Towards a new age in the treatment of multiple myeloma

Discovery of a Potent and Selective Naphthyridine-Based Chemical Probe for Casein Kinase 2

Naphthyridine-based inhibitors were synthesized to yield a potent and cell-active inhibitor of casein kinase 2 (CK2). Compound 2 selectively inhibits CK2α and CK2α' when profiled broadly, thereby making it an exquisitely selective chemical probe for CK2. A negative control that is structurally related but lacks a key hinge-binding nitrogen (7) was designed on the basis of structural studies. Compound 7 does not bind CK2α or CK2α' in cells and demonstrates excellent kinome-wide selectivity. Differential anticancer activity was observed when compound 2 was profiled alongside a structurally distinct CK2 chemical probe: SGC-CK2-1. This naphthyridine-based chemical probe (2) represents one of the best available small molecule tools with which to interrogate biology mediated by CK2.

High chymotrypsin-like activity in the plasma of patients with newly diagnosed multiple myeloma treated with bortezomib is predictive of a better response and longer PFS

Proteasome inhibitors (PIs) such as bortezomib constitute an important part of the modern standard therapy for multiple myeloma (MM). In this study, we set out to assess whether proteasome concentration and chymotrypsin-like (ChT-L) activity could serve as potential biomarkers defining the likelihood of response to treatment with bortezomib, in order to identify patients who are more likely to respond to treatment with PI. We analysed proteasome concentration and ChT-L activity in the plasma of 78 patients with newly diagnosed MM during treatment with or without proteasome inhibitors. Values of all the studied parameters in the group of responders decreased sharply from the initial levels already after the third cycle of chemotherapy and remained significantly lower until the end of treatment. On the other hand, in the group of non-responders, there was an increase in the measured proteasome parameters already after the third cycle, and they remained high during the next cycles of therapy. We also showed that high baseline proteasome ChT-L activity values might prognosticate longer progression-free survival (PFS) in patients treated with PI. Our findings demonstrate that measuring plasma proteasome ChT-L activity can be used as a powerful biomarker for predicting clinical response to treatment and PFS in patients with newly diagnosed MM.

Cost of Illness in Patients with Multiple Myeloma in Italy: The CoMiM Study

Aims and background

Multiple myeloma is the second most common hematological cancer. Although it accounts for only a relatively small percentage of all cancer types, the costs associated with managing multiple myeloma are considerable. Available studies are mainly focused on health care costs. The Costo del Mieloma Multiplo (Cost of MM, CoMiM) study investigated the cost of illness of multiple myeloma in Italy during one year of disease management.

Methods

CoMiM is a retrospective, prevalence-based, multi-center, cross-sectional study based on a stratified sample of patients seen during normal clinical practice (asymptomatic; symptomatic on drugs; symptomatic receiving autologous stem cell transplantation; plateau/remission). Demographics, clinical history, health care and non-health care resource consumption data were collected. Costs were evaluated from the societal viewpoint and expressed in Euro 2008.

Results

Data on 236 patients were analyzed (39 asymptomatic, 17%; 29 symptomatic receiving autologous stem-cell transplantation, 12%; 105 symptomatic receiving drugs, 44%; 63 plateau/remission, 27%). The total cost of illness reached € 19,267.1 ± 25,078.6 (asymptomatic, € 959.3 ± 1091.6; symptomatic receiving drugs, € 21,707.8 ± 21,785.3; symptomatic receiving autologous stem-cell transplantation, € 59,243.7 ± 24,214.0; plateau/remission, € 8130.7 ± 15,092.5). The main cost drivers of total cost of illness were drugs and hospital admissions (46.1% and 29.4%, respectively). Antineoplastics and immunomodulators drove the cost of drugs (21.6% and 21.1% of the total cost of illness). Cost of antineoplastics was led by bortezomib (97.4%), whereas the cost driver for immunomodulators was lenalidomide (99.4%). Cost of hospitalization funded by the Italian National Health Service was strongly influenced by transplantation (94.6%), whereas chemotherapy and skeletal fractures did not exceed 1% and 2%, respectively.

Conclusions

Despite some limitations, the CoMiM study provides Italian health care decision-makers with an insight into the stratified cost of illness of multiple myeloma patients.

Targeting MET kinase with the small-molecule inhibitor amuvatinib induces cytotoxicity in primary myeloma cells and cell lines

BACKGROUND

MET is a receptor tyrosine kinase that is activated by the ligand HGF and this pathway promotes cell survival, migration, and motility. In accordance with its oncogenic role, MET is constitutively active, mutated, or over-expressed in many cancers. Corollary to its impact, inhibition of MET kinase activity causes reduction of the downstream signaling and demise of cells. In myeloma, a B-cell plasma malignancy, MET is neither mutated nor over-expressed, however, HGF is increased in plasma or serum obtained from myeloma patients and this was associated with poor prognosis. The small-molecule, amuvatinib, inhibits MET receptor tyrosine kinase. Based on this background, we hypothesized that targeting the HGF/MET signaling pathway is a rational approach to myeloma therapy and that myeloma cells would be sensitive to amuvatinib.

METHODS

Expression of MET and HGF mRNAs in normal versus malignant plasma cells was compared during disease progression. Cell death and growth as well as MET signaling pathway were assessed in amuvatinib treated primary myeloma cells and cell lines.

RESULTS

There was a progressive increase in the transcript levels of HGF (but not MET) from normal plasma cells to refractory malignant plasma cells. Amuvatinib readily inhibited MET phosphorylation in primary CD138+ cells from myeloma patients and in concordance, increased cell death. A 48-hr amuvatinib treatment in high HGF-expressing myeloma cell line, U266, resulted in growth inhibition. Levels of cytotoxicity were time-dependent; at 24, 48, and 72 h, amuvatinib (25 μM) resulted in 28%, 40%, and 55% cell death. Consistent with these data, there was an amuvatinib-mediated decrease in MET phosphorylation in the cell line. Amuvatinib at concentrations of 5, 10, or 25 μM readily inhibited HGF-dependent MET, AKT, ERK and GSK-3-beta phosphorylation. MET-mediated effects were not observed in myeloma cell line that has low MET and/or HGF expression.

CONCLUSIONS

These data suggest that at the cellular level MET/HGF pathway inclines with myeloma disease progression. Amuvatinib, a small molecule MET kinase inhibitor, is effective in inducing growth inhibition and cell death in myeloma cell lines as well as primary malignant plasma cells. These cytostatic and cytotoxic effects were associated with an impact on MET/HGF pathway.

Modulation of eIF5A expression using SNS01 nanoparticles inhibits NF-κB activity and tumor growth in murine models of multiple myeloma

Despite recent advances in the first-line treatment of multiple myeloma, almost all patients eventually experience relapse with drug-resistant disease. New therapeutic modalities are needed, and to this end, SNS01, a therapeutic nanoparticle, is being investigated for treatment of multiple myeloma. The antitumoral activity of SNS01 is based upon modulation of eukaryotic translation initiation factor 5A (eIF5A), a highly conserved protein that is involved in many cellular processes including proliferation, apoptosis, differentiation and inflammation. eIF5A is regulated by post-translational hypusine modification, and overexpression of hypusination-resistant mutants of eIF5A induces apoptosis in many types of cancer cells. SNS01 is a polyethylenimine (PEI)-based nanoparticle that contains both a B-cell-specific expression plasmid expressing a non-hypusinable mutant of eIF5A and a small interfering RNA (siRNA) which depletes endogenous hypusinated eIF5A. Reducing hypusine-modified eIF5A levels was found to inhibit phosphorylation and activity of ERK MAPK and nuclear factor-κB (NF-κB), and thus sensitize myeloma cells to apoptosis resulting from transfection of a plasmid expressing eIF5A(K50R). SNS01 exhibited significant antitumoral activity in both KAS-6/1 (95% inhibition; P < 0.05) and RPMI 8226 (59% inhibition; P < 0.05) multiple myeloma xenograft models following systemic administration. These results highlight the potential of using this approach as a new therapeutic strategy for multiple myeloma.

Naltrindole inhibits human multiple myeloma cell proliferation in vitro and in a murine xenograft model in vivo

It has been demonstrated previously that immune cell activation and proliferation were sensitive to the effects of naltrindole, a nonpeptidic δ-opioid receptor-selective antagonist; therefore, we hypothesized that human multiple myeloma (MM) would be a valuable model for studying potential antineoplastic properties of naltrindole. [(3)H]naltrindole exhibited saturable, low-affinity binding to intact human MM cells; however, the pharmacological profile of the binding site differed considerably from the properties of δ-, κ-, and μ-opioid receptors, and opioid receptor mRNA was not detected in MM cells by reverse transcriptase-polymerase chain reaction. Naltrindole inhibited the proliferation of cultured human U266 MM cells in a time- and dose-dependent manner with an EC(50) of 16 μM. The naltrindole-induced inhibition of U266 cell proliferation was not blocked by a 10-fold molar excess of naltrexone, a nonselective opioid antagonist. Additive inhibition of MM cell proliferation was observed when using a combination of naltrindole with the histone deacetylase inhibitor sodium valproate, the proteasome inhibitor bortezomib, the glucocorticoid receptor agonist dexamethasone, and the HMG CoA reductase inhibitor simvastatin. Treatment of U266 cells with naltrindole significantly decreased the level of the active, phosphorylated form of the kinases, extracellular signal-regulated kinase and Akt, which may be related to its antiproliferative activity. The antiproliferative activity of naltrindole toward MM cells was maintained in cocultures of MM and bone marrow-derived stromal cells, mimicking the bone marrow microenvironment. In vivo, naltrindole significantly decreased tumor cell volumes in human MM cell xenografts in severe combined immunodeficient mice. We hypothesize that naltrindole inhibits the proliferation of MM cells through a nonopioid receptor-dependent mechanism.

Interleukin-6, osteopontin and Raf/MEK/ERK signaling modulate the sensitivity of human myeloma cells to alkylphosphocholines

Alkylphosphocholines are highly active against multiple myeloma (MM) cells in vitro and are devoid of myelotoxicity. Little is known about the determinants of MM cell responsiveness or resistance to these drugs. In this study we investigated the effects of disease-relevant cytokines, such as interleukin-6 (IL-6) and osteopontin (OPN), on the in vitro antimyeloma activity of erufosine and perifosine. The role of the Raf/MEK/ERK pathway was also studied. Exogenous IL-6 reduced the cytotoxicity of erufosine against OPM-2 cells and, to a smaller extent, against U-266 cells. This was accompanied by inhibition of apoptosis in OPM-2 cells. The efficacy of perifosine was similarly affected, but to a greater extent. IL-6 slightly enhanced the sensitivity of RPMI-8226 cells to erufosine, thus emphasizing the heterogeneity of MM. Induced overexpression of OPN isoforms made OPM-2 cells less sensitive to erufosine. In all cases of IL-6- or OPN-induced resistance, the effective concentrations of erufosine were still within the clinically achievable range. Like other alkylphosphocholines, erufosine enhanced Raf/MEK/ERK signaling in MM cells but in some cases this contributed to cytotoxicity.

Interplay between histone deacetylases and autophagy--from cancer therapy to neurodegeneration

Histone deacetylases (HDACs) are chromatin modifiers that alter gene expression but also exert a broad range of functions outside the nucleus by deacetylating non-histone target proteins. They gained growing attention for their implications in disease treatment, mainly through research using HDAC-inhibiting compounds. Understanding the effects of HDAC function and deregulation has therefore become an important focus for both basic and applied research. One of the described effects of HDAC inhibition is induction of autophagy. Autophagy is a ubiquitous process of recycling cellular components in response to starvation or stress and therefore crucial for cell homeostasis. Because of its role in managing anomalous protein overloads, autophagy is of great interest for neurodegenerative disease research. However, autophagy can also promote cell death, which puts it in the focus of cancer research. This review provides an overview of what we know of the impact of HDACs on the autophagy pathway and describes the fields where promising progress has been achieved, although one has to state that the work to illuminate the connections has just begun. Therefore, one focus is the effect of HDAC inhibition on autophagy in several types and models of cancer, which aims to find combinations of treatments that circumvent the ability of cancer cells to escape from cell death. Another recently emerged aspect is the direct involvement of the cytosolic deacetylase HDAC6 in autophagy progression, which is of great potential for revealing disease mechanisms in neurodegeneration.

Isolation of aggresomes and other large aggregates

Upon permanent stresses and in various diseases, small protein aggregates may accumulate in cells and cause toxicity. A recently discovered protective system transports these aggregates to the centrosome location via microtubules, to form a large agglomerate of aggregates called the aggresomes. Here, we describe a newly developed method for isolating aggresomes. This principle can also be used for purification of other large structures and even organelles.

Lenalidomide is effective as salvage therapy in refractory or relapsed multiple myeloma: analysis of the Spanish Compassionate Use Registry in advanced patients

We evaluated the clinical results of lenalidomide (Len) as a compassionate salvage therapy in refractory/relapsed multiple myeloma (MM) patients. A nationwide multi-centre, retrospective research study was performed to evaluate clinical data from patients with advanced MM for which compassionate use of lenalidomide was requested. The primary endpoints were the overall response rate (ORR) and the time to progression (TTP). Secondary objectives included safety and overall survival (OS) since starting of lenalidomide therapy. Data collected from the Spanish Compassionate Use Registry included 111 patients treated in 2006-2008. The median (range) number of previous treatment lines was 3 (1-8). The median duration of lenalidomide treatment while on study was of 4.9 months (1-18). Dexamethasone was given concomitantly with Len in 89% of patients. The ORR was 66% (4% of patients had stringent complete, 11% complete and 11% very good partial responses). Median TTP and OS were 13.0 and 17.4 months, respectively. The depth of response was significantly associated with a longer OS. Toxicity, mainly myelosuppression, was predictable and manageable with Len dose adjustments and cytokine support. Lenalidomide as salvage compassionate therapy in refractory/relapsed MM showed, in this series of heavily pre-treated patients, similar efficacy to that reported in pivotal clinical trials with acceptable tolerance.

Calcium channel blocker verapamil enhances endoplasmic reticulum stress and cell death induced by proteasome inhibition in myeloma cells

The proteasome inhibitor bortezomib is clinically approved for the treatment of multiple myeloma. However, long-term remissions are difficult to achieve, and myeloma cells often develop secondary resistance to proteasome inhibitors. We recently demonstrated that the extraordinary sensitivity of myeloma cells toward bortezomib is dependent on their extensive immunoglobulin synthesis, thereby triggering the terminal unfolded protein response (UPR). Here, we investigated whether verapamil, an inhibitor of the multidrug resistance (MDR) gene product, can enhance the cytotoxicity of bortezomib. The combination of bortezomib and verapamil synergistically decreased the viability of myeloma cells by inducing cell death. Importantly, bortezomib-mediated activation of major UPR components was enhanced by verapamil. The combination of bortezomib and verapamil resulted in caspase activation followed by poly(ADP-ribose) polymerase cleavage, whereas nuclear factor kappaB (NF-kappaB) activity declined in myeloma cells. Also, we found reduced immunoglobulin G secretion along with increased amounts of ubiquitinylated proteins within insoluble fractions of myeloma cells when using the combination treatment. Verapamil markedly induced reactive oxygen species production and autophagic-like processes. Furthermore, verapamil decreased MDR1 expression. We conclude that verapamil increased the antimyeloma effect of bortezomib by enhancing ER stress signals along with NF-kappaB inhibition, leading to cell death. Thus, the combination of bortezomib with verapamil may improve the efficacy of proteasome inhibitory therapy.

Lenalidomide in multiple myeloma: an evidence-based review of its role in therapy

INTRODUCTION

Multiple myeloma (MM) is a relatively common and incurable hematological malignancy. Currently, there is no single standard therapy, with choice of treatment dependent on individual patient factors. Lenalidomide is an immunomodulatory drug with potent antitumor, antiangiogenic, immunomodulatory, and proapoptotic activity in MM.

AIMS

To evaluate the evidence for the use of lenalidomide in its current indication in relapsed or refractory MM, and additionally its investigational use for the treatment of newly diagnosed MM.

EVIDENCE REVIEW

In patients with relapsed and refractory MM, adding lenalidomide to high-dose dexamethasone significantly improves response rates and time-to-progression, relative to high-dose dexamethasone alone. This translates into a significant extension of overall survival (with a median extension of 9.1 months in a pivotal phase III study). Outcome is independent of patient age, number of previous therapies, type of previous therapy (including thalidomide or autologous stem cell transplantation), renal impairment, and beta(2)-microglobulin level. Evidence suggests that combining lenalidomide with low-dose dexamethasone improves outcomes in patients with newly diagnosed disease and is superior to lenalidomide combined with high-dose dexamethasone. Myelosuppression is the predominant toxicity observed, although some studies have shown high incidences of venous thromboembolism in the absence of prophylactic antithrombotic anticoagulation therapy. There is currently only limited evidence regarding the health economics of lenalidomide. ROLE IN THERAPY: The encouraging results obtained with lenalidomide alone and in combination with dexamethasone in patients with relapsed or refractory MM have led to its adoption as a recommended therapy in patients who have received at least one prior treatment. Emerging evidence supports the ongoing investigation of lenalidomide in combination with low-dose dexamethasone, and in other combinations including bortezomib, for use both in relapsed, refractory, and newly diagnosed MM.

Erucylphospho-N,N,N-trimethylpropylammonium (erufosine) is a potential antimyeloma drug devoid of myelotoxicity

PURPOSE

Erufosine is an i.v. injectable alkylphosphocholine which is active against various haematological malignancies in vitro. In the present study, its effects on multiple myeloma (MM) cell lines and on murine and human hematopoietic progenitor cells (HPCs) were investigated.

METHODS

The following MM cell lines were used: RPMI-8226, U-266 and OPM-2. The cytotoxicity of erufosine against these cell lines was determined by the MTT-dye reduction assay. Bcl-2, Bcl-X(L) and pAkt expression levels, activation of caspases, as well as cleavage of PARP, were studied by Western blotting. Migration was evaluated by a modified Boyden-chamber assay. The haematologic toxicity of erufosine was assessed using clonogenicity assays with normal HPCs of murine or human origin.

RESULTS

Significant cytotoxic activity of erufosine against the MM cell lines was found. Comparison of the characteristics of erufosine-induced cell death in the three cell lines revealed a complex mode of action with apoptotic mechanisms prevailing in OPM-2 cells and non-apoptotic mechanisms prevailing in U-266 cells. The sensitivity of the MM cell lines to erufosine-induced apoptosis correlated inversely with the Bcl-X(L) expression level. Erufosine participated in synergistic interactions with various drugs. Furthermore, it showed potent migration-inhibiting activity in RPMI-8226 cells. Erufosine was not toxic to normal HPCs of murine or human origin and even stimulated progenitors from human umbilical cord blood to form granulocyte/macrophage colonies. Moreover, erufosine ameliorated the toxicity of bendamustine to murine HPCs.

CONCLUSIONS

Overall, the data presented reveal that erufosine could have potential as an antimyeloma drug and deserves further development.

Erucylphospho-N,N,N-trimethylpropylammonium shows substantial cytotoxicity in multiple myeloma cells

Multiple myeloma (MM) is a frequent hematological malignancy that is incurable despite recent developments, such as proteasome and angiogenic inhibitors. Erucylphospho-N,N,N-trimethylpropylammonium (erufosine) is an i.v. injectable alkylphosphocholine with antineoplastic activity based on an unusual mode of action and is currently undergoing clinical trials in leukemia patients. The aim of this investigation was to evaluate the efficacy of erufosine in MM cells and to study the modulation of cell-death pathways. The cytotoxicity of erufosine against three MM cell lines (RPMI-8226, U-266, and OPM-2) was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide-dye reduction assay. All MM cell lines responded to erufosine, RPMI-8226 cells being most and U-266 being least sensitive. The respective IC(50) values were 3.2 and 16.2 micromol/L. Various cell-death characteristics were studied in response to erufosine, such as morphological changes, oligonucleosomal DNA fragmentation, caspase activation, and poly (ADP)-ribose polymerase cleavage. Erufosine was found to cause cell shrinkage, chromatin condensation, and caspase-8 and -3 activation. Taken together, our data indicate that erufosine is a potential antimyeloma drug eliciting specific features of apoptotic cell death in vitro.

Long-term follow-up on overall survival from the MM-009 and MM-010 phase III trials of lenalidomide plus dexamethasone in patients with relapsed or refractory multiple myeloma

We present a pooled update of two large, multicenter MM-009 and MM-010 placebo-controlled randomized phase III trials that included 704 patients and assessed lenalidomide plus dexamethasone versus dexamethasone plus placebo in patients with relapsed/refractory multiple myeloma (MM). Patients in both studies were randomized to receive 25 mg daily oral lenalidomide or identical placebo, plus 40 mg oral dexamethasone. In this pooled analysis, using data up to unblinding (June 2005 for MM-009 and August 2005 for MM-010), treatment with lenalidomide plus dexamethasone significantly improved overall response (60.6 vs 21.9%, P<0.001), complete response rate (15.0 vs 2.0%, P<0.001), time to progression (median of 13.4 vs 4.6 months, P<0.001) and duration of response (median of 15.8 months vs 7 months, P<0.001) compared with dexamethasone-placebo. At a median follow-up of 48 months for surviving patients, using data up to July 2008, a significant benefit in overall survival (median of 38.0 vs 31.6 months, P=0.045) was retained despite 47.6% of patients who were randomized to dexamethasone-placebo receiving lenalidomide-based treatment after disease progression or study unblinding. Low beta(2)-microglobulin and low bone marrow plasmacytosis were associated with longer survival. In conclusion, these data confirm the significant response and survival benefit with lenalidomide and dexamethasone.

Dendritic cells and monocyte/macrophages that create the IL-6/APRIL-rich lymph node microenvironments where plasmablasts mature

IL-6 and APRIL influence the growth, differentiation, and survival of normal and neoplastic Ab-forming cells (AFC). In this study, we identify two subsets of myeloid cells that associate with the AFC and are the main producers of these factors during a T-dependent Ab response to alum-precipitated protein in mouse lymph nodes. First CD11c(+)CD8alpha(-) dendritic cells located in the perivascular area of the T zone provide about half of the IL-6 mRNA produced in the node together with significant amounts of APRIL mRNA. The number of these cells increases during the response, at least in part due to local proliferation. The second subset comprises Gr1(+)CD11b(+)F4/80(+) monocyte/macrophages. These colonize the medullary cords during the response and are the other main IL-6 mRNA producers and the greatest source of APRIL mRNA. This medullary cord monocyte/macrophage subset results in local increase of APRIL mRNA that mirrors the polarity of CXCL12 expression in the node. The distribution of these myeloid cell subsets correlates with a gradient of AFC maturation assessed by progressive loss of Ki67 as AFC pass from the B cell follicle along the perivascular areas to the medullary cords.

Targeting MET transcription as a therapeutic strategy in multiple myeloma

Multiple myeloma (MM) is an incurable indolent malignancy with an average lifespan of 3 years, underscoring the need for new therapies. Studies have shown that the receptor MET and its ligand hepatocyte growth factor play an important role in proliferation, migration, adhesion, and survival of MM cells. Hence, an effective way to decrease MET receptor may act as a viable therapeutic option. Since MET mRNA and protein have short half-lives, we hypothesized that transcription inhibitor will reduce MET transcript and protein levels and this will lead to cell death. Pharmacological (flavopiridol) and molecular (shRNA) transcription inhibitor were used to impede formation of MET transcripts. The diminution of global RNA synthesis with flavopiridol was related to phosphorylation status of Ser residues (r (2) = 0.90 and 0.92 for Ser2 and Ser5) on the C-terminal-domain of RNA polymerase II. This was accompanied with a time-dependent decrease in MET transcript, which reached to less than 30% (1 microM) and 10% (3 microM) by 24 h. This decline in transcript level was directly associated with a reduction in MET protein level (r (2) = 0.82) and resulted in cell death. Assessment of MET in MM survival was done by using shRNA targeted towards MET. When cells were infected with shRNA viral construct, there was increased cell death with a decline in MET transcript and protein. Taken together, our study demonstrates that MET plays a critical role in the survival and removal or lowering of MET by flavopiridol or shRNA results in the demise of MM cells.

Input of DNA microarrays to identify novel mechanisms in multiple myeloma biology and therapeutic applications

Multiple myeloma is a B-cell neoplasia characterized by the proliferation of a clone of malignant plasma cells in the bone marrow. We review here the input of gene expression profiling of myeloma cells and of their tumor microenvironment to develop new tumor classifiers, to better understand the biology of myeloma cells, to identify some mechanisms of drug sensitivity and resistance, to identify new myeloma growth factors, and to depict the complex interactions between tumor cells and their microenvironment. We discuss how these findings may improve the clinical outcome of this still incurable disease.

Lenalidomide: a new therapy for multiple myeloma

The last decade has seen rapid evolution in the management of multiple myeloma. Cytogenetic, molecular, and proteomic techniques have led to a better understanding of the pathophysiology and prognostic markers of this heterogeneous malignancy. New immunomodulatory drugs, such as lenalidomide, which interrupt myeloma growth and survival pathways have entered into clinical usage. Combined with dexamethasone, oral lenalidomide has proved to be highly effective in patients whose disease has become resistant to conventional therapy. Currently, several clinical trials are ongoing in order to define the optimal use of this new agent and its combinations across the spectrum of patients with myeloma. Whether the ultimate outcome of future research will be a single-treatment solution for all patients, or whether treatments will become better-tailored to the individual (based on prognostic markers and pre-existing co-morbidities) has yet to be determined.