids. These glycan structures form the "glycome" and play an integral role in cell-cell and cell-matrix interactions through modulation of adhesion and cell trafficking. Glycosylation is increasingly recognized as a modulator of the malignant phenotype of cancer cells, where the interaction between cells and the tumor micro-environment is altered to facilitate processes such as drug resistance and metastasis. Changes in glycosylation of cell surface adhesion molecules such as selectin ligands, integrins and mucins have been implicated in the pathogenesis of several solid and hematological malignancies, often with prognostic implications. In this review we focus on the functional significance of alterations in cancer cell glycosylation, in terms of cell adhesion, trafficking and the metastatic cascade and provide insights into the prognostic and therapeutic implications of recent findings in this fast-evolving niche.

Targeting survival and cell trafficking in multiple myeloma and Waldenstrom macroglobulinemia using pan-class I PI3K inhibitor, buparlisib

The phosphatidylinositol-3 kinase (PI3K) pathway is activated in multiple myeloma (MM) and Waldenstrom Macroglobulenima (WM), and plays a crucial role in tumor progression and drug resistance. In this study, we characterized the role of pan-class I PI3K inhibition on cell trafficking and survival of MM and WM cells. We tested the effect of pan-class I PI3K inhibition by siRNA silencing or pharmacologic inhibition with buparlisib on MM cell survival, apoptosis and cell cycle in vitro and tumor growth and mobilization of MM cells in vivo. We then evaluated buparlisib-dependent mechanisms of induced MM cell mobilization. Moreover, the effect of buparlisib on cell survival, apoptosis, and adhesion of WM cells to bone marrow stromal cells (BMSCs) has been evaluated. We showed that buparlisib induced toxicity in MM cells, supported by induction of apoptosis and cell cycle arrest. Buparlisib was also found to reduce tumor progression in vivo. Importantly, buparlisib enhanced MM cell mobilization in vivo which was driven by decreased adhesion of MM cells to BMSCs and increased chemotaxis via up-regulation of CXCR4 expression. Similar to its effects on MM cells, buparlisib also induced cell survival and apoptosis, and decreased adhesion in WM cells. These data highlight the critical contribution of class I PI3K signaling to the regulation of survival and cell dissemination in B-cell malignancies.

Abstract 4855: Proteomic characterization of the extracellular matrix in multiple myeloma

Background:

The extracellular matrix is a major component of the tumor microenvironment, contributing to the regulation of cell survival, proliferation, differentiation and metastasis. In multiple myeloma (MM) ECM components, such as integrins, fibronectin and collagens, have been shown are critical to the pathogenesis of MM and the development of drug resistance. To date, despite some knowledge of the composition of the ECM in tumors, detailed profiling of the composition of the ECM in MM has not been carried out. Recent advances in proteomics have led to the characterization of the ECM and ECM-related proteins (“matrisome”) in normal human tissues and tumors in a systematic and comprehensive approach.

Methods:

Tumor Xenograft models; MM1S-GFP-Luc+ cells (5x106) were injected intravenously into SCID-Bg mice (n=4/group) and animals underwent weekly bioluminescent imaging (BLI). Mice were sacrificed after two weeks in order to mimic early tumor development (luminescence= 1x105 p/sec/cm2/sr). and compared to mice demonstrating high tumor burden (1x108 p/sec/cm2/sr) 5 weeks post injection. Human bone marrow aspirates; Whole bone marrow was obtained from MM patients (newly diagnosed n=9, relapsed n=9) and healthy human donors (n=9) following written informed consent. Sequential extractions of whole pooled bone marrow from mice and individual bone marrow humans was performed using the CNMCS(Cytosol/Nucleus/Membrane/Cytoskeleton) Compartmental Protein Extraction Kit (Cytomol, CA). Following this, proteins underwent reversed-phase high performance liquid chromatography followed by tandem mass spectrometry (MS). Identified peptide spectra were counted as a semi quantitative measure of abundance.

Results:

We detected a total of 1202, 982 and 329 unique proteins from enriched whole bone marrow samples from relapsed patients, newly diagnosed patients and mice, respectively. Of these, critical ECM components such as laminins, matrix metalloproteinases and collagens were found to be enriched in human MM ECM in comparison to healthy donors with increased abundance apparent with disease progression in mice. Specifically Bone Marrow Proteoglycan and Proteoglycan 3 were amongst the ECM proteins significantly enriched in the ECM of newly diagnosed patients. PRG3 is a p53 responsive gene that has been demonstrated to be upregulated in apoptotic cells in several cancers, including CLL. The ECM protein Elastin, the expression of which is closely associated with the invasive/metastatic potential of various cancer types, was also upregulated in the MM ECM where it may play an important role in the tumor-ECM interaction.

Conclusions:

We have profiled the ECM in MM using mass spectrometry with a view to determining the specific components that may be important in MM disease biology. Through this approach molecular mechanisms that influence MM development and progression can be uncovered and potential targets for therapy identified.

Citation Format: Siobhan V. Glavey, Alexandra Naba, Manuela Gambella, Alberto Rocci, Antonio Sacco, John Asara, Antonio Palumbo, Richard O. Hynes, Aldo M. Roccaro, Irene M. Ghobrial. Proteomic characterization of the extracellular matrix in multiple myeloma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4855. doi:10.1158/1538-7445.AM2014-4855

AKT as a therapeutic target in multiple myeloma

INTRODUCTION

Multiple myeloma remains an incurable malignancy with poor survival. Novel therapeutic approaches capable of improving outcomes in patients with multiple myeloma are urgently required. AKT is a central node in the phosphatidylinositol-3-kinase/AKT/mammalian target of rapamycin signaling pathway with high expression in advanced and resistant multiple myeloma. AKT contributes to multiple oncogenic functions in multiple myeloma which may be exploited therapeutically. Promising preclinical data has lent support for pursuing further development of AKT inhibitors in multiple myeloma. Lead drugs are now entering the clinic.

AREAS COVERED

The rationale for AKT inhibition in multiple myeloma, pharmacological subtypes of AKT inhibitors in development, available results of clinical studies of AKT inhibitors and suitable drug partners for further development in combination with AKT inhibition in multiple myeloma are discussed.

EXPERT OPINION

AKT inhibitors are a welcome addition to the armamentarium against multiple myeloma and promising clinical activity is being reported from ongoing trials in combination with established and/or novel treatment approaches. AKT inhibitors may be set to improve patient outcomes when used in combination with synergistic drug partners.

Training for Translation – The Physician Scientist’s Career Path

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A detailed evaluation of the current renal response criteria in AL amyloidosis: is it time for a revision?

Organ response correlates with overall survival in patients with immunoglobulin light chain amyloidosis and is the goal of treatment. This study evaluates the current renal response criteria and their ability to predict overall survival. Patients with immunoglobulin light chain amyloidosis who underwent autologous stem cell transplantation between 1995 and 2010 were recruited. Eligibility criteria included >1 g/dL of proteinuria, dialysis independence at baseline and within the first year of autologous stem cell transplantation, and a minimum follow-up of 1 year. Responses were assessed by the best values after autologous stem cell transplantation. The difference between involved and uninvolved serum free light chain levels was used to determine hematologic response. Increases in serum creatinine were calculated from the highest creatinine after autologous stem cell transplantation. Inclusion and exclusion criteria were met by 141 patients. These patients had a median follow-up of 52 months. Superior overall survival was observed in patients with a >75% reduction in proteinuria and those who had a >95% reduction had additional benefits. The overall survival of patients with >50% to ≤75% proteinuria was similar to that of patients with ≤50% reduction. A rise in serum creatinine >25% was not associated with a poorer outcome in patients with a >75% reduction in proteinuria. Deeper hematologic responses were associated with higher rates of proteinuria reduction. These results suggest that further evaluation of the current renal response criteria is needed. In particular, discrimination of the renal response into complete and partial categories and modification of the serum creatinine requirement seem justified.

Posterior pharyngeal candidiasis in the absence of clinically overt oral involvement: a cross-sectional study

PURPOSE

Although oropharyngeal candidiasis is associated with inhaled corticosteroid (ICS) usage, there is sparse data on the prevalence of posterior pharyngeal candidiasis in those without any detectable oral candidiasis on clinical examination. We systematically investigated the relationship between oral candidiasis on clinical examination and the presence of posterior pharyngeal candidiasis at bronchoscopy.

METHODS

We conducted a cross-sectional study on a convenience sample of 100 patients undergoing bronchoscopy at our institution. Patients were assessed for symptoms of and risk factors for candida infection and had an examination of their oropharynx for evidence of candidiasis before bronchoscopy. They subsequently had a detailed assessment for posterior candidiasis at bronchoscopy. We performed a posteriori subgroup analysis, which focused solely on those patients on ICS maintenance therapy.

RESULTS

Median age was 54.7 (27-84) years, and 55 patients were male; 47 % of patients were on ICS, and 20 % of this cohort received recent oral corticosteroids. Twenty-eight percent of this convenience sample had posterior pharyngeal candidiasis; however, only 10.7 % (3/28) of these patients had clinically detectable oral candidiasis on clinical examination before bronchoscopy. Factors that were independently associated with the presence of pharyngeal candidiasis at bronchoscopy were OR (95 % CI) ICS usage 6.9 (2.5-19.2), particularly fluticasone usage 6.8 (2.62-17.9) and the presence of dysphonia 3.2 (1.3-8.0). In the subgroup analysis of ICS usage, posterior pharyngeal candidiasis was correlated with the presence of dysphonia but was not independently associated with fluticasone or budesonide dosage.

CONCLUSIONS

This study demonstrates that posterior pharyngeal candidiasis in the absence of clinically overt oral candidiasis is frequent amongst ICS users. A history of ICS use, particularly fluticasone usage, as well as the presence of dysphonia are associated with posterior pharyngeal candidiasis at bronchoscopy, even in the absence of clinically overt oral involvement.

Acute kidney injury during leukocyte engraftment after autologous stem cell transplantation in patients with light-chain amyloidosis

Engraftment syndrome (ES) is a complication of hematopoietic stem cell transplantation characterized by fever, rash, and non-cardiogenic pulmonary edema. Acute kidney injury (AKI) has been recognized but is considered a minor criterion in one and excluded another definition of ES. We have noted a high incidence of AKI in patients with immunoglobulin light-chain amyloidosis (AL) undergoing autologous stem cell transplant (ASCT) around the time of leukocyte engraftment. This study was conducted to further investigate the relationship between AKI and ES. Data were collected from 377 AL patients who underwent ASCT from 7/1997 to 10/2009. Patients who experienced an elevation of serum creatinine >0.5 mg/dL within 4 days of leukocyte engraftment and anyone who presented with signs associated with ES regardless of renal manifestations were included. Forty-one patients met criteria. Twelve were excluded for positive cultures (10), acute interstitial nephritis (1), and acute cellular rejection (1). In addition to AKI (93.1%), patients also exhibit fever (82.7%), hypotension (51.7%), rash (48.2%), edema (93.1%), diarrhea (69.0%), conjunctival hemorrhage (31.0%), pulmonary edema (31.0%), pulmonary hemorrhage (13.8%), and transient encephalopathy (17.2%). Patient with pulmonary involvement were more likely to require dialysis but was not statistically significant. AKI was very common during leukocyte engraftment in AL patients. While infectious etiology accounted for some of the AKI, most appeared to be associated with ES. After infection is ruled out, ES should be considered in the differential diagnosis when evaluating AKI in this population.

Umbilical artery tone in maternal obesity

BACKGROUND

The increasing prevalence of obesity constitutes a major health problem in obstetrics with implications for feto-maternal growth and wellbeing. This study investigated and compared the contractile properties of umbilical arteries excised from obese women, with those excised from women with a normal body mass index (BMI).

METHODS

Sections of umbilical artery were obtained from umbilical cord samples immediately after delivery and mounted for isometric recording in organ tissue baths under physiological conditions. Cumulative additions of 5-Hydroxytryptamine (5-HT) and Prostaglandin F-2alpha (PgF2alpha) were added in the concentration range of 1 nmol/L to 10 micromol/L. Control vessels were exposed to Krebs physiological salt solution (PSS) only. The resultant effects of each drug addition were measured using the Powerlab hardware unit.

RESULTS

5-HT exerted a significant effect on human umbilical artery tone at concentrations of 100 nmol/L, 1 micromol/L, and 10 micromol/L in normal (n = 5; P < 0.05) and obese (n = 5; P < 0.05) women. The contractile effect was significantly greater in vessels from obese women {Mean Maximum Tension (MMT) = 4.2532 g} than in those from women of normal BMI (MMT = 2.97 g; P < 0.05). PgF2alpha exerted a significant contractile effect on vessels at 1 micromol/L and 10 micromol/L concentrations when compared with controls (n = 5; P < 0.05). There was a non-significant trend towards an enhanced tone response in vessels from obese women (MMT = 3.02 g; n = 5), in comparison to vessels from women of a normal BMI (MMT = 2.358 g; n = 5; P > 0.05).

CONCLUSION

These findings support the hypothesis that endogenous regulation of umbilical artery tone is altered in association with maternal obesity. This may be linked to the cardiovascular effects of secretory products of adipose tissue, with implications for the feto-maternal circulation.

Uterorelaxant effect of ghrelin on human myometrial contractility

OBJECTIVE

Ghrelin is a peptide that regulates maternal appetite and energy expenditure as well as playing a role in fetal nutrition. The purpose of the study was to investigate the effects of ghrelin on human myometrial contractility in vitro.

STUDY DESIGN

Biopsy specimens of human myometrium were obtained at elective cesarean section (n = 21). Dissected myometrial strips suspended under isometric conditions, undergoing spontaneous and oxytocin-induced contractions, were exposed to cumulative additions of ghrelin in the concentration range of 1 nmol/L to 1 micromol/L. Control experiments were performed simultaneously.

RESULT

Ghrelin exerted an inhibitory effect on contractility, compared with control strips. The mean maximal inhibition values were as follows: 33.66% +/- 2.63% for spontaneous contractions (n = 6; P < .05), and 31.55% +/- 4.64% for oxytocin-induced contractions (n = 6; P < .05).

CONCLUSION

This inhibitory effect of ghrelin on uterine contractions suggests it plays a physiologic role in regulation of myometrial activity and further studies to evaluate the signaling pathways involved may help to define this role. These findings highlight the emerging role of metabolic modulation of myometrium, and particularly at extremes of body mass index measurements.

Inhibitory effect of leptin on human uterine contractility in vitro

OBJECTIVE

The purpose of this study was to investigate the effects of leptin on human uterine contractility in vitro.

STUDY DESIGN

Biopsies of human myometrium were obtained at elective cesarean section (n = 18). Dissected myometrial strips suspended under isometric conditions, undergoing spontaneous and oxytocin-induced contractions, were exposed to cumulative additions of leptin in the concentration range of 1 nmol/L to 1 micromol/L. Control strips were run simultaneously. Integrals of contractile activity were measured using the PowerLab hardware unit and Chart v3.6 software.

RESULTS

Leptin exerted a potent and cumulative inhibitory effect on spontaneous and oxytocin-induced contractions compared to control strips. The mean maximal inhibition values were as follows: 46.794 +/- 5.133% (n = 6; P < .001) for spontaneous contractions and 42.323 +/- 3.692% (n = 6; P < .001) for oxytocin-induced contractions. There was an apparent reduction in both frequency and amplitude of contractions.

CONCLUSION

This physiologic inhibitory effect of leptin on uterine contractility may play a role in the dysfunctional labor process associated with maternal obesity, and the resultant high cesarean section rates.