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

Emerging biological insights and novel treatment strategies in multiple myeloma

INTRODUCTION

Survival in multiple myeloma (MM) has improved significantly in the past 10 years due to new treatments, such as thalidomide and lenalidomide (immunomodulatory drugs or IMiDs) bortezomib and advances in supportive care. Nevertheless, almost all MM patients show disease relapse and develop drug resistance.

AREAS COVERED

The authors review the therapeutic approach for untreated MM patients. Furthermore, the prognostic stratification of patients and the proposed risk-adapted strategy are discussed. Finally, preclinical and clinical data regarding newer antimyeloma agents, currently undergoing examination such as proteasome inhibitors (PIs, carfilzomib), IMiDs (pomalidomide), epigenetic agents (histone deacetylase inhibitors vorinostat and panobinostat), humanized monoclonal antibodies (elotuzumab and MOR03087) and targeted therapies (inhibitors of NF-κB, MAPK, HSP90 and AKT) are reported.

EXPERT OPINION

MM patient outcome has remarkably improved due to the use of three to four drug combination therapies including PIs and IMiDs, which target the tumor in its bone marrow microenvironment, however MM treatment remains challenging. The use of high-throughput techniques has allowed to discover new insights into MM biology. The identification of candidate therapeutic targets and availability of respective investigative agents will allow for a substantial progress in the development and implementation of personalized medicine in MM.

Lenalidomide (Revlimid), bortezomib (Velcade) and dexamethasone for heavily pretreated relapsed or refractory multiple myeloma

The combination of lenalidomide, bortezomib and dexamethasone (RVD) has shown excellent efficacy in patients with relapsed or refractory multiple myeloma (RRMM). The aim of our study was to assess the efficacy and toxicity profile of RVD for patients with advanced RRMM. We retrospectively reviewed the records of all patients with RRMM treated with RVD between March 2009 and December 2011. Thirty patients received ≥ 1 full cycle of RVD. Primary endpoints were overall response rate (ORR), progression-free survival (PFS) and overall survival (OS). After a median of 5 cycles (1-16), a very good partial response (VGPR) was seen in 10%, partial response (PR) in 36.7% and stable disease (SD) in 13.3% (ORR of 46.7%). Disease progression occurred in 21 patients at a median of 3 months (range 1.41-4.59). Eight patients (26%) experienced grade 3/4 adverse events, including anemia, neutropenia, muscle weakness and pneumonia. No patient experienced worsening peripheral neuropathy. Although RVD has been previously shown to be effective in RRMM, the ORR and PFS we observed were affected by very advanced disease status and heavy prior exposure to novel agents. Nevertheless, six of these patients with RRMM experienced a benefit of ≥ 6 months, suggesting synergism of this immunomodulatory derivative/proteasome inhibitor combination and/or re-establishment of drug sensitivity by an emergent myeloma clone.

Novel immunomodulatory compounds in multiple myeloma

INTRODUCTION

The treatment options for patients with multiple myeloma (MM) remain limited. Immunomodulatory agents (IMiDs), such as thalidomide and lenalidomide, have changed the landscape in the treatment of patients with MM while newer IMiDs such as pomalidomide are showing promise in early clinical trials.

AREAS COVERED

This review focuses on the biologic rationales of IMiDs and the clinical results supporting their use in MM. It includes data on the new IMiD, pomalidomide and also explores the possible utility of combining IMiDs with other agents. A PubMed search and abstracts from oncology scientific meetings (ASCO and ASH) of articles related to IMiDs and MM was conducted.

EXPERT OPINION

IMiDs have shown clinical activity as single agents and in combination. Thalidomide was the first in class drug. Lenalidomide has a better toxicity profile than thalidomide. Pomalidomide may overcome resistance to lenalidomide indicating differences in their mechanisms of action and resistance. Molecular biomarkers may allow us to identify patients who will respond to IMiDs.

Phase 1 study of pomalidomide MTD, safety, and efficacy in patients with refractory multiple myeloma who have received lenalidomide and bortezomib

This phase 1 dose-escalation study determined the maximum tolerated dose (MTD) of oral pomalidomide (4 dose levels) administered on days 1 to 21 of each 28-day cycle in patients with relapsed and refractory multiple myeloma (RRMM). After four cycles, patients who progressed or had not achieved minimal response (serum and urine M-protein reduction of ≥ 25% and ≥ 50%) could receive dexamethasone 40 mg per week. Safety and efficacy were evaluated. Thirty-eight patients who had received both bortezomib and lenalidomide (median 6 prior therapies) were enrolled; 63% were refractory to both lenalidomide and bortezomib. There were four dose-limiting toxicities (grade 4 neutropenia) at 5 mg per day and so the MTD was 4 mg per day. Rates of peripheral neuropathy and venous thromboembolism were low (≤ 5%). Among the 38 patients enrolled (including 22 with added dexamethasone), 42% achieved minimal response or better, 21% achieved partial response or better, and 3% achieved complete response. Median duration of response, progression-free survival, and overall survival were 4.6, 4.6, and 18.3 months, respectively. Pomalidomide 4 mg per day on days 1 to 21 of each 28-day cycle, with or without dexamethasone (40 mg/week), has encouraging activity with manageable toxicity in RRMM, including those refractory to both lenalidomide and bortezomib. This study is registered at http://www.clinicaltrials.gov as #NCT00833833.

Computational gene network analysis reveals TNF-induced angiogenesis

Background

TNF (Tumor Necrosis Factor-α) induces HUVEC (Human Umbilical Vein Endothelial Cells) to proliferate and form new blood vessels. This TNF-induced angiogenesis plays a key role in cancer and rheumatic disease. However, the molecular system that underlies TNF-induced angiogenesis is largely unknown.

Methods

We analyzed the gene expression changes stimulated by TNF in HUVEC over a time course using microarrays to reveal the molecular system underlying TNF-induced angiogenesis. Traditional k-means clustering analysis was performed to identify informative temporal gene expression patterns buried in the time course data. Functional enrichment analysis using DAVID was then performed for each cluster. The genes that belonged to informative clusters were then used as the input for gene network analysis using a Bayesian network and nonparametric regression method. Based on this TNF-induced gene network, we searched for sub-networks related to angiogenesis by integrating existing biological knowledge.

Results

k-means clustering of the TNF stimulated time course microarray gene expression data, followed by functional enrichment analysis identified three biologically informative clusters related to apoptosis, cellular proliferation and angiogenesis. These three clusters included 648 genes in total, which were used to estimate dynamic Bayesian networks. Based on the estimated TNF-induced gene networks, we hypothesized that a sub-network including IL6 and IL8 inhibits apoptosis and promotes TNF-induced angiogenesis. More particularly, IL6 promotes TNF-induced angiogenesis by inducing NF-κB and IL8, which are strong cell growth factors.

Conclusions

Computational gene network analysis revealed a novel molecular system that may play an important role in the TNF-induced angiogenesis seen in cancer and rheumatic disease. This analysis suggests that Bayesian network analysis linked to functional annotation may be a powerful tool to provide insight into disease.

Lenalidomide in multiple myeloma: Current status and future potential

The clinical development of lenalidomide (Revlimid™), then pomalidomide (Actimid™) as members of immunomodulatory drugs (IMiDs) for the treatment of multiple myeloma (MM), exemplifies how insight into disease biology can lead to design of effective therapeutic agents. Increased experience and understanding of IMiD's diverse biological effects has lead to rational design of lenalidomide-based treatment-regimens over recent years. However, much about lenalidomide is yet to be understood and fully exploited. Here, we review what is known of lenalidomide's biological effects, clinical certainties and uncertainties in the treatment of MM, and explore its future potential with other synergistic therapeutic agents.

Immunomodulatory drugs lenalidomide and pomalidomide inhibit multiple myeloma-induced osteoclast formation and the RANKL/OPG ratio in the myeloma microenvironment targeting the expression of adhesion molecules

Multiple myeloma (MM)-induced osteoclast (OC) formation is mainly due to an imbalance of the receptor activator NF-κB ligand (RANKL)-osteoprotegerin (OPG) ratio in favor of RANKL in the bone microenvironment and to the CCL3 production by MM cells. The purpose of the study was to investigate the effect of the immunomodulatory drugs on RANKL/OPG ratio, the production of pro-osteoclastogenic cytokines, and MM-induced OC formation. We found that in vivo concentrations of both lenalidomide (LEN) and pomalidomide (POM) significantly blunted RANKL upregulation normalizing the RANKL/OPG ratio in human osteoprogenitor cells (PreOBs) when co-cultured with MM cells and also inhibited CCL3 production by MM cells. A reduction in CD49d expression, a molecule critically involved in RANKL upregulation in the MM microenvironment, accompanied this effect. Consistently, the pro-osteoclastogenic property of MM cells co-cultured with PreOBs was reduced by both LEN and POM. We further investigated the effect of these drugs on the transcriptional profile of both MM cells and PreOBs by microarray analysis, which showed that adhesion molecules, such as ITGA8 and ICAM2, are significantly downregulated in MM cells. Our data suggest that LEN and POM inhibit MM-induced OC formation through normalization of the RANKL/OPG ratio targeting the expression of adhesion molecules by MM cells.

Can we change the disease biology of multiple myeloma?

Despite improvements in disease management, multiple myeloma (MM) remains incurable. Conventional treatment methods are unsatisfactory, leading to a pattern of regression and remission, and ultimately failure. This pattern suggests that one of the possible strategies for improving outcomes is continuous therapy to maintain suppression of the surviving tumor cells. Optimal management of MM requires potent agents and modalities with direct tumoricidal activity, which can also provide continuous suppression of the residual tumor to prevent disease relapse. Immunomodulatory agents exert immunomodulatory and tumoricidal effects, and cause disruption of stromal cell support from the bone marrow microenvironment. Therefore continuous therapy with immunomodulatory agents may be able to provide both tumor reduction and tumor suppression, enabling physicians to consider the possibility of incorporating continuous therapy into the treatment paradigm of patients with MM.

Isosteric analogs of lenalidomide and pomalidomide: synthesis and biological activity

A series of analogs of the immunomodulary drugs lenalidomide (1) and pomalidomide (2), in which the amino group is replaced with various isosteres, was prepared and assayed for immunomodulatory activity and activity against cancer cell lines. The 4-methyl and 4-chloro analogs 4 and 15, respectively, displayed potent inhibition of tumor necrosis factor-α (TNF-α) in LPS-stimulated hPBMC, potent stimulation of IL-2 in a human T cell co-stimulation assay, and anti-proliferative activity against the Namalwa lymphoma cell line. Both of these analogs displayed oral bioavailability in rat.

Practical approaches to the use of lenalidomide in multiple myeloma: a canadian consensus

In Canada, lenalidomide combined with dexamethasone (Len/Dex) is approved for use in relapsed or refractory multiple myeloma (RRMM). Our expert panel sought to provide an up-to-date practical guide on the use of lenalidomide in the managing RRMM within the Canadian clinical setting, including management of common adverse events (AEs). The panel concluded that safe, effective administration of Len/Dex treatment involves the following steps: (1) lenalidomide dose adjustment based on creatinine clearance and the extent of neutropenia or thrombocytopenia, (2) dexamethasone administered at 20-40 mg/week, and (3) continuation of treatment until disease progression or until toxicity persists despite dose reduction. Based on available evidence, the following precautions should reduce the risk of common Len/Dex AEs: (1) all patients treated with Len/Dex should receive thromboprophylaxis, (2) erythropoiesis-stimulating agents (ESAs) should be used cautiously, and (3) females of child-bearing potential and males in contact with such females must use multiple contraception methods. Finally, while Len/Dex can be administered irrespective of prior therapy and in all prognostic subsets, patients with chromosomal deletion 17(p13) have less favorable outcomes with all treatments, including Len/Dex. New directions for the use of lenalidomide in RRMM are also considered.

PSGL-1/selectin and ICAM-1/CD18 interactions are involved in macrophage-induced drug resistance in myeloma

Chemoresistance is the major obstacle in multiple myeloma (MM) management. We previously showed that macrophages protect myeloma cells, on a cell contact basis, from melphalan or dexamethasone-induced apoptosis in vitro. In this study, we found that macrophage-mediated myeloma drug resistance was also seen with purified macrophages from myeloma patients' bone marrow (BM) in vitro and was confirmed in vivo using the human myeloma-SCID (severe combined immunodeficient) mouse model. By profiling differentially regulated and paired plasma membrane protein genes, we showed that PSGL-1 (P-selectin glycoprotein ligand-1)/selectins and ICAM-1/CD18 played an important role in macrophage-mediated myeloma cell drug resistance, as blocking antibodies against these molecules or genetic knockdown of PSGL-1 or ICAM-1 in myeloma cells repressed macrophages' ability to protect myeloma cells. Interaction of macrophages and myeloma cells via these molecules activated Src and Erk1/2 kinases and c-myc pathways and suppressed caspase activation induced by chemotherapy drugs. Thus, our study sheds new light on the mechanism of drug resistance in MM and provides novel targets for improving the efficacy of chemotherapy in patients.

Model of translational cancer research in multiple myeloma

Recently, intensive laboratory and preclinical studies have identified and validated therapeutic molecular targets in multiple myeloma (MM). The introduction of novel agents such as the proteasome inhibitor bortezomib and the immunomodulatory drugs thalidomide and lenalidomide, which were rapidly translated from preclinical studies at the Dana-Farber Cancer Institute into clinical trials, has changed the treatment paradigm and markedly extended overall survival; MM has therefore become a remarkable example of translational cancer research in new drug development. In this article, with the aim of determining the key factors underlying success in translational research, we focus on our studies of MM at Dana-Farber Cancer Institute as well as at our institutes. The identification of these key factors will help to promote translational cancer research not only in MM but also in other hematologic malignancies and solid tumors, to develop novel therapies, to overcome drug resistance, and to thereby improve the prognosis of cancer patients. (Cancer Sci, doi: 10.1111/j.1349-7006.2012.02384.x, 2012)

Thalidomide: an old drug with new action

Thalidomide is a drug that, since its development, has made history in the world of medicine--having been withdrawn and now has returned with a boom as an anticancer and immunomodulatory drug. However, its mode of action in various diseases (i.e. different types of hematologic malignancies, solid tumors) as well as in various infections (i.e. pneumonia, tuberculosis, HIV infection etc.) and related inflammatory conditions is not well understood. As the immune system plays an important role in the pathogenesis of both infection-related as well as noninfectious (i.e. cancer) inflammatory diseases, much research has been done in the past few years to discover and design better immunomodulatory agents. Such immunomodulatory agents should be able to target the immune system in such a way that host suffers minimum damage and normal function of the immune system remains intact. In the present review an attempt is made to highlight the immunomodulatory action of thalidomide in various pathologic conditions.

Lenalidomide in the treatment of young patients with multiple myeloma: from induction to consolidation/maintenance therapy

Multiple myeloma is the second most common hematologic malignancy. It accounts for 20,580 new cancer cases in the USA in 2009, including 11,680 cases in men, 8,900 cases in women, and 10,580 deaths overall. Although the disease remains still incurable, outcomes have improved substantially over recent years thanks to the use of high-dose therapy and the availability of novel agents, such as the immunomodulatory drugs thalidomide and lenalidomide, and the proteasome inhibitor bortezomib. Various trials have shown the advantages linked to the use of novel agents in the transplant and not-transplant settings. In particular, this paper will present an overview of the results achieved with lenalidomide-containing combinations in patients eligible for high-dose therapies, namely, young patients. The advantages obtained should always be outweighed with the toxicity profile associated with the regimen used. Therefore, here, we will also provide a description of the main adverse events associated with lenalidomide and its combination.

A phthalimide derivative that inhibits centrosomal clustering is effective on multiple myeloma

Despite the introduction of newly developed drugs such as lenalidomide and bortezomib, patients with multiple myeloma are still difficult to treat and have a poor prognosis. In order to find novel drugs that are effective for multiple myeloma, we tested the antitumor activity of 29 phthalimide derivatives against several multiple myeloma cell lines. Among these derivatives, 2-(2,6-diisopropylphenyl)-5-amino-1H-isoindole-1,3- dione (TC11) was found to be a potent inhibitor of tumor cell proliferation and an inducer of apoptosis via activation of caspase-3, 8 and 9. This compound also showed in vivo activity against multiple myeloma cell line KMS34 tumor xenografts in ICR/SCID mice. By means of mRNA display selection on a microfluidic chip, the target protein of TC11 was identified as nucleophosmin 1 (NPM). Binding of TC11 and NPM monomer was confirmed by surface plasmon resonance. Immunofluorescence and NPM knockdown studies in HeLa cells suggested that TC11 inhibits centrosomal clustering by inhibiting the centrosomal-regulatory function of NPM, thereby inducing multipolar mitotic cells, which undergo apoptosis. NPM may become a novel target for development of antitumor drugs active against multiple myeloma.

Lenalidomide enhances anti-myeloma cellular immunity

Lenalidomide is an effective therapeutic agent for multiple myeloma that exhibits immunomodulatory properties including the activation of T and NK cells. The use of lenalidomide to reverse tumor-mediated immune suppression and amplify myeloma-specific immunity is currently being explored. In the present study, we examined the effect of lenalidomide on T-cell activation and its ability to amplify responses to a dendritic cell-based myeloma vaccine. We demonstrate that exposure to lenalidomide in the context of T-cell expansion with direct ligation of CD3/CD28 complex results in polarization toward a Th1 phenotype characterized by increased IFN-γ, but not IL-10 expression. In vitro exposure to lenalidomide resulted in decreased levels of regulatory T cells and a decrease in T-cell expression of the inhibitory marker, PD-1. Lenalidomide also enhanced T-cell proliferative responses to allogeneic DCs. Most significantly, lenalidomide treatment potentiated responses to the dendritic cell/myeloma fusion vaccine, which were characterized by increased production of inflammatory cytokines and increased cytotoxic lymphocyte-mediated lysis of autologous myeloma targets. These findings indicate that lenalidomide enhances the immunologic milieu in patients with myeloma by promoting T-cell proliferation and suppressing inhibitory factors, and thereby augmenting responses to a myeloma-specific tumor vaccine.

Mechanism of immunomodulatory drugs in multiple myeloma

Multiple myeloma is the second most common hematological cancer in the world. It is characterized by accumulation of malignant plasma cells in the bone marrow, osteolytic lesions and monoclonal immunoglobulins in blood/urine. With the introduction of immunomodulatory drugs into the treatment protocol, the outcome of multiple myeloma patients has dramatically improved with more than 30% of patients surviving for 10 years thus shifting multiple myeloma to a treatable condition.

Immunomodulatory drugs and active immunotherapy for chronic lymphocytic leukemia

BACKGROUND

The last decade witnessed the emergence of several therapeutic options for patients with chronic lymphocytic leukemia (CLL) for first-line and relapsed settings. The vast majority of patients with relapsed or refractory CLL carry poor prognostic features, which are strong predictors of shorter overall survival and resistance to first-line treatment, particularly fludarabine-based regimens.

METHODS

This article highlights the current role of immunomodulatory drugs (IMiDs) and active immunotherapy as treatment options for this select group. The rationale of using IMiDs is discussed from the perspective of lenalidomide as a novel active agent. Relevant clinical trials using IMiDs alone or in combinations are discussed. New immunotherapeutic experimental approaches are also described.

RESULTS

As a single agent, lenalidomide offers an overall response rate of 32% to 47% in patients with relapsed/refractory disease. Recent studies have shown promising activity as a single agent in treatment-naive patients. The combination of lenalidomide with immunotherapy (rituximab and ofatumumab) has also shown clinical responses. Encouraging preclinical and early clinical data have been observed with different immunotherapeutic approaches.

CONCLUSIONS

The use of IMiDs alone or in combination with immunotherapy represents a treatment option for relapsed/refractory or treatment-naive patients. Mature data and further studies are needed to validate overall and progression-free survival. The toxicity profile of lenalidomide might limit its use and delay further studies. Immunotherapy offers another potential alternative, but further understanding of the immunogenicity of CLL cells and the mechanisms of tumor fl are reaction is needed to improve the outcomes in this field.

Evidence-based case report: multiple thrombotic episodes associated with lenalidomide and dexamethasone therapy for multiple myeloma

Lenalidomide in combination with dexamethasone is a treatment for patients with relapsed or refractory myeloma. Although this combination demonstrates a high level of efficacy, it further exacerbates the hypercoaguable state that exists within myeloma. Thromboprophylactic regimen require careful selection and if warfarin is chosen, assiduous monitoring is required to ensure it will be clinically effective. We report the case of one patient who experienced multiple thrombotic events despite anticoagulant or antiplatelet thromboprophylaxis and review the contributing factors.

Isoliquiritigenin inhibits the growth of multiple myeloma via blocking IL-6 signaling

Previous studies have suggested that isoliquiritigenin (ISL) has anti-carcinogenic activity in several kinds of solid tumors, however, little is known about the effects of ISL on hematologic malignancies. In this study, we investigated the effects of ISL on multiple myeloma (MM) cells both in vitro and in vivo. The results showed that ISL could inhibit the growth of MM cells and induce their apoptosis in time- and dose-dependent manners. ISL exhibited significant anti-tumor activity in MM xenograft models and synergistically enhanced the anti-myeloma activity of adriamycin. Further analysis demonstrated that ISL not only downregulated IL-6 expression but also significantly decreased levels of phosphorylated ERK and STAT3 and could inhibit phosphorylation levels of ERK and STAT3 induced by recombinant human IL-6, which are critical signaling proteins in IL-6 signaling regulation networks. Taken together, our findings suggested that ISL could inhibit the growth of MM via blocking IL-6 signaling and might serve as a promising therapeutic agent for treatment of MM.

Novel agents derived from the currently approved treatments for MM: novel proteasome inhibitors and novel IMIDs

INTRODUCTION

Several novel proteasome inhibitors (PIs) and immunomodulatory agents (IMIDs) with similar, but not exactly the same, mechanisms of action than their predecessors have been developed in the last years with three different aims: to increase the efficacy; to overcome the resistance and to exhibit a better toxicity profile.

AREAS COVERED

This review summarizes the mechanism of action of novel PIs (carfilzomib, ONX-0912, MLN-9708, marizomib and CEP-18770) and IMIDs (pomalidomide), stressing the similarities and differences with their parental drugs. It also reviews their most updated clinical results. A search of the recent literature in published papers and abstracts from the most important oncology scientific meetings (ASCO and ASH) has been performed.

EXPERT OPINION

Novel PIs and IMIDs show clinical activity as single agents and in combination with dexamethasone, with similar or even higher efficacy than their predecessors; moreover, they may even overcome resistance to their parental drugs, indicating that there are some differences in their mechanisms of action and resistance. The investigation of these mechanisms of resistance and ways to overcome it would allow the optimization of the sequential use of these agents, and the design of novel therapeutic strategies and more appropriate scientifically based combinations.

Thalidomide maintenance therapy for patients with multiple myeloma: meta-analysis

We performed a meta-analysis of randomized controlled trials comparing thalidomide maintenance with other regimens after induction chemotherapy for multiple myeloma. Overall, 6 trials including 2786 patients were identified. Patients treated with thalidomide maintenance had marginally better overall survival (hazard ratio HR 0.83, P=0.07). The improvement was especially prominent in a subgroup of studies using corticosteroids with thalidomide (HR 0.70, P=0.02). Thalidomide improved progression-free survival (HR 0.65, P<0.01), but had more frequent venous thrombosis (risk difference 0.024, P<0.05) and peripheral neuropathy (risk difference 0.072, P<0.01). These results suggest that thalidomide maintenance with corticosteroids is effective in prolonging survival for multiple myeloma.

Detection of serum tumor markers in multiple myeloma using the CLINPROT system

The discovery of biomarkers unique to multiple myeloma (MM) is of great importance to clinical practice. This study was designed to identify serum tumor marker candidates of MM in the mass range of 700-10000 Da. Serum samples from 48 MM patients and 74 healthy controls were collected and classified into a training dataset (MM/controls: 26/26) and a testing dataset (MM/controls: 22/48). Weak cation exchange magnetic beads, MALDI-TOF MS and analytic software in the CLINPROT system were used to do serum sample pre-fractionation, data acquisition and data analysis. Peak statistics were performed using Welch's t test. Mass spectra from the two model generation cohorts in the training dataset were analyzed by the Supervised Neural Network Algorithm (SNNA) in ClinProTools((TM)) to identify the mass peaks with the highest separation power. The resulting diagnostic model was subsequently validated in the testing dataset. A total of 89 discriminating mass peaks were detected by ClinProTools((TM)) in the range of 700-10000 Da using a signal to noise threshold of 3.0. Of these, 49 peaks had statistical significance (P < 0.0001) and four peaks with the highest separation power were picked up by SNNA to form a diagnostic model. This model achieved high sensitivity (86.36 %) and specificity (87.5 %) in the validation in the testing dataset. Using CLINPROT system and MB-WCX we found four novel biomarker candidates. The diagnostic model built by the four peaks achieved high sensitivity and specificity in validation. CLINPROT system is a powerful and reliable tool for clinical proteomic research.

Preclinical predictors of anticancer drug efficacy: critical assessment with emphasis on whether nanomolar potency should be required of candidate agents

In the current paradigm of anticancer drug development, candidate compounds are evaluated by testing their in vitro potency against molecular targets relevant to carcinogenesis, their effect on cultured cancer cells, and their ability to inhibit cancer growth in animal models. We discuss the key assumptions inherent in these approaches. In recent years, great emphasis has been placed on selecting for development compounds with nanomolar in vitro potency, expecting that they will be efficacious and safer based on the assumption that they can be used at lower doses ("the nanomolar rule"). However, this rule ignores critical parameters affecting efficacy and toxicity such as physiochemical and absorption, distribution, metabolism and excretion properties, off-target effects, and multitargeting activities. Thus, uncritical application of the nanomolar rule may reject efficacious compounds or select ineffective or toxic compounds. We present examples of efficacious chemotherapeutic (alkylating agents, hormonal agents, antimetabolites, thalidomide, and valproic acid) and chemopreventive (aspirin and sulindac) agents having millimolar potency and compounds with nanomolar potency (cyclooxygenase-2 inhibitors) that, nevertheless, failed or proved to be unsafe. The effect of candidate drugs on animal models of cancer is a better predictor of human drug efficacy; particularly useful are tumor xenografts. Given the cost of failure at clinical stages, it is imperative to keep in mind the limitations of the nanomolar rule and use relevant in vivo models early in drug discovery to prioritize candidates. Although in vivo models will continue having a major role in cancer drug development, more robust approaches that combine high predictive ability with simplicity and low cost should be developed.

Latest advances and current challenges in the treatment of multiple myeloma

Effectively treating patients with multiple myeloma is challenging. The development of therapeutic regimens over the past decade that incorporate the proteasome inhibitor bortezomib and the immunomodulatory drugs thalidomide and lenalidomide has been the cornerstone of improving the outcome of patients with myeloma. Although these treatment regimens have improved patient survival, nearly all patients eventually relapse. Our improved understanding of the biology of the disease and the importance of the microenvironment has translated into ongoing work to help overcome the challenge of relapse. Several classes of agents including next-generation proteasome inhibitors, immunomodulatory agents, selective histone-deacetylase inhibitors, antibody and antitumor immunotherapy approaches are currently undergoing preclinical and clinical evaluation. This Review provides an update on the latest advances in the treatment of multiple myeloma. In particular, we focus on novel therapies including modulating protein homeostasis, kinases inhibitors, targeting accessory cells and cytokines, and immunomodulatory agents. A discussion of the challenges associated with these therapeutic approaches is also presented.

Celastrol inhibits proliferation and induces chemosensitization through down-regulation of NF-κB and STAT3 regulated gene products in multiple myeloma cells

BACKGROUND AND PURPOSE

Activation of pro-inflammatory transcription factors NF-κB and signal transducer and activator of transcription 3 (STAT3) is one of the major contributors to both pathogenesis and chemoresistance in multiple myeloma (MM), which results in high mortality rate. Thus, in the present study, we investigated whether celastrol could suppress the proliferation and induce chemosensitization of MM cells by interfering with NF-κB and STAT3 activation pathways.

EXPERIMENTAL APPROACH

The effects of celastrol were investigated using both a virtual predictive tumour cell system and different MM cell lines resistant to doxorubicin, melphalan and bortezomib.

KEY RESULTS

Celastrol inhibited the proliferation of MM cell lines regardless of whether they were sensitive or resistant to bortezomib and other conventional chemotherapeutic drugs. It also synergistically enhanced the apoptotic effects of thalidomide and bortezomib. This correlated with the down-regulation of various proliferative and anti-apoptotic gene products including cyclin D1, Bcl-2, Bcl-xL, survivin, XIAP and Mcl-1. These effects of celastrol were mediated through suppression of constitutively active NF-κB induced by inhibition of IκBα kinase activation; and the phosphorylation of IκBα and of p65. Celastrol also inhibited both the constitutive and IL6-induced activation of STAT3, which induced apoptosis as indicated by an increase in the accumulation of cells in the sub-G1 phase, an increase in the expression of pro-apoptotic proteins and activation of caspase-3.

CONCLUSIONS AND IMPLICATIONS

Thus, based on our experimental findings, we conclude that celastrol may have great potential as a treatment for MM and other haematological malignancies.

Update on immunomodulatory drugs (IMiDs) in hematologic and solid malignancies

INTRODUCTION

Thalidomide and its analogs [small molecule immunomodulatory drugs (IMiDs®)] are among the most successful new therapeutic agents of recent years. Thalidomide is now an integral part of multiple myeloma (MM) therapy. Lenalidomide has been approved for the treatment of patients with relapsed MM and 5q-myelodysplastic syndromes (MDS). Currently, more than 400 clinical trials are evaluating the activity of lenalidomide, alone or in combination with other conventional or novel therapies, in newly diagnosed MM and 5q-MDS. Based on their broad range of actions within the tumor microenvironment, IMiDs are currently also evaluated in a wide variety of additional hematologic and solid malignancies.

AREAS COVERED

This paper reviews the historic development of thalidomide and its derivatives and presents novel insights into their mode of action. Moreover, it discusses up-to-date clinical trials investigating IMiDs and potential future research and therapeutic perspectives in MM and other malignancies.

EXPERT OPINION

Although IMiDs have emerged as powerful agents for the treatment of hematologic and solid tumors, more preclinical and clinical studies are urgently needed both to increase our knowledge of their mechanisms of action, and to optimize their clinical use, in order to further improve the patient's quality of life and survival.

The 39th David A. Karnofsky Lecture: bench-to-bedside translation of targeted therapies in multiple myeloma

Multiple myeloma (MM) is a remarkable example of rapid bench-to-bedside translation in new drug development. The proteasome inhibitor bortezomib and immunomodulatory drug lenalidomide targeted MM cells in the bone marrow (BM) microenvironment to overcome conventional drug resistance in laboratory and animal models and were rapidly translated into clinical trials demonstrating their efficacy in patients with relapsed and then newly diagnosed MM, with a doubling of the median survival as a direct result. The future is even brighter. First, immune-based therapies are being developed (eg, elotuzumab monoclonal antibody [MoAb]; CD138DM immunotoxin; MM cell-dendritic cell vaccines; CD138, CS-1, and XBP-1 peptide vaccines; anti-17 MoAb; and other treatments to overcome causes of immune dysfunction). Second, promising next-generation agents target the MM cell in its microenvironment (eg, deubiquitinating enzyme inhibitors; chymotryptic [carfilzomib, Onyx 0912, MLN 9708] and broader [NPI-0052] proteasome inhibitors; immunoproteasome inhibitors; and pomalidamide). Moreover, agents targeting bone biology (eg, zoledronic acid, anti-DKK-1 MoAb, anti-B-cell activating factor MoAb and bortezomib, Btk inhibitor) show promise not only in preserving bone integrity but also against MM. Third, rationally based combination therapies, including bortezomib with Akt, mammalian target of rapamycin, or histone deacetylase inhibitors, are active even in bortezomib-refractory MM. Finally, genomics is currently being used in the definition of MM heterogeneity, new target discovery, and development of personalized therapy. Myeloma therefore represents a paradigm for targeting the tumor in its microenvironment, which has already markedly improved patient outcome in MM and has great potential in other hematologic malignancies and solid tumors as well.

Intrinsic modulation of lymphocyte function by stromal cell network: advance in therapeutic targeting of cancer

Advances in tumor biology have demonstrated a point of critical importance: tumor are established as an intersection of malignant clone cells and surrounding stromal cells. The stroma is composed of nonhematopoietic cells, including connective tissue cells, blood vessels, nerves, fat and smooth muscle cells, in the extracellular matrix niche. Recent studies have demonstrated that stromal cells regulate immune responses by: coordinating lymphocyte homing, differentiation, activation and antigen responses; inducing tolerance; and maintaining immunologic memory. Hence, elucidation of the interaction between stromal cells and lymphocytes is essential for generating effective immunotherapies. In this article, we summarize what is currently known about the interactions between stromal cells and lymphocytes in the tumor microenvironment, as well as potential immunotherapeutic approaches targeting stroma-lymphocyte interactions; both in the context of our work on multiple myeloma, and of recent literature in both solid tumors and hematologic malignancies.

Evaluation of antiproliferative effect of N-(alkyladamantyl)phthalimides in vitro

A series of (1-adamantyl)phthalimides, 1-4, and (2-adamantyl)phthalimides, 5-8, characterized by different chain length between the adamantyl and the phthalimide moiety were synthesized, as well as 1- and 2-adamantylphthalimides substituted by nitro 9, 10, and amino group 11, 12, and phthalimides bearing homoadamantyl 13 and protoadamantyl substituent 14 and 15. The compounds were tested for antiproliferative activity in vitro on a series of five human cancer lines: MCF-7 (breast carcinoma), SW 620 (colon carcinoma), HCT 116 (colon carcinoma), MOLT-4 (acute lymphoblastic leukemia), H 460 (lung carcinoma), and a non-tumor cell line HaCaT (human keratinocytes). All compounds except nitro derivatives 9 and 10 exhibited antiproliferative activity. The activity was generally better in the 2-adamantyl series 5-8 and in the compounds having the longest alkyl spacers as in 4 and 8, or with an amino group as in 9 and 10. The most active compounds with the propylene spacer 4 and 8 showed the highest selectivity toward tumor cells. The activity was found to be due to a delay in the progress through the cell cycle at G1/S phase.

Compartment-Specific Bioluminescence Imaging platform for the high-throughput evaluation of antitumor immune function

Conventional assays evaluating antitumor activity of immune effector cells have limitations that preclude their high-throughput application. We adapted the recently developed Compartment-Specific Bioluminescence Imaging (CS-BLI) technique to perform high-throughput quantification of innate antitumor activity and to show how pharmacologic agents (eg, lenalidomide, pomalidomide, bortezomib, and dexamethasone) and autologous BM stromal cells modulate that activity. CS-BLI-based screening allowed us to identify agents that enhance or inhibit innate antitumor cytotoxicity. Specifically, we identified compounds that stimulate immune effector cells against some tumor targets but suppressed their activity against other tumor cells. CS-BLI offers rapid, simplified, and specific evaluation of multiple conditions, including drug treatments and/or cocultures with stromal cells and highlights that immunomodulatory pharmacologic responses can be heterogeneous across different types of tumor cells. This study provides a framework to identify novel immunomodulatory agents and to prioritize compounds for clinical development on the basis of their effect on antitumor immunity.

Safety and efficacy of lenalidomide in relapsed or refractory multiple myeloma

Lenalidomide is an oral immunomodulatory drug that has helped improve outcomes in multiple myeloma (MM) patients. Combination lenalidomide and dexamethasone (Len+Dex) has been shown to increase response rates and prolong survival compared with dexamethasone alone in patients with relapsed or refractory MM (RRMM). Clinical benefit may be greatest when Len+Dex is given at first relapse, and continued treatment appears to provide greater depth of response and improved survival outcomes. The most common adverse events associated with Len+Dex are cytopenias, which are predictable and manageable. Len+Dex is associated with an increased risk of venous thromboembolism, which necessitates adequate prophylaxis. The risk of second primary malignancies does not appear to be increased in patients with RRMM treated with lenalidomide-based therapy. Here we review the safety and efficacy of Len+Dex in RRMM, and provide an overview of data from Spain on the use of Len+Dex in RRMM.

The clinical safety of lenalidomide in multiple myeloma and myelodysplastic syndromes

INTRODUCTION

Lenalidomide is an IMiDs® oral immunomodulatory compound developed for the treatment of patients with multiple myeloma (MM) and myelodysplastic syndromes (MDS). Long-term continuous treatment with lenalidomide beyond first response may be important to optimize responses and delay relapse.

AREAS COVERED

This review summarizes the lenalidomide mechanism of action, pharmacodynamics, key clinical studies with a focus on safety and post-marketing surveillance data. The necessity for early adverse-event management, including dose modifications for neutropenia and thrombocytopenia, and venous thromboembolism prophylaxis, where applicable, in order to maintain patients on treatment and achieve optimal efficacy, is discussed. Secondary primary malignancies in MM and progression to acute myeloid leukemia in MDS patients in the context of lenalidomide treatment are also discussed. Finally, as lenalidomide is renally excreted, the requirement for dose adjustment according to creatinine clearance is discussed.

EXPERT OPINION

Lenalidomide is highly effective and generally well tolerated. Most adverse events occur early during the course of treatment and are manageable. Lenalidomide is not associated with peripheral neuropathy and has a lack of cumulative toxicity, making it an effective treatment option for long-term use in the management of MM and low/intermediate-1-risk MDS, specifically with chromosome 5q deletion with or without other cytogenetic abnormalities.

Management of myeloma: an Italian perspective

Multiple myeloma remains a fatal plasma cell malignancy. However, new insights into the disease biology and immunology have identified molecular mechanisms, underling functional interactions between plasma cells and the bone marrow microenvironment that have become molecular targets of so-called "new drugs" such as thalidomide, lenalidomide, and bortezomib. Recently, the combinations of new drugs with melphalan and prednisone in elderly patients, and with autologous stem cell transplantation in induction and/or maintenance schedules in younger patients have significantly prolonged overall survival. Optimal combinations and timing are a matter of debate. Moreover, management of side effects is a key clinical target to improve long-term quality of life. Many randomized phase III studies are currently in progress to address these issues. Whether these new advancements in myeloma treatment will eventually translate into a long chronic phase or a monoclonal gammopathy of undetermined significance-like status for the majority of patients remains, however, still unanswered.

The role of maintenance thalidomide therapy in multiple myeloma: MRC Myeloma IX results and meta-analysis

Thalidomide maintenance has the potential to modulate residual multiple myeloma (MM) after an initial response. This trial compared the effect of thalidomide maintenance and no maintenance on progression-free survival (PFS) and overall survival (OS) in MM patients. After intensive or nonintensive induction therapy, 820 newly diagnosed MM patients were randomized to open-label thalidomide maintenance until progression, or no maintenance. Interphase FISH (iFISH) analysis was performed at study entry. Median PFS was significantly longer with thalidomide maintenance (log-rank P < .001). Median OS was similar between regimens (log-rank P = .40). Patients with favorable iFISH showed improved PFS (P = .004) and a trend toward a late survival benefit. Patients with adverse iFISH receiving thalidomide showed no significant PFS benefit and worse OS (P = .009). Effective relapse therapy enhanced survival after progression, translating into a significant OS benefit. Meta-analysis of this and other studies show a significant late OS benefit (P < .001, 7-year difference hazard ratio = 12.3; 95% confidence interval, 5.5-19.0). Thalidomide maintenance significantly improves PFS and can be associated with improved OS. iFISH testing is important in assessing the clinical impact of maintenance therapy. Overview analysis demonstrated that thalidomide maintenance was associated with a significant late OS benefit. This trial was registered at www.isrctn.org as #ISRCTN68454111.

The rise, fall and subsequent triumph of thalidomide: lessons learned in drug development

Perhaps no other drug in modern medicine rivals the dramatic revitalization of thalidomide. Originally marketed as a sedative, thalidomide gained immense popularity worldwide among pregnant women because of its effective anti-emetic properties in morning sickness. Mounting evidence of human teratogenicity marked a dramatic fall from grace and led to widespread social, legal and economic ramifications. Despite its tragic past thalidomide emerged several decades later as a novel and highly effective agent in the treatment of various inflammatory and malignant diseases. In 2006 thalidomide completed its remarkable renaissance becoming the first new agent in over a decade to gain approval for the treatment of plasma cell myeloma. The catastrophic collapse yet subsequent revival of thalidomide provides important lessons in drug development. Never entirely abandoned by the medical community, thalidomide resurfaced as an important drug once the mechanisms of action were further studied and better understood. Ongoing research and development of related drugs such as lenalidomide now represent a class of irreplaceable drugs in hematological malignancies. Further, the tragedies associated with this agent stimulated the legislation which revamped the FDA regulatory process, expanded patient informed consent procedures and mandated more transparency from drug manufacturers. Finally, we review recent clinical trials summarizing selected medical indications for thalidomide with an emphasis on hematologic malignancies. Herein, we provide a historic perspective regarding the up-and-down development of thalidomide. Using PubMed databases we conducted searches using thalidomide and associated keywords highlighting pharmacology, mechanisms of action, and clinical uses.