Engineered nanomedicine for myeloma and bone microenvironment targeting

Bone is a favorable microenvironment for tumor growth and a frequent destination for metastatic cancer cells. Targeting cancers within the bone marrow remains a crucial oncologic challenge due to issues of drug availability and microenvironment-induced resistance. Herein, we engineered bone-homing polymeric nanoparticles (NPs) for spatiotemporally controlled delivery of therapeutics to bone, which diminish off-target effects and increase local drug concentrations. The NPs consist of poly(d,l-lactic-co-glycolic acid) (PLGA), polyethylene glycol (PEG), and bisphosphonate (or alendronate, a targeting ligand). The engineered NPs were formulated by blending varying ratios of the synthesized polymers: PLGA-b-PEG and alendronate-conjugated polymer PLGA-b-PEG-Ald, which ensured long circulation and targeting capabilities, respectively. The bone-binding ability of Ald-PEG-PLGA NPs was investigated by hydroxyapatite binding assays and ex vivo imaging of adherence to bone fragments. In vivo biodistribution of fluorescently labeled NPs showed higher retention, accumulation, and bone homing of targeted Ald-PEG-PLGA NPs, compared with nontargeted PEG-PLGA NPs. A library of bortezomib-loaded NPs (bone-targeted Ald-Bort-NPs and nontargeted Bort-NPs) were developed and screened for optimal physiochemical properties, drug loading, and release profiles. Ald-Bort-NPs were tested for efficacy in mouse models of multiple myeloma (MM). Results demonstrated significantly enhanced survival and decreased tumor burden in mice pretreated with Ald-Bort-NPs versus Ald-Empty-NPs (no drug) or the free drug. We also observed that bortezomib, as a pretreatment regimen, modified the bone microenvironment and enhanced bone strength and volume. Our findings suggest that NP-based anticancer therapies with bone-targeting specificity comprise a clinically relevant method of drug delivery that can inhibit tumor progression in MM.The incidence of bone metastasis is common in 60–80% of cancer patients (1). During bone metastasis, cancer cells induce a sequence of changes in the microenvironment such as secreting cytokines to increase the activity of osteoclasts via the parathyroid hormone-related protein (PTHrP), receptor activator of nuclear factor-κB ligand (RANKL), and interleukin-6 (IL-6), resulting in increased bone resorption and secretion of growth factors from the bone matrix (2). This creates a “vicious cycle” of bone metastasis, where bone marrow becomes packed with cancer cells that develop resistance to conventional chemotherapy, and leads to devastating consequences of bone fractures, pain, hypercalcaemia, and spinal cord and nerve compression syndromes (2, 3). Multiple myeloma (MM) is a plasma cell cancer that proliferates primarily in bone marrow and causes osteolytic lesions (1). Antiresorption agents, such as bisphosphonates, may alleviate bone pain, but they are ineffective at inducing bone healing or osteogenesis in MM patients (4).Bortezomib is a proteasome inhibitor that has shown marked antitumor effects in patients with MM. Proteasome inhibitors, such as bortezomib, are also effective at increasing bone formation, both preclinically and clinically (5–9). However, the major drawback of bortezomib use in early stages of MM development is its toxicity, specifically, peripheral neuropathy (5). Therefore, we aimed to develop a method to deliver bortezomib with decreased off-target side effects by using bone-specific, bortezomib-loaded nanoparticles (NPs). The NP system was based on biodegradable, biocompatible, and Food and Drug Administration (FDA)-approved components, which are both clinically and translationally relevant. NPs derived from poly(d,l-lactic-co-glycolic acid) (PLGA), a controlled release polymer system, are an excellent choice because their safety in the clinic is well established (10, 11). Polyethylene glycol (PEG)-functionalized PLGA NPs are especially desirable as PEGylated polymeric NPs have significantly reduced systemic clearance compared with similar particles without PEG (12, 13). A number of FDA-approved drugs in clinical practice use PEG for improved pharmaceutical properties such as enhanced circulation in vivo (12, 13). To target NPs to bone [rich in the mineral hydroxyapatite (HA)], the calcium ion-chelating molecules of bisphosphonates represent a promising class of ligands (14). Bisphosphonates, upon systemic administration, are found to deposit in bone tissue, preferentially at the high bone turnover sites, such as the metastatic bone lesions, with minimal nonspecific accumulation (14) and were used herein to deliver NPs to the bone.A few systems explored for MM treatment have been tested in vitro including the following: (i) snake venom and silica NPs (15); (ii) thymoquinone and PLGA-based particles (16); (iii) curcumin and poly(oxyethylene) cholesteryl ether (PEG-Chol) NPs (17), polyethylenimine-based NPs for RNAi in MM (18), paclitaxel-Fe₃O₄ NPs (19), and liposomes (20). However, none of the above-mentioned systems have aimed to manipulate the bone marrow microenvironment rather than the myeloma cells directly (21). To date, there are no reports of using bone-targeted, controlled release, polymeric NPs with stealth properties for MM therapy. In this study, we designed NPs bearing three main components: (i) a targeting element that can selectively bind to bone mineral; (ii) a layer of stealth (PEG) to minimize immune recognition and enhance circulation; and (iii) a biodegradable polymeric material, forming an inner core, that can deliver therapeutics and/or diagnostics in a controlled manner. In this study, the physicochemical properties of a range of NPs was investigated (including NP size, charge, targeting ligand density, drug loading, and drug release kinetics) and an optimal formulation with ideal properties and maximal drug encapsulation was used for in vivo efficacy studies. We fine-tuned the NP targeting ligand density to optimize its bone-binding ability and further investigated its application for targeting myeloma in the bone microenvironment. We believe our NP system has the potential to increase drug availability by improving pharmacokinetics and biodistribution that can provide bone microenvironment specificity, which may increase the therapeutic window and most certainly decrease the off-target effects (12, 13).     

Current use of monoclonal antibodies in the treatment of multiple myeloma

Multiple myeloma (MM) is the second most common haematological malignancy after non‐Hodgkin lymphoma. Despite the improvement in outcomes over the last decade with the introduction of novel therapies, such as immunomodulatory agents (IMiDs) and proteasome inhibitors (PIs), MM remains an incurable disease. Patients who are both refractory to IMiDs and PIs carry a particularly dismal prognosis. The development of targeted therapy in the form of monoclonal antibodies has shifted the treatment paradigm of this disease, resulting in unprecedented response rates, even among the highest‐risk patients. In this review, we will summarize the mechanism of action and provide an overview of the clinical trials that have led to the US Food and Drug Administration approval of Daratumumab and Elotuzumab, and their current use in the treatment of MM.     

Targeted idiotype-fusion DNA vaccines for human multiple myeloma: preclinical testing

Objectives: A homodimeric fusion DNA vaccine targeting idiotype (Id) to antigen‐presenting cells (APC) induced robust tumor protection in a mouse model of multiple myeloma (MM). Similar Id vaccine molecules were generated for four patients with MM with three main objectives: (i) do the vaccine molecules induce bona fide anti‐Id immune responses in mice? (ii) does targeting of the vaccine molecules to APC enhance immune responses? (iii) can anti‐Id antibodies, generated as by‐product in vaccinated mice, be used to establish sensitive assays for complete remission (CR) prior to patient vaccination? Methods: Chimeric vaccine molecules targeting patient Id to mouse major histocompatibility complex (MHC) class II molecules were genetically constructed for four patients with MM. Results: DNA vaccination of mice with chimeric vaccines targeting patient Id to mouse MHC class II molecules elicited antibodies specific for the patient’s myeloma protein. Targeting MHC class II greatly enhanced anti‐Id responses. Mouse anti‐Id antibodies were used to establish myeloma protein–specific enzyme‐linked immunosorbent assays (ELISAs) that were between 75 and 1500 times more sensitive than conventional serum protein electrophoresis and immunofixation. Conclusions: These results pave the way for testing targeted DNA Id vaccines in patients in CR. Id‐ and patient‐specific ELISA could be established affording evaluation of CR depth beyond current serological methods.     

Novel therapies for multiple myeloma

Multiple myeloma (MM) continues to evade cure by conventional therapies, increasing the urgency for new, biologically based treatments. Reviewed in this discussion are novel chemotherapies under clinical trial that capitalize upon greater comprehension of tumor pathophysiology. In targeting tumor biology, these therapies serve as a model of treatment with great potential for improving outcomes in patients with MM.     

Polyphyllin I induces cell cycle arrest and apoptosis in human myeloma cells via modulating β‐catenin signaling pathway

Multiple myeloma (MM) is an indolent B‐cell disease characterized by clonal proliferation of malignant plasma cells. Multiple myeloma remains incurable despite new targeted drugs and development of drug resistance or intolerable toxicity emerges as a major problem. Therefore, design, identification, and validation of novel chemicals with therapeutic potential are clearly needed for MM treatment. Here, we explore polyphyllin I (PPI), a major active constituent extracted from Paris polyphyllin, its inhibitory effects and its mechanisms in MM cells in vitro. We found that PPI inhibited the proliferation of myeloma cells. The combination of PPI with dexamethasone, doxorubicin, arsenic trioxide, or bortezomib enhanced the inhibition of cell growth. As analyzed by flow cytometry, MM cells were arrested at G2/M phase and apoptotic cells increased in a time‐dependent manner. Morphological changes of cells undergoing apoptosis were observed under light microscope. To explore the mechanism of apoptosis induced by PPI, we next examined whether the Wingless‐Int (Wnt)/β‐catenin signaling pathway played a role in the PPI‐induced growth inhibition in MM cells. The canonical Wnt signaling pathway is activated in MM cells through constitutively active β‐catenin, a messenger molecule relevant to growth, survival, and migration of MM cells. Western blotting was used to measure the protein levels of β‐catenin, and PPI treatment led to downregulating the expression of β‐catenin protein and was followed by inhibition of β‐catenin nuclear localization. As a result, β‐catenin downstream targets, such as cyclin D1 and survivin, were downregulated. To the best of our knowledge, this is the first report identifying anti‐proliferative potency of PPI against myeloma cells. PPI blocks β‐catenin nuclear translocation and decreasing expression of the downstream targets of β‐catenin. Our results suggest that PPI is a novel inhibitor of β‐catenin activity with potential anti‐myeloma efficacy.     

Bone marrow infiltration by multiple myeloma causes anemia by reversible disruption of erythropoiesis

Multiple myeloma (MM) infiltrates bone marrow and causes anemia by disrupting erythropoiesis, but the effects of marrow infiltration on anemia are difficult to quantify. Marrow biopsies of newly diagnosed MM patients were analyzed before and after four 28‐day cycles of nonerythrotoxic remission induction chemotherapy. Complete blood cell counts and serum paraprotein concentrations were measured at diagnosis and before each chemotherapy cycle. At diagnosis, marrow area infiltrated by myeloma correlated negatively with hemoglobin, erythrocytes, and marrow erythroid cells. After successful chemotherapy, patients with less than 30% myeloma infiltration at diagnosis had no change in these parameters, whereas patients with more than 30% myeloma infiltration at diagnosis increased all three parameters. Clinical data were used to develop mathematical models of the effects of myeloma infiltration on the marrow niches of terminal erythropoiesis, the erythroblastic islands (EBIs). A hybrid discrete‐continuous model of erythropoiesis based on EBI structure/function was extended to sections of marrow containing multiple EBIs. In the model, myeloma cells can kill erythroid cells by physically destroying EBIs and by producing proapoptotic cytokines. Following chemotherapy, changes in serum paraproteins as measures of myeloma cells and changes in erythrocyte numbers as measures of marrow erythroid cells allowed modeling of myeloma cell death and erythroid cell recovery, respectively. Simulations of marrow infiltration by myeloma and treatment with nonerythrotoxic chemotherapy demonstrate that myeloma‐mediated destruction and subsequent reestablishment of EBIs and expansion of erythroid cell populations in EBIs following chemotherapy provide explanations for anemia development and its therapy‐mediated recovery in MM patients. Am. J. Hematol. 91:371–378, 2016. © 2016 Wiley Periodicals, Inc.     

Engineering of self-assembled nanoparticle platform for precisely controlled combination drug therapy

The genomic revolution has identified therapeutic targets for a plethora of diseases, creating a need to develop robust technologies for combination drug therapy. In the present work, we describe a self-assembled polymeric nanoparticle (NP) platform to target and control precisely the codelivery of drugs with varying physicochemical properties to cancer cells. As proof of concept, we codelivered cisplatin and docetaxel (Dtxl) to prostate cancer cells with synergistic cytotoxicity. A polylactide (PLA) derivative with pendant hydroxyl groups was prepared and conjugated to a platinum(IV) [Pt(IV)] prodrug, c,t,c-[Pt(NH(3))(2)(O(2)CCH(2)CH(2)COOH)(OH)Cl(2)] [PLA-Pt(IV)]. A blend of PLA-Pt(IV) functionalized polymer and carboxyl-terminated poly(D,L-lactic-co-glycolic acid)-block-poly(ethylene glycol) copolymer in the presence or absence of Dtxl, was converted, in microfluidic channels, to NPs with a diameter of ～100 nm. This process resulted in excellent encapsulation efficiency (EE) and high loading of both hydrophilic platinum prodrug and hydrophobic Dtxl with reproducible EEs and loadings. The surface of the NPs was derivatized with the A10 aptamer, which binds to the prostate-specific membrane antigen (PSMA) on prostate cancer cells. These NPs undergo controlled release of both drugs over a period of 48-72 h. Targeted NPs were internalized by the PSMA-expressing LNCaP cells via endocytosis, and formation of cisplatin 1,2-d(GpG) intrastrand cross-links on nuclear DNA was verified. In vitro toxicities demonstrated superiority of the targeted dual-drug combination NPs over NPs with single drug or nontargeted NPs. This work reveals the potential of a single, programmable nanoparticle to blend and deliver a combination of drugs for cancer treatment.     

Targeted therapy with MXD3 siRNA,anti‐CD22 antibody and nanoparticles for precursor B‐cell acute lymphoblastic leukaemia

Conventional chemotherapy for precursor B‐cell (preB) acute lymphoblastic leukaemia (ALL) has limitations that could be overcome by targeted therapy. Previously, we discovered a potential therapeutic molecular target, MDX3 (MAX dimerization protein 3), in preB ALL. In this study, we hypothesize that an effective siRNA therapy for preB ALL can be developed using antiCD22 antibody (αCD22 Ab) and nanoparticles. We composed nanocomplexes with super paramagnetic iron oxide nanoparticles (SPIO NPs), αCD22 Abs and MXD3 siRNA molecules based on physical interactions between the molecules. We demonstrated that the MXD3 siRNA‐αCD22 Ab‐SPIO NP complexes entered leukaemia cells and knocked down MXD3, leading the cells to undergo apoptosis and resulting in decreased live cell counts in the cell line Reh and in primary preB ALL samples in vitro. Furthermore, the cytotoxic effects of the MXD3 siRNA‐αCD22 Ab‐SPIO NP complexes were significantly enhanced by addition of the chemotherapy drugs vincristine or doxorubicin. We also ruled out potential cytotoxic effects of the MXD3 siRNA‐αCD22 Ab‐SPIO NP complexes on normal primary haematopoietic cells. Normal B cells were affected while CD34‐positive haematopoietic stem cells and non‐B cells were not. These data suggest that MXD3 siRNA‐αCD22 Ab‐SPIO NP complexes have the potential to be a new targeted therapy for preB ALL.     

Micelles as potential drug delivery systems for colorectal cancer treatment

Despite the significant progress in cancer therapy, colorectal cancer (CRC) remains one of the most fatal malignancies worldwide. Chemotherapy is currently the mainstay therapeutic modality adopted for CRC treatment. However, the long-term effectiveness of chemotherapeutic drugs has been hampered by their low bioavailability, non-selective tumor targeting mechanisms, non-specific biodistribution associated with low drug concentrations at the tumor site and undesirable side effects. Over the last decade, there has been increasing interest in using nanotechnology-based drug delivery systems to circumvent these limitations. Various nanoparticles have been developed for delivering chemotherapeutic drugs among which polymeric micelles are attractive candidates. Polymeric micelles are biocompatible nanocarriers that can bypass the biological barriers and preferentially accumulate in tumors via the enhanced permeability and retention effect. They can be easily engineered with stimuli-responsive and tumor targeting moieties to further ensure their selective uptake by cancer cells and controlled drug release at the desirable tumor site. They have been shown to effectively improve the pharmacokinetic properties of chemotherapeutic drugs and enhance their safety profile and anticancer efficacy in different types of cancer. Given that combination therapy is the new strategy implemented in cancer therapy, polymeric micelles are suitable for multidrug delivery and allow drugs to act concurrently at the action site to achieve synergistic therapeutic outcomes. They also allow the delivery of anticancer genetic material along with chemotherapy drugs offering a novel approach for CRC therapy. Here, we highlight the properties of polymeric micelles that make them promising drug delivery systems for CRC treatment. We also review their application in CRC chemotherapy and gene therapy as well as in combination cancer chemotherapy.     

Checkpoint immunotherapy for cancer: superior survival,unaccustomed toxicities

Novel cancer immunotherapy antibodies are moving from clinical trials into routine practice, delivering sustained benefits and prolonged survival to patients with melanoma, lung, kidney and other cancers. These immunostimulatory antibodies non‐specifically activate the patient's own immune system by inhibiting immune system checkpoint proteins. This mechanism of action is entirely different to traditional cancer treatments, such as chemotherapy. While there are virtually no immediate toxicities, serious life‐threatening autoimmune side‐effects such as colitis, dermatitis, hypophysitis, pneumonitis and hepatitis can occur, sometimes starting long after the treatment has been given. Recognition, referral and prompt treatment with immunosuppressive drugs like corticosteroids can control these immune‐related side‐effects without compromising efficacy. This exciting new class of drugs is defining a new paradigm in cancer therapy.     

Precise engineering of targeted nanoparticles by using self-assembled biointegrated block copolymers

There has been progressively heightened interest in the development of targeted nanoparticles (NPs) for differential delivery and controlled release of drugs. Despite nearly three decades of research, approaches to reproducibly formulate targeted NPs with the optimal biophysicochemical properties have remained elusive. A central challenge has been defining the optimal interplay of parameters that confer molecular targeting, immune evasion, and drug release to overcome the physiological barriers in vivo. Here, we report a strategy for narrowly changing the biophysicochemical properties of NPs in a reproducible manner, thereby enabling systematic screening of optimally formulated drug-encapsulated targeted NPs. NPs were formulated by the self-assembly of an amphiphilic triblock copolymer composed of end-to-end linkage of poly(lactic-co-glycolic-acid) (PLGA), polyethyleneglycol (PEG), and the A10 aptamer (Apt), which binds to the prostate-specific membrane antigen (PSMA) on the surface of prostate cancer (PCa) cells, enabling, respectively, controlled drug release, "stealth" properties for immune evasion, and cell-specific targeting. Fine-tuning of NP size and drug release kinetics was further accomplished by controlling the copolymer composition. By using distinct ratios of PLGA-b-PEG-b-Apt triblock copolymer with PLGA-b-PEG diblock copolymer lacking the A10 Apt, we developed a series of targeted NPs with increasing Apt densities that inversely affected the amount of PEG exposure on NP surface and identified the narrow range of Apt density when the NPs were maximally targeted and maximally stealth, resulting in most efficient PCa cell uptake in vitro and in vivo. This approach may contribute to further development of targeted NPs as highly selective and effective therapeutic modalities.     

Malignant lymphoma, multiple myeloma and myeloproliferative diseases in the elderly

Hematopoietic and immune function tend to deteriorate in the elderly. The incidence of hematologic diseases in the elderly is increasing as the percentage of elderly people in the whole population increases. Acute leukemia, myelodysplastic syndrome, malignant lymphoma, multiple myeloma, and myelodysplastic syndromes are commonly seen in the elderly. Malignant lymphomas are frequently seen in the elderly, and many elderly patients have poor performance status, and because they are more likely to suffer from impaired cardiac, respiratory, hepatic and renal function, as well as glucose intolerance, they are also more likely to suffer side effects due to chemotherapy. Particularly in patients aged over 80 years, to avoid side effects it is essential to adjust dosage and route of administration of chemotherapy. Although age is a significant negative prognostic factor for non-Hodgkin's lymphoma, it is possible for patients to enter complete remission with improvement of host-side factors. The clinical application of Rituximab is expected to improve chemotherapy outcomes in elderly B-cell lymphoma. The median age at the time of initial diagnosis of multiple myeloma (MM) is 60-70 years, and age is a negative prognostic factor. Clinically, higher rates of infection and heavy comorbidity are characteristic of this condition in the elderly. Although the incidence of bony lesions in elderly patients with MM is not different from the non-elderly, they do have a higher incidence of bone pain and pathologic fractures compared with the non-elderly patients. As the response to chemotherapy is good in the elderly, it is worth trying chemotherapy for MM. Polycythemia vera must be treated in the elderly, because chemotherapy decreases the incidence of thrombosis.     

Multiple Myeloma: Treatment is Getting Individualized

Multiple myeloma (MM) is a heterogeneous disease with varied outcome. The novel agents including two major classes of drugs; the immunomodulatory drugs and the proteasome inhibitors with unprecedented response rates, have replaced conventional chemotherapy. With monoclonal antibodies on the horizon, outcome of this disorder will further improve. Progression in risk stratification systems has made it possible to predict the disease course as well as outcome in myeloma patients with disease categorization into low to high risk. In addition, detection of minimal residual disease by serum free light chain assay, flow cytometry, molecular techniques like polymerase chain reaction and positron emission tomography scan is playing an important role in modifying the treatment. An extensive research in the disease biology has improved our knowledge regarding interplay between myeloma cells and elements of the bone marrow microenvironment which contribute to sustain proliferation and survival as well as de novo drug resistance. Again, insight into the role of genetic and epigenetic interactions in MM has exposed new molecular targets. All these have opened the gateway for novel therapeutic strategies with focus on risk based individualized therapy.     

Serum concentrations of DKK‐1 decrease in patients with multiple myeloma responding to anti‐myeloma treatment

Lytic bone destruction is a hallmark of multiple myeloma (MM) and is because of an uncoupling of bone remodeling. Secretion of Dickkopf (DKK)‐1 by myeloma cells is a major factor which causes inhibition of osteoblast precursors. In this study, the effect of different treatment regimens for MM on serum DKK‐1 was evaluated and correlated with the response to treatment in 101 myeloma patients receiving bortezomib, thalidomide, lenalidomide, adriamycin and dexamethasone (AD) or high‐dose chemotherapy (HDCT) followed by autologous stem cell transplantation (ASCT). At baseline, myeloma patients had increased serum DKK‐1 as compared with patients with MGUS (mean 3786 pg/mL vs. 1993 pg/mL). There was no difference between previously untreated MM patients and patients at relapse. A significant decrease of DKK‐1 after therapy was seen in the following groups: Bortezomib (4059 pg/mL vs. 1862 pg/mL, P = 0.016), lenalidomide (11837 pg/mL vs. 4374 pg/mL, P = 0.039), AD (1668 pg/mL vs. 1241 pg/mL, P = 0.016), and AD + HDCT + ASCT (2446 pg/mL vs. 1082 pg/mL, P = 0.001). Thalidomide led to a non‐significant decrease in DKK‐1 (1705 pg/mL vs. 1269 pg/mL, P = 0.081). Within all groups, a significant decrease of DKK‐1 was only seen in responders (i.e. patients achieving complete remission or partial remission), but not in non‐responders. We show for the first time that serum DKK‐1 levels decrease in myeloma patients responding to treatment, irrespective of the regimen chosen. These data suggest that myeloma cells are the main source of circulating DKK‐1 protein and provide a framework for clinical trials on anti‐DKK‐1 treatment in MM.     

Recurrent cardiotoxicity potentiated by the interaction of proteasome inhibitor and immunomodulatory therapy for the treatment of multiple myeloma

Patients with multiple myeloma (MM) have improved treatment options, including immunomodulatory drugs (IMiDs) and proteasome inhibitors (PIs). Despite their efficacy, increased rates of cardiovascular (CV) complications occur in patients exposed to some of these therapies. While previous research has focused on identifying the toxicities inherent to each specific agent, the CV side effects may be potentiated by the combination of PIs and IMiDs plus dexamethasone. We present a patient with MM with recurrent cardiotoxicity only when exposed to combination PI and IMiD‐based therapy. We also review the literature in this context, and propose a potential algorithm for cardiotoxicity prevention in this population.     

Nanoparticle-mediated drug delivery to tumor vasculature suppresses metastasis

Integrin alphanubeta3 is found on a subset of tumor blood vessels where it is associated with angiogenesis and malignant tumor growth. We designed an alphanubeta3-targeted nanoparticle (NP) encapsulating the cytotoxic drug doxorubicin (Dox) for targeted drug delivery to the alphanubeta3-expressing tumor vasculature. We observed real-time targeting of this NP to tumor vessels and noted selective apoptosis in regions of the alphanubeta3-expressing tumor vasculature. In clinically relevant pancreatic and renal cell orthotopic models of spontaneous metastasis, targeted delivery of Dox produced an antimetastatic effect. In fact, alphanubeta3-mediated delivery of this drug to the tumor vasculature resulted in a 15-fold increase in antimetastatic activity without producing drug-associated weight loss as observed with systemic administration of the free drug. These findings reveal that NP-based delivery of cytotoxic drugs to the alphanubeta3-positive tumor vasculature represents an approach for treating metastatic disease.     

Multiple myeloma: chemotherapy or transplantation in the era of new drugs

Objective: To review the current results of studies incorporating novel agents in multiple myeloma (MM) and discuss the role of autologous stem‐cell transplantation (ASCT) in the era of new active drugs for the treatment of this disease. The outlook for patients with symptomatic MM is changing with the introduction of bortezomib, thalidomide, and lenalidomide into the repertoire of available chemotherapeutic agents. Compared with standard chemotherapy, a survival benefit has been reported for the first time in 30 yrs. Methods: Articles published in English between 1969 and 2008 were identified by searching PubMed for ‘myeloma’, ‘diagnosis’, ‘thalidomide’, ‘bortezomib’, ‘lenalidomide’, ‘dexamethasone’, ‘prednisone’, ‘doxorubicin’, ‘cyclophosphamide’, ‘melphalan’, ‘combination chemotherapy’, and ‘autologous transplantation’. Results: In randomized studies, bortezomib, thalidomide, and lenalidomide have each been combined with dexamethasone, alkylating agents, or doxorubicin, and such combinations resulted in significant improvement in progression‐free survival. Conclusions: The incorporation of new drugs as induction therapy along with ASCT appears to produce very good partial response rates, slightly superior to those achieved by conventional chemotherapy with new drugs. How to best optimize induction, consolidation, and maintenance therapy and how to best select and prepare patients for ASCT are still to be determined. Randomized trials are needed to directly compare the current best chemotherapeutic approach with best ASCT strategies and to guide clinical practice for patients with MM.     

Nanoparticles for targeted delivery of therapeutics and small interfering RNAs in hepatocellular carcinoma

Hepatocellular carcinoma(HCC) is the 5th most common malignancy which is responsible for more than half million annual mortalities; also, it is the third leading cause of cancer related death. Unfavorablesystemic side-effects of chemotherapeutic agents and susceptibility to the degradation of small interfering RNAs(si RNAs), which can knock down a specific gene involved in the disease, have hampered their clinical application. So, it could be beneficial to develop an efficient carrier for the stabilization and specific delivery of drugs and si RNA to cells. Targeted nanoparticles have gained considerable attention as an efficient drug and gene delivery system, which is due to their capability in achieving the highest accumulation of cytotoxic agents in tumor tissue, modifiable drug pharmacokinetic- and bio-distribution, improved effectiveness of treatment, and limited sideeffects. Recent studies have shed more light on the advantages of novel drug loaded carrier systems vs free drugs. Most of the animal studies have reported improvement in treatment efficacy and survival rate using novel carrier systems. Targeted delivery may be achieved passively or actively. In passive targeting, no ligand as homing device is used, while targeting is achieved by incorporating the therapeutic agent into a macromolecule or nanoparticle that passively reaches the target organ. However, in active targeting, the therapeutic agent or carrier system is conjugated to a tissue or cell-specific receptor which is overexpressed in a special malignancy using a ligand called a homing device. This review covers a broad spectrum of targeted nanoparticles as therapeutic and nonviral si RNA delivery systems, which are developed for enhanced cellular uptake and targeted gene silencing in vitro and in vivo and their characteristics and opportunities for the clinical applications of drugs and therapeutic si RNA are discussed in this article. Asialoglycoprotein receptors, low-density lipoprotein, ganglioside GM1 cell surface ligand, epidermal growth factor receptor receptors, monoclonal antibodies, retinoic acid receptors, integrin receptors targeted by Arg-Gly-Asp peptide, folate, and transferrin receptors are the most widely studied cell surface receptors which are used for the site specific delivery of drugs and si RNA-based therapeutics in HCC and discussed in detail in this article.     

Bendamustine in multiple myeloma

The advent of high‐dose melphalan with autologous stem‐cell transplantation (ASCT), the availability of novel agents such as thalidomide, lenalidomide (immunomodulatory drugs or IMiDs) and bortezomib (proteasome inhibitor) and improvements in supportive care have allowed to increase overall survival in multiple myeloma (MM) patients; nevertheless, MM remains an incurable pathology. For this reason, newer agents are required for continued disease control. Bendamustine is an old drug rediscovered in the last decade. In fact, its unique mechanism of action with structural similarities to both alkylating agents and antimetabolities, but which is not cross‐resistant to alkylating agents, has reawakened interest in the use of this drug in the treatment of MM. Studies have proven the safety and efficacy of bendamustine administered alone or in combination with new drugs in both upfront and relapse/refractory settings of MM patients, including those with renal impairment. Moreover, bendamustine has been successfully used as conditioning for autologous stem‐cell transplantation. Finally, the use of bendamustine does not compromise peripheral blood stem‐cell collection. This drug is generally well tolerated, with the majority of adverse events being due to myelosuppression. Non‐haematological adverse events are infrequent and usually mild.     

Myeloma stem cell concepts,heterogeneity and plasticity of multiple myeloma

Multiple myeloma (MM) is a haematological malignancy characterized by the accumulation of clonal plasma cells (PCs) in the bone marrow (BM). Although novel therapeutic strategies have prolonged survival of patients, the disease remains difficult to treat with a high risk of relapse. The failure of therapy is thought to be associated with a persistent population of the so‐called MM stem cells or myeloma initiating cells (MIC) that exhibit tumour‐initiating potential, self‐renewal and resistance to chemotherapy. However, the population responsible for the origin and sustainability of tumour mass has not been clearly characterized so far. This review summarizes current myeloma stem cell concepts and suggests that high phenotypic and intra‐clonal heterogeneity, together with plasticity potential of MM might be other contributing factors explaining discrepancies among particular concepts and contributing to the treatment failure.