Thalidomide and its analogs overcome drug resistance of human multiple myeloma cells to conventional therapy

Role of Immune Cells and Immunotherapy in Multiple Myeloma

The clinical signs of multiple myeloma, a plasma cell (PC) dyscrasia, include bone loss, renal damage, and paraproteinemia. It can be defined as the uncontrolled growth of malignant PCs within the bone marrow. The distinctive bone marrow milieu that regulates the progression of myeloma disease involves interactions between plasma and stromal cells, and myeloid and lymphoid cells. These cells affect the immune system independently or because of a complicated web of interconnections, which promotes disease development and immune evasion. Due to the importance of these factors in the onset of disease, various therapeutic strategies have been created that either target or improve the immunological processes that influence disease progression. The immune system has a role in the mechanism of action of multiple myeloma treatments. The main contributions of immune cells to the bone marrow microenvironment, as well as how they interact and how immune regulation might lead to therapeutic effects, are covered in this study.

Improved Side Effect Profile of Alternate-Day Dosing of Lenalidomide

Myelodysplastic syndrome (MDS) is a heterogeneous hematological condition associated with cytopenia, inadequate blood cell synthesis, and the risk of developing acute myeloid leukemia (AML). Patients are divided into risk groups according to the International Prognostic Scoring System (IPSS) to help direct therapy. Allogeneic stem cell transplantation, despite its limitations, is curative. Medical management, such as the use of lenalidomide, has potential benefits but can cause adverse effects that require dose regimen modification. Lenalidomide is approved for low-risk MDS with 5q deletion (5q- MDS). In this case study, a 79-year-old woman with 5q- MDS was switched from a daily regimen to an alternate-day lenalidomide dose schedule to achieve complete remission with fewer adverse effects. The management of hematological toxicity and the mechanisms of action of lenalidomide are discussed. We recommend individualized treatment strategies and additional research to improve MDS management.

Cereblon influences the timing of muscle differentiation in Ciona tadpoles

Thalidomide has a dark history as a teratogen, but in recent years, its derivates have been shown to function as potent chemotherapeutic agents. These drugs bind cereblon (CRBN), the substrate receptor of an E3 ubiquitin ligase complex, and modify its degradation targets. Despite these insights, remarkably little is known about the normal function of cereblon in development. Here, we employ Ciona, a simple invertebrate chordate, to identify endogenous Crbn targets. In Ciona, Crbn is specifically expressed in developing muscles during tail elongation before they acquire contractile activity. Crbn expression is activated by Mrf, the ortholog of MYOD1, a transcription factor important for muscle differentiation. CRISPR/Cas9-mediated mutations of Crbn lead to precocious onset of muscle contractions. By contrast, overexpression of Crbn delays contractions and is associated with decreased expression of contractile protein genes such as troponin. This reduction is possibly due to reduced Mrf protein levels without altering Mrf mRNA levels. Our findings suggest that Mrf and Crbn form a negative feedback loop to control the precision of muscle differentiation during tail elongation.

Plausibility of natural immunomodulators in the treatment of COVID-19-A comprehensive analysis and future recommendations

The COVID-19 pandemic has inflicted millions of deaths worldwide. Despite the availability of several vaccines and some special drugs approved for emergency use to prevent or treat this disease still, there is a huge concern regarding their effectiveness, adverse effects, and most importantly, their efficacy against the new variants. A cascade of immune-inflammatory responses is involved with the pathogenesis and severe complications with COVID-19. People with dysfunctional and compromised immune systems display severe complications, including acute respiratory distress syndrome, sepsis, multiple organ failure etc., when they get infected with the SARS-CoV-2 virus. Plant-derived natural immune-suppressant compounds, such as resveratrol, quercetin, curcumin, berberine, luteolin, etc., have been reported to inhibit pro-inflammatory cytokines and chemokines. Therefore, natural products with immunomodulatory and anti-inflammatory potential could be plausible targets to treat this contagious disease. This review aims to delineate the clinical trials status and outcomes of natural compounds with immunomodulatory potential in COVID-19 patients along with the outcomes of their in-vivo studies. In clinical trials several natural immunomodulators resulted in significant improvement of COVID-19 patients by diminishing COVID-19 symptoms such as fever, cough, sore throat, and breathlessness. Most importantly, they reduced the duration of hospitalization and the need for supplemental oxygen therapy, improved clinical outcomes in patients with COVID-19, especially weakness, and eliminated acute lung injury and acute respiratory distress syndrome. This paper also discusses many potent natural immunomodulators yet to undergo clinical trials. In-vivo studies with natural immunomodulators demonstrated reduction of a wide range of proinflammatory cytokines. Natural immunomodulators that were found effective, safe, and well tolerated in small-scale clinical trials are warranted to undergo large-scale trials to be used as drugs to treat COVID-19 infections. Alongside, compounds yet to test clinically must undergo clinical trials to find their effectiveness and safety in the treatment of COVID-19 patients.

Evidence-based mechanisms of synergy with IMiD agent-based combinations in multiple myeloma

Treatment of multiple myeloma (MM) has seen great advances in recent years, and a key contributor to this change has been the effective use of combination therapies, which have improved both the depth and duration of patient responses. IMiD agents (lenalidomide and pomalidomide) have both tumoricidal and immunostimulatory functions, and due to their multiple mechanisms of action have become the backbone of numerous combination treatments in the newly diagnosed and relapsed/refractory settings. Although IMiD agent-based combination regimens provide improved clinical outcomes for patients with MM, the mechanisms underpinning these combinations are not well understood. In this review we describe the potential mechanisms of synergy leading to the enhanced activity observed when IMiD agents and other drug classes are used in combination through interrogation of the current knowledge surrounding their mechanism of actions.

Lenalidomide in Multiple Myeloma: Review of Resistance Mechanisms, Current Treatment Strategies and Future Perspectives

Multiple myeloma (MM) is the second most common hematologic malignancy, accounting for approximately 1% of all cancers. Despite the initial poor prognosis for MM patients, their life expectancy has improved significantly with the development of novel agents. Immunomodulatory drugs (IMiDs) are widely used in MM therapy. Their implementation has been a milestone in improving the clinical outcomes of patients. The first molecule belonging to the IMiDs was thalidomide. Subsequently, its novel derivatives, lenalidomide (LEN) and pomalidomide (POM), were implemented. Almost all MM patients are exposed to LEN, which is the most commonly used IMiD. Despite the potent anti-MM activity of LEN, some patients eventually relapse and become LEN-resistant. Drug resistance is one of the greatest challenges of modern oncology and has become the main cause of cancer treatment failures. The number of patients receiving LEN is increasing, hence the problem of LEN resistance has become a great obstacle for hematologists worldwide. In this review, we intended to shed more light on the pathophysiology of LEN resistance in MM, with particular emphasis on the molecular background. Moreover, we have briefly summarized strategies to overcome LEN resistance and we have outlined future directions.

A phase II multi-arm study of magrolimab combinations in patients with relapsed/refractory multiple myeloma

Magrolimab is a monoclonal antibody that blocks CD47, a 'do not eat me' signal overexpressed on tumor cells. CD47 is overexpressed in multiple myeloma (MM), which contributes to its pathogenesis. Preclinical studies have shown that CD47 blockade induces macrophage activation, resulting in elimination of myeloma cells, and that there is synergy between magrolimab and certain anticancer therapies. These findings suggest that magrolimab-based combinations may have a therapeutic benefit in MM. This phase II study investigates magrolimab in combination with commonly used myeloma therapies in patients with relapsed/refractory MM and includes a safety run-in phase followed by a dose-expansion phase. Primary end points include the incidence of dose-limiting toxicities and adverse events (safety run-in) and the objective response rate (dose expansion).

Mechanism of immunomodulatory drug resistance and novel therapeutic strategies in multiple myeloma

OBJECTIVE

The mechanism of immunomodulatory drugs (IMiDs) resistance to multiple myeloma (MM) cells has been gradually demonstrated by recently studies, and some potential novel strategies have been confirmed to have antimyeloma activity and be associated with IMiD activity in MM.

METHODS

This article searched the Pubmed library, reviewed some recently studies related to IMiD resistance to MM cells and summarized some potent agents to improve IMiD resistance to MM cells.

RESULTS

Studies have confirmed that cereblon is a primary direct protein target of IMiDs. IRF4 not only is affected by the IKZF protein but also can directly inhibit the expression of BMF and BIM, thereby promoting the survival of MM cells. Additionally, the expression of IRF4 and MYC also plays an important role in three important signaling pathways (Wnt, STAT3 and MAPK/ERK) related to IMiD resistance. Notably, MYC, a downstream factor of IRF4, may be upregulated by BRD4, and upregulation of MYC promotes cell proliferation in MM and disease progression. Recently, some novel therapeutic agents targeting BRD4, a histone modification-related 'reader' of epigenetic marks, or other important factors (e.g. TAK1) in relevant signaling pathways have been developed and they may provide new options for relapse/refractory MM therapy, such as BET inhibitors, CBP/EP300 inhibitors, dual-target BET-CBP/EP300 inhibitors, TAK1 inhibitors, and they may provide new options for relapsed/refractory MM therapy.

CONCLUSIONS

Accumulated studies have revealed that some key factors associated with the mechanism of IMiD resistance to MM cells. Some agents represent promising new therapeutics of MM to regulate the IRF4/MYC axis by inhibiting BRD4 expression or signaling pathway activation.

Reshaping the tumor microenvironment: The versatility of immunomodulatory drugs in B-cell neoplasms

Immunomodulatory drugs (IMiDs) such as thalidomide, lenalidomide and pomalidomide are antitumor compounds that have direct tumoricidal activity and indirect effects mediated by multiple types of immune cells in the tumor microenvironment (TME). IMiDs have shown remarkable therapeutic efficacy in a set of B-cell neoplasms including multiple myeloma, B-cell lymphomas and chronic lymphocytic leukemia. More recently, the advent of immunotherapy has revolutionized the treatment of these B-cell neoplasms. However, the success of immunotherapy is restrained by immunosuppressive signals and dysfunctional immune cells in the TME. Due to the pleiotropic immunobiological properties, IMiDs have shown to generate synergetic effects in preclinical models when combined with monoclonal antibodies, immune checkpoint inhibitors or CAR-T cell therapy, some of which were successfully translated to the clinic and lead to improved responses for both first-line and relapsed/refractory settings. Mechanistically, despite cereblon (CRBN), an E3 ubiquitin ligase, is considered as considered as the major molecular target responsible for the antineoplastic activities of IMiDs, the exact mechanisms of action for IMiDs-based TME re-education remain largely unknown. This review presents an overview of IMiDs in regulation of immune cell function and their utilization in potentiating efficacy of immunotherapies across multiple types of B-cell neoplasms.

What's Old is New: The Past, Present and Future Role of Thalidomide in the Modern-Day Management of Multiple Myeloma

Immunomodulatory drugs (IMiDs) have become an integral part of therapy for both newly diagnosed and relapsed/refractory multiple myeloma (RRMM). IMiDs bind to cereblon, leading to the degradation of proteins involved in B-cell survival and proliferation. Thalidomide, a first-generation IMiD, has little to no myelosuppressive potential, negligible renal clearance, and long-proven anti-myeloma activity. However, thalidomide's adverse effects (e.g., somnolence, constipation, and peripheral neuropathy) and the advent of more potent therapeutic options has led to the drug being less frequently used in many countries, including the US and Canada. Newer-generation IMiDs, such as lenalidomide and pomalidomide, are utilized far more frequently. In numerous previous trials, salvage therapy with thalidomide (50-200 mg/day) plus corticosteroids (with or without selected cytotoxic or targeted agents) has been shown to be effective and well-tolerated in the RRMM setting. Hence, thalidomide-based regimens remain important alternatives for heavily pretreated patients, especially for those who have no access to novel therapies and/or are not eligible for their use (due to renal failure, high-grade myelosuppression, or significant comorbidities). Ongoing and future trials may provide further insights into the current role of thalidomide, especially by comparing thalidomide-containing regimens with protocols based on newer-generation IMiDs and by investigating thalidomide's association with novel therapies (e.g., antibody-drug conjugates, bispecific antibodies, and chimeric antigen receptor T cells).

Metabolic Vulnerabilities in Multiple Myeloma

Multiple myeloma (MM) remains an incurable malignancy with eventual emergence of refractory disease. Metabolic shifts, which ensure the availability of sufficient energy to support hyperproliferation of malignant cells, are a hallmark of cancer. Deregulated metabolic pathways have implications for the tumor microenvironment, immune cell function, prognostic significance in MM and anti-myeloma drug resistance. Herein, we summarize recent findings on metabolic abnormalities in MM and clinical implications driven by metabolism that may consequently inspire novel therapeutic interventions. We highlight some future perspectives on metabolism in MM and propose potential targets that might revolutionize the field.

Mcl-1 Inhibition: Managing Malignancy in Multiple Myeloma

Multiple myeloma (MM) is a plasma cells neoplasm. The overexpression of Bcl-2 family proteins, particularly myeloid cell leukemia 1 (Mcl-1), plays a critical role in the pathogenesis of MM. The overexpression of Mcl-1 is associated with drug resistance and overall poor prognosis of MM. Thus, inhibition of the Mcl-1 protein considered as a therapeutic strategy to kill the myeloma cells. Over the last decade, the development of selective Mcl-1 inhibitors has seen remarkable advancement. This review presents the critical role of Mcl-1 in the progression of MM, the most prominent BH3 mimetic and semi-BH3 mimetic that selectively inhibit Mcl-1, and could be used as single agent or combined with existing therapies.

ERK signaling mediates resistance to immunomodulatory drugs in the bone marrow microenvironment

Immunomodulatory drugs (IMiDs) have markedly improved patient outcome in multiple myeloma (MM); however, resistance to IMiDs commonly underlies relapse of disease. Here, we identify that tumor necrosis factor (TNF) receptor-associated factor 2 (TRAF2) knockdown (KD)/knockout (KO) in MM cells mediates IMiD resistance via activation of noncanonical nuclear factor κB (NF-κB) and extracellular signal-regulated kinase (ERK) signaling. Within MM bone marrow (BM) stromal cell supernatants, TNF-α induces proteasomal degradation of TRAF2, noncanonical NF-κB, and downstream ERK signaling in MM cells, whereas interleukin-6 directly triggers ERK activation. RNA sequencing of MM patient samples shows nearly universal ERK pathway activation at relapse on lenalidomide maintenance therapy, confirming its clinical relevance. Combination MEK inhibitor treatment restores IMiD sensitivity of TRAF2 KO cells both in vitro and in vivo. Our studies provide the framework for clinical trials of MEK inhibitors to overcome IMiD resistance in the BM microenvironment and improve patient outcome in MM.

Pomalidomide Plus Low-Dose Dexamethasone in Relapsed/Refractory Multiple Myeloma Patients: Results of the Real-World "POWERFUL" Study

The “POWERFUL” multicenter, retrospective, and prospective study investigated the effectiveness of pomalidomide plus low-dose dexamethasone (POM/LoDex) therapy in relapsed/refractory multiple myeloma in routine care in Greece. Ninety-nine eligible adult patients treated with POM/LoDex according to the approved label after having received ≥2 prior therapies, including lenalidomide and bortezomib, were consecutively enrolled between 16 November 2017 and 21 February 2019 in 18 hematology departments. Fifty patients (50.5%) started POM/LoDex as third-line treatment. During the treatment period (median: 8.3 months; range: 0.3–47.6 months), the median POM dose was 4 mg/day, and 31.3% of the patients received additional antimyeloma agents. The overall response rate was 32.3%. During a median follow-up period of 13.8 months (Kaplan–Meier estimate), the median progression-free survival (PFS) was 10.5 months (95% CI: 7.4–14.4). The PFS was not significantly different between patients receiving POM/LoDex in the third versus later line of therapy, nor between patients receiving concomitant antimyeloma therapy versus POM/LoDEx doublet. During the prospective safety data collection period (median: 7.6 months) among patients with prospective follow-up (N = 75), POM-related adverse event incidence rate was 42.7% (serious: 18.7%; grade  ≥  3 hematological POM-related adverse events: 8.0%). Only neutropenia (13.3%) was reported at a frequency ≥10%. In conclusion, in this real-world study, POM/LoDex displayed a long PFS with no new safety signals emerging.

Understanding the Role of T-Cells in the Antimyeloma Effect of Immunomodulatory Drugs

Immunomodulatory drugs (IMiDs) are effective treatments for patients with multiple myeloma. IMiDs have pleotropic effects including targeting the myeloma cells directly, and improving the anti-myeloma immune response. In the absence of myeloma cells, lenalidomide and pomalidomide induce CD4⁺ T cell secretion of IL-2 and indirect activation of Natural Killer (NK) cells. In the context of T cell receptor ligation, IMiDs enhance T cell proliferation, cytokine release and Th1 responses, both in vivo and in vitro. Furthermore, combination treatment of IMiDs and myeloma-targeting monoclonal antibodies eg. daratumumab (anti-CD38) and elotuzumab (anti-SLAMF7), checkpoint inhibitors, or bispecific T cell engagers showed synergistic effects, mainly via enhanced T and NK cell dependent cellular toxicity and T cell proliferation. Conversely, the corticosteroid dexamethasone can impair the immune modulatory effects of IMiDs, indicating that careful choice of myeloma drugs in combination with IMiDs is key for the best anti-myeloma therapeutic efficacy. This review presents an overview of the role for T cells in the overall anti-myeloma effects of immunomodulatory drugs.

Phenotypic screening with target identification and validation in the discovery and development of E3 ligase modulators

The use of phenotypic screening was central to the discovery and development of novel thalidomide analogs, the IMiDs (immunomodulatory drugs) agents. With the discovery that these agents bind the E3 ligase, CRL4^CRBN, and alter its substrate specificity, there has been a great deal of endeavor to discover other small molecules that can modulate alternative E3 ligases. Furthermore, the chemical properties necessary for drug discovery and the rules by which neo-substrates are selected for degradation are being defined in the context of phenotypic alterations in specific cellular systems. This review gives a detailed summary of these recent advances and the methodologies being exploited to understand the mechanism of action of emerging protein degradation therapies.

Multi-omics tumor profiling technologies to develop precision medicine in multiple myeloma

Multiple myeloma (MM), the second most common hematologic cancer, is caused by accumulation of aberrant plasma cells in the bone marrow. Its molecular causes are not fully understood and its great heterogeneity among patients complicates therapeutic decision-making. In the past decades, development of new therapies and drugs have significantly improved survival of MM patients. However, resistance to drugs and relapse remain the most common causes of mortality and are the major challenges to overcome. The advent of high throughput omics technologies capable of analyzing big amount of clinical and biological data has changed the way to diagnose and treat MM. Integration of omics data (gene mutations, gene expression, epigenetic information, and protein and metabolite levels) with clinical histories of thousands of patients allows to build scores to stratify the risk at diagnosis and predict the response to treatment, helping clinicians to make better educated decisions for each particular case. There is no doubt that the future of MM treatment relies on personalized therapies based on predictive models built from omics studies. This review summarizes the current treatments and the use of omics technologies in MM, and their importance in the implementation of personalized medicine.

Thalidomide and its metabolite 5-hydroxythalidomide induce teratogenicity via the cereblon neosubstrate PLZF

Thalidomide causes teratogenic effects by inducing protein degradation via cereblon (CRBN)-containing ubiquitin ligase and modification of its substrate specificity. Human P450 cytochromes convert thalidomide into two monohydroxylated metabolites that are considered to contribute to thalidomide effects, through mechanisms that remain unclear. Here, we report that promyelocytic leukaemia zinc finger (PLZF)/ZBTB16 is a CRBN target protein whose degradation is involved in thalidomide- and 5-hydroxythalidomide-induced teratogenicity. Using a human transcription factor protein array produced in a wheat cell-free protein synthesis system, PLZF was identified as a thalidomide-dependent CRBN substrate. PLZF is degraded by the ubiquitin ligase CRL4CRBN in complex with thalidomide, its derivatives or 5-hydroxythalidomide in a manner dependent on the conserved first and third zinc finger domains of PLZF. Surprisingly, thalidomide and 5-hydroxythalidomide confer distinctly different substrate specificities to mouse and chicken CRBN, and both compounds cause teratogenic phenotypes in chicken embryos. Consistently, knockdown of Plzf induces short bone formation in chicken limbs. Most importantly, degradation of PLZF protein, but not of the known thalidomide-dependent CRBN substrate SALL4, was induced by thalidomide or 5-hydroxythalidomide treatment in chicken embryos. Furthermore, PLZF overexpression partially rescued the thalidomide-induced phenotypes. Our findings implicate PLZF as an important thalidomide-induced CRBN neosubstrate involved in thalidomide teratogenicity.

CC-90009, a novel cereblon E3 ligase modulator, targets acute myeloid leukemia blasts and leukemia stem cells

A number of clinically validated drugs have been developed by repurposing the CUL4-DDB1-CRBN-RBX1 (CRL4CRBN) E3 ubiquitin ligase complex with molecular glue degraders to eliminate disease-driving proteins. Here, we present the identification of a first-in-class GSPT1-selective cereblon E3 ligase modulator, CC-90009. Biochemical, structural, and molecular characterization demonstrates that CC-90009 coopts the CRL4CRBN to selectively target GSPT1 for ubiquitination and proteasomal degradation. Depletion of GSPT1 by CC-90009 rapidly induces acute myeloid leukemia (AML) apoptosis, reducing leukemia engraftment and leukemia stem cells (LSCs) in large-scale primary patient xenografting of 35 independent AML samples, including those with adverse risk features. Using a genome-wide CRISPR-Cas9 screen for effectors of CC-90009 response, we uncovered the ILF2 and ILF3 heterodimeric complex as a novel regulator of cereblon expression. Knockout of ILF2/ILF3 decreases the production of full-length cereblon protein via modulating CRBN messenger RNA alternative splicing, leading to diminished response to CC-90009. The screen also revealed that the mTOR signaling and the integrated stress response specifically regulate the response to CC-90009 in contrast to other cereblon modulators. Hyperactivation of the mTOR pathway by inactivation of TSC1 and TSC2 protected against the growth inhibitory effect of CC-90009 by reducing CC-90009-induced binding of GSPT1 to cereblon and subsequent GSPT1 degradation. On the other hand, GSPT1 degradation promoted the activation of the GCN1/GCN2/ATF4 pathway and subsequent apoptosis in AML cells. Collectively, CC-90009 activity is mediated by multiple layers of signaling networks and pathways within AML blasts and LSCs, whose elucidation gives insight into further assessment of CC-90009s clinical utility. These trials were registered at www.clinicaltrials.gov as #NCT02848001 and #NCT04336982).

Immunotherapy and Immunomodulation in Myeloproliferative Neoplasms

Myeloproliferative neoplasms are characterized by chronic inflammation. The discovery of constitutively active JAK-STAT signaling associated with driver mutations has led to clinical and translational breakthroughs. Insights into the other pathways and novel factors of potential importance are being actively investigated. Various classes of agents with immunomodulating or immunosuppressive properties have been used with varying degrees of success in treating myeloproliferative neoplasms. Early clinical trials are investigating the feasibility, effectiveness, and safety of immune checkpoint inhibitors, cell-based immunotherapies, and SMAC mimetics. The dynamic landscape of immunotherapy and immunomodulation in myeloproliferative neoplasms is the topic of the present review.

Pomalidomide restores immune recognition of primary effusion lymphoma through upregulation of ICAM-1 and B7-2

Pomalidomide (Pom) is an immunomodulatory drug that has efficacy against Kaposi’s sarcoma, a tumor caused by Kaposi’s sarcoma-associated herpesvirus (KSHV). Pom also induces direct cytotoxicity in primary effusion lymphoma (PEL), a B-cell malignancy caused by KSHV, in part through downregulation of IRF4, cMyc, and CK1α as a result of its interaction with cereblon, a cellular E3 ubiquitin ligase. Additionally, Pom can reverse KSHV-induced downregulation of MHCI and co-stimulatory immune surface molecules ICAM-1 and B7-2 on PELs. Here, we show for the first time that Pom-induced increases in ICAM-1 and B7-2 on PEL cells lead to an increase in both T-cell activation and NK-mediated cytotoxicity against PEL. The increase in T-cell activation can be prevented by blocking ICAM-1 and/or B7-2 on the PEL cell surface, suggesting that both ICAM-1 and B7-2 are important for T-cell co-stimulation by PELs. To gain mechanistic insights into Pom’s effects on surface markers, we generated Pom-resistant (PomR) PEL cells, which showed about 90% reduction in cereblon protein level and only minimal changes in IRF4 and cMyc upon Pom treatment. Pom no longer upregulated ICAM-1 and B7-2 on the surface of PomR cells, nor did it increase T-cell and NK-cell activation. Cereblon-knockout cells behaved similarly to the pomR cells upon Pom-treatment, suggesting that Pom’s interaction with cereblon is necessary for these effects. Further mechanistic studies revealed PI3K signaling pathway as being important for Pom-induced increases in these molecules. These observations provide a rationale for the study of Pom as therapy in treating PEL and other KSHV-associated tumors.

Primary effusion lymphoma (PEL) is an aggressive B-cell lymphoma caused by Kaposi’s sarcoma-associated herpesvirus (KSHV). KSHV encodes various genes that enable infected cells to evade recognition and elimination by the immune system. PEL cells are poorly recognized by T-cells and NK cells, partly due to KSHV-induced downregulation of immune stimulatory surface molecules ICAM-1 and B7-2. We previously found that a cereblon-binding immunomodulatory drug pomalidomide (Pom) can restore the levels of these markers on PELs. Here, we show that the increases in ICAM-1 and B7-2 induced by Pom leads to a functional increase in the recognition and killing of PELs by both T-cells and NK cells. Further, exposure of both the PEL cells and T-cells to Pom lead to an even higher T-cell stimulation providing strong evidence that Pom could help PEL patients by providing specific immune-stimulatory effect. We further perform mechanistic studies and show that Pom’s cellular binding partner cereblon as well as the PI3K pathway are important for Pom-mediated increases in these surface markers.

Oncolytic herpes simplex virus type 1 (HSV-1) in combination with lenalidomide for plasma cell neoplasms

Oncolytic viruses exert an anti-tumour effect through two mechanisms: direct oncolytic and indirect immune-mediated mechanisms. Although oncolytic herpes simplex virus type 1 (HSV-1) has been approved for melanoma treatment and is being examined for its applicability to a broad spectrum of malignancies, it is not known whether it has an anti-myeloma effect. In the present study, we show that the third-generation oncolytic HSV-1, T-01, had a direct oncolytic effect on five of six human myeloma cell lines in vitro. The anti-tumour effect was enhanced in the presence of peripheral blood mononuclear cells (PBMCs) from healthy individuals and, to a lesser extent, from patients with myeloma. The enhancing effect of PBMCs was abrogated by blocking type I interferons (IFNs) or by depleting plasmacytoid dendritic cells (pDCs) or natural killer (NK) cells, suggesting that pDC-derived type I IFNs and NK cells dominated the anti-tumour effect. Furthermore, the combination of T-01 and lenalidomide exhibited enhanced cytotoxicity, and the triple combination of T-01, lenalidomide and IFN-α had a maximal effect. These data indicate that oncolytic HSV-1 represents a viable therapy for plasma cell neoplasms through direct oncolysis and immune activation governed by pDCs and NK cells. Lenalidomide is likely to augment the anti-myeloma effect of HSV-1.

Actors on the Scene: Immune Cells in the Myeloma Niche

Two mechanisms are involved in the immune escape of cancer cells: the immunoediting of tumor cells and the suppression of the immune system. Both processes have been revealed in multiple myeloma (MM). Complex interactions between tumor plasma cells and the bone marrow (BM) microenvironment contribute to generate an immunosuppressive milieu characterized by high concentration of immunosuppressive factors, loss of effective antigen presentation, effector cell dysfunction, and expansion of immunosuppressive cell populations, such as myeloid-derived suppressor cells, regulatory T cells and T cells expressing checkpoint molecules such as programmed cell death 1. Considering the great immunosuppressive impact of BM myeloma microenvironment, many strategies to overcome it and restore myeloma immunosurveillance have been elaborated. The most successful ones are combined approaches such as checkpoint inhibitors in combination with immunomodulatory drugs, anti-monoclonal antibodies, and proteasome inhibitors as well as chimeric antigen receptor (CAR) T cell therapy. How best to combine anti-MM therapies and what is the optimal timing to treat the patient are important questions to be addressed in future trials. Moreover, intratumor MM heterogeneity suggests the crucial importance of tailored therapies to identify patients who might benefit the most from immunotherapy, reaching deeper and more durable responses.

Immunotherapeutic and Targeted Approaches in Multiple Myeloma

The multiple myeloma (MM) therapeutic landscape has evolved significantly with the approval of numerous novel agents, including next generation proteasome inhibitors (PIs), immunomodulatory agents (IMIDs), and monoclonal antibodies (MoABs) targeting CD38 and SLAMF7. While these discoveries have led to an unprecedented improval in patient outcomes, the disease still remains incurable. Immunotherapeutic approaches have shown substantial promise in recent studies of chimeric antigen receptor T-cell (CAR T-cell) therapy, bispecific antibodies, and antibody drug conjugates targeting B-cell maturation antigen (BCMA). This review will highlight these novel and targeted therapies in MM, with particular focus on PIs, IMIDs, MoAb and BCMA-directed immunotherapy.

Current developments in the combination therapy of relapsed/refractory multiple myeloma

INTRODUCTION

Therapy for patients with multiple myeloma has improved dramatically over the past decade following the introduction of novel agents and combinations across the disease spectrum. When relapse or refractory disease develops, non-cross-resistant drugs, most often used in multidrug regimens, have provided significant improvements in patient outcomes. Despite these advances, myeloma remains incurable and additional therapeutic approaches, based on emerging molecular and cellular biology, are moving rapidly through development phases. Approaches new to myeloma, including antibody-drug conjugates, T-cell-directed therapies, and novel small molecules, are poised to bring in the next wave of treatment.

AREAS COVERED

This review addresses recent data for the management of relapsed/refractory disease, rationale for agent and regimen selection and combinations, and options showing early promise in trials. Literature and abstracts pertaining to trial data published or presented up to 2019 are included.

EXPERT OPINION

Therapeutic strategies continue to evolve in myeloma, with the application of existing platforms (e.g., antibody-drug conjugates) to target relevant biology (e.g., B cell maturation antigen). Within the next year, there will be additional agents approved for those with advanced disease, and combinations as well as placement in sequencing will deepen responses and improve outcomes for patients.

Early Transcriptomic Changes upon Thalidomide Exposure Influence the Later Neuronal Development in Human Embryonic Stem Cell-Derived Spheres

Stress in early life has been linked with the development of late-life neurological disorders. Early developmental age is potentially sensitive to several environmental chemicals such as alcohol, drugs, food contaminants, or air pollutants. The recent advances using three-dimensional neural sphere cultures derived from pluripotent stem cells have provided insights into the etiology of neurological diseases and new therapeutic strategies for assessing chemical safety. In this study, we investigated the neurodevelopmental effects of exposure to thalidomide (TMD); 2,2′,4,4′-tetrabromodiphenyl ether; bisphenol A; and 4-hydroxy-2,2′,3,4′,5,5′,6-heptachlorobiphenyl using a human embryonic stem cell (hESC)-derived sphere model. We exposed each chemical to the spheres and conducted a combinational analysis of global gene expression profiling using microarray at the early stage and morphological examination of neural differentiation at the later stage to understand the molecular events underlying the development of hESC-derived spheres. Among the four chemicals, TMD exposure especially influenced the differentiation of spheres into neuronal cells. Transcriptomic analysis and functional annotation identified specific genes that are TMD-induced and associated with ERK and synaptic signaling pathways. Computational network analysis predicted that TMD induced the expression of DNA-binding protein inhibitor ID2, which plays an important role in neuronal development. These findings provide direct evidence that early transcriptomic changes during differentiation of hESCs upon exposure to TMD influence neuronal development in the later stages.

Undo the brake of tumour immune tolerance with antibodies, peptide mimetics and small molecule compounds targeting PD-1/PD-L1 checkpoint at different locations for acceleration of cytotoxic immunity to cancer cells

Recent clinical success of immunotherapy that inhibits the negative immune regulatory pathway programmed cell death protein-1/PD-1 ligand 1 (PD-1/PD-L1) has initiated a new era in the treatment of metastatic cancer. However, greater challenges remain to treat all cancers. The molecular architecture in the immune synapse constituting positive engagements for immune activation and negative checkpoints against immune hyperactivity is regulated dynamically by interaction between proteostasis and tumour microenvironment. This article reviews recent progresses in our understandings of the cellular and molecular mechanisms of the negative checkpoint PD-1/PD-L1 behaviours in immune tolerance of tumourigenesis and metastasis. We provide an overview on PD-L1 gene expression regulation, protein turnover, intra- and extracellular trafficking, exosome-mediated inter-cellular transport, molecular interface peptide mimetics, inhibitory chemical compounds such as metformin, and antibody dynamics. We summarise PD-L1 post-translational modifications including glycosylation, palmitoylation, phosphorylation and ubiquitination, reflecting future research directions and opportunities in identifying tumour-specific signalling targets, their regulatory molecules and pathways for intervention into various types of cancers.

Immunomodulatory drugs activate NK cells via both Zap-70 and cereblon-dependent pathways

Immunomodulatory drugs (IMiDs) lenalidomide and pomalidomide show remarkable anti-tumor activity in multiple myeloma (MM) via directly inhibiting MM cell growth in the bone marrow (BM) microenvironment and promoting immune effector cell function. They are known to bind to the ubiquitin 3 ligase CRBN complex and thereby trigger degradation of IKZF1/3. In this study, we demonstrate that IMiDs also directly bind and activate zeta-chain-associated protein kinase-70 (Zap-70) via its tyrosine residue phosphorylation in T cells. IMiDs also triggered phosphorylation of Zap-70 in NK cells. Importantly, increased granzyme-B (GZM-B) expression and NK cell activity triggered by IMiDs is associated with Zap-70 activation and inhibited by Zap-70 knockdown, independent of CRBN. We also demonstrate a second mechanism whereby IMiDs trigger GZM-B and NK cytotoxicity which is CRBN- and IKZF3-mediated and inhibited by knockdown of CRBN or IKZF-3, independent of Zap-70. Our studies therefore show that IMiDs can enhance NK and T cell cytotoxicity in (1) ZAP-70-mediated CRBN independent, as well as (2) CRBN-mediated ZAP-70 independent mechanisms; and provide the framework for developing novel therapeutics to activate Zap-70 and thereby enhance T and NK anti-MM cytotoxicity.

Treatment response and prognosis of POEMS syndrome coexisting with Castleman disease

POEMS (polyneuropathy, organomegaly, endocrinopathy monoclonal gammopathy, and skin changes) syndrome is occasionally associated with Castleman disease (CD) and their prognosis is considered as poorer than that in POEMS alone patients. To elucidate recent prognosis of POEMS syndrome coexisting with CD, we reviewed clinical data of 102 patients with POEMS syndrome treated at our institution between 2000 and 2018 and compared clinical characteristics, response to treatment, and prognosis between POEMS patients with biopsy-proven CD (POEMS-CD) and those without it. Fourteen POEMS-CD patients and 56 POEMS alone patients were identified, and the remaining 32 patients with unbiopsied lymphadenopathy were excluded. POEMS-CD patients significantly showed earlier onset and less severe neuropathic symptoms. Most of the POEMS-CD patients were treated with thalidomide and dexamethasone (n = 10, 71%), and subsequently received autologous stem cell transplantation (n = 6, 43%). Response to thalidomide was better in patients with POEMS-CD than those with POEMS alone (90% vs 43% clinical response, [p = .012]; 80% vs 45% normalization of serum VEGF levels, [p = .079]). The 10-year overall survival (95% confidence interval) was 89% (50-98%) in POEMS-CD patients and 61% (42-77%) in those with POEMS alone. POEMS syndrome associated with CD constitutes a subgroup of POEMS syndromes characterized by earlier onset, mild polyneuropathy, and favorable response to treatment. Recognition of this subgroup is significant for determination of therapeutic strategy.

Multiple Myeloma: Available Therapies and Causes of Drug Resistance

Multiple myeloma (MM) is the second most common blood cancer. Treatments for MM include corticosteroids, alkylating agents, anthracyclines, proteasome inhibitors, immunomodulatory drugs, histone deacetylase inhibitors and monoclonal antibodies. Survival outcomes have improved substantially due to the introduction of many of these drugs allied with their rational use. Nonetheless, MM patients successively relapse after one or more treatment regimens or become refractory, mostly due to drug resistance. This review focuses on the main drugs used in MM treatment and on causes of drug resistance, including cytogenetic, genetic and epigenetic alterations, abnormal drug transport and metabolism, dysregulation of apoptosis, autophagy activation and other intracellular signaling pathways, the presence of cancer stem cells, and the tumor microenvironment. Furthermore, we highlight the areas that need to be further clarified in an attempt to identify novel therapeutic targets to counteract drug resistance in MM patients.

Biological Background of Resistance to Current Standards of Care in Multiple Myeloma

A high priority problem in multiple myeloma (MM) management is the development of resistance to administered therapies, with most myeloma patients facing successively shorter periods of response and relapse. Herewith, we review the current knowledge on the mechanisms of resistance to the standard backbones in MM treatment: proteasome inhibitors (PIs), immunomodulatory agents (IMiDs), and monoclonal antibodies (mAbs). In some cases, strategies to overcome resistance have been discerned, and an effort should be made to evaluate whether resensitization to these agents is feasible in the clinical setting. Additionally, at a time in which we are moving towards precision medicine in MM, it is equally important to identify reliable and accurate biomarkers of sensitivity/refractoriness to these main therapeutic agents with the goal of having more efficacious treatments and, if possible, prevent the development of relapse.

Development of a physiologically based pharmacokinetic model for intravenous lenalidomide in mice

PURPOSE

Lenalidomide is used widely in B-cell malignancies for its immunomodulatory activity. It is primarily eliminated via the kidneys, with a significant proportion of renal elimination attributed to active processes. Lenalidomide is a weak substrate of P-glycoprotein (P-gp), though it is unclear whether P-gp is solely responsible for lenalidomide transport. This study aimed to determine whether the current knowledge of lenalidomide was sufficient to describe the pharmacokinetics of lenalidomide in multiple tissues.

METHODS

A physiologically based pharmacokinetic model was developed using the Open Systems Pharmacology Suite to explore the pharmacokinetics of lenalidomide in a variety of tissues. Data were available for mice dosed intravenously at 0.5, 1.5, 5, and 10 mg/kg, with concentrations measured in plasma, brain, heart, kidney, liver, lung, muscle, and spleen. P-gp expression and activity were sourced from the literature.

RESULTS

The model predictions in plasma, liver, and lung were representative of the observed data (median prediction error 13%, - 10%, and 30%, respectively, with 90% confidence intervals including zero), while other tissue predictions showed sufficient similarity to the observed data. Contrary to the data, model predictions for the brain showed no drug reaching brain tissue when P-gp was expressed at the blood-brain barrier. The data were better described by basolateral transporters at the intracellular wall. Local sensitivity analysis showed that transporter activity was the most sensitive parameter in these models for exposure.

CONCLUSION

As P-gp transport at the blood-brain barrier did not explain the observed brain concentrations alone, there may be other transporters involved in lenalidomide disposition.

Targeting histone deacetylase 3 (HDAC3) in the bone marrow microenvironment inhibits multiple myeloma proliferation by modulating exosomes and IL-6 trans-signaling

Multiple myeloma (MM) is an incurable cancer that derives pro-survival/proliferative signals from the bone marrow (BM) niche. Novel agents targeting not only cancer cells, but also the BM-niche have shown the greatest activity in MM. Histone deacetylases (HDACs) are therapeutic targets in MM and we previously showed that HDAC3 inhibition decreases MM proliferation both alone and in co-culture with bone marrow stromal cells (BMSC). In this study, we investigate the effects of HDAC3 targeting in BMSCs. Using both BMSC lines as well as patient-derived BMSCs, we show that HDAC3 expression in BMSCs can be induced by co-culture with MM cells. Knock-out (KO), knock-down (KD), and pharmacologic inhibition of HDAC3 in BMSCs results in decreased MM cell proliferation; including in autologous cultures of patient MM cells with BMSCs. We identified both quantitative and qualitative changes in exosomes and exosomal miRNA, as well as inhibition of IL-6 trans-signaling, as molecular mechanisms mediating anti-MM activity. Furthermore, we show that HDAC3-KD in BM endothelial cells decreases neoangiogenesis, consistent with a broad effect of HDAC3 targeting in the BM-niche. Our results therefore support the clinical development of HDAC3 inhibitors based not only on their direct anti-MM effects, but also their modulation of the BM microenvironment.

Anticancer Activity and Underlying Mechanism of Phytochemicals against Multiple Myeloma

Multiple myeloma (MM)-a common hematologic malignancy of plasma cells-accounts for substantial mortality and morbidity rates. Due to the advent of novel therapies such as immunomodulatory drugs (IMiDs), proteasome inhibitors (PIs), and monoclonal antibodies (mAbs), response rates were increased and free survival and overall survival have been elevated. However, adverse events including toxicity, neuropathy or continuous relapse are still problems. Thus, development of novel drugs which have less side effects and more effective is needed. This review aims to recapitulate the pharmacologic anti-MM mechanisms of various phytochemicals, elucidating their molecular targets. Keywords related to MM and natural products were searched in PUBMED/MEDLINE. Phytochemicals have been reported to display a variety of anti-MM activities, including apoptosis, cell cycle arrest, antiangiogenesis, and miRNA modulation. Some phytochemicals sensitize the conventional therapies such as dexamethasone. Also, there are clinical trials with phytochemicals such as agaricus, curcumin, and Neovastat regarding MM treatment. Taken together, this review elucidated and categorized the evidences that natural products and their bioactive compounds could be potent drugs in treating MM.

Therapeutic Effects of a Novel Phenylphthalimide Analog for Corneal Neovascularization and Retinal Vascular Leakage

Purpose

Neovascularization (NV) and retinal vascular leakage are major causes of impaired vision in ocular diseases. The purpose of this study was to identify novel phenylphthalimide analogs with therapeutic effects on NV and vascular leakage and to explore the mechanism of action.

Methods

Antiangiogenic activities of novel phenylphthalimide analogs were assessed in vitro by using VEGF ELISA and endothelial cell proliferation assay. Their efficacies on retinal vascular leakage were evaluated using rat models of oxygen-induced retinopathy (OIR) and streptozotocin (STZ)-induced diabetes. The in vivo antiangiogenic activity was evaluated using topical administration in the alkali burn-induced corneal NV model. The expression of VEGF and intercellular adhesion molecule-1 (ICAM-1) were measured using ELISA.

Results

Thalidomide and three novel analogs all showed inhibitory effects on endothelial cell proliferation and VEGF expression in vitro. Through intravitreal injection, all of the compounds reduced retinal vascular leakage in the OIR and STZ-induced diabetic models. Among these compounds, (2,6-diisopropylphenyl)-5-amino-1H-isoindole-1,3-dione (DAID) displayed the most potent efficacy and reduced retinal vascular leakage in a dose-dependent manner in both the OIR and STZ-diabetes models. Topical administration of DAID also inhibited alkali burn-induced corneal NV. Furthermore, DAID attenuated the overexpression of VEGF and ICAM-1 in the retina of the OIR model. Intravitreal injection of DAID did not result in any detectable side effects, as shown by electroretinogram and retinal histological analysis.

Conclusions

DAID is a novel phenylphthalimide analog with potent effects on NV and retinal vascular leakage through downregulation of VEGF and inflammatory factors and has therapeutic potential.

Synergistic Antimyeloma Activity of Dendritic Cells and Pomalidomide in a Murine Myeloma Model

We have previously shown that immunization with tumor antigen-loaded dendritic cells (DCs) and the immunomodulating drug, lenalidomide, synergistically potentiates the enhancing antitumor immunity in a myeloma mouse model. In this study, we investigated the immunogenicity of DCs combined with pomalidomide and dexamethasone in a myeloma mouse model. MOPC-315 cells were injected subcutaneously to establish myeloma-bearing mice. Four test groups were used to mimic clinical protocol: (1) PBS control, (2) DCs, (3) pomalidomide + dexamethasone, and (4) DCs + pomalidomide + dexamethasone. The combination of DCs plus pomalidomide and dexamethasone displayed greater inhibition of tumor growth compared to the other groups. This effect was closely related with reduced numbers of immune suppressor cells including myeloid-derived suppressor cells, M2 macrophages, and regulatory T cells, with the induction of immune effector cells such as CD4⁺ and CD8⁺ T cells, memory T cells, natural killer (NK) cells, and M1 macrophages, and with the activation of T lymphocytes and NK cells in the spleen. Moreover, the level of the immunosuppressive factor vascular endothelial growth factor was significantly reduced in the tumor microenvironment. The collective findings in the murine myeloma model suggest that tumor antigen-loaded DCs combined with pomalidomide and dexamethasone synergistically enhance antitumor immunity by skewing the immune-suppressive status toward an immune-supportive status.

Glucocorticoids in multiple myeloma: past, present, and future

Glucocorticoids are a backbone of treatment for multiple myeloma in both the upfront and relapsed/refractory setting. While glucocorticoids have single agent activity in multiple myeloma, in the modern era, they are paired with novel agents to induce high clinical response rates. On the other hand, toxicities of steroid therapy limit high dose delivery and impact patient quality of life. We provide a history of steroid use in multiple myeloma with the aim to understand how steroids have emerged and persisted in the treatment of multiple myeloma. We review mechanisms of glucocorticoid sensitivity and resistance and highlight potential future directions to evaluate steroid responsiveness. Further research in this area will aid in optimizing steroid utilization and help determine when glucocorticoid therapy may no longer benefit patients.

Lenalidomide and Programmed Death-1 Blockade Synergistically Enhances the Effects of Dendritic Cell Vaccination in a Model of Murine Myeloma

The therapeutic efficacy of dendritic cell (DC)-based immunotherapy may be potentiated in combination with other anticancer therapies that enhance DC function by modulating immune responses and the tumor microenvironment. In this study, we investigated the efficacy of DC vaccination in combination with lenalidomide and programmed death (PD)-1 blockade in a model of murine myeloma. MOPC-315 cell lines were injected subcutaneously to establish myeloma-bearing mice and the following five test groups were established: PBS control, DCs, DCs + lenalidomide, DCs + PD-1 blockade, and DCs + lenalidomide + PD-1 blockade. The combination of DCs plus lenalidomide and PD-1 blockade more potently inhibited tumor growth compared to the other groups. This effect was associated with a reduction in immune suppressor cells (such as myeloid-derived suppressor cells, M2 macrophages, and regulatory T cells) and an increase in immune effector cells [such as CD4⁺ and CD8⁺ T cells, natural killer (NK) cells, and M1 macrophages] in the spleen. Functional activities of cytotoxic T lymphocytes and NK cells were also enhanced by the triple combination. Levels of immunosuppressive cytokines, such as TGF-β and IL-10, were significantly reduced in the tumor microenvironment. These findings suggest that the combination of DCs plus lenalidomide and PD-1 blockade synergistically establishes a robust anti-myeloma immunity through a two-way mechanism, which inhibits immunosuppressive cells while activating effector cells with superior polarization of the Th1/Th2 balance in favor of the tumor immune response. This result should provide an experimental ground for incorporating check point inhibitors to existing immunotherapeutic modalities against multiple myeloma.

Update on the role of lenalidomide in patients with multiple myeloma

Lenalidomide is a derivative of thalidomide and belongs to the class of drugs known as the immunomodulatory drugs (IMiDs). The IMiDs have played a large role in improving the survival outcomes of patients with multiple myeloma. In particular, lenalidomide is currently standard of care in the newly diagnosed setting, in the maintenance setting post-autologous stem cell transplant, as well as in the relapsed/refractory setting. While the combination of lenalidomide and various proteasome inhibitors has proven particularly effective, there are emerging data demonstrating the effectiveness of lenalidomide in combination with other important classes of drugs including the monoclonal antibodies. Recent studies have provided insight into the molecular target of lenalidomide and the other IMiDs, although there is still much to be learned regarding the mechanisms by which lenalidomide affects the myeloma cell and the immune system. Here we review the molecular mechanisms of action, side effects, and the results of the clinical trials which have led to the widespread incorporation of lenalidomide into the myeloma therapeutic armamentarium.

Repositioning of anti-cancer drug candidate, AZD7762, to an anti-allergic drug suppressing IgE-mediated mast cells and allergic responses via the inhibition of Lyn and Fyn

Mast cells are critical effector cells in IgE-mediated allergic responses. The aim of this study was to investigate the anti-allergic effects of 3-[(aminocarbonyl)amino]-5-(3-fluorophenyl)-N-(3S)-3-piperidinyl-2-thiophenecarboxamide (AZD7762) in vitro and in vivo. AZD7762 inhibited the antigen-stimulated degranulation from RBL-2H3 (IC₅₀, ∼27.9 nM) and BMMCs (IC₅₀, ∼99.3 nM) in a dose-dependent manner. AZD7762 also inhibited the production of TNF-α and IL-4. As the mechanism of its action, AZD7762 inhibited the activation of Syk and its downstream signaling proteins, such as Linker of activated T cells (LAT), phospholipase (PL) Cγ1, Akt, and mitogen-activated protein (MAP) kinases (Erk1/2, p38, and JNK) in mast cells. In in vitro protein kinase assay, AZD7762 inhibited the activity of Lyn and Fyn kinases, which are important for the activation of Syk in mast cells. Furthermore, AZD7762 also suppressed the degranulation of LAD2 human mast cells (IC₅₀, ∼49.9 nM) and activation of Syk in a dose-dependent manner. As observed in experiments with mast cells in vitro, AZD7762 inhibited antigen-mediated passive cutaneous anaphylaxis in mice (ED₅₀, ∼35.8 mg/kg). Altogether, these results suggest that AZD7762 could be used as a new therapeutic agent for mast cell-mediated allergic diseases.

In Vivo Assessment of the Effect of CYP1A2 Inhibition and Induction on Pomalidomide Pharmacokinetics in Healthy Subjects

Pomalidomide is an immunomodulatory drug, and the dosage of 4 mg per day taken orally on days 1‐21 of repeated 28‐day cycles has been approved in the European Union and the United States to treat patients with relapsed/refractory multiple myeloma. In vitro data showed that pomalidomide is a substrate of multiple cytochrome P450 (CYP) isozymes and that its oxidative metabolism is mediated primarily by CYP1A2 and CYP3A4, with minor contributions from CYP2C19 and CYP2D6. The effect of CYP1A2 inhibition by fluvoxamine (a strong CYP1A2 inhibitor) and CYP1A2 induction by smoking on pomalidomide pharmacokinetics in healthy subjects has been assessed in 2 separate phase 1 open‐label, single‐dose studies. Following administration of a single oral dose of 4 mg pomalidomide, the plasma exposure when coadministered with fluvoxamine was 225.1% and 123.7% of that when administered alone for the total plasma exposure (AUC_0‐inf) and the plasma peak exposure (C_max), respectively. In smokers with elevated CYP1A2 activity demonstrated by high caffeine clearance (a marker of CYP1A2 induction), the AUC_0‐inf was 32.3% lower, whereas the C_max was 14.4% higher than that in nonsmokers. In addition, pomalidomide was safe and well tolerated as a single oral dose of 4 mg in healthy male smokers and nonsmokers ≥ 40 to ≤ 80 years old, and a single oral dose of 4 mg pomalidomide coadministered with multiple oral 50‐mg doses of the CYP1A2 inhibitor fluvoxamine compared with pomalidomide alone was safe and well tolerated by the healthy male subjects.

An Open-Label, Phase 1 Study to Assess the Effects of Hepatic Impairment on Pomalidomide Pharmacokinetics

Pomalidomide is an immunomodulatory drug and the dosage of 4 mg per day taken orally on days 1-21 of repeated 28-day cycles has been approved in the European Union and United States to treat patients with relapsed/refractory multiple myeloma. Because pomalidomide is extensively metabolized prior to excretion, a total of 32 subjects (8 healthy subjects in group 1; 8 subjects with severe hepatic impairment in group 2; 8 subjects with moderate hepatic impairment in group 3; and 8 subjects with mild hepatic impairment in group 4) were enrolled in a multicenter, open-label, single-dose study to assess the impact of hepatic impairment on pomalidomide exposure. Following administration of a single oral dose of 4-mg pomalidomide, the geometric mean ratios of pomalidomide total plasma exposures (AUC) were 171.5%, 157.5%, and 151.2% and the geometric mean ratios of pomalidomide plasma peak exposures (C_max ) were 75.8%, 94.8%, and 94.2% for subjects with severe, moderate, or mild hepatic impairment, respectively, versus healthy subjects. Pomalidomide administered as a single oral 4-mg dose was safe and well tolerated by healthy subjects and subjects with severe, moderate, or mild hepatic impairment. Based on the pharmacokinetic results from this study, the pomalidomide prescribing information approved by the US Food and Drug Administration recommends for patients with mild or moderate hepatic impairment (Child-Pugh classes A or B), a 3-mg starting daily dose (25% dose reduction) and for patients with severe hepatic impairment (Child-Pugh class C), a 2-mg starting daily dose (50% dose reduction).

Immunomodulatory Drugs Exert Anti-Leukemia Effects in Acute Myeloid Leukemia by Direct and Immunostimulatory Activities

Immunomodulatory drugs (IMiDs) are anticancer drugs with immunomodulatory, anti-angiogenesis, anti-proliferative, and pro-apoptotic properties. IMiDs are currently used for the treatment of multiple myeloma, myelodysplastic syndrome, and B-cell lymphoma; however, little is known about efficacy in acute myeloid leukemia (AML). We proposed in this study to investigate the relevance of IMiDs therapy for AML treatment. We evaluated the effect of IMiDs on primary AML blasts (n = 24), and the impact in natural killer (NK) cell-mediated immunosurveillance of AML. Using primary AML cells and an immunodeficient mouse leukemia xenograft model, we showed that IMiDs induce AML cell death in vitro and impair leukemia progression in vivo. In addition, treatment of AML blasts with IMiDs resulted in enhanced allogeneic NK cell anti-leukemia reactivity. Treatment by pomalidomide of AML blasts enhanced lysis, degranulation, and cytokine production by primary allogeneic NK cells. Furthermore, the treatment with lenalidomide of patients with myeloid malignancies resulted in NK cell phenotypic changes similar to those observed in vitro. IMiDs increased CD56 and decreased NKp30, NKp46, and KIR2D expression on NK cells. Finally, AML blasts treatment with IMiDs induced phenotypic alterations including downregulation of HLA-class I. The effect of pomalidomide was not correlated with cereblon expression and A/G polymorphism in AML cells. Our data revealed, a yet unobserved, dual effects on AML affecting both AML survival and their sensitivity to NK immunotherapy using IMiDs. Our study encourages continuing investigation for the use of IMiDs in AML, especially in combination with conventional therapy or immunotherapy strategies.

Various Signaling Pathways in Multiple Myeloma Cells and Effects of Treatment on These Pathways

Multiple myeloma (MM) results from malignancy in plasma cells and occurs at ages > 50 years. MM is the second most common hematologic malignancy after non-Hodgkin lymphoma, which constitutes 1% of all malignancies. Despite the great advances in the discovery of useful drugs for this disease such as dexamethasone and bortezomib, it is still an incurable malignancy owing to the development of drug resistance. The tumor cells develop resistance to apoptosis, resulting in greater cell survival, and, ultimately, develop drug resistance by changing the various signaling pathways involved in cell proliferation, survival, differentiation, and apoptosis. We have reviewed the different signaling pathways in MM cells. We reached the conclusion that the most important factor in the drug resistance in MM patients is caused by the bone marrow microenvironment with production of adhesion molecules and cytokines. Binding of tumor cells to stromal cells prompts cytokine production of stromal cells and launches various signaling pathways such as Janus-activated kinase/signal transduction and activator of transcription, Ras/Raf/MEK/mitogen-activated protein kinase, phosphatidyl inositol 3-kinase/AKT, and NF-KB, which ultimately lead to the high survival rate and drug resistance in tumor cells. Thus, combining various drugs such as bortezomib, dexamethasone, lenalidomide, and melphalan with compounds that are not common, including CTY387, LLL-12, OPB31121, CNTO328, OSI-906, FTY720, triptolide, and AV-65, could be one of the most effective treatments for these patients.

The role of elotuzumab in the treatment of relapsed or refractory multiple myeloma

PURPOSE

The pharmacology, pharmacokinetics, clinical efficacy and safety, cost, and place in therapy of elotuzumab for treatment of relapsed or refractory multiple myeloma (MM) are reviewed.

SUMMARY

Elotuzumab is a humanized monoclonal antibody that targets the signaling lymphocytic activation molecule (SLAM) protein SLAMF7 and facilitates an antibody-dependent cellular cytotoxicity interaction between myeloma cells and natural killer cells. Elotuzumab has U.S. marketing approval for use in combination with lenalidomide and dexamethasone in patients with relapsed or refractory MM who have received 1-3 previous therapies; this regimen is among the preferred regimens for relapsed or refractory MM recommended by the National Comprehensive Cancer Network (NCCN). A Phase III trial involving 321 patients demonstrated a median progression-free survival duration of 19.4 months with elotuzumab plus lenalidomide and dexamethasone versus 14.9 months with lenalidomide and dexamethasone alone (hazard ratio for progression or death, 0.70; 95% confidence interval, 0.57-0.85; p < 0.001). Common adverse effects of elotuzumab-lenalidomide-dexamethasone therapy include hematologic toxicities, fatigue, pyrexia, diarrhea, constipation, muscle spasms, and cough. Elotuzumab plus bortezomib and dexamethasone is an NCCN-recommended alternative option for relapsed or refractory MM.

CONCLUSION

While elotuzumab plus lenalidomide and dexamethasone is a promising regimen for patients with MM, it is only one of several regimens recommended by NCCN for relapsed or refractory MM. Key factors in patient selection for elotuzumab therapy include adverse effects, prior treatments received, and cost considerations.

Pomalidomide, bortezomib and low-dose dexamethasone in lenalidomide-refractory and proteasome inhibitor-exposed myeloma

This phase 1 dose-escalation study evaluated pomalidomide, bortezomib (subcutaneous (SC) or intravenous (IV)) and low-dose dexamethasone (LoDEX) in lenalidomide-refractory and proteasome inhibitor-exposed relapsed or relapsed and refractory multiple myeloma (RRMM). In 21-day cycles, patients received pomalidomide (1-4 mg days 1-14), bortezomib (1-1.3 mg/m2 days 1, 4, 8 and 11 for cycles 1-8; days 1 and 8 for cycle ⩾9) and LoDEX. Primary endpoint was to determine the maximum tolerated dose (MTD). Thirty-four patients enrolled: 12 during escalation, 10 in the MTD IV bortezomib cohort and 12 in the MTD SC bortezomib cohort. Patients received a median of 2 prior lines of therapy; 97% bortezomib exposed. With no dose-limiting toxicities, MTD was defined as the maximum planned dose: pomalidomide 4 mg, bortezomib 1.3 mg/m2 and LoDEX. All patients discontinued treatment by data cutoff (2 April 2015). The most common grade 3/4 treatment-emergent adverse events were neutropenia (44%) and thrombocytopenia (26%), which occurred more frequently with IV than SC bortezomib. No grade 3/4 peripheral neuropathy or deep vein thrombosis was reported. Overall response rate was 65%. Median duration of response was 7.4 months. Pomalidomide, bortezomib and LoDEX was well tolerated and effective in lenalidomide-refractory and bortezomib-exposed patients with RRMM.