Multidrug resistance in haematological malignancies

Transcriptional Regulation of Yin-Yang 1 Expression through the Hypoxia Inducible Factor-1 in Pediatric Acute Lymphoblastic Leukemia

Yin-Yang transcription factor 1 (YY1) is involved in tumor progression, metastasis and has been shown to be elevated in different cancers, including leukemia. The regulatory mechanism underlying YY1 expression in leukemia is still not understood. Bioinformatics analysis reveal three Hypoxia-inducible factor 1-alpha (HIF-1α) putative binding sites in the YY1 promoter region. The regulation of YY1 by HIF-1α in leukemia was analyzed. Mutation of the putative YY1 binding sites in a reporter system containing the HIF-1α promoter region and CHIP analysis confirmed that these sites are important for YY1 regulation. Leukemia cell lines showed that both proteins HIF-1α and YY1 are co-expressed under hypoxia. In addition, the expression of mRNA of YY1 was increased after 3 h of hypoxia conditions and affect several target genes expression. In contrast, chemical inhibition of HIF-1α induces downregulation of YY1 and sensitizes cells to chemotherapeutic drugs. The clinical implications of HIF-1α in the regulation of YY1 were investigated by evaluation of expression of HIF-1α and YY1 in 108 peripheral blood samples and by RT-PCR in 46 bone marrow samples of patients with pediatric acute lymphoblastic leukemia (ALL). We found that the expression of HIF-1α positively correlates with YY1 expression in those patients. This is consistent with bioinformatic analyses of several databases. Our findings demonstrate for the first time that YY1 can be transcriptionally regulated by HIF-1α, and a correlation between HIF-1α expression and YY1 was found in ALL clinical samples. Hence, HIF-1α and YY1 may be possible therapeutic target and/or biomarkers of ALL.

Overexpression of GRP78/BiP in P-Glycoprotein-Positive L1210 Cells is Responsible for Altered Response of Cells to Tunicamycin as a Stressor of the Endoplasmic Reticulum

P-glycoprotein (P-gp, ABCB1 member of the ABC (ATP-binding cassette) transporter family) localized in leukemia cell plasma membranes is known to reduce cell sensitivity to a large but well-defined group of chemicals known as P-gp substrates. However, we found previously that P-gp-positive sublines of L1210 murine leukemia cells (R and T) but not parental P-gp-negative parental cells (S) are resistant to the endoplasmic reticulum (ER) stressor tunicamycin (an N-glycosylation inhibitor). Here, we elucidated the mechanism of tunicamycin resistance in P-gp-positive cells. We found that tunicamycin at a sublethal concentration of 0.1 µM induced retention of the cells in the G1 phase of the cell cycle only in the P-gp negative variant of L1210 cells. P-gp-positive L1210 cell variants had higher expression of the ER stress chaperone GRP78/BiP compared to that of P-gp-negative cells, in which tunicamycin induced larger upregulation of CHOP (C/EBP homologous protein). Transfection of the sensitive P-gp-negative cells with plasmids containing GRP78/BiP antagonized tunicamycin-induced CHOP expression and reduced tunicamycin-induced arrest of cells in the G1 phase of the cell cycle. Taken together, these data suggest that the resistance of P-gp-positive cells to tunicamycin is due to increased levels of GRP78/BiP, which is overexpressed in both resistant variants of L1210 cells.

A pharmacodynamic model of clinical synergy in multiple myeloma

BACKGROUND

Multiagent therapies, due to their ability to delay or overcome resistance, are a hallmark of treatment in multiple myeloma (MM). The growing number of therapeutic options in MM requires high-throughput combination screening tools to better allocate treatment, and facilitate personalized therapy.

METHODS

A second-order drug response model was employed to fit patient-specific ex vivo responses of 203 MM patients to single-agent models. A novel pharmacodynamic model, developed to account for two-way combination effects, was tested with 130 two-drug combinations. We have demonstrated that this model is sufficiently parameterized by single-agent and fixed-ratio combination responses, by validating model estimates with ex vivo combination responses for different concentration ratios, using a checkerboard assay. This new model reconciles ex vivo observations from both Loewe and BLISS synergy models, by accounting for the dimension of time, as opposed to focusing on arbitrary time-points or drug effect. Clinical outcomes of patients were simulated by coupling patient-specific drug combination models with pharmacokinetic data.

FINDINGS

Combination screening showed 1 in 5 combinations (21.43% by LD50, 18.42% by AUC) were synergistic ex vivo with statistical significance (P < 0.05), but clinical synergy was predicted for only 1 in 10 combinations (8.69%), which was attributed to the role of pharmacokinetics and dosing schedules.

INTERPRETATION

The proposed framework can inform clinical decisions from ex vivo observations, thus providing a path toward personalized therapy using combination regimens.

FUNDING

This research was funded by the H. Lee Moffitt Cancer Center Physical Sciences in Oncology (PSOC) Grant (1U54CA193489-01A1) and by H. Lee Moffitt Cancer Center's Team Science Grant. This work has been supported in part by the PSOC Pilot Project Award (5U54CA193489-04), the Translational Research Core Facility at the H. Lee Moffitt Cancer Center & Research Institute, an NCI-designated Comprehensive Cancer Center (P30-CA076292), the Pentecost Family Foundation, and Miles for Moffitt Foundation.

3-Aryl-4-nitrobenzothiochromans S,S-dioxide: From Calcium-Channel Modulators Properties to Multidrug-Resistance Reverting Activity

Our research groups have been involved for many years in studies aimed at identifying new active organic compounds endowed with pharmacological properties. In this work, we focused our attention on the evaluation of cardiovascular and molecular drug resistance (MDR) reverting activities of some nitrosubstituted sulphur-containing heterocycles. Firstly, we have examined the effects of 4-nitro-3-(4-methylphenyl)-3,6-dihydro-2H-thiopyran S,S-dioxide 5, and have observed no activity. Then we have extended our investigation to the 3-aryl-4-nitrobenzothiochromans S,S-dioxide 6 and 7, and have observed an interesting biological profile. Cardiovascular activities were assessed for all compounds using ex vivo studies, while the MDR reverting effect was evaluated only for selected compounds using tumor cell lines. All compounds were shown to affect cardiovascular parameters. Compound 7i exerted the most effect on negative inotropic activity, while 6d and 6f could be interesting molecules for the development of more active ABCB1 inhibitors. Both 6 and 7 represent structures of large possible biological interest, providing a scaffold for the identification of new ABCB1 inhibitors.

Nanomedicines for the treatment of hematological malignancies

Hematological malignancies (HM) are a collection of malignant transformations originating from cells in the primary or secondary lymphoid organs. Leukemia, lymphoma, and multiple myeloma comprise the three major types of HM. Current treatment consists of bone marrow transplantation, radiotherapy, immunotherapy and chemotherapy. Although, many chemotherapeutic drugs are clinically available for the treatment of HM, the use of these agents is limited due to dose-related toxicity and lack of specificity to tumor tissue. Moreover, the poor pharmacokinetic profile of most of the chemotherapeutics requires high dosage and frequent administration to maintain therapeutic levels at the target site, both increasing adverse effects. This underlines an urgent need for a suitable drug delivery system to improve efficacy, safety, and pharmacokinetic properties of conventional therapeutics. Nanomedicines have proven to enhance these properties for anticancer therapeutics. The most extensively studied nanomedicine systems are lipid-based nanoparticles and polymeric nanoparticles. Typically, nanomedicines are small sub-micron sized particles in the size range of 20-200 nm. The biocompatible and biodegradable nature of nanomedicines makes them attractive vehicles to improve drug delivery. Their small size allows them to extravasate and accumulate at malignant sites passively by means of the enhanced permeability and retention (EPR) effect, resulting from rapid angiogenesis and inflammation. Moreover, the specificity to the target tissue can be further enhanced by surface modification of nanoparticles. This review describes currently available therapies as well as limitations and potential advantages of nanomedicine formulations for treatment of various types of HM. Additionally, recent investigational and approved nanomedicine formulations and their limited applications in HM are discussed.

Pilot study: duodenal MDR1 and COX2 gene expression in cats with inflammatory bowel disease and low-grade alimentary lymphoma

Objectives Multidrug resistance 1 (MDR1) encodes a protein called P-glycoprotein (P-gp), which serves as an efflux pump membrane protein implicated in intestinal homeostasis and drug resistance. Cyclooxygenase-2 (COX2) is a key enzyme in the synthesis of proinflammatory prostaglandins, tumourigenesis and in mucosal defence. Despite the importance of MDR1 and COX2, changes in their mRNA levels have not been studied in cats with inflammatory bowel disease (IBD) and low-grade alimentary lymphoma (LGAL). The present study aimed to determine the mRNA levels of MDR1 and COX2 in cats with IBD and LGAL, and to evaluate their correlation with clinical signs, histological severity and between genes. Methods Cats diagnosed with IBD (n = 20) and LGAL (n = 9) between 2008 and 2015 were included in the current study. Three healthy animals composed the healthy control cats group in which endoscopy was performed immediately before the ovariohysterectomy. All duodenal biopsy samples were obtained by endoscopy. Feline chronic enteropathy activity index was calculated for all cases. IBD histopathology was classified according to severity. MDR1 and COX2 mRNA levels were determined by absolute reverse transcriptase-quantitative real-time PCR. Results Statistically significant differences were observed for MDR1 and COX2 mRNA levels between the IBD and LGAL groups. No correlations were observed between molecular gene expression, feline chronic enteropathy activity index and histological grading for IBD, and between MDR1 and COX2 genes. However, a positive statistically significant correlation was observed between MDR1 and COX2 expression in the duodenum of cats. Conclusions and relevance MDR1 and COX2 gene expression is increased in cats with LGAL compared with cats with IBD. The control group tended to have lower values than both diseased groups. These results suggest that these genes may be involved in the pathogenesis of IBD or LGAL in cats.

Upregulation of miR-142-3p Improves Drug Sensitivity of Acute Myelogenous Leukemia through Reducing P-Glycoprotein and Repressing Autophagy by Targeting HMGB1

miR-142-3p was reported to be downregulated in acute myelogenous leukemia (AML) and acted as a novel diagnostic marker. However, the regulatory effect of miR-142-3p on drug resistance of AML cells and its underlying mechanism have not been elucidated. Here, we found that miR-142-3p was significantly downregulated and high mobility group box 1 (HMGB1) was dramatically upregulated in AML samples and cells, as well as drug-resistant AML cells. P-gp level and autophagy were markedly enhanced in HL-60/ADR and HL-60/ATRA cells. miR-142-3p overexpression improved drug sensitivity of AML cells by inhibiting cell viability and promoting apoptosis, and inhibited P-gp level and autophagy in drug-resistant AML cells, whereas HMGB1 overexpression obviously reversed these effect. HMGB1 was demonstrated to be a target of miR-142-3p, and miR-142-3p negatively regulated HMGB1 expression. In conclusion, our study elucidated that upregulation of miR-142-3p improves drug sensitivity of AML through reducing P-glycoprotein and repressing autophagy by targeting HMGB1, contributing to better understanding the molecular mechanism of drug resistance in AML.

Overexpression of survivin via activation of ERK1/2, Akt, and NF-κB plays a central role in vincristine resistance in multiple myeloma cells

The acquisition of anti-cancer drug resistance is a major limitation of chemotherapy for multiple myeloma (MM) and it is thus important to identify the mechanisms by which MM cells develop such drug resistance. In a previous study, we showed that multidrug resistance (MDR) involves the overexpression of MDR1 and survivin in vincristine-resistant RPMI8226/VCR cells. However, the underlying mechanism of MDR remains unclear. In this study, we investigated the mechanism of MDR in RPMI8226/VCR cells, and found that RPMI8226/VCR cells exhibit increased levels of activated ERK1/2, Akt, and NF-κB, while the levels of activated mTOR, p38MAPK, and JNK do not differ between RPMI8226/VCR cells and their vincristine-susceptible counterparts. In addition, the inhibition of ERK1/2, Akt, or NF-κB by inhibitors reversed the drug-resistance of RPMI8226/VCR cells via the suppression of survivin expression, but did not affect MDR1 expression; RNA silencing of survivin expression completely reversed vincristine resistance, while MDR1 silencing only weakly suppressed vincristine resistance in RPMI8226/VCR cells. These results indicate that enhanced survivin expression via the activation of ERK1/2, Akt, and NF-κB plays a critical role in vincristine resistance in RPMI8226/VCR cells. Our findings suggest that ERK1/2, Akt, and NF-κB inhibitors are potentially useful as anti-MDR agents for the treatment of vincristine-resistant MM.

Drug resistance in multiple myeloma: latest findings and new concepts on molecular mechanisms

In the era of new and mostly effective therapeutic protocols, multiple myeloma still tends to be a hard-to-treat hematologic cancer. This hallmark of the disease is in fact a sequel to drug resistant phenotypes persisting initially or emerging in the course of treatment. Furthermore, the heterogeneous nature of multiple myeloma makes treating patients with the same drug challenging because finding a drugable oncogenic process common to all patients is not yet feasible, while our current knowledge of genetic/epigenetic basis of multiple myeloma pathogenesis is outstanding. Nonetheless, bone marrow microenvironment components are well known as playing critical roles in myeloma tumor cell survival and environment-mediated drug resistance happening most possibly in all myeloma patients. Generally speaking, however; real mechanisms underlying drug resistance in multiple myeloma are not completely understood. The present review will discuss the latest findings and concepts in this regard. It reviews the association of important chromosomal translocations, oncogenes (e.g. TP53) mutations and deranged signaling pathways (e.g. NFκB) with drug response in clinical and experimental investigations. It will also highlight how bone marrow microenvironment signals (Wnt, Notch) and myeloma cancer stem cells could contribute to drug resistance in multiple myeloma.

2,3,7,8-Tetrachlorodibenzo-p-dioxin induced cell-specific drug transporters with acquired cisplatin resistance in cisplatin sensitive cancer cells

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) can induce drug transporter genes such as the ATP-binding cassette G member 2 (ABCG2), which contributes to multidrug resistance. We investigated the effect of TCDD pretreatment on drug transporters induction from cancer cells of various origins. Cell viabilities after treatment of cisplatin were measured to evaluate acquiring cisplatin resistance by TCDD. Acquring cisplatin resistance was found only in cisplatin senstivie cancer cells including gastric SNU601, colon LS180, brain CRT-MG and lymphoma Jurkat cells which showed a significant increase in cell viability after combined treatment with TCDD and cisplatin. High increase of ABCG2 gene expression was found in SNU601 and LS180 cells with a mild increase in the expression of the ABCC3, ABCC5,and SLC29A2 genes in SNU601 cells, and of major vault protein (MVP) in LS180 cells. The AhR inhibitor kaempferol suppressed the upregulation of ABCG2 expression and reversed the TCDD-induced increase in cell viability in LS180 cells. However, in CRT-MG cells, other transporter genes including ABCC1, ABCC5, ABCA3, ABCA2, ABCB4, ABCG1, and SLC29A1 were up-regulated. These findings suggested the acquiring cisplatin resistance by TCDD associated with cancer cell-type-specific induction of drug transporters.

The role of P-glycoprotein in drug resistance in multiple myeloma

Multiple myeloma (MM) is a malignant neoplastic cancer of the plasma cells that involves the bone marrow. The majority of patients with MM initially respond to chemotherapy, but they eventually become resistant to later drug therapy. One of the reasons for drug resistance in patients with MM is efflux transporters. P-glycoprotein (P-gp) is the most studied of the multidrug resistance proteins, and is up-regulated in response to many chemotherapeutic drugs. This up-regulation of P-gp causes a decrease in the intracellular accumulation of these drugs, limiting their therapeutic efficacy. In this review, we focus on the role of P-gp in drugs used for patients with MM. P-gp has been found to be an important factor with regard to drug resistance in many of the drug classes used in the treatment of MM (proteasome inhibitors, anthracyclines, alkylating agents and immunomodulators are examples). Thus, our further understanding of its mechanism and inhibitory effects will help us decrease drug resistance in patients with MM.

The network of P-glycoprotein and microRNAs interactions

Overexpression of P-glycoprotein (P-gp) contributes to the multidrug resistance (MDR) phenotype found in many cancer cells. P-gp has been identified as a promising molecular target, although attempts to find successful therapies to counteract its function as a drug efflux pump have largely failed to date. Apart from its role in drug efflux, P-gp may have other cellular functions such as being involved in apoptosis, and is found in various locations in the cell. Its expression is highly regulated, namely by microRNAs (miRNAs or miRs). In addition, P-gp may regulate the expression of miRs in the cell. Furthermore, both P-gp and miRs may be found in microvesicles or exosomes and may be transported to neighboring, drug-sensitive cells. Here, we review this current issue together with recent evidence of this network of interactions between P-gp and miRs.

Expression of multidrug resistance (MDR) proteins andin vitrodrug resistance in acute leukemias

The expression of the multidrug resistance (MDR) proteins may influence the outcome of treatment in patients with acute leukemia. The aim of this study was to determine the IC50 of cytotoxic drugs (cytosine arabinoside, ara-C and daunorubicin, dnr) using the in vitro 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)2H-tetrazolium, inner salt (MTS) assay method. A total of 82 newly diagnosed acute leukemia cases (43 adult myeloid leukaemia, AML cases and 39 acute lymphoblastic leukaemia, ALL cases) and 16 relapsed cases (8 AML cases and 8 ALL cases) were studied. The MTS assay was performed using two cytotoxic drugs, dnr and ara-C. Cells were incubated with different concentrations of drugs for 4 days and the IC50 was extrapolated from the viability curve. In newly diagnosed cases, we found that childhood ALL samples showed higher IC50 values of dnr (0.040 +/- 2.320) compared to adult AML samples (0.021 +/- 0.158). In contrast, newly diagnosed adult AML samples showed higher IC50 values of ara-C (0.157 +/- 0.529) compared to childhood ALL samples (0.100 +/- 2.350). In relapsed cases, two samples of childhood ALL showed IC50 values of dnr (0.910 +/- 1.760) and ara-C (1.310 +/- 2.390), which was higher compared to childhood AML samples (0.129 +/- 0.214 and 0.210 +/- 0.003, respectively). However, there was no correlation between IC50 values of these drugs tested with clinical outcome. In conclusion, we found that MTS assay is an easy, rapid and non laborious method to study in vitro drug resistance in acute leukaemia cases.

Multidrug resistance-associated protein 1 predicts relapse in Iranian childhood acute lymphoblastic leukemia

Multidrug resistance (MDR) is a main cause of failure in the chemotherapeutic treatment of malignant disorders. One of the well-known genes responsible for drug resistance encodes the multidrug resistance- associated protein (MRP1). The association of MRP1 with clinical drug resistance has not systematically been investigated in Iranian pediatric leukemia patients. We therefore applied real-time RT-PCR technology to study the association between the MRP1 gene and MDR phenotype in Iranian pediatric leukemia patients. We found that overexpression of MRP1 occurred in most Iranian pediatric leukemia patients at relapse. However, no relation between MRP1 mRNA levels and other clinical characteristics, including cytogenetic subgroups and FAB subtypes, was found.

Acute erythroid leukemia

CONTEXT

Acute erythroid leukemia (AEL) is an uncommon type of acute myeloid leukemia (AML), representing less than 5% of all cases. Acute erythroid leukemia is characterized by a predominant erythroid proliferation, and in the current World Health Organization (WHO) classification scheme there are 2 subtypes: erythroleukemia (erythroid/myeloid leukemia) and pure erythroid leukemia. Morphologic findings are most important for establishing the diagnosis. The erythroleukemia subtype, which is most common, is defined as the presence of 50% or more erythroid precursors and 20% or more blasts in the nonerythroid component. The pure erythroid leukemia subtype is composed of 80% or more immature erythroblasts. Although these morphologic criteria appear straightforward, AEL overlaps with other types of AML and myelodysplastic syndrome that are erythroid rich.

OBJECTIVE

To provide an update of AEL, including clinical presentation, morphologic features, immunophenotype, and cytogenetic and molecular data. As the erythroleukemia subtype is most common, the literature and this review are biased towards this subtype of AEL.

DATA SOURCES

Clinicopathologic, cytogenetic, and molecular information were extracted from our review of pertinent literature and a subset of AEL cases in the files of The University of Texas M. D. Anderson Cancer Center (Houston) and University of South Alabama (Mobile).

CONCLUSIONS

The current WHO criteria for establishing the diagnosis of AEL reduce the frequency of this entity, as cases once classified as the erythroleukemia subtype are now reclassified as other types of AML, particularly AML with myelodysplasia-related changes and therapy-related AML. This reclassification also may have prognostic significance for patients with the erythroleukemia subtype of AEL. In contrast, the current WHO criteria appear to have little impact on the frequency and poor prognosis of patients with the pure erythroid leukemia subtype of AEL. Molecular studies, preferably using high-throughput methods, are needed for a better understanding of the pathogenesis of AEL, and for developing diagnostic and prognostic markers.

PXR-mediated induction of P-glycoprotein by anticancer drugs in a human colon adenocarcinoma-derived cell line

Purpose

The development of multidrug resistance (MDR) is one of the major limitations in the treatment of cancer. Induction of P-glycoprotein (Pgp) has been regarded as one of the main mechanisms underlying anticancer drug-induced MDR. Since the induction of Pgp is (in part) regulated by the pregnane X receptor (PXR), the ability of several widely used anticancer drugs to activate PXR-mediated Pgp induction was investigated.

Methods

A Pgp-reporter gene assay was employed to determine the ability of a panel of widely used anticancer drugs to induce Pgp. To further assess whether PXR could be involved in the induction of Pgp by anticancer drugs, Pgp protein expression after treatment with the anticancer drugs was determined in both wild-type and PXR-knocked down LS180 cells. Furthermore, the effect of the anticancer drugs on the intracellular accumulation of the Pgp-probes rhodamine 123 and doxorubicin was determined.

Results

Our study showed that vincristine, tamoxifen, vinblastine, docetaxel, cyclophosphamide, flutamide, ifosfamide and paclitaxel activate PXR-mediated Pgp induction, and were additionally shown to affect the intracellular accumulation of the Pgp probe rhodamine 123. Moreover, PXR activation was also shown to reduce the cytotoxic activity of the Pgp substrate doxorubicin in colon cancer cells.

Conclusion

Our results indicate that several anticancer drugs can activate PXR-mediated induction of Pgp and affect the accumulation of Pgp substrates.

Induction of heme oxygenase-1 in normal and malignant B lymphocytes by 15-deoxy-Delta(12,14)-prostaglandin J(2) requires Nrf2

Heme-oxygenase-1 (HO-1) is induced in response to oxidative stress and is believed to be a cytoprotective and anti-inflammatory enzyme. It is unknown whether normal or malignant human B-lineage cells express HO-1. 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)) is an interesting electrophilic lipid mediator able to increase oxidative stress in B cells. Here, we tested normal and malignant human B-lineage cells for their ability to express HO-1 in response to 15d-PGJ(2), as well as the signaling pathways required for HO-1 expression. 15d-PGJ(2) potently induced HO-1 protein expression in normal and malignant B cells. Malignant B cells exhibited a greater induction of HO-1 protein compared to normal B lymphocytes. Using siRNA directed against the transcription factor Nrf2 and B cells isolated from Nrf2-deficient mice, we show that HO-1 induction by 15d-PGJ(2) is dependent on Nrf2. These results show that, compared to normal B lymphocytes, malignant B cells have a greater capacity to increase their HO-1 protein levels in response to 15d-PGJ(2). We speculate that the ability to highly express HO-1 by malignant B cells could confer a survival advantage.

siRNA-based targeting of antiapoptotic genes can reverse chemoresistance in P-glycoprotein expressing chondrosarcoma cells

BACKGROUND

High expression of P-glycoprotein is one of the well-known mechanisms of chemoresistance in chondrosarcomas. However, the role of antiapoptotic proteins, a common mechanism responsible for chemoresistance in other tumors, has not been well studied in chondrosarcomas. We examined the importance of P-glycoprotein and antiapoptotic proteins in the chemoresistance to doxorubicin of two Grade II chondrosarcoma cell lines, JJ012 and SW1353.

RESULTS

We confirmed that both chondrosarcoma cell types expressed P-glycoprotein and antiapoptotic proteins (Bcl-2, Bcl-xL and XIAP). siRNA knockdown as well as pharmacologic inhibitors of cell survival proteins (Bcl-2, Bcl-xL and XIAP) enhanced apoptosis of chemoresistant chondrosarcoma cells by up to 5.5 fold at 0.1 micromol and 5.5 fold at 1 micromol doxorubicin. These chemosensitizing effects were comparable to those of P-glycoprotein inhibition by siRNA or pharmacologic inhibitor.

CONCLUSION

These findings suggest that antiapoptotic proteins play a significant role in the chemoresistance of chondrosarcoma cells independent of P-glycoprotein. Based on the results, a new siRNA-based therapeutic strategy targeting antiapoptotic genes can be designed to overcome the chemoresistance of chondrosarcomas which is often conferred by P-glycoprotein.

Immunohistochemical expression of multidrug resistance proteins in mature T/NK-cell lymphomas

Multidrug resistance (MDR) is defined as resistance of tumor cells to a wide spectrum of structurally and functionally unrelated drugs. One of the most important mechanisms in mediating MDR is that involving cellular drug efflux transporters. Drug resistance is a common and formidable obstacle to therapy in mature T/NK-cell lymphomas and the MDR phenotype is thought to be one of the contributing mechanisms. In this study we assessed the immunohistochemical expression of P-gp (P-glycoprotein), MRP-1 (multidrug resistance associated protein 1), BCRP (breast cancer resistance protein) and LRP (lung resistance protein) in 45 mature T/NK-cell lymphomas diagnosed at our hospital. We detected P-gp expression in 31% (13/42), MRP-1 expression in 74% (31/42), BCRP in 78% (32/41) and LRP in 59% (26/44) of the cases. These findings show that our T/NK-cell lymphoma cases display high frequency of MDR protein expression.

Immunohistochemical expression and clinical significance of P-glycoprotein in previously untreated extranodal NK/T-cell lymphoma, nasal type

Overexpression of P-glycoprotein (P-gp) has been identified by a variety of methods in NK cells and NK malignancies. The aim of this study was to determine the clinical significance of P-gp in previously untreated extranodal NK/T-cell lymphoma, nasal type. Tumor specimens from 30 patients initially treated with CHOP or CHOP-based chemotherapy were examined by immunohistochemistry using JSB-1, a monoclonal antibody recognizing the intracellular epitope of P-gp molecule. Twenty cases (67%) were positive for P-gp expression. The complete response rate achieved in P-gp positive patients was significantly lower than in P-gp negative ones (20% vs. 60%, P = 0.045). With a median follow-up of 25 months, the 2-year progression-free survival (PFS) and overall survival (OS) rates for all patients were 66 and 69%, respectively. Compared with both PFS and OS rates of P-gp positive patients, those of P-gp negative patients showed a trend of benefit that did not reach statistical significance for borderline P values (PFS: 90% vs. 54%, P = 0.1057; OS: 90% vs. 61%, P = 0.2028). Our results suggest that P-gp expression is related with poor treatment outcomes of extranodal NK/T-cell lymphoma, nasal type.

Detection of BCR-ABL gene mutations in Philadelphia chromosome positive leukemia patients resistant to STI-571 cancer therapy

The ABL-BCR fusion protein is a constitutively activated tyrosine kinase thought to play a central role in chronic myeloid leukemia (CML) and Philadelphia (Ph) chromosome acute lymphoid leukemia (ALL). Targeting the tyrosine kinase activity of ABL-BCR has been shown to be a promising therapeutic strategy in treating this disorder. Among the tyrosine kinase inhibitors, STI571 is a very effective therapeutic agent when administered to CML patients in the stable chronic phase. However, it has been reported that many CML patients with blast cell crisis treated with STI571 relapsed and became resistant to STI571. In order to understand the possible molecular mechanisms underlying STI571 resistance caused by ABL gene mutations, we investigated 19 patients (18 CML patients and 1 Ph (+) ALL patient) who either relapsed after initial response or had no response to STI571 treatment. We used polymerase chain reaction followed by restriction fragment length polymorphism (PCR-RFLP) analysis, dHPLC, and direct DNA sequencing to analyze any possible mutations in exons 5 to 9 of the ABL gene. Our results showed that 5 out of 19 patients had various mutations between exons 5 and 7 of the ABL gene. The Ph (+) ALL patient had a Glu255Lys mutation in exon 5 and a Thr315Ile mutation in exon 7. The Glu255Lys substitution has a G to A change, and the Thr315Ile substitution has a C to T change in the ABL gene. The other unique mutations found in this study include: Tyr253His, Met351Thr, GAA tri-nucleotides insertion, and Leu213Pro.

Small-molecule inhibition of proteasome and silencing by vascular endothelial cell growth factor-specific siRNA induce additive antitumor activity in multiple myeloma

Angiogenesis plays an important role in the pathogenesis and progression in multiple myeloma (MM), and MM cells secrete vascular endothelial growth factor (VEGF), which further promotes proliferation of the tumor cells. Therefore, we evaluated the anti-myeloma effect of VEGF small interfering RNA (siRNA) silencing in MM cells and whether it can be augmented by the additional application of bortezomib directed against the 26S proteasome. After transfection with VEGF siRNA, we observed a reduction of VEGF expression in all studied cell lines: OPM-2, RPMI-8226, INA-6, Jurkat, Raji, and Karpas-299, as well as in cells of MM and lymphoma patients. VEGF siRNA significantly induced apoptosis and inhibited proliferation in OPM-2 cells (P<0.0001), RPMI-8226 (P<0.0001), and INA-6 (P<0.01) versus controls. Cotreatment with VEGF siRNA and bortezomib in MM cells resulted in an exaggerated inhibition of proliferation and induction of apoptosis compared with VEGF siRNA or bortezomib alone (P<0.001). In addition, the combination of VEGF siRNA and bortezomib significantly (P<0.01) reversed multidrug resistance gene 1-dependent resistance of MM cells. Our data suggest that small-molecule inhibition of proteasome and silencing by VEGF-specific siRNA may be associated with an additive antitumor activity and might be a suitable target for new, therapeutic strategies using RNA interference in MM.

Expression of MRP1 gene in acute leukemia

CONTEXT AND OBJECTIVE

Overexpression of the multidrug resistance-associated protein 1 (MRP1) gene has been linked with resistance to chemotherapy in vitro, but little is known about its clinical impact on acute leukemia patients. Our aim was to investigate the possible association between MRP1 gene expression level and clinical outcomes among Iranian leukemia patients.

DESIGN AND SETTING

This was an analytical cross-sectional study on patients referred to the Hematology, Oncology and Stem Cell Research Center, Sharyatee Public Hospital, whose diagnosis was acute myelogenous leukemia (AML) or acute lymphoblastic leukemia (ALL). All molecular work was performed at NIGEB (public institution).

METHODS

To correlate with prognostic markers and the clinical outcome of acute leukemia, MRP1 gene expression was assessed in 35 AML cases and 17 ALL cases, using the quantitative real-time polymerase chain reaction and comparing this to the chemotherapy response type.

RESULTS

Mean expression in AML patients in complete remission (0.032 +/- 0.031) was significantly lower than in relapsed cases (0.422 +/- 0.297). In contrast, no significant difference in MRP1 mRNA level was observed between complete remission and relapsed ALL patients. There was a difference in MRP1 expression between patients with unfavorable and favorable cytogenetic prognosis (0.670 +/- 0.074 and 0.028 +/- 0.013, respectively). MRP1 expression in M5 was significantly higher (p-value = 0.001) than in other subtypes.

CONCLUSIONS

The findings suggest that high MRP1 expression was associated with poor clinical outcome and was correlated with the M5 subtype and poor cytogenetic subgroups among AML patients but not among ALL patients.

Genetic alterations determine chemotherapy resistance in childhood T-ALL: modelling in stage-specific cell lines and correlation with diagnostic patient samples

Acquired drug resistance eventually leads to treatment failure in T-cell acute lymphoblastic leukaemia (T-ALL). Immunophenotypic and cytogenetic heterogeneities within T-ALL influence susceptibility to cytotoxic therapy, and little is known about the mechanisms of drug resistance at specific stages of T-cell ontogeny. We developed tolerance to therapeutic concentrations of daunorubicin (DNR) and L-asparaginase (L-asp) in Jurkat (CD1a(-), sCD3(+)) and Sup T1 (CD1a(+), sCD3(-)) cell lines, having respective 'mature' and 'cortical' stages of developmental arrest. DNR resistant cells acquired multidrug resistance: 310-fold increased resistance to vincristine (VCR) and a 120-fold increased resistance to prednisolone (PRED). Microarray analysis identified upregulation of asparagine synthetase (ASNS) and argininosuccinate synthase 1 (ASS1) to cell lines with acquired resistance to L-asp, and in the case of DNR, upregulation of ATP-binding cassette B1 (ABCB1). Suppression of ABCB1, ASNS and ASS1 by RNA interference revealed their functional relevance to acquired drug resistance. Expression profiling of these genes in 80 T-ALL patients showed correlation with treatment response. This study expands the pool of available drug resistant cell lines having cortical and mature stages of developmental arrest, introduces three new drug resistant T-ALL cell lines, and identifies gene interactions leading to L-asp and DNR resistance.

Addition of cyclosporin A to the combination of mitoxantrone and etoposide to overcome resistance to chemotherapy in refractory or relapsing acute myeloid leukaemia: a randomised phase II trial from HOVON, the Dutch-Belgian Haemato-Oncology Working Group for adults

Cyclosporin A (CsA) inhibits the P-gp pump that can be responsible for failure of cytostatic treatment in acute myeloid leukaemia (AML). Eighty patients with relapsing/refractory AML were randomly assigned to mitoxantrone (M) and etoposide (VP) (MVP) in unmitigated antileukaemic doses with or without CsA, to investigate if toxicity was manageable and if antileukaemic therapy could be improved. CsA did not delay haematological recovery, but fewer CsA patients received post-induction therapy because of haematological and non-haematological toxicity. CR rate was 43% for MVP and 53% for CsA; DFS was 9 and 8 months, and OS 8 and 9 months, respectively. Seventeen of 38 CR patients proceeded to stem cell transplantation (SCT). After a median follow-up of 66 months, six patients were still alive. Addition of CsA did not improve treatment outcome, possibly due to inadequate post-induction therapy as a result of increased toxicity.

New immunotoxins targeting CD123, a stem cell antigen on acute myeloid leukemia cells

The specific alpha subunit of the interleukin-3 receptor (IL-3Ralpha, CD123) is strongly expressed in various leukemic blasts and leukemic stem cells and seems to be an excellent target for the therapy of leukemias. In this study, immunotoxins were developed to target CD123 only, which bypasses the dependence on other subunits to form intact IL-3R. Three anti-CD123 hybridomas (26292, 32701, and 32716) were selected on the basis of their affinity for CD123. Total RNAs were extracted from the 3 anti-CD123 hybridomas and used to clone the fragment of variable region (Fvs). The Fvs were assembled into single chain Fvs and fused to a 38-kd fragment of Pseudomonas exotoxin A to make recombinant immunotoxins. 26292(Fv)-PE38 was found to have the highest cytotoxic activity on the CD123 expressing leukemia cell line TF-1. It bound the cells with a kd of 3.5 nM. Another immunotoxin, 32716(Fv)-PE38, belonging to a different epitope group, had a similar binding ability but was less active, demonstrating the role of epitope selection in immunotoxin action. The cytotoxic activity of 26292(Fv)-PE38 was increased from 200 to about 40 ng/mL by mutating the REDLK sequence at the C terminus to KDEL. 26292(Fv)-PE38-KDEL was specifically cytotoxic to several CD123 expressing cell lines (TF-1, Molm-13, and Molm-14) with good CD123 expression but not to ML-1 or U937 with low or absent expression. In conclusion, 26292(Fv)-PE38-KDEL shows good cytotoxic activity against CD123 expressing cell lines, and merits further development for the possible treatment of acute myeloid leukemia and other CD123 expressing malignancies.

MDR1, MRP1 and LRP expression in patients with untreated acute leukaemia: Correlation with 99mTc-MIBI bone marrow scintigraphy

BACKGROUND

Chemotherapy failure linked to multidrug-resistance (MDR) plays an important role in many cancer types, including leukaemia. It is believed that overexpression of some of membrane or intracellular proteins confers the MDR phenotype to cancer cells. (99m)Tc-sestamibi (MIBI) is a transport substrate for the Pgp pump. We assessed the bone marrow uptake of (99m)Tc-MIBI and its correlation with messenger RNA (mRNA) levels of MDR1, multidrug-resistance associated protein-1 (MRP1) and lung resistance protein (LRP) in acute leukaemia.

METHODS

A total of 26 patients (age range 17-72 years; mean age 51.88+/-2.52 years) with newly diagnosed acute leukaemia were included in the study. The expression of MDR1, MRP1 and LRP on mRNA levels were assessed by quantitative RT-PCR in the blast cells. The MIBI uptake in the bone marrow was evaluated using a quantitative scoring system with determination of the tumour-to-background ratios for the bone marrow areas. The correlation between the quantitative RT-PCR results and MIBI uptake was analysed by using Spearman's rank correlation coefficients with two-tailed test of significance.

RESULTS

There was an inverse relationship between (99m)Tc-MIBI uptake of bone marrow and both mRNA levels of MDR1 and MRP1 (P=0.000, r= -0.733 and P=0.001, r= -0.610, respectively). No correlation was found between MIBI uptake and mRNA levels of LRP.

CONCLUSION

Increased expression of MDR1 and MRP1 correlates with a low accumulation of (99m)Tc-MIBI in bone marrow areas in patients with acute leukaemia. (99m)Tc-MIBI bone marrow scintigraphy can identify the MDR1 and MRP1 phenotype, but not LRP, in patients with acute leukaemia.

Complete remission induced by gemtuzumab ozogamicin in a Jehovah's Witness patient with acute myelogenous leukemia

We report an interesting case of acute myelogenous leukemia (AML) in a Jehovah's Witness patient. A 61-year-old woman, a Jehovah's Witness, consulted our hospital because of continuous fever and refractory pharyngitis. The white blood cell count was increased with myeloblasts and monoblasts, both of which showed positivity for CD33. The level of WT1 messenger RNA (mRNA) in the bone marrow was 130,000 copies/microg RNA. The patient's diagnosis was AML (M4). Because complete remission (CR) was not obtained with 2 courses of chemotherapy consisting of acrarubicin and cytarabine, we tried gemtuzumab ozogamicin (GO) with informed consent. No major side effects appeared, and CR was obtained after 2 courses of GO, which decreased the WT1 mRNA level to 480 copies/microg RNA. The patient has been in CR for 6 months with ubenimex. This case suggests that GO can be one of the treatment options in similar situations, although it should be used with considerable care.

A phase I/II study of arsenic trioxide/bortezomib/ascorbic acid combination therapy for the treatment of relapsed or refractory multiple myeloma

PURPOSE

This multicenter, open-label, phase I/II dose escalation study assessed the safety/tolerability and initial efficacy of arsenic trioxide/bortezomib/ascorbic acid (ABC) combination therapy in patients with relapsed/refractory multiple myeloma.

EXPERIMENTAL DESIGN

Enrolled in six cohorts, patients were given arsenic trioxide (0.125 or 0.250 mg/kg), bortezomib (0.7, 1.0, or 1.3 mg/m(2)), and a fixed dose of ascorbic acid (1 g) i.v. on days 1, 4, 8, and 11 of a 21-day cycle for a maximum of eight cycles. The primary end point was safety/tolerability of the ABC regimen.

RESULTS

Twenty-two patients (median age, 63 years) were enrolled, having failed a median of 4 (range, 3-9) prior therapies. One occurrence of grade 4 thrombocytopenia was observed. One patient had asymptomatic arrhythmia and withdrew from the study. Objective responses were observed in 6 (27%) patients, including two partial responses and four minor responses. Median progression-free survival was 5 months (95% confidence interval, 2-9 months), and median overall survival had not been reached. The 12-month progression-free survival and overall survival rates were 34% and 74%, respectively. One (minor response) of six patients receiving the lowest dose of bortezomib (0.7 mg/m(2)) and 5 (2 partial responses and 3 minor responses) of 16 patients receiving the higher doses (1.0 or 1.3 mg/m(2)) responded.

CONCLUSIONS

The ABC regimen was well tolerated by most patients, and it produced preliminary signs of efficacy with an objective response rate of 27% in this heavily pretreated study population. These findings warrant further clinical evaluation of the ABC combination for treatment of relapsed/refractory multiple myeloma.

Gene Dosage Is Not Responsible for the Upregulation of MRP1 Gene Expression in Adult Leukemia Patients

BACKGROUND

Upregulation of multidrug resistance-associated protein (MRP1) gene has been detected in many in vitro systems and could be the basis of the drug resistance phenotype in vivo. Increase in gene dosage and overexpression are two major mechanisms for increasing MRP1 expression level. In many drug resistant cell lines, MRP1 gene amplification has been detected. However, it is not yet known whether gene amplification plays a role in inducing the multidrug resistance phenotype clinically.

METHODS

To establish whether MRP1 gene copy number is a common feature of the upregulation of MRP1 expression in cancer patients, we studied the MRP1 gene copy number in leukemia patients by fluorescent in situ hybridization (FISH) and real-time PCR. This involved determination of the MRP1 gene copy number and mRNA level in the peripheral blood of 52 adult leukemic patients and ten healthy volunteers. The leukemic CCRF-CEM cell line (drug sensitive) and its drug-resistant subline CCRF-E1000, which has MRP1 overexpression, were used as controls.

RESULTS

The MRP1 gene copy number in CCRF-CEM was normal but increased significantly in CCRF-E1000 cell line. However, in the presence or absence of MRP1 overexpression, increase in gene dosage was not detected in patients.

CONCLUSIONS

Our data suggest that the increase in MRP1 gene dosage observed in resistant cell lines is not responsible for the upregulation of MRP1 expression in leukemic patients.

Methods and goals for the use of in vitro and in vivo chemosensitivity testing

Sensitive, specific, and accurate methods to assay chemosensitivity are needed to (1) screen new therapeutic agents, (2) identify patterns of chemosensitivity for different tumor types, (3) establish patterns of cross-resistance and sensitivity in treatment of naïve and relapsing tumors, (4) identify genomic and proteomic profiles associated with sensitivity, (5) correlate in vitro response with preclinical in vivo effects and clinical outcomes for a particular therapeutic agent, and (6) tailor chemotherapy regimens to individual patients. Various methods are available to achieve these end points, including several in vitro clonogenic and proliferation assays, cell metabolic activity assays, molecular assays to monitor expression of markers for responsiveness, drug resistance, and for induction of apoptosis, in vivo tumor growth and survival assays in metastatic and orthotopic models, and in vivo imaging assays. The advantages and disadvantages of the specific assays are discussed. A summary of research questions related to chemosensitivity testing is also included.

Detection of the MDR1 P-glycoprotein expression and function

Acquired and intrinsic multidrug resistance is the major reason for the failure of anticancer chemotherapy. The most important component of clinical multidrug resistance is mediated by P-glycoprotein (Pgp), an ABC transporter encoded by the MDR1 gene and expressed on the membrane of tumor and normal cells. Sensitive and reproducible detection of Pgp expression and function are critical for the development of new MDR1 drugs and clinical protocols aimed at modulating Pgp-mediated multidrug resistance. The most commonly used methods for detecting Pgp distribution and functional activity have major flaws when used in routine clinical diagnostics. In this chapter, we describe and compare these techniques and introduce a new method for simultaneous detection of Pgp expression and function--the UIC2 Shift assay.

IAP family protein expression correlates with poor outcome of multiple myeloma patients in association with chemotherapy-induced overexpression of multidrug resistance genes

Multidrug-resistant (MDR) multiple myeloma (MM) patients who fail chemotherapy frequently express MDR1 protein, which serves as an efflux pump that protects neoplastic cells. The expression of lung resistance protein (LRP), which mediates intercellular and nucleocytoplasmic transport, is also correlated with chemotherapy resistance and shorter survival of MM patients. Here, we investigated the chemotherapy-induced change of MDR expression in MM patients using quantitative RT-PCR. Overall expression levels of MDR1 and LRP in MM patients were significantly higher than those in control subjects and increased after chemotherapy. More than half of the patients exhibited increased expression of MDR1 (14/26) or LRP (17/26) after chemotherapy. Also, the expression of inhibitor of apoptosis proteins (IAP) was determined in association with the prognosis of the patients. Among patients with increased MDR1-expression after chemotherapy, those with a poor outcome exhibited significant increases in survivin, cIAP1, cIAP2, and XIAP expression by chemotherapy compared with those with a good prognosis. Similarly, in the LRP expression-increased group, patients with a poor outcome showed significant increases of cIAP1 and cIAP2 expression compared with those with longer survival. In patients with reduced-MDR1 or LRP expression after chemotherapy, changes in the expression of IAPs induced by chemotherapy did not correlate with their prognosis. These findings indicate that IAP family proteins might play a role in worsening the prognosis of MM patients in association with chemotherapy-induced overexpression of MDR1 or LRP.

In vitro and in vivo reversal of MDR1-mediated multidrug resistance by KT-5720: Implications on hematological malignancies

Multidrug resistance (MDR) due to over-expression of the MDR1 (ABCB1) gene and its P-glycoprotein (Pgp) product is an obstacle in the treatment of hematological malignancies. In this study, we have evaluated the potency of KT-5720 to reverse Pgp-dependent MDR in vitro and in vivo. KT-5720 (but not its close derivatives, K252a and K252b) reversed multidrug resistance of LM1/MDR cell line at non-toxic concentrations and increased accumulation of rhodamine 123 (Rh123). KT-5720 significantly reversed MDR1-dependent resistance of primary malignant cells from patients with chronic myelogenous leukemia in blast crisis (CML-BC) and advanced multiple myeloma (MM). Moreover, KT-5720 (at 5 mg/kg) sensitized the bone marrow of MDR1 transgenic mice model towards daunorubicin (at 8 mg/kg) without general toxic effects. Therefore, KT-5720 can be considered as candidate for combination therapy in various hematological malignancies where Pgp activity is a major impediment for cure.

Increased expression of multidrug resistance gene (MDR1) at relapse in a child with acute lymphoblastic leukemia

Modern treatment protocols lead to complete remission in a high proportion of patients with childhood acute lymphoblastic leukemia (ALL). However, a large number of them show a relapse of the disease. Treatment failure in these patients is mainly attributable to de novo or acquired resistance to a wide variety of cytotoxic drugs, which is called multi drug resistance (MDR). Expression of multi drug resistance 1 gene (MDR1) is implicated in the drug-resistance mechanism. In order to contribute further information we present a rare case of a 15-month old girl with newly diagnosed CALLA positive pre-B acute lymphoblastic leukemia with favourable prognostic factors at diagnosis who experienced a relapse of the disease. Using reverse transcriptase polymerase chain reaction method, m-RNA expression of the MDR1 gene upon relapse, was five-fold compared with that at diagnosis. This is the first report on increased mRNA expression at relapse in a paired sample of a child with ALL in our region.

Overcoming MDR-associated chemoresistance in HL-60 acute myeloid leukemia cells by targeting sphingosine kinase-1

We examined the involvement of sphingosine kinase-1, a critical regulator of the sphingolipid balance, in susceptibility to antineoplastic agents of either sensitive or multidrug-resistant acute myeloid leukemia cells. Contrary to parental HL-60 cells, doxorubicin and etoposide failed to trigger apoptosis in chemoresistant HL-60/Doxo and HL-60NP16 cells overexpressing MRP1 and MDR1, respectively. Chemosensitive HL-60 cells displayed sphingosine kinase-1 inhibition coupled with ceramide generation. In contrast, chemoresistant HL-60/ Doxo and HL-60/VP16 had sustained sphingosine kinase-1 activity and did not produce ceramide during treatment. Enforced expression of sphingosine kinase-1 in chemosensitive HL-60 cells resulted in marked inhibition of apoptosis that was mediated by blockade of mitochondrial cytochrome c efflux hence suggesting a control of apoptosis at the pre-mitochondrial level. Incubation with cell-permeable ceramide of chemoresistant cells led to a sphingosine kinase-1 inhibition and apoptosis both prevented by sphingosine kinase-1 over-expression. Furthermore, F-12509a, a new sphingosine kinase inhibitor, led to ceramide accumulation, decrease in sphingosine 1-phosphate content and caused apoptosis equally in chemosensitive and chemoresistant cell lines that is inhibited by adding sphingosine 1-phosphate or overexpressing sphingosine kinase-1. F-12509a induced classical apoptosis hallmarks namely nuclear fragmentation, caspase-3 cleavage as well as downregulation of antiapoptotic XIAP, and release of cytochrome c and SMAC/Diablo.

[Expression of multidrug resistance (MDR)-associated proteins in solid tumors]

The causes of drug resistance in tumor cells vary widely. The present study aims to provide an update of multidrug resistance in tumor cells and, in particular, of multidrug resistance-associated proteins.

Comparison of CHOP versus CIOP in good prognosis younger patients with histologically aggressive non-Hodgkin lymphoma

CHOP (cyclophosphamide, doxorubicin, vincristine and prednisolone) has been the standard chemotherapy regimen used for diffuse large cell lymphomas for over 30 years. Idarubicin is a 4-demethoxy-anthracycline analogue of daunorubicin that has proven activity in non-Hodgkin lymphoma, and has been reported to cause less cardiotoxicity. We therefore initiated a randomised trial of standard dose CHOP versus CIOP (cyclophosphamide, idarubicin, vincristine and prednisolone), in which doxorubicin 50 mg/m2 was substituted by idarubicin 10 mg/m2, a dose thought to have equivalent anti-lymphoma activity. This trial was closed prematurely after 211 patients had completed therapy when a lower complete remission (CR) rate was noted in the CIOP arm. The formal results with long-term follow up are now reported. Overall response rate was 84% in the CHOP arm and 78% in the CIOP arm, CR rates were 70% and 52% respectively in all patients (P=0.013) and 73% and 52% respectively for the eligible patients (P=0.0084). At a median of 8 years follow-up, 4-year progression-free survival for all patients was 56% in the CHOP arm and 40% in the CIOP arm (P=0.0096). Overall survival for all patients was 65% in the CHOP arm and 56% in the CIOP arm (P=0.14). Results for eligible patients were comparable. CIOP containing idarubicin at a dose of 10 mg/m2 is clearly inferior to standard CHOP.

Expression of the MDR1 and MRP genes in patients with lymphoma with primary bone marrow involvement

Expression of MDR1 and MRP genes in patients with low-grade and high-grade non-Hodgkin's lymphomas with primary bone marrow involvement before and after chemotherapy was investigated. The data demonstrate that overexpression of MDR1 and MRP genes in hematological malignancies elevates in patients after chemotherapy and correlates with poor clinic prognosis and more frequent recurrences of the malignancies.