From the bench to the bedside: emerging new treatments in multiple myeloma

Synergy between BRD9- and IKZF3-Targeting as a Therapeutic Strategy for Multiple Myeloma

Progress in the treatment of multiple myeloma (MM) has resulted in improvement in the survival rate. However, there is still a need for more efficacious and tolerated therapies. We and others have shown that bromodomain-containing protein 9 (BRD9), a member of the non-canonical SWI/SNF chromatin remodeling complex, plays a role in MM cell survival, and targeting BRD9 selectively blocks MM cell proliferation and synergizes with IMiDs. We found that synergy in vitro is associated with the downregulation of MYC and Ikaros proteins, including IKZF3, and overexpression of IKZF3 or MYC could partially reverse synergy. RNA-seq analysis revealed synergy to be associated with the suppression of pathways associated with MYC and E2F target genes and pathways, including cell cycle, cell division, and DNA replication. Stimulated pathways included cell adhesion and immune and inflammatory response. Importantly, combining IMiD treatment and BRD9 targeting, which leads to the downregulation of MYC protein and upregulation of CRBN protein, was able to override IMiD resistance of cells exposed to iberdomide in long-term culture. Taken together, our results support the notion that combination therapy based on agents targeting BRD9 and IKZF3, two established dependencies in MM, represents a promising novel therapeutic strategy for MM and IMiD-resistant disease.

Targeting of mitochondrial fission through natural flavanones elicits anti-myeloma activity

BACKGROUND

Mitochondrial alterations, often dependent on unbalanced mitochondrial dynamics, feature in the pathobiology of human cancers, including multiple myeloma (MM). Flavanones are natural flavonoids endowed with mitochondrial targeting activities. Herein, we investigated the capability of Hesperetin (Hes) and Naringenin (Nar), two aglycones of Hesperidin and Naringin flavanone glycosides, to selectively target Drp1, a pivotal regulator of mitochondrial dynamics, prompting anti-MM activity.

METHODS

Molecular docking analyses were performed on the crystallographic structure of Dynamin-1-like protein (Drp1), using Hes and Nar molecular structures. Cell viability and apoptosis were assessed in MM cell lines, or in co-culture systems with primary bone marrow stromal cells, using Cell Titer Glo and Annexin V-7AAD staining, respectively; clonogenicity was determined using methylcellulose colony assays. Transcriptomic analyses were carried out using the Ion AmpliSeq™ platform; mRNA and protein expression levels were determined by quantitative RT-PCR and western blotting, respectively. Mitochondrial architecture was assessed by transmission electron microscopy. Real time measurement of oxygen consumption was performed by high resolution respirometry in living cells. In vivo anti-tumor activity was evaluated in NOD-SCID mice subcutaneously engrafted with MM cells.

RESULTS

Hes and Nar were found to accommodate within the GTPase binding site of Drp1, and to inhibit Drp1 expression and activity, leading to hyperfused mitochondria with reduced OXPHOS. In vitro, Hes and Nar reduced MM clonogenicity and viability, even in the presence of patient-derived bone marrow stromal cells, triggering ER stress and apoptosis. Interestingly, Hes and Nar rewired MM cell metabolism through the down-regulation of master transcriptional activators (SREBF-1, c-MYC) of lipogenesis genes. An extract of Tacle, a Citrus variety rich in Hesperidin and Naringin, was capable to recapitulate the phenotypic and molecular perturbations of each flavanone, triggering anti-MM activity in vivo.

CONCLUSION

Hes and Nar inhibit proliferation, rewire the metabolism and induce apoptosis of MM cells via antagonism of the mitochondrial fission driver Drp1. These results provide a framework for the development of natural anti-MM therapeutics targeting aberrant mitochondrial dependencies.

An mTORC1 to HRI signaling axis promotes cytotoxicity of proteasome inhibitors in multiple myeloma

Multiple myeloma (MM) causes approximately 20% of deaths from blood cancers. Notwithstanding significant therapeutic progress, such as with proteasome inhibitors (PIs), MM remains incurable due to the development of resistance. mTORC1 is a key metabolic regulator, which frequently becomes dysregulated in cancer. While mTORC1 inhibitors reduce MM viability and synergize with other therapies in vitro, clinically, mTORC1 inhibitors are not effective for MM. Here we show that the inactivation of mTORC1 is an intrinsic response of MM to PI treatment. Genetically enforced hyperactivation of mTORC1 in MM was sufficient to compromise tumorigenicity in mice. In vitro, mTORC1-hyperactivated MM cells gained sensitivity to PIs and hypoxia. This was accompanied by increased mitochondrial stress and activation of the eIF2α kinase HRI, which initiates the integrated stress response. Deletion of HRI elevated the toxicity of PIs in wt and mTORC1-activated MM. Finally, we identified the drug PMA as a robust inducer of mTORC1 activity, which synergized with PIs in inducing MM cell death. These results help explain the clinical inefficacy of mTORC1 inhibitors in MM. Our data implicate mTORC1 induction and/or HRI inhibition as pharmacological strategies to enhance MM therapy by PIs.

HDAC6-Selective Inhibitor Overcomes Bortezomib Resistance in Multiple Myeloma

Although multiple myeloma (MM) patients benefit from standard bortezomib (BTZ) chemotherapy, they develop drug resistance, resulting in relapse. We investigated whether histone deacetylase 6 (HDAC6) inhibitor A452 overcomes bortezomib resistance in MM. We show that HDAC6-selective inhibitor A452 significantly decreases the activation of BTZ-resistant markers, such as extracellular signal-regulated kinases (ERK) and nuclear factor kappa B (NF-κB), in acquired BTZ-resistant MM cells. Combination treatment of A452 and BTZ or carfilzomib (CFZ) synergistically reduces BTZ-resistant markers. Additionally, A452 synergizes with BTZ or CFZ to inhibit the activation of NF-κB and signal transducer and activator of transcription 3 (STAT3), resulting in decreased expressions of low-molecular-mass polypeptide 2 (LMP2) and LMP7. Furthermore, combining A452 with BTZ or CFZ leads to synergistic cancer cell growth inhibition, viability decreases, and apoptosis induction in the BTZ-resistant MM cells. Overall, the synergistic effect of A452 with CFZ is more potent than that of A452 with BTZ in BTZ-resistant U266 cells. Thus, our findings reveal the HDAC6-selective inhibitor as a promising therapy for BTZ-chemoresistant MM.

Overcoming cancer therapeutic bottleneck by drug repurposing

Ever present hurdles for the discovery of new drugs for cancer therapy have necessitated the development of the alternative strategy of drug repurposing, the development of old drugs for new therapeutic purposes. This strategy with a cost-effective way offers a rare opportunity for the treatment of human neoplastic disease, facilitating rapid clinical translation. With an increased understanding of the hallmarks of cancer and the development of various data-driven approaches, drug repurposing further promotes the holistic productivity of drug discovery and reasonably focuses on target-defined antineoplastic compounds. The "treasure trove" of non-oncology drugs should not be ignored since they could target not only known but also hitherto unknown vulnerabilities of cancer. Indeed, different from targeted drugs, these old generic drugs, usually used in a multi-target strategy may bring benefit to patients. In this review, aiming to demonstrate the full potential of drug repurposing, we present various promising repurposed non-oncology drugs for clinical cancer management and classify these candidates into their proposed administration for either mono- or drug combination therapy. We also summarize approaches used for drug repurposing and discuss the main barriers to its uptake.

Inhibition of HSP90 overcomes melphalan resistance through downregulation of Src in multiple myeloma cells

Multiple myeloma (MM) is the second most common hematologic malignancy. In spite of the development of new therapeutic agents, MM remains incurable due to multidrug resistance (MDR) and the 5-year survival rate is approximately 50%. Thus, further study is needed to investigate the mechanism of MDR and improve MM prognosis. Heat shock protein 90 (HSP90) is a molecular chaperone that is responsible for the stability of a number of client proteins, most of which are involved in tumor progression. Therefore, HSP90 inhibitors represent potential new therapeutic agents for cancer. Furthermore, inhibition of HSP90 leads to degradation of client proteins, overcoming acquired anti-cancer drug resistance. In this study, we assessed the role of HSP90 in MDR using established melphalan-resistant MM cells. We found that expression of HSP90 was higher in melphalan-resistant MM cells than in parent cells and that HSP90 inhibitors KW-2478 and NUV-AUY922 restored drug sensitivity to the level observed in parent cells. Activation of the unfolded protein response is a hallmark of MM, and expression of endoplasmic reticulum stress signaling molecules is reduced in melphalan-resistant cells; however, KW-2478 did not affect endoplasmic reticulum stress signaling. We demonstrated that treatment with KW-2478 decreased expression of Src, a client of HSP90, and suppressed the activity of ERK, Akt, and NF-κB. Our findings indicate that inhibition of HSP90 results in suppression of Src and its downstream effectors, including ERK, Akt, and NF-κB, and therefore that HSP90 inhibitors could be useful for treatment of MDR MM.

Proteasome-associated deubiquitinases and cancer

Maintenance of protein homeostasis is a crucial process for the normal functioning of the cell. The regulated degradation of proteins is primarily facilitated by the ubiquitin proteasome system (UPS), a system of selective tagging of proteins with ubiquitin followed by proteasome-mediated proteolysis. The UPS is highly dynamic consisting of both ubiquitination and deubiquitination steps that modulate protein stabilization and degradation. Deregulation of protein stability is a common feature in the development and progression of numerous cancer types. Simultaneously, the elevated protein synthesis rate of cancer cells and consequential accumulation of misfolded proteins drives UPS addiction, thus sensitizing them to UPS inhibitors. This sensitivity along with the potential of stabilizing pro-apoptotic signaling pathways makes the proteasome an attractive clinical target for the development of novel therapies. Targeting of the catalytic 20S subunit of the proteasome is already a clinically validated strategy in multiple myeloma and other cancers. Spurred on by this success, promising novel inhibitors of the UPS have entered development, targeting the 20S as well as regulatory 19S subunit and inhibitors of deubiquitinating and ubiquitin ligase enzymes. In this review, we outline the manner in which deregulation of the UPS can cause cancer to develop, current clinical application of proteasome inhibitors, and the (pre-)clinical development of novel inhibitors of the UPS.

Kinase inhibitors as potential agents in the treatment of multiple myeloma

Recent years have witnessed a dramatic increase in the number of therapeutic options available for the treatment of multiple myeloma (MM) - from immunomodulating agents to proteasome inhibitors to histone deacetylase (HDAC) inhibitors and, most recently, monoclonal antibodies. Used in conjunction with autologous hematopoietic stem cell transplantation, these modalities have nearly doubled the disease's five-year survival rate over the last three decades to about 50%. In spite of these advances, MM still is considered incurable as resistance and relapse are common. While small molecule protein kinase inhibitors have made inroads in the therapy of a number of cancers, to date their application to MM has been less than successful. Focusing on MM, this review examines the roles played by a number of kinases in driving the malignant state and the rationale for target development in the design of a number of kinase inhibitors that have demonstrated anti-myeloma activity in both in vitro and in vivo xenograph models, as well as those that have entered clinical trials. Among the targets and their inhibitors examined are receptor and non-receptor tyrosine kinases, cell cycle control kinases, the PI3K/AKT/mTOR pathway kinases, protein kinase C, mitogen-activated protein kinase, glycogen synthase kinase, casein kinase, integrin-linked kinase, sphingosine kinase, and kinases involved in the unfolded protein response.

Selinexor Overcomes Hypoxia-Induced Drug Resistance in Multiple Myeloma

Increased levels of the nuclear export protein, exportin 1 (XPO1), were demonstrated in multiple myeloma (MM) patients. Targeting XPO1 with selinexor (the selective inhibitor of nuclear export; SINE compound KPT-330) demonstrates broad antitumor activity also in patient cells resistant to bortezomib; hence, it is a promising target in MM patients. Hypoxia is known to mediate tumor progression and drug resistance (including bortezomib resistance) in MM cells. In this study, we tested the effects of selinexor alone or in combination with bortezomib in normoxia and hypoxia on MM cell survival and apoptosis in vitro and in vivo. In vitro, selinexor alone decreased survival and increased apoptosis, resensitizing MM cells to bortezomib. In vivo, we examined the effects of selinexor alone on tumor initiation and tumor progression, as well as selinexor in combination with bortezomib, on tumor growth in a bortezomib-resistant MM xenograft mouse model. Selinexor, used as a single agent, delayed tumor initiation and tumor progression, prolonging mice survival. In bortezomib-resistant xenografts, selinexor overcame drug resistance, significantly decreasing tumor burden and extending mice survival when combined with bortezomib.

Novel Proteasome Inhibitors and Histone Deacetylase Inhibitors: Progress in Myeloma Therapeutics

The unfolded protein response is responsible for the detection of misfolded proteins and the coordination of their disposal and is necessary to maintain the cellular homoeostasis. Multiple myeloma cells secrete large amounts of immunoglobulins, proteins that need to be correctly folded by the chaperone system. If this process fails, the misfolded proteins have to be eliminated by the two main garbage-disposal systems of the cell: proteasome and aggresome. The blockade of either of these systems will result in accumulation of immunoglobulins and other toxic proteins in the cytoplasm and cell death. The simultaneous inhibition of the proteasome, by proteasome inhibitors (PIs) and the aggresome, by histone deacetylase inhibitors (HDACi) results in a synergistic increase in cytotoxicity in myeloma cell lines. This review provides an overview of mechanisms of action of second-generation PIs and HDACi in multiple myeloma (MM), the clinical results currently observed with these agents and assesses the potential therapeutic impact of the different agents in the two classes. The second-generation PIs offer benefits in terms of increased efficacy, reduced neurotoxicity as off-target effect and may overcome resistance to bortezomib because of their different chemical structure, mechanism of action and biological properties. HDACi with anti-myeloma activity in clinical development discussed in this review include vorinostat, panobinostat and selective HDAC6 inhibitor, ricolinostat.

Nanoparticle delivery systems, general approaches, and their implementation in multiple myeloma

Multiple myeloma (MM) is a hematological malignancy that remains incurable, with relapse rates >90%. The main limiting factor for the effective use of chemotherapies in MM is the serious side effects caused by these drugs. The emphasis in cancer treatment has shifted from cytotoxic, non-specific chemotherapies to molecularly targeted and rationally designed therapies showing greater efficacy and fewer side effects. Traditional chemotherapy has shown several disadvantages such as lack of targeting capabilities, systemic toxicity, and side effects; low therapeutic index, as well as most anticancer drugs, has poor water solubility. Nanoparticle delivery systems (NPs) are capable of targeting large doses of chemotherapies into the target area while sparing healthy tissues, overcoming the limitations of traditional chemotherapy. Here, we review the current state of the art in nanoparticle-based strategies designed to treat MM. Many nanoparticle delivery systems have been studied for myeloma using non-targeted NPs (liposomes, polymeric NPs, and inorganic NPs), triggered NPs, as well as targeted NPs (VLA-4, ABC drug transporters, bone microenvironment targeting). The results in preclinical and clinical studies are promising; however, there remains much to be learned in the emerging field of nanomedicine in myeloma.

Molecular chaperone GRP78 enhances aggresome delivery to autophagosomes to promote drug resistance in multiple myeloma

Despite the clinical benefit of the proteasome inhibitor bortezomib, multiple myeloma (MM) patients invariably relapse through poorly defined mechanisms. Myeloma cells inevitably develop chemoresistance that leads to disease relapse and patient-related deaths. Studies in tumor cell lines and biopsies obtained from patients refractory to therapy have revealed that myeloma cells adapt to stress by inducing expression of glucose-regulated protein 78 (GRP78), an endoplasmic reticulum (ER) chaperone with anti-apoptotic properties. Treatment of myeloma cells with bortezomib increased GRP78 levels and activated GRP78-dependent autophagy. Expression profiling indicated that GRP78-encoding HSPA5 was significantly upregulated in bortezomib-resistant cells. Co-treatment with the anti-diabetic agent metformin suppressed GRP78 and enhanced the anti-proliferative effect of bortezomib. Bortezomib treatment led to GRP78 co-localization with proteotoxic protein aggregates, known as aggresomes. Pharmacologic suppression, genetic ablation or mutational inactivation of GRP78 followed by bortezomib treatment led to the accumulation of aggresomes but impaired autophagy and enhanced anti-myeloma effect of bortezomib. GRP78 was co-immunoprecipitated with the KDEL receptor, an ER quality control regulator that binds proteins bearing the KDEL motif to mediate their retrieval from the Golgi complex back to the ER. Taken together, we demonstrate that inhibition of GRP78 functional activity disrupts autophagy and enhances the anti-myeloma effect of bortezomib.

A CD138-independent strategy to detect minimal residual disease and circulating tumour cells in multiple myeloma

CD138 (also termed SDC1) has been the gold-standard surface marker to detect multiple myeloma (MM) cells for decades; however, drug-resistant residual and circulating MM cells were shown to have lower expression of this marker. In this study, we have shown that residual MM cells following bortezomib treatment are hypoxic. This combination of drug exposure and hypoxia down-regulates their CD138 expression, thereby making this marker unsuitable for detecting residual or other hypoxic MM cells, such as circulating tumour cells, in MM. Hence, we developed an alternative biomarker set which detects myeloma cells independent of their hypoxic and CD138 expression status in vitro, in vivo and in primary MM patients. The new markers were able to identify a clonal CD138-negative population as minimal residual disease in the bone marrow and peripheral blood of MM patients. Further investigation to characterize the role of this population as a prognostic marker in MM is warranted.

Tris DBA palladium overcomes hypoxia-mediated drug resistance in multiple myeloma

Despite recent progress in novel and targeted therapies, multiple myeloma (MM) remains a therapeutically challenging incurable disease. The regulation of important cellular processes and its link to cancer presented Src as an attractive target for MM. We suggest a novel strategy to improve the treatment of MM and overcome the drug resistance for the current therapeutic agents by specific inhibition of Src in MM cells by Tris (Dibenzylideneacetone) dipalladium (Tris DBA). Tris DBA reduces proliferation, induces G1 arrest and apoptosis in MM cells. Tris DBA showed additive effect with proteasome inhibitors reducing proliferation, cell cycle signaling, and increasing apoptosis more than each drug alone. Tris DBA overcame hypoxia-induced effects such as enhanced chemotaxis or drug resistance to proteasome inhibitors by inhibition of HIF1α expression. Moreover, we found that Tris DBA is an effective anti-myeloma agent alone or in combination with other targeted drugs and that it reverses hypoxia-induced drug resistance in myeloma.

A phase 1/2 study of oral panobinostat combined with melphalan for patients with relapsed or refractory multiple myeloma

Panobinostat is a histone deacetylase inhibitor that has shown synergistic preclinical anti-myeloma activity when combined with other agents, recently exhibiting synergy with the alkylating agent melphalan (Sanchez et al., Leuk Res 35(3):373-379, 2011). This phase 1/2 trial investigated the safety and efficacy of panobinostat in combination with melphalan for relapsed/refractory multiple myeloma patients. There were four different trial treatment schedules due to tolerability issues, with the final treatment schedule (treatment schedule D) consisting of panobinostat (15 or 20 mg) and melphalan (0.05 or 0.10 mg/kg), both administered on days 1, 3, and 5 of a 28-day cycle. A total of 40 patients were enrolled; 3 in treatment schedule A, 9 in schedule B, 7 in schedule C, and finally 21 schedule D. Patients had been treated with a median of four regimens (range, 1-16) and two prior bortezomib-containing regimens (range, 0-9). Maximum-tolerated dose was established at 20 mg panobinostat and 0.05 mg/kg melphalan in treatment schedule D. Overall, 3 patients (7.5 %) achieved ≥partial response (two very good PRs and one PR) while 23 exhibited stable disease and 14 showed progressive disease. All three responders were enrolled in cohort 2 of treatment schedule B (panobinostat 20 mg thrice weekly continuously with melphalan 0.05 mg/kg on days 1, 3, and 5). Neutropenia and thrombocytopenia were common, with 30.8 and 23.1 % of patients exhibiting ≥grade 3, respectively. Panobinostat + melphalan appears to have tolerability issues in a dosing regimen capable of producing a response. Care must be taken to balance tolerability and efficacy with this combination.

An historic perspective of proteasome inhibition

The ubiquitin-proteasome system (UPS) and associated signaling pathways are regarded today as an exciting area of development for novel therapeutics. However, two decades ago, following the discovery and elucidation of ubiquitin and the 26S proteasome as key mediators of protein turnover, the concept of inhibiting the UPS was not even considered a feasible therapeutic approach due to the assumption that inhibition of this pathway would have widespread deleterious effects. Subsequent clinical developments with the first-in-class proteasome inhibitor bortezomib have radically overturned that view, with the proteasome now recognized as a validated target and proteasome inhibition demonstrated to be a highly successful treatment for a number of hematologic malignancies. Here we provide a historic perspective on the emergence of proteasome inhibition, sharing some of the lessons learned along the way. We describe the development of bortezomib and the elucidation of the effects of its novel mechanism of action, and place the cutting-edge work described elsewhere in this issue in the context of these historic developments.

Selenium-containing histone deacetylase inhibitors for melanoma management

Melanoma incidence and mortality rates continue to increase each year. Lack of clinically viable agents, drug combinations, effective targeted delivery approaches and success inhibiting targets in tumor tissue have made this disease one of the most difficult to treat, which makes prevention an important option for decreasing disease incidence and mortality rates. Inhibiting histone deacetylases (HDAC) is an approach currently being explored to more effectively treat melanoma but use for prevention has not been explored. In this study, novel selenium containing derivatives of the FDA approved HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) called 5-phenylcarbamoylpentyl selenocyanide (PCP-SeCN) and Bis{5-phenylcarbamoylpentyl} diselenide (B(PCP)-2Se) were created and efficacy tested for preventing early melanocytic lesion development in skin. Topical application of PCP-SeCN and B(PCP)-2Se inhibited melanocytic lesion development in laboratory-generated skin by up to 87% with negligible toxicological effect. Mechanistically, PCP-SeCN and B(PCP)-2Se inhibited HDAC activity and had new inhibitory properties by moderating Akt activity to induce cellular apoptosis as demonstrated by an increase in the sub-G₀-G₁ cell population, and cleaved caspase-3 as well as PARP levels. Furthermore, PCP-SeCN and B(PCP)-2Se inhibited cell proliferation by inhibiting cyclin D1 expression and increasing p21 levels. Thus, PCP-SeCN and B(PCP)-2Se are potential melanoma chemopreventive agents with enhanced efficacy compared with SAHA due to new PI3 kinase pathway inhibitory properties.

The human immunodeficiency virus-1 protease inhibitor nelfinavir impairs proteasome activity and inhibits the proliferation of multiple myeloma cells in vitro and in vivo

BACKGROUND

Multiple myeloma is characterized by the accumulation of tumor plasma cells in the bone marrow. Despite therapeutic improvements brought by proteasome inhibitors such as bortezomib, myeloma remains an incurable disease. In a variety of human cancers, human immunodeficiency virus protease inhibitors (e.g. nelfinavir) effectively inhibit tumor progression, but their impact on myeloma is unknown. We assessed the in vitro and in vivo effects of nelfinavir on multiple myeloma.

DESIGN AND METHODS

The effects of nelfinavir (1-10 μM) on proteasome activity, proliferation and viability of myeloma cell lines and plasma cells from patients were assessed by measuring PERK, AKT, STAT3 and ERK1/2 phosphorylation and CHOP expression with immunoblotting or flow cytometry. The in vivo effect was assessed in NOD/SCID mice injected with luciferase expressing human myeloma cell lines and treated with nelfinavir at a dose of 75 mg/kg/day. Tumor progression was evaluated using a bioluminescent system.

RESULTS

Nelfinavir inhibited 26S chymotrypsin-like proteasome activity, impaired proliferation and triggered apoptosis of the myeloma cell lines and fresh plasma cells. It activated the pro-apoptotic unfolded protein response pathway by inducing PERK phosphorylation and CHOP expression. Cell death triggered by nelfinavir treatment correlated with decreased phosphorylation of AKT, STAT3 and ERK1/2. Nelfinavir enhanced the anti-proliferative activity of bortezomib, dexamethasone and histone deacetylase inhibitors and delayed tumor growth in a myeloma mouse model.

CONCLUSIONS

These results suggest that nelfinavir, used at a pharmacological dosage, alone or in combination, may be useful in the treatment of myeloma. Our data provide a preclinical basis for clinical trials using nelfinavir in patients with myeloma.

Preclinical activity, pharmacodynamic, and pharmacokinetic properties of a selective HDAC6 inhibitor, ACY-1215, in combination with bortezomib in multiple myeloma

Histone deacetylase (HDAC) enzymatic activity has been linked to the transcription of DNA in cancers including multiple myeloma (MM). Therefore, HDAC inhibitors used alone and in combination are being actively studied as novel therapies in MM. In the present study, we investigated the preclinical activity of ACY-1215, an HDAC6-selective inhibitor, alone and in combination with bortezomib in MM. Low doses of ACY-1215 combined with bortezomib triggered synergistic anti-MM activity, resulting in protracted endoplasmic reticulum stress and apoptosis via activation of caspase-3, caspase-8, and caspase-9 and poly (ADP) ribosome polymerase. In vivo, the anti-MM activity of ACY-1215 in combination with bortezomib was confirmed using 2 different xenograft SCID mouse models: human MM injected subcutaneously (the plasmacytoma model) and luciferase-expressing human MM injected intravenously (the disseminated MM model). Tumor growth was significantly delayed and overall survival was significantly prolonged in animals treated with the combination therapy. Pharmacokinetic data showed peak plasma levels of ACY-1215 at 4 hours after treatment coincident with an increase in acetylated α-tubulin, a marker of HDAC6 inhibition, by immunohistochemistry and Western blot analysis. These studies provide preclinical rationale for acetylated α-tubulin use as a pharmacodynamic biomarker in future clinical trials.

Histone deacetylase inhibitors demonstrate significant preclinical activity as single agents, and in combination with bortezomib in Waldenström's macroglobulinemia

We studied the role of histone deacetylase inhibitors in Waldenstrom's macroglobulinemia (WM). Gene expression profiling of bone marrow CD19+ cells from 30 patients and 10 healthy donors showed overexpression of HDAC4, HDAC9, and Sirt5, with validation of HDAC9 overexpression by q-PCR in primary and BCWM.1 cells. Suberoylanilide hydroxamic acid, trichostatin A, panobinostat, and sirtinol demonstrated dose-dependent killing of BCWM.1 cells. TSA showed the greatest potency with IC50 of 70 nM. Importantly, HDAC9 activity was decreased following TSA treatment suggesting an essential role for this HDAC in WM therapy. The combination of bortezomib plus HDAC inhibitors resulted in at least additive tumor cell killing in BCWM.1 cells. TSA and bortezomib-induced apoptosis depended on a similar set of caspase activation, whereas their effect on cell cycle regulators was distinctly different. These results provided a framework for examining HDAC inhibitors as monotherapy, as well as combination therapy with bortezomib in WM.

Defibrotide blunts the prothrombotic effect of thalidomide on endothelial cells

Patients with multiple myeloma (MM) are at relatively high risk of developing thromboembolic events such deep venous thrombosis (DVT) where thalidomide therapy has been identified to increase this risk. Defibrotide (DF), a polydisperse oligonucleotide, showed previously to counteract the alterations in endothelial cells (ECs) induced by lipopolysaccharide. It prompts us to investigate the impact of thalidomide on ECs and whether DF modulates changes in fibrinolysis induced by thalidomide. In this in vitro study, MM by itself alters the profibrinolytic potential of ECs decreasing the tissue plasminogen activator (t-PA) and increasing the plasminogen activator inhibitor 1 (PAI-1) levels which is potentiated by thalidomide. Defibrotide was able to counteract these effects. Additionally, DF upregulated the t-PA and downregulated PAI-1 gene expression modulated by thalidomide. Defibrotide also protects ECs from thalidomide-mediated cell death without interfering with its antitumor effects. These findings support DF clinical use for the prevention of DVT induced by immunomodulatory drugs.

Heat-shock protein 90 inhibitors as antitumor agents: a survey of the literature from 2005 to 2010

INTRODUCTION

Heat-shock protein 90 (Hsp90) is a validated novel anticancer target with unique features. As a molecular chaperone, Hsp90 is implicated in maintaining the conformation, stability, activity and cellular localization of several key oncogenic client proteins that are involved in signal transduction pathways leading to proliferation, cell-cycle progression, apoptosis, angiogenesis and metastasis. As a result, inhibitors of Hsp90 achieve their promising anticancer activity through disruption of the Hsp90 protein function, thereby freezing the chaperone cycle; this in turn decreases the affinity of Hsp90 for client proteins, thus leading to proteasome-mediated degradation of oncogenic client proteins within cancer cells.

AREAS COVERED

This review provides recent background information on Hsp90 inhibitors. It also highlights a panel of compounds of interest reported in patents and discusses the clinical results of the promising drug candidates.

EXPERT OPINION

In the past 5 years, Hsp90 inhibitors have remained the focus of much interest as new potential anticancer agents. A large variety of scaffolds were studied in both academia and industry. Consequently, these significant research efforts have provided several promising drug candidates for further clinical development. Further progress in the development of Hsp90 inhibitors, combined with a deeper understanding of the chaperon characteristics, strengthens their promise in cancer therapy.

Molecular target characterization and antimyeloma activity of the novel, insulin-like growth factor 1 receptor inhibitor, GTx-134

PURPOSE

Therapeutic strategies that target insulin-like growth factor 1 receptor (IGF-1R) hold promise in a wide variety of cancers including multiple myeloma (MM). In this study, we describe GTx-134, a novel small-molecule inhibitor of IGF-1R and insulin receptor (IR) and characterized its antitumor activity in preclinical models of MM.

EXPERIMENTAL DESIGN

The activity of GTx-134 as a single agent and in combination was tested in MM cell lines and primary patient samples. Downstream effector proteins and correlation with apoptosis was evaluated. Cytotoxcity in bone marrow stroma coculture experiments was assessed. Finally, the in vivo efficacy was evaluated in a human myeloma xenograft model.

RESULTS

GTx-134 inhibited the growth of 10 of 14 myeloma cell lines (<5 μmol/L) and induced apoptosis. Sensitivity to GTx-134 correlated with IGF-1R signal inhibition. Expression of MDR-1 and CD45 were associated with resistance to GTx-134. Coculture with insulin-growth factor-1 (IGF-1) or adherence to bone marrow stroma conferred modest resistance, but did not overcome GTx-134-induced cytotoxicity. GTx-134 showed in vitro synergies when combined with dexamethasone or lenalidomide. Further, GTx-134 enhanced the activity of PD173074, a fibroblast growth factor receptor 3 (FGFR3) inhibitor, against t(4;14) myeloma cells. Therapeutic efficacy of GTx-134 was shown against primary cells and xenograft tumors. Although dysregulation of glucose homeostasis was observed in GTx-134-treated mice, impairment of glucose tolerance was modest.

CONCLUSIONS

These studies support the potential therapeutic efficacy of GTx-134 in MM. Further, they provide a rationale for clinical application in combination with established antimyeloma treatments and novel targeted therapies.

Potentiation of apoptosis by histone deacetylase inhibitors and doxorubicin combination: cytoplasmic cathepsin B as a mediator of apoptosis in multiple myeloma

Background:

Although inhibitors of histone deacetylase inhibitors (HDACis) in combination with genotoxins potentiate apoptosis, the role of proteases other than caspases in this process remained elusive. Therefore, we examined the potentiation of apoptosis and related mechanisms of HDACis and doxorubicin combination in a panel of myeloma cell lines and in 25 primary myelomas.

Results:

At IC₅₀ concentrations, sodium butyrate (an HDACi) or doxorubicin alone caused little apoptosis. However, their combination potentiated apoptosis and synergistically reduced the viability of myeloma cells independent of p53 and caspase 3–7 activation. Potentiated apoptosis correlated with nuclear translocation of apoptosis-inducing factor, suggesting the induction of caspase 3- and 7-independent pathways. Consistent with this, butyrate and doxorubicin combination significantly increased the activity of cytoplasmic cathepsin B. Inhibition of cathepsin B either with a small-molecule inhibitor or downregulation with a siRNA reversed butyrate- and doxorubicin-potentiated apoptosis. Finally, ex vivo, clinically relevant concentrations of butyrate or SAHA (suberoylanilide hydroxamic acid, vorinostat, an HDACi in clinical testing) in combination with doxorubicin significantly (P<0.0001) reduced the survival of primary myeloma cells.

Conclusions:

Cathepsin B has a prominent function in mediating apoptosis potentiated by HDACi and doxorubicin combinations in myeloma. Our results support a molecular model of lysosomal–mitochondrial crosstalk in HDACi- and doxorubicin-potentiated apoptosis through the activation of cathepsin B.

Cytotoxicity on human cancer cells of ophidiacerebrosides isolated from the African starfish Narcissia canariensis

The starfish Narcissia canariensis harvested from the coasts off Dakar, Senegal, was investigated for glycolipids (GL). This report deals with the isolation, characterization and biological activity of a fraction F13-3 separated from the GL mixture and selected according to its ability to inhibit KB cell proliferation after 72 hours of treatment. Firstly, a GL mixture F13 was obtained that accounted for 1.36% of starfish biomass (dry weight) and 0.36% of total lipids. The fraction F13-3 obtained from F13 contained three homologous GL identified as peracetylated derivatives on the basis of chemical and spectroscopic evidence. These contained a β-glucopyranoside as sugar head, a 9-methyl-branched 4,8,10-triunsaturated long-chain aminoalcohol as sphingoid base and amide-linked 2-hydroxy fatty acid chains. The majority (63%) had an amide-linked 2-hydroxydocosanoic acid chain and was identified as the ophidiacerebroside-C, firstly isolated from the starfish Ophidiaster ophidiamus. The minor components of F13-3 differed by one more or one less methylene group, and corresponded to ophidiacerebroside-B and -D. We found that F13-3 displayed an interesting cytotoxic activity over 24 hours on various adherent human cancerous cell lines (multiple myeloma, colorectal adenocarcinoma and glioblastoma multiforme) with an IC₅₀ of around 20 μM.

Novel therapeutic strategies in multiple myeloma: role of the heat shock protein inhibitors

Despite advances in understanding the molecular pathogenesis of multiple myeloma and promising new therapies, almost all patients eventually relapse with resistant disease. There is therefore a strong rationale for combining novel therapies that target intrinsic molecular pathways mediating multiple myeloma cell resistance. One such protein family is the heat shock proteins (HSP), especially the HSP90 family. Heat shock protein inhibitors have been identified as promising cancer treatments as, while they only inhibit a single biologic function, the chaperone-protein association, their effect is widespread as it results in the destruction of numerous client proteins. This article reviews the preclinical and clinical data, which support the testing of HSP90 inhibitors as cancer drugs and update the reader on the current status of the ongoing clinical trials of HSP90 inhibitors in multiple myeloma.

A mechanistic rationale for MEK inhibitor therapy in myeloma based on blockade of MAF oncogene expression

Modulating aberrant transcription of oncogenes is a relatively unexplored opportunity in cancer therapeutics. In approximately 10% of multiple myelomas, the initiating oncogenic event is translocation of musculoaponeurotic fibrosarcoma oncogene homolog (MAF), a transcriptional activator of key target genes, including cyclinD2. Our prior work showed that MAF is up-regulated in an additional 30% of multiple myeloma cases. The present study describes a common mechanism inducing MAF transcription in both instances. The second mode of MAF transcription occurred in myelomas with multiple myeloma SET domain (MMSET) translocation. MMSET knockdown decreased MAF transcription and cell viability. A small-molecule screen found an inhibitor of mitogen-activated protein kinase kinase (MEK), which activates extracellular signal-regulated kinase (ERK)-MAP kinases, reduced MAF mRNA in cells representing MMSET or MAF subgroups. ERK activates transcription of FOS, part of the AP-1 transcription factor. By chromatin immunoprecipitation, FOS bound the MAF promoter, and MEK inhibition decreased this interaction. MEK inhibition selectively induced apoptosis in MAF-expressing myelomas, and FOS inactivation was similarly toxic. Reexpression of MAF rescued cells from death induced by MMSET depletion, MEK inhibition, or FOS inactivation. The data presented herein demonstrate that the MEK-ERK pathway regulates MAF transcription, providing molecular rationale for clinical evaluation of MEK inhibitors in MAF-expressing myeloma.

Vorinostat plus bortezomib for the treatment of relapsed/refractory multiple myeloma: a case series illustrating utility in clinical practice

INTRODUCTION

Increasing numbers of patients are presenting with relapsed/refractory multiple myeloma (MM) following treatment with bortezomib. Therefore, there is a need for effective and well-tolerated treatment strategies after failure of bortezomib-based regimens. Vorinostat, a histone deacetylase inhibitor, has demonstrated antiproliferative and proapoptotic activity alone and in combination with bortezomib in preclinical models of MM. Preliminary results from ongoing phase I trials have demonstrated the clinical activity of vorinostat in combination with bortezomib in patients with MM. This case series reports our experience of combined vorinostat and bortezomib in 6 patients with relapsed/refractory MM after previous bortezomib.

MATERIALS AND METHODS

Patients received oral vorinostat 300 mg or 400 mg once daily (days 1-14) and bortezomib 1.3 mg/m2 on days 1, 4, 8, and 11 in a 21-day cycle.

RESULTS

All patients derived clinical benefit from combined vorinostat and bortezomib, with objective response observed in 5 of the 6 patients (> or = minimal response), including 1 very good partial response; stable disease was observed in the remaining patient. Patients remained on therapy until disease progression. Combined vorinostat and bortezomib therapy was well tolerated: grade 2 nausea and diarrhea were the only adverse events reported. No patients discontinued therapy because of toxicity, and no dose adjustments were required for either agent.

CONCLUSION

These results suggest that combined vorinostat and bortezomib therapy is effective in patients with relapsed/refractory MM after failure of previous bortezomib-based regimens and support further evaluation of this combination in randomized trials.

Combined proteasome and histone deacetylase inhibition: A promising synergy for patients with relapsed/refractory multiple myeloma

Multiple myeloma (MM) is an incurable disease characterized by the accumulation of malignant plasma cells in the bone marrow. Recently, an improved understanding of the biology of the disease has led to the development of targeted agents such as the proteasome inhibitor bortezomib and the immunomodulatory agents thalidomide and lenalidomide; however, MM remains incurable. The combination of bortezomib and an HDAC inhibitor synergistically induces MM cell apoptosis and may be of value in the treatment of patients with relapsed/refractory MM. This review examines the potential of combined proteasome and HDAC inhibition in the treatment of relapsed/refractory MM.

HDAC inhibition synergistically enhances alkylator-induced DNA damage responses and apoptosis in multiple myeloma cells

Histone deacetylase (HDAC) inhibitors induce chromatin destabilization. We sought to determine whether HDAC inhibition may amplify alkylator-induced mitotic cell death in multiple myeloma (MM) cells. The combination of SNDX-275, a class I HDAC inhibitor, with melphalan, showed a powerful synergism on growth inhibition with the combination index ranged from 0.27 to 0.75 in MM1.S and RPMI8226 cells. Their combinations as compared with either agent alone promoted much more caspase-dependent apoptosis. Flow cytometry analysis showed that SNDX-275 had minimal effects on cell cycle progression of MM1.S cells, but clearly increased the percentage of S phase in RPMI8226 cells associated with an upregulation in p21(waf1) and a reduction in cyclin D1 and E2F1. Melphalan alone significantly arrested both MM1.S and RPMI8226 cells at S phase and enhanced expression of p53 and p21(waf1). Furthermore, studies on DNA damage response revealed that phospho-histone H2A.X (gammaH2A.X), a hall marker of DNA double strand break, along with phosphorylated CHK1 (P-CHK1) and CHK2 (P-CHK2) was dramatically induced by SNDX-275 or melphalan. The increase in gammaH2A.X and P-CHK1 was considerably higher on combination than either agent alone. These molecular changes correlated well with the significant increase in mitotic catastrophe. Our data indicate that SNDX-275 synergistically enhances melphalan-induced apoptosis in MM cells via intensification of DNA damage, suggesting that SNDX-275 in combination with melphalan may be a novel therapeutic strategy for MM.

In vitro and in vivo rationale for the triple combination of panobinostat (LBH589) and dexamethasone with either bortezomib or lenalidomide in multiple myeloma

BACKGROUND

Combinations of drug treatments based on bortezomib or lenalidomide plus steroids have resulted in very high response rates in multiple myeloma. However, most patients still relapse, indicating the need for novel combination partners to increase duration of response or to treat relapsed disease. We explored the antimyeloma activity of triple combinations of these well-established schemes with panobinostat, a novel deacetylase inhibitor with a multi-targeted profile.

DESIGN AND METHODS

The activity of these combinations was explored in vitro in cell lines by using MTT and annex-in V, ex vivo by flow cytometry, and in vivo using two different murine models of human myeloma: one bearing a subcutaneous plasmacytoma and another with a disseminated myeloma. Moreover, gene expression profiling and immunohistochemical studies were performed.

RESULTS

The addition of panobinostat (LBH589) to dexamethasone and either bortezomib or lenalidomide resulted in clear potentiation in multiple myeloma cell lines, freshly isolated plasma cells, and murine models of multiple myeloma. The quantification of the potency of these combinations by using the Chou-Talalay method showed synergistic combination indices for all of them. This effect derived from the deregulation of a cluster of genes that was completely different from the sum of genes affected by the single agents (895 and 1323 genes exclusively deregulated by panobinostat and dexamethasone plus bortezomib or lenalidomide, respectively). Functional experiments, such as annexin V staining, cell cycle analysis, and immunohistochemical studies also supported this potentiation. Anti-myeloma efficacy was confirmed in an extramedullary plasmacytoma model and a disseminated luciferized model, in which panobinostat also provided a marked benefit in bone disease.

CONCLUSIONS

The potent activity, together with the exclusive mechanistic profile, provides the rationale for the clinical evaluation of these drug combinations in multiple myeloma.

Evaluation of the proteasome inhibitor MLN9708 in preclinical models of human cancer

The proteasome was validated as an oncology target following the clinical success of VELCADE (bortezomib) for injection for the treatment of multiple myeloma and recurring mantle cell lymphoma. Consequently, several groups are pursuing the development of additional small-molecule proteasome inhibitors for both hematologic and solid tumor indications. Here, we describe MLN9708, a selective, orally bioavailable, second-generation proteasome inhibitor that is in phase I clinical development. MLN9708 has a shorter proteasome dissociation half-life and improved pharmacokinetics, pharmacodynamics, and antitumor activity compared with bortezomib. MLN9708 has a larger blood volume distribution at steady state, and analysis of 20S proteasome inhibition and markers of the unfolded protein response confirmed that MLN9708 has greater pharmacodynamic effects in tissues than bortezomib. MLN9708 showed activity in both solid tumor and hematologic preclinical xenograft models, and we found a correlation between greater pharmacodynamic responses and improved antitumor activity. Moreover, antitumor activity was shown via multiple dosing routes, including oral gavage. Taken together, these data support the clinical development of MLN9708 for both hematologic and solid tumor indications.

Insights into defibrotide: an updated review

Defibrotide is a polydisperse oligonucleotide with antiatherosclerotic, anti-inflammatory, anti-ischaemic, pro-fibrinolytic and antithrombotic actions without significant systemic anticoagulant effects. It has been used in the treatment of various cardiovascular disorders, and especially in endothelial complications of allogeneic stem-cell transplantation. We reviewed the published work for the mechanism of action and clinical use of defibrotide to consolidate data and to describe new applications of this drug. We reviewed the most relevant papers on defibrotide published from November 1982 to January 2008. (selected through PubMed), and used recent meeting abstracts as sources for this review. Reports have suggested that defibrotide has clinical efficacy for treatment and prophylaxis of hepatic sinusoidal obstruction syndrome occurring after stem-cell transplantation. Animal models have clearly shown the potential antineoplastic effect of this drug. Further clinical investigations are needed to clarify this new application.

Anti-myeloma activity of the novel 2-aminothienopyrimidine Hsp90 inhibitor NVP-BEP800

The 90 kD heat shock protein (Hsp90) molecular chaperone sustains multiple components of oncogenic pathways and has recently emerged as a therapeutic target that is now being clinically tested in a number of malignancies. In order to address formulation issues and to deal with possible resistance mechanisms against small molecule Hsp90 inhibitors, a range of compounds based on different molecular scaffolds are now being developed. The present study preclinically tested the effects of the novel 2-aminothienopyrimidine class Hsp90 inhibitor NVP-BEP800, which is suitable for oral formulations, on multiple myeloma cells from established cell lines and on a larger cohort (n = 40) of primary myeloma samples. The drug effectively and specifically killed the majority of primary myeloma cells in coculture with bone marrow stromal cells and reliably entailed molecular consequences of Hsp90 blockade - such as survival pathway breakdown and client protein depletion - in multiple myeloma cells from cell lines as well as from patients. Collectively, the properties of this novel drug support clinical testing in multiple myeloma.

Multiple myeloma

Multiple myeloma is characterised by clonal proliferation of malignant plasma cells, and mounting evidence indicates that the bone marrow microenvironment of tumour cells has a pivotal role in myeloma pathogenesis. This knowledge has already expanded treatment options for patients with multiple myeloma. Prototypic drugs thalidomide, bortezomib, and lenalidomide have each been approved for the treatment of this disease by targeting both multiple myeloma cells and the bone marrow microenvironment. Although benefit was first shown in relapsed and refractory disease, improved overall response, duration of response, and progression-free and overall survival can be achieved when these drugs are part of first-line regimens. This treatment framework promises to improve outcome not only for patients with multiple myeloma, but also with other haematological malignancies and solid tumours.

Molecular and cellular mechanisms of CLL: novel therapeutic approaches

The mainstay of therapy of chronic lymphocytic leukemia (CLL) is cytotoxic chemotherapy; however, CLL is still an incurable disease with resistance to therapy developing in the majority of patients. In recent years, our understanding of the biological basis of CLL pathogenesis has substantially improved and novel treatment strategies are emerging. Tailoring and individualizing therapy according to the molecular and cellular biology of the disease is on the horizon, and advances with targeted agents such as monoclonal antibodies combined with traditional chemotherapy have lead to improved remission rates. The proposed key role of the B-cell receptor (BCR) in CLL pathogenesis has led to a number of possible opportunities for therapeutic exploitation. We are beginning to understand that the microenvironment is of utmost importance in CLL because certain T-cell subsets and stromal cells support the outgrowth and development of the malignant clone. Furthermore, an increase in our understanding of the deregulated cell-death machinery in CLL is a prerequisite to developing new targeted strategies that might be more effective in engaging with the cell-death machinery. This Review summarizes the progress made in understanding these features of CLL biology and describes novel treatment strategies that have also been exploited in current clinical trials.

Nuclear effects of ethanol-induced proteasome inhibition in liver cells

Alcohol ingestion causes alteration in several cellular mechanisms, and leads to inflammation, apoptosis, immunological response defects, and fibrosis. These phenomena are associated with significant changes in the epigenetic mechanisms, and subsequently, to liver cell memory. The ubiquitin-proteasome pathway is one of the vital pathways in the cell that becomes dysfunctionial as a result of chronic ethanol consumption. Inhibition of the proteasome activity in the nucleus causes changes in the turnover of transcriptional factors, histone modifying enzymes, and therefore, affects epigenetic mechanisms. Alcohol consumption has been associated with an increase in histone acetylation and a decrease in histone methylation, which leads to gene expression changes. DNA and histone modifications that result from ethanol-induced proteasome inhibition are key players in regulating gene expression, especially genes involved in the cell cycle, immunological responses, and metabolism of ethanol. The present review highlights the consequences of ethanol-induced proteasome inhibition in the nucleus of liver cells that are chronically exposed to ethanol.

EUROCARE-4. Survival of cancer patients diagnosed in 1995-1999. Results and commentary

EUROCARE-4 analysed about three million adult cancer cases from 82 cancer registries in 23 European countries, diagnosed in 1995-1999 and followed to December 2003. For each cancer site, the mean European area-weighted observed and relative survival at 1-, 3-, and 5-years by age and sex are presented. Country-specific 1- and 5-year relative survival is also shown, together with 5-year relative survival conditional to surviving 1-year. Within-country variation in survival is analysed for selected cancers. Survival for most solid cancers, whose prognosis depends largely on stage at diagnosis (breast, colorectum, stomach, skin melanoma), was highest in Finland, Sweden, Norway and Iceland, lower in the UK and Denmark, and lowest in the Czech Republic, Poland and Slovenia. France, Switzerland and Italy generally had high survival, slightly below that in the northern countries. There were between-region differences in the survival for haematologic malignancies, possibly due to differences in the availability of effective treatments. Survival of elderly patients was low probably due to advanced stage at diagnosis, comorbidities, difficult access or lack of availability of appropriate care. For all cancers, 5-year survival conditional to surviving 1-year was higher and varied less with region, than the overall relative survival.

Targeted therapies in multiple myeloma

Increasing knowledge of the biology of multiple myeloma led the way for the development of novel drugs that have changed the management of the disease. New treatments target not only to the malignant plasma cell but also target the interactions of myeloma cells with their microenvironment. Several preclinical studies have identified potential targets and drugs are developed that act on pathways crucial for myeloma cell survival, proliferation, migration and drug resistance. The identification of active agents in the laboratory is followed by rationally designed clinical studies that validate these drugs, either as single agents or in combinations with other active drugs. These novel agents may be either small molecules or monoclonal antibodies targeting receptors, kinase activity of receptors or key molecules within critical pathways, intracellular maintenance mechanisms and immune modulation.

Survival trends in European cancer patients diagnosed from 1988 to 1999

We analysed data from 49 cancer registries in 18 European countries over the period 1988-1999 to delineate time trends in cancer survival. Survival increased in Europe over the study period for all cancer sites that were considered. There were major survival increases in 5 year age-adjusted relative survival for prostate (from 58% to 79%), colon and rectum (from 48% to 54% men and women), and breast (from 74% to 83%). Improvements were also significant for stomach (from 22% to 24%), male larynx (from 62% to 64%), skin melanoma (from 78% to 83%), Hodgkin disease (from 77% to 83%), non-Hodgkin lymphoma (from 49% to 56%), leukaemias (from 37% to 42%), and for all cancers combined (from 34% to 39% in men, and from 52% to 59% in women). Survival did not change significantly for female larynx, lung, cervix or ovary. The largest increases in survival typically occurred in countries with the lowest survival, and contributed to the overall reduction of survival disparities across Europe over the study period. Differences in the extent of PSA testing and mammographic screening, and increasing use of colonoscopy and faecal blood testing together with improving cancer care are probably the major underlying reasons for the improvements in survival for cancers of prostate, breast, colon and rectum. The marked survival improvements in countries with poor survival may indicate that these countries have made efforts to adopt the new diagnostic procedures and the standardised therapeutic protocols in use in more affluent countries.

Bone marrow microenvironment and the identification of new targets for myeloma therapy

The development of multiple myeloma (MM) is a complex multi-step process involving both early and late genetic changes in the tumor cell as well as selective supportive conditions by the bone marrow (BM) microenvironment. Indeed, it is now well established that MM cell-induced disruption of the BM homeostasis between the highly organized cellular and extracellular compartments supports MM cell proliferation, survival, migration and drug resistance through activation of various signaling (for example, PI3K/Akt, JAK/Stat-, Raf/MEK/MAPK-, NFkappaB- and Wnt-) pathways. Based on our enhanced understanding of the functional importance of the MM BM microenvironment and its inter-relation with the MM cell resulting in homing, seeding, proliferation and survival, new molecular targets have been identified and derived treatment regimens in MM have already changed fundamentally during recent years. These agents include thalidomide, its immunomodulatory derivative lenalidomide and the proteasome inhibitor bortezomib, which mediate tumor cytotoxicity in the BM milieu. Ongoing studies are further delineating MM pathogenesis in the BM to enhance cytotoxicity, avoid drug resistance and improve patient outcome.

153Sm: its use in multiple myeloma and report of a clinical experience

BACKGROUND

In the past years the bone seeking radiopharmaceutical samarium lexidronam ((153)Sm-EDTMP) has been increasingly used alone or in conjunction with chemotherapy and/or bisphosphonates for the treatment of painful bone metastasis.

OBJECTIVE

Its use has been explored in different solid tumours. In this report we explore its interesting characteristics and describe our experience in multiple myeloma (MM).

METHODS

(153)Sm-EDTMP has an affinity for bone and concentrates in areas of bone turnover. It decays as a therapeutic beta-emission and at the same time as gamma-photon that can be used for tracking its concentration with bone scan imaging. Ten patients with symptomatic MM were treated to achieve pain control.

RESULTS

Encouraging results were obtained in MM patients. The use of this radioisotope could be largely improved.