Search

Myeloid cell leukemia sequence 1 (MCL-1) is an antiapoptotic protein that plays a key role in promoting cell survival in multiple myeloma (MM), acute myeloid leukemia (AML), and non-Hodgkin lymphoma (NHL). Overexpression of MCL-1 is associated with treatment resistance and poor prognosis; thus, MCL-1 inhibitors are rational therapeutic options for malignancies depending on MCL-1. Several MCL-1 inhibitors have entered clinical trials, including AZD5991, S64315, AMG 176, and AMG 397. A key area of investigation is whether MCL-1 inhibitors will complement the activity of BCL-2 inhibitors, such as venetoclax, and synergistically enhance anti-tumor efficacy when given in combination with other anti-cancer drugs. Another important question is whether a safe therapeutic window can be found for this new class of inhibitors. In summary, inhibition of MCL-1 shows potential as a treatment for hematologic malignancies and clinical evaluation of MCL-1 inhibitors is currently underway., (Copyright © 2020 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Selinexor is an oral, small molecule inhibitor of the nuclear export protein exportin 1 with demonstrated activity in hematologic and solid malignancies. Side effects associated with selinexor include nausea, vomiting, fatigue, diarrhea, decreased appetite, weight loss, thrombocytopenia, neutropenia, and hyponatremia. We reviewed 437 patients with multiple myeloma treated with selinexor and assessed the kinetics of adverse events and impact of supportive care measures. Selinexor reduced both platelets and neutrophils over the first cycle of treatment and reached a nadir between 28 and 42 days. Platelet transfusions and thrombopoietin receptor agonists were effective at treating thrombocytopenia, and granulocyte colony stimulating factors were effective at resolving neutropenia. The onset of gastrointestinal side effects (nausea, vomiting, and diarrhea) was most common during the first 1-2 weeks of treatment. Nausea could be mitigated with 5-HT3 antagonists and either neurokinin 1 receptor antagonists, olanzapine, or cannbainoids. Loperamide and bismuth subsalicylate ameliorated diarrhea. The primary constitutional side effects of fatigue and decreased appetite could be managed with methylphenidate, megestrol, cannabinoids or olanzapine, respectively. Hyponatremia was highly responsive to sodium replacement. Selinexor has well-established adverse effects that mainly occur within the first 8 weeks of treatment, are reversible, and respond to supportive care.

Background: Carfilzomib is approved by the US Food and Drug Administration for the treatment of patients with relapsed and refractory multiple myeloma (MM) who have received at least 2 previous treatments. The approval was based on phase II trials that used a starting dose of 20 mg/m(2) escalated to a target dose of 27 mg/m(2) in cycle 2. We examined dose-outcome relationships in MM patients who received these 2 carfilzomib doses., Materials and Methods: Patient data from 4 cohorts of MM patients treated with single-agent carfilzomib in phase II trials were examined post hoc. The relationship between administered doses and overall response rate (ORR) was assessed using logistic regression models. Secondary analyses were performed using Cox regression models to assess the association between administered doses and time to event outcomes and using generalized estimating equations for cycle-specific response status (CSRS)., Results: A total of 476 intention to treat patients were enrolled, 461 of whom were evaluable for efficacy. In the primary analysis, adjustment for cohort and baseline covariates yielded an odds ratio for ORR of 1.28 (95% confidence interval, 1.16-1.41; P < .001) for each 1 mg/m(2) increase in the average administered dose of carfilzomib per patient (up to 27 mg/m(2)). Qualitatively similar and statistically significant results were seen for the association between administered dose and CSRS, duration of response, time to progression, progression-free survival, and overall survival when adjusted for cohort and baseline covariates., Conclusion: This post hoc analysis provides evidence for a dose-response relationship between the administered dose of carfilzomib and efficacy., (Copyright © 2015 Elsevier Inc. All rights reserved.)

While survival times have increased over the last decade, most patients with multiple myeloma (MM) eventually relapse and become refractory to therapy. The treatment of patients with relapsed and/or refractory MM is frequently further complicated by the presence of pre-existing comorbidities that arise from an advanced disease state and of toxicities stemming from prior antimyeloma treatment. Carfilzomib and pomalidomide have recently been approved for the treatment of patients with relapsed and refractory MM. While these agents represent important additions to the available treatment options, the identification of patients who may best benefit from the use of each of therapy is still being investigated. A number of patient-related and disease-related factors may impact treatment efficacy and/or tolerability, and the clinical presentation and medical history of each patient must be carefully considered to optimize treatment. Here, we review results from carfilzomib and pomalidomide clinical trials in patients with relapsed and/or refractory MM who also have baseline comorbidities or treatment-induced or disease-induced complications (including the presence of renal impairment, cardiac risk factors, peripheral neuropathy, or high-risk chromosomal abnormalities) to evaluate the safety and efficacy of the two agents in these difficult-to-treat patients and to provide treatment recommendations specific to each scenario., (© The Author 2015. Published by Oxford University Press on behalf of the European Society for Medical Oncology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Natural quinones, often linked with cellular oxidation processes, exhibit pronounced biological activity. In particular, the structurally unique isothiazolonaphthoquinone aulosirazole, isolated from blue-green alga, possesses selective antitumor cytotoxicity, although its mechanism of action is unknown. The first synthesis of aulosirazole uses a route centered upon a late-stage regioselective Diels-Alder reaction. The structurally related natural product pronqodine A, an inhibitor of prostaglandin release, and analogues thereof, were also prepared for comparison. Biological evaluation of the compounds identified one potential target as the immunoregulatory enzyme indoleamine-2,3-dioxygenase (IDO). The isothiazoloquinones are also efficient substrates for the human quinone reductase NQO1, and undergo intracellular NQO1-dependent redox cycling resulting in the generation of reactive oxygen species, and at lower doses have the potential to alter the ratio of intracellular oxidized to reduced pyridine nucleotides., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

An important determinant of the growth inhibitory activity of indolequinones against pancreatic cancer cells is substitution on the 2-position with 2-unsubstituted derivatives being markedly more potent. A series of indolequinones bearing a range of substituents on nitrogen and at the indolylcarbinyl position was prepared by copper(II)-mediated reaction of bromoquinones and enamines, followed by functional group interconversions. The compounds were then assayed for their ability to inhibit the growth of pancreatic cancer cells. The pKa of the leaving group at the 3-position was shown to influence growth inhibitory activity that is consistent with the proposed mechanism of action of reduction, loss of leaving group and formation of a reactive iminium species. Substitutions on the indole nitrogen were well tolerated with little influence on growth inhibitory activity while substitutions at the 5- and 6-positions larger than methoxy led to decreased activity. The studies presented define the range of substitutions of 2-unsubstituted indolequinones required for optimal growth inhibitory activity.

Several cytogenetic abnormalities are associated with poor outcomes in multiple myeloma (MM). We prospectively analyzed the impact of cytogenetic abnormalities on outcomes during the phase 2 PX-171-003-A1 study of single-agent carfilzomib for relapsed and refractory MM. In the response-evaluable population (257/266), fluorescence in situ hybridization (FISH)/conventional cytogenetic profiles were available for 229 patients; 62 (27.1%) had high-risk cytogenetics--del 17p13, t(4;14) or t(14;16) by interphase FISH or deletion 13 or hypodiploidy by metaphase cytogenetics--and 167 (72.9%) had standard-risk profiles. Generally, baseline characteristics were similar between the subgroups, but International Staging System stage III disease was more common in high- vs standard-risk patients (41.9% vs 27.5%) as was Eastern Cooperative Oncology Group performance status 1/2 (85.5% vs 68.3%). Overall response was comparable between the subgroups (25.8% vs 24.6%, respectively; P=0.85), while time-to-event end points showed a trend of shorter duration in high-risk patients, including median duration of response (5.6 months (95% confidence interval (CI) 3.7-7.8) vs 8.3 months (95% CI 5.6-12.3)) and overall survival (9.3 (95% CI 6.5-13.0) vs 19.0 months (95% CI 15.4-NE); P=0.0003). Taken together, these findings demonstrate that single-agent carfilzomib is efficacious and has the potential to at least partially overcome the impact of high-risk cytogenetics in heavily pre-treated patients with MM.

Quinones represent a large and diverse class of antitumor drugs and many quinones are approved for clinical use or are currently undergoing evaluation in clinical trials. For many quinones reduction to the hydroquinone has been shown to play a key role in their antitumor activity. The two-electron reduction of quinones by NQO1 has been shown to be an efficient pathway to hydroquinone formation. NQO1 is expressed at high levels in many human solid tumors making this enzyme ideally suited for intracellular drug activation. Cellular levels of NQO1 are influenced by the NQO1*2 polymorphism. Individuals homozygous for the NQO1*2 allele are NQO1 null and homozygous NQO1*2*2 cell lines have been shown to be more resistant to antitumor quinones when compared to isogenic cell lines overexpressing NQO1. In this review we will discuss the role of NQO1 in the sensitivity and resistance of human cancers to the quinone antitumor drugs mitomycin C, β-lapachone and the benzoquinone ansamycin class of Hsp90 inhibitors including 17-AAG. The role of NQO1 in the bioreductive activation of mitomycin C remains controversial but pre-clinical data strongly suggests a role for NQO1 in the activation of β-lapachone and the benzoquinone ansamycin class of Hsp90 inhibitors. Despite a large volume of preclinical data demonstrating that NQO1 is an important determinant of sensitivity to these antitumor quinones there is little information on whether the clinical response to these agents is influenced by the NQO1*2 polymorphism. The availability of simple assays for the determination of the NQO1*2 polymorphism should facilitate clinical testing of this hypothesis., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Indolequinones (IQs) were developed as potential antitumor agents against human pancreatic cancer. IQs exhibited potent antitumor activity against the human pancreatic cancer cell line MIA PaCa-2 with growth inhibitory IC(50) values in the low nanomolar range. IQs were found to induce time- and concentration-dependent apoptosis and to be potent inhibitors of thioredoxin reductase 1 (TR1) in MIA PaCa-2 cells at concentrations equivalent to those inducing growth-inhibitory effects. The mechanism of inhibition of TR1 by the IQs was studied in detail in cell-free systems using purified enzyme. The C-terminal selenocysteine of TR1 was characterized as the primary adduction site of the IQ-derived reactive iminium using liquid chromatography-tandem mass spectrometry analysis. Inhibition of TR1 by IQs in MIA PaCa-2 cells resulted in a shift of thioredoxin-1 redox state to the oxidized form and activation of the p38/c-Jun NH(2)-terminal kinase (JNK) mitogen-activated protein kinase (MAPK) signaling pathway. Oxidized thioredoxin is known to activate apoptosis signal-regulating kinase 1, an upstream activator of p38/JNK in the MAPK signaling cascade and this was confirmed in our study providing a potential mechanism for IQ-induced apoptosis. These data describe the redox and signaling events involved in the mechanism of growth inhibition induced by novel inhibitors of TR1 in human pancreatic cancer cells.

Promising new drugs are being evaluated for treatment of multiple myeloma (MM), but their impact should be measured against the expected outcome in patients failing current therapies. However, the natural history of relapsed disease in the current era remains unclear. We studied 286 patients with relapsed MM, who were refractory to bortezomib and were relapsed following, refractory to or ineligible to receive, an IMiD (immunomodulatory drug), had measurable disease, and ECOG PS of 0, 1 or 2. The date patients satisfied the entry criteria was defined as time zero (T(0)). The median age at diagnosis was 58 years, and time from diagnosis to T(0) was 3.3 years. Following T(0), 213 (74%) patients had a treatment recorded with one or more regimens (median=1; range 0-8). The first regimen contained bortezomib in 55 (26%) patients and an IMiD in 70 (33%). A minor response or better was seen to at least one therapy after T(0) in 94 patients (44%) including ≥ partial response in 69 (32%). The median overall survival and event-free survival from T(0) were 9 and 5 months, respectively. This study confirms the poor outcome, once patients become refractory to current treatments. The results provide context for interpreting ongoing trials of new drugs.

Abstract A phase 1 study of IPI-504 (retaspimycin hydrochloride) administered intravenously twice weekly for 2 weeks at 22.5, 45, 90, 150, 225, 300 or 400 mg/m(2) followed by 10 days off-treatment was conducted to determine the safety and maximum tolerated dose (MTD) of IPI-504 in patients with relapsed or relapsed/refractory multiple myeloma (MM). Anti-tumor activity and pharmacokinetics were also evaluated. Eighteen patients (mean age 60.5 years; median 9 prior therapies) were enrolled. No dose-limiting toxicities (DLTs) were reported for IPI-504 doses up to 400 mg/m(2). The most common treatment-related adverse event was grade 1 infusion site pain (four patients). All other treatment-related events were assessed as grade 1 or 2 in severity. The area under the curve (AUC) increased with increasing dose, and the mean half-life was approximately 2-4 h for IPI-504 and its metabolites. Four patients had stable disease, demonstrating modest single-agent activity in relapsed or relapsed/refractory MM.

The ubiquitin-proteasome pathway regulates bone formation through osteoblast differentiation. We analyzed variation alkaline phosphatase (ALP) during carfilzomib treatment. Data from 38 patients enrolled in the PX-171-003 and 29 patients in PX-171-004 studies, for patients with relapsed/refractory myeloma, were analyzed. All patients received 20 mg/m(2) of carfilzomib on Days 1, 2, 8, 9, 15, and 16 of a 28-day cycle. Sixty-seven patients from ALP data were evaluable. In PX-171-003, the ORR (>PR) was 18% and the clinical benefit response (CBR; >MR) was 26%, while in PX-171-004, the ORR was 35.5% overall and 57% in bortezomib-naive patients. ALP increment from baseline was statistically different in patients who achieved ≥ VGPR compared with all others on Days 1 (P = 0.0049) and 8 (P = 0.006) of Cycle 2. In patients achieving a VGPR or better, ALP increased more than 15 units per liter at Cycle 2 Day 1 over baseline. An ALP increase over the same period of time was seen in 26%, 13% and 11% of patients achieving PR, MR, and SD, respectively. This retrospective analysis of patients with relapsed or refractory myeloma treated with single-agent carfilzomib indicates that early elevation in ALP is associated with subsequent myeloma response., (© 2011 John Wiley & Sons A/S.)

Lenalidomide is an active treatment for multiple myeloma (MM) and is increasingly used as part of the initial treatment of this disease. Recent reports have suggested decreases in the number of CD34+ cells collected and increases in the failure rate among patients whose initial therapy contained lenalidomide when mobilized with G-CSF alone. A retrospective data analysis of 364 patients with MM who underwent stem cell mobilization and attempted harvest at the Hospital of the University of Pennsylvania between January 2002 and December 2007 was performed. Forty-three of the patients received lenalidomide in their induction regimen, and were mobilized with either CY and G-CSF or G-CSF alone. The number of apheresis cycles and the failure rate were lower, whereas the mean number of collected stem cells was higher in patients who were mobilized with CY and G-CSF in comparison with G-CSF alone. This suggests that lenalidomide does not prevent the harvest of adequate numbers of CD34 cells for autologous stem cell transplant, but mobilization with G-CSF and CY may be required to obtain adequate numbers of stem cells. Finally, in our study, the number of lenalidomide cycles did not correlate with stem cell yield.

The indolequinone ES936 {5-methoxy-1,2-dimethyl-3-[(4-nitrophenoxy)methyl]indole-4,7-dione} was previously developed in our lab as an antitumor agent against pancreatic cancer. The objective of this study was to identify indolequinones with improved potency against pancreatic cancer and to define their mechanisms of action. Pancreatic cancer cell lines PANC-1, MIA PaCa-2, and BxPC-3 were used in in vitro assays [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) and clonogenic assays]; indolequinones displayed potent cytotoxicity against all three cell lines, and two specific classes of indolequinone were particularly potent agents. These indolequinones induced caspase-dependent apoptosis but no redox cycling or oxidative stress in MIA PaCa-2 and BxPC-3 cells. Selected indolequinones were also screened against the NCI-60 cell line panel and were found to be particularly effective against colon, renal, and melanoma cancer cells. A potential target of these indolequinones was identified as thioredoxin reductase. Indolequinones were found to be potent inhibitors of thioredoxin reductase activity both in pancreatic cancer cells and in cell-free systems. The mechanism of action of the indolequinones was shown to involve metabolic reduction, loss of a leaving group to generate a reactive electrophile resulting in alkylation of the selenocysteine residue in the active site of thioredoxin reductase. In vivo efficacy of the indolequinones was also tested in the MIA PaCa-2 pancreatic tumor xenograft in nude mice, and lead indolequinones demonstrated high efficacy and low toxicity. Inhibition of thioredoxin reductase represents a potential novel target in pancreatic cancer and may provide a biomarker of effect of lead indolequinones in this type of cancer.

2,5-Diaziridinyl-3-(hydroxymethyl)-6-methyl-1,4-benzoquinone (RH1) is a novel antitumor diaziridinyl benzoquinone derivative designed to be bioactivated by the two-electron reductase NAD(P)H:quinone oxidoreductase (NQO1) and is currently in clinical trials. NQO1 is expressed at high levels in many solid tumors. RH1 cytotoxicity has been shown previously to be NQO1-dependent. The purpose of this study was to investigate whether other reducing enzymes such as cytochrome b(5) reductase (b5R), cytochrome P450 reductase (P450R), dihydronicotinamide riboside:quinone oxidoreductase 2 (NQO2), and xanthine oxidase/xanthine dehydrogenase (XO/XDH) also contribute to the bioactivation and cytotoxicity of RH1 in human tumor cells. For these studies, we established a series of stable MDA468 breast cancer cell lines overexpressing various levels of NQO1, b5R, P450R, and NQO2 and compared RH1-induced growth inhibition [3-(4,5-dimethylthiazol-2,5-diphenyl)tetrazolium and sulforhodamine B analysis] and interstrand DNA cross-linking (comet analysis) in both parental MDA468 cells and transfected clones. RH1 toxicity correlated with NQO1 and NQO2 but not with either b5R or P450R activity levels in the respective series of transfected MDA468 cell clones. Enzymatic assays showed that RH1 was an in vitro substrate for xanthine oxidase. However, XO/XDH protein and activity could not be detected in a variety of human tumor cell lines. These studies suggest that NQO1 and NQO2 are the principal enzymatic determinants of RH1 bioactivation in MDA468 tumor cells and that b5R, P450R, and XDH/XO are unlikely to play major roles. Our studies also suggest that NQO2 may be particularly relevant as a bioactivation system for RH1 in NQO1-deficient tumors such as leukemias and lymphomas.

The enzyme human NAD(P)H quinone oxidoreductase-1 (NQO1), which is overexpressed in several types of tumor cell, is considered a design target for cancer therapeutics. We identify new coumarin-based competitive inhibitors of NQO1, one of which is nanomolar. Using computational docking and molecular dynamics, we obtain insights into the structural basis of inhibition. Selected inhibitors were then assessed for off-target effects associated with dicoumarol and were found to have differing effects on superoxide formation and mitochondrial respiration. A comparison of NQO1 inhibition and off-target effects for dicoumarol and its derivatives suggests that the ability of dicoumarol to kill cancer cells is independent of NQO1 inhibition, that cellular superoxide production by dicoumarol does not seem linked to NQO1 inhibition but may be related to mitochondrial decoupling, and that superoxide does not appear to be a major determinant of cytotoxicity. Implications are discussed for NQO1 inhibition as an anticancer drug design target and superoxide generation as the dicoumarol-mediated mechanism of cytotoxicity.

NAD(P)H:quinone oxidoreductase 1 is a proposed target in pancreatic cancer. We describe the synthesis of a series of indolequinones, based on the 5- and 6-methoxy-1,2-dimethylindole-4,7-dione chromophores with a range of phenolic leaving groups at the (indol-3-yl)methyl position. The ability of these indolequinones to function as mechanism-based inhibitors of purified recombinant human NQO1 was evaluated, as was their ability to inhibit both NQO1 and cell growth in human pancreatic MIA PaCa-2 tumor cells. The inhibition of rhNQO1 was related to the pKa of the leaving group: compounds with poorer phenolic leaving groups were poor inhibitors whereas those with more acidic leaving groups were more efficient inhibitors. These inhibition data also correlated with the inhibition NQO1 in MIA PaCa-2 cells. However, the data demonstrate that NQO1 inhibition does not correlate with growth inhibitory activity, at least in the MIA PaCa-2 cell line, suggesting that targets in addition to NQO1 need to be considered to explain the potent growth inhibitory activity of this series of indolequinones in human pancreatic cancer cells.

NAD(P)H:quinone oxidoreductase 1 (NQO1) is currently an emerging target in pancreatic cancer. In this report, we describe a series of indolequinones, based on 5-methoxy-1,2-dimethyl-3-[(4-nitrophenoxy)methyl]indole-4,7-dione (ES936), and evaluate NQO1 inhibition and growth inhibitory activity in the human pancreatic MIA PaCa-2 tumor cell line. The indolequinones with 4-nitrophenoxy, 4-pyridinyloxy, and acetoxy substituents at the (indol-3-yl)methyl position were NADH-dependent inhibitors of recombinant human NQO1, indicative of mechanism-based inhibition. However, those with hydroxy and phenoxy substituents were poor inhibitors of NQO1 enzyme activity, due to attenuated elimination of the leaving group. The ability of this series of indolequinones to inhibit recombinant human NQO1 correlated with NQO1 inhibition in MIA PaCa-2 cells. The examination of indolequinone interactions in complex with NQO1 from computational-based molecular docking simulations supported the observed biochemical data with respect to NQO1 inhibition. The design of both NQO1-inhibitory and noninhibitory indolequinone analogues allowed us to test the hypothesis that NQO1 inhibition was required for growth inhibitory activity in MIA PaCa-2 cells. ES936 and its 6-methoxy analogue were potent inhibitors of NQO1 activity and cell proliferation; however, the 4-pyridinyloxy and acetoxy compounds were also potent inhibitors of NQO1 activity but relatively poor inhibitors of cell proliferation. In addition, the phenoxy compounds, which were not inhibitors of NQO1 enzymatic activity, demonstrated potent growth inhibition. These data demonstrate that NQO1 inhibitory activity can be dissociated from growth inhibitory activity and suggest additional or alternative targets to NQO1 that are responsible for the growth inhibitory activity of this series of indolequinones in human pancreatic cancer.

The enzyme NAD(P)H:quinone oxidoreductase 1 (NQO1) has been found to be up-regulated in pancreatic cancer as well as many other solid tumors. A recent study showed that inhibition of NQO1 in pancreatic cancer cells using the nonselective inhibitor dicumarol suppressed the malignant phenotype. The authors suggested that inhibition of cell growth might result from an increase in intracellular superoxide production due to inhibition of NQO1. We have recently shown that NQO1 can directly scavenge superoxide and this effect may become physiologically relevant in cells containing high NQO1 levels. We therefore tested the hypothesis that 5-methoxy-1,2-dimethyl-3-[(4-nitrophenoxy)methyl]indole-4,7-dione (ES936), a specific mechanism-based inhibitor of NQO1, would be an effective agent for the treatment of pancreatic tumors. The human pancreatic tumor cell lines BxPC-3 and MIA PaCa-2 contain high levels of NQO1 activity and protein as verified by immunoblot and immunocytochemical staining of human pancreatic tumor cells. ES936 treatment inhibited NQO1 activity by >98% in MIA PaCa-2 and BxPC-3 cells. In addition, ES936 treatment induced growth inhibition [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay] in MIA PaCa-2 and BxPC-3 cells with an IC(50) of 108 and 365 nmol/L, respectively. Treatment of MIA PaCa-2 cells with ES936 also inhibited the ability of these cells to form colonies and grow in soft agar in a dose-dependent manner. Treatment of mice carrying MIA PaCa-2 xenograft tumors with ES936 resulted in a significant difference in growth rates in ES936-treated and DMSO-treated (control) tumors. Our data did not show an increase in either intracellular superoxide production or oxygen consumption after treatment of cells with ES936, contrary to the effects seen with dicumarol. In summary, mechanism-based inhibitors of NQO1, such as ES936, may be useful therapeutic agents for the treatment of pancreatic cancer, although the underlying mechanism seems to be independent of superoxide generation.

Although follicular lymphoma (FL) is generally responsive to conventional-dose chemotherapy, improved survival in patients with this disease has been difficult to demonstrate. High-dose chemo/radiotherapy followed by autologous stem-cell transplantation (ASCT) can improve response rates, although its effects on survival remain controversial. Between 1990 and 2003, we transplanted 49 patients with low-grade FL at our institution. Twenty-two patients (45%) had undergone histologic transformation at the time of ASCT. In all, 44 patients (90%) had relapsed disease and five patients (10%) were resistant to chemotherapy at the time of transplantation. After ASCT, 30 patients (61%) were in complete remission (CR). The median overall survival (OS) has not been reached, while the median event-free survival (EFS) is 2.4 years. At a median follow-up of 5.5 years (longest 12.4 years), a plateau has been reached with 56% of patients remaining alive, and 35% event-free. ASCT was well tolerated except for two (4%) treatment-related deaths. In multivariable analysis, CR after ASCT and age less than 60 years are the best predictors of EFS and OS. ASCT is thus a safe therapeutic approach in FL, resulting in long-term EFS and OS for some patients, even with transformed disease.

Background: Bortezomib, a boronic acid dipeptide, is a novel proteasome inhibitor that has been shown in preclinical and phase 1 studies to have antimyeloma activity., Methods: In this multicenter, open-label, nonrandomized, phase 2 trial, we enrolled 202 patients with relapsed myeloma that was refractory to the therapy they had received most recently. Patients received 1.3 mg of bortezomib per square meter of body-surface area twice weekly for 2 weeks, followed by 1 week without treatment, for up to eight cycles (24 weeks). In patients with a suboptimal response, oral dexamethasone (20 mg daily, on the day of and the day after bortezomib administration) was added to the regimen. The response was evaluated according to the criteria of the European Group for Blood and Marrow Transplantation and confirmed by an independent review committee., Results: Of 193 patients who could be evaluated, 92 percent had been treated with three or more of the major classes of agents for myeloma, and in 91 percent, the myeloma was refractory to the therapy received most recently. The rate of response to bortezomib was 35 percent, and those with a response included 7 patients in whom myeloma protein became undetectable and 12 in whom myeloma protein was detectable only by immunofixation. The median overall survival was 16 months, with a median duration of response of 12 months. Grade 3 adverse events included thrombocytopenia (in 28 percent of patients), fatigue (in 12 percent), peripheral neuropathy (in 12 percent), and neutropenia (in 11 percent). Grade 4 events occurred in 14 percent of patients., Conclusions: Bortezomib, a member of a new class of anticancer drugs, is active in patients with relapsed multiple myeloma that is refractory to conventional chemotherapy., (Copyright 2003 Massachusetts Medical Society)

Adjunctive anti-bone resorption therapy has become an important part of multiple myeloma (MM) treatment. Currently, no definite evidence exists that this therapy increases survival. We examined a cohort of 13 of 167 patients (8%) treated with the M-2 protocol who received adjuvant gallium nitrate (GN) treatment for osteolysis, and then compared the outcome of these patients to all individuals treated with the M-2 regimen. The stage at diagnosis was IA in two patients, IIIA in 10 patients and IIIB in one. Median age at diagnosis was 51 years (range 35-73). Median (range) of entry data were: paraprotein level: 6000mg/dl (3058-8675); beta2M: 2.7mg/l, (1.2-9.6); LDH: 166U/l (142-237); hemoglobin: 10.2 g/dl (8.3-12.6); albumin: 3.7 g/dl (2.5-5.0); calcium: 10.0 mg/dl (8.3-14.5); creatinine: 1.2 mg/dl (0.7-2.7). Median survival in these patients was 87+ months from time of diagnosis compared with 48 months for all other patients treated on the M-2 protocol. We identified a subgroup of patients with remarkably prolonged survival who had received M-2 chemotherapy and GN. Survival in this group markedly exceeds expectations for patients with advanced stage disease and poor prognostic features. The administration of GN may have a positive impact on survival either by decreasing skeletal complications or through a direct action of GN on the complex cytokine network involved in the proliferation of the malignant myeloma cell.

A series of indolequinones bearing various functional groups has been synthesized, and the effects of substituents on the metabolism of the quinones by recombinant human NAD(P)H:quinone oxidoreductase (NQO1) were studied. Thus 5-methoxyindolequinones were prepared by the Nenitzescu reaction, followed by functional group interconversions. The methoxy group was subsequently displaced by amine nucleophiles to give a series of amine-substituted quinones. Metabolism of the quinones by NQO1 revealed that, in general, compounds with electron-withdrawing groups at the indole 3-position were among the best substrates, whereas those with amine groups at the 5-position were poor substrates. Compounds with a leaving group at the 3-indolyl methyl position generally inactivated the enzyme. The toxicity toward non-small-cell lung cancer cells with either high NQO1 activity (H460) or no detectable activity (H596) was also studied in representative quinones. Compounds which were good substrates for NQO1 showed the highest selectivity between the two cell lines.

Multiple myeloma (MM) is a B cell malignancy characterized by the expansion of monoclonal Ig-secreting plasma cells with low proliferative activity. It is postulated that inhibition of physiologic cell death is an underlying factor in the pathophysiology of MM. The development of chemoresistance is a common feature in patients with MM. In the present studies, hexamethylene bisacetamide (HMBA), a hybrid polar compound that is a potent inducer of terminal differentiation of various transformed cells, is shown to inhibit the growth of several human myeloma cell lines (ARP-1, U266, and RPMI 8226), including doxorubicin-resistant RPMI 8226 variants that overexpress the multidrug-resistance gene, MDR-1, and its product, p-glycoprotein. In addition to growth arrest and suppression of clonogenicity, HMBA induces apoptosis both in freshly isolated human myeloma cells and in cell lines, as determined by morphologic alterations, cell cycle distribution and endonucleosomal DNA fragmentation. Further, HMBA decreases BCL-2 protein expression in myeloma cells within 12-48 hr. Overexpression of BCL-2 protein in ARP-1 cells confers resistance to HMBA-induced apoptosis. Taken together, these data suggest that HMBA is a potent inducer of apoptosis in human myeloma cells, which may act through suppressing the anti-apoptotic function of the bcl-2 gene. HMBA, and related hybrid polar compounds, may prove useful in the management of this presently incurable disease.

Aberrant glycosylation of mucins on the surface of adenocarcinomas leads to exposure of novel tumor-associated epitopes potentially recognizable by the immune system. Monoclonal antibodies (mAbs) have been developed against some of these epitopes. One such mAb, denoted CC49, recognizes the tumor-associated glycoprotein TAG-72. Most adenocarcinomas, including breast, colon, ovarian, prostate, and gastric, express some form of this molecule, recognizable by the CC49 antibody. The widespread distribution of the antigen on transformed cells makes the CC49 mAb a potentially powerful tool in numerous immunotherapy contexts. In the course of our studies with CC49 and certain of its molecularly engineered derivatives, we screened a number of human hematopoietic cell lines for TAG-72 expression by flow cytometry using CC49. We found that the T-cell line, Jurkat, had a higher level of CC49 mAb binding than any of the carcinoma cell lines previously evaluated in our laboratory. In addition, the myelomonocytic cell line Tf-1 and the erythroleukemia cell line K562 were also positive for CC49 mAb binding by flow-cytometric analysis. However, peripheral blood lymphocytes and certain other hematopoietic cell lines were not able to bind the CC49 mAb. Immunoblot analyses of cell extracts from the CC49 reactive lines indicated distinct protein species reactive with the CC49 antibody. In some instances, cells expressing these reactive proteins were susceptible to antibody-dependent cellular cytotoxicity using a chimeric derivative of the CC49 antibody. These results indicate that the cell membrane expression of molecules recognized by CC49 extends beyond adenocarcinomas to certain cell lines of hematopoietic origin.

Bioreductive antitumor quinones require reductive metabolism to produce their cytotoxic effects. A series of these compounds was screened for relative rates of reduction by the two-electron reductase, NAD(P)H:quinone oxidoreductase (DTD). The antitumor quinones streptonigrin (SN), 2,5-diaziridinyl-3-phenyl-1,4-benzoquinone (PDZQ), 2,5-diaziridinyl-3,6-dimethyl-1,4-benzoquinine (MeDZQ), and [3-hydroxymethyl-5-aziridinyl-1-methyl-2-(1H-indole-4,7-dione)-propen ol] (EO9) were all excellent substrates for recombinant rat and human DTD. All four compounds were reduced by DTD at least 100 times faster than the clinically important bioreductive alkylating agent, mitomycin C (MC). Reduction of the antitumor quinones was generally 4-5 times more efficient by rat DTD than by human DTD. The exception was EO9, which, surprisingly, was reduced 23 times faster by rat DTD than by human DTD. The rate of reduction of each individual quinone was similar under either aerobic or anaerobic conditions, suggesting that DTD may be an important activating enzyme in the hypoxic fraction of solid tumors. The cytotoxicity of MeDZQ and MC was examined in a panel of human breast and lung cancer cell lines. The data showed good correlations between DTD activity and toxicity for both MeDZQ (r = 0.57, p = 0.054) and MC (r = 0.69, p = 0.020), confirming biochemical data that both compounds are bioactivated by DTD. In addition, IC50 values were in general lower for MeDZQ than for MC in cell lines containing elevated DTD, a finding that was consistent with metabolic data that indicated that MeDZQ was a better substrate for DTD than MC. SR, defined as the ratio of the IC50 value for the H596 NSCLC cell line (undetectable DTD activity) to the IC50 value for the H460 NSCLC cell line (high DTD activity), were determined for all five antitumor quinones. SN was the most selective (SR = 86) followed by EO9 (SR = 62), MeDZQ (SR = 17), and MC (SR = 11). Surprisingly, PDZQ, an excellent substrate for DTD, was toxic to both cell lines (SR = 1.8). These data suggest that antitumor quionones that are substrates for DTD may be selectively toxic to tumors with high DTD activity and may be useful in the treatment of those tumors.

The metabolisms of two standard electron acceptors and a series of bioreductive antitumor compounds by purified rat and human DT-diaphorases (DTD) were compared. DTD was purified from rat liver cytosol and from Escherichia coli in which rat liver or human lung tumor DTD complementary DNA was expressed. Km and kcat values for menadione and 2,6-dichlorophenolindophenol reduction were similar for the three enzyme preparations except that rat E. coli DTD had 2-3-fold higher kcat values for both menadione and 2,6-dichlorophenolindophenol and a 2-3-fold higher Km for menadione than either rat liver or human E. coli DTD. Reduction of the antitumor compounds was 1.9-4.9 times faster with rat E. coli DTD than with human E. coli DTD. The antitumor compounds were reduced in the following order by rat E. coli DTD: 2,5-dimethyl-3,6-diaziridinyl-1,4-benzoquinone > streptonigrin > mitomycin A > diaziquone > mitomycin C (MC) > 5-(aziridin-1-yl)-2,4-dinitrobenzamide. The order was the same for human E. coli DTD with one exception; diaziquone was reduced slightly faster than mitomycin A. Metabolism of doxorubicin could not be detected using rat or human E. coli DTD. MC-induced DNA cross-linking was also more efficient using rat E. coli DTD relative to human E. coli DTD. Metabolism of MC by rat and human E. coli DTD was also compared under aerobic and hypoxic conditions. Rates of reduction of MC and metabolite formation were similar under aerobic and hypoxic conditions, and the toxicity of MC to DTD-rich HT-29 cells was also similar in aerobic and hypoxic conditions. In contrast, the toxicity of MC to DTD-deficient BE cells was potentiated markedly under hypoxia. These data show that although small catalytic differences between rat and human E. coli DTD can be observed, compounds such as 2,5-dimethyl-3,6-diaziridinyl-1,4-benzoquinone and streptonigrin are still excellent substrates for the human enzyme and may be useful in the therapy of tumors high in DTD activity. In addition, metabolism of MC by rat and human E. coli DTD was similar in aerobic and hypoxic conditions; in agreement with these data, cytotoxicity of MC to a DTD-rich cell line was oxygen independent. Increased MC cytotoxicity under hypoxia appears to be mediated by enzymes other than DTD.

Because of the elevated DT-diaphorase (DTD) activity in certain tumors such as human nonsmall cell lung cancer (NCSLC), DTD is a potential target on which to base the development of new antitumor compounds. Mitomycin C is the most effective single agent used for the therapy of NSCLC and is metabolized and bioactivated by DTD. Mitomycin C is a poor substrate for DTD, however, and its metabolism is pH-dependent. We have therefore focused on identifying more efficient substrates for DTD. We have developed a metabolic and cytotoxicity screen that identifies compounds which are efficiently bioactivated by DTD. This screen utilizes both aerobic and hypoxic conditions and cell lines with both elevated and deficient DTD activity as an index of selectivity. Using the screen described above, we have identified [3-hydroxy-5-aziridinyl-1-methyl-2-(1H-indole-4,7-indione)-prop-be ta-en- alpha-ol] (E09), 2,5-diaziridinyl-1,4-benzoquinone (MeDZQ), and streptonigrin as compounds that are most efficiently bioactivated by DTD and exert selective cytotoxicity. Although certain tumors such as NSCLC have elevated DTD activity, we have characterized a point mutation at position 609 in the DTD cDNA, which codes for a proline to serine change in the protein and leads to a loss of enzyme activity. We have characterized this mutation in both BE human colon carcinoma cells and H596 human NSCLC cells. This mutation and resulting lack of DTD activity complicates the use of agents designed to target DTD in tumors.(ABSTRACT TRUNCATED AT 250 WORDS)

A series of 2,5-bis-substituted 3,6-diaziridinyl-1,4-benzoquinones have been tested for their ability to be reduced by the two-electron NAD(P)H:(quinone acceptor) oxidoreductase [DT-diaphorase (DTD); EC 1.6.99.2]. Symmetrically alkyl-substituted carbamoyl ester analogs of 2,5-ethyl(carboethoxyamino)3,6-diaziridinyl-1,4- benzoquinone [AZQ], 3,6-diaziridinyl-1,4-benzoquinone (DZQ), and its 2,5-dimethyl derivative (MeDZQ) were tested. The rate of reduction by DTD was DZQ greater than MeDZQ greater than n-butyl- (D5) greater than sec-butyl- (D7) greater than n-propyl- (D3) greater than methyl- (D1) greater than ethyl- (AZQ) greater than i-butyl- (D6) greater than i-propyl- (D4) substituted derivatives. The hydroxyethylamino analog (BZQ) was not a substrate for DTD. The order of toxicity to HT-29 human colon carcinoma cells (at 1-log cell kill) was MeDZQ greater than DZQ greater than BZQ greater than D1 greater than D5 greater than AZQ greater than D7 greater than D3 greater than D6 greater than D4. Dicumarol, a known inhibitor of DTD, was capable of inhibiting the cytotoxicity of DZQ, MeDZQ, AZQ, D3, D4, D5, D6, and D7, with little inhibition of D1 cytotoxicity. Alkaline elution assays suggested that DZQ induced DNA strand breaks, whereas MeDZQ induced DNA interstrand crosslinks in HT-29 cells. The formation of both classes of lesions was inhibited by dicumarol. DZQ and MeDZQ were 5-6-fold less cytotoxic to the DTD-deficient BE cell line, whereas BZQ was more cytotoxic to this cell line than the HT-29 cell line. BZQ was capable of inducing dicumarol-insensitive DNA interstrand crosslinks in both cell lines. In summary, these data show a trend between the rate of reduction by DTD of an analog and its ability to induce cytotoxicity in HT-29 cells, and they support a role for DTD in the bioreductive activation of AZQ and its analogs.

DT-diaphorase (DTD) mediated reduction of a series of 2,5-bis-substituted-3,6-diaziridinyl-1,4-benzoquinones was found to increase the level of DNA interstrand cross-linking (ISC) formed at neutral pH with an enhancement observed as the pH was decreased to 5.8. The analogues used were symmetrically alkyl-substituted carbamoyl ester analogues of AZQ (D1-D7), 3,6-diaziridinyl-1,4-benzoquinone (DZQ), the 2,5-dimethyl derivative (MeDZQ), and a 2,5-bis[(2-hydroxyethyl)amino] analogue (BZQ). At pH 5.8, the level of DNA ISC induced by enzymatic reduction was as follows: DZQ greater than MeDZQ much greater than D1 (methyl) greater than D3 (n-propyl) greater than D2 (AZQ; ethyl) greater than D5 (n-butyl) greater than D7 (sec-butyl) greater than D4 (isopropyl) D6 greater than (isobutyl). A similar trend was observed at pH 7.2. The level of DNA ISC induced by BZQ, which is not a substrate for DTD, was not increased by enzymatic reduction. Dicumarol, a known inhibitor of DTD, was capable of inhibiting the DNA ISC induced by these quinones upon enzymatic reduction. MeDZQ and DZQ reacted with guanines, as measured by Maxam and Gilbert sequencing, with a sequence selectivity similar to that of the nitrogen mustard class of antitumor agents. Enzymatic reduction of DZQ and MeDZQ by DTD was found to alter their sequence-selective alkylation. Reduced DZQ showed enhanced guanine alkylation in 5'-GC-3' sequences and new sites of adenine alkylation in 5'-(A/T)AA-3' sequences. Reduced MeDZQ only showed new sites of adenine alkylation at 5'-(A/T)AA-3' sequences but no enhancement of guanine alkylation. The new sites of adenine alkylation were found to be inhibited in the presence of magnesium and rapidly converted into apurinic sites.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of DT-diaphorase in bioreductive activation of mitomycin C was examined using HT-29 and BE human carcinoma cells which have high and low levels of DT-diaphorase activity, respectively. HT-29 cells were more sensitive to mitomycin C-induced cytotoxicity than the DT-diaphorase-deficient BE cell line. Mitomycin C induced DNA interstrand cross-linking in HT-29 cells but not in BE cells. Both mitomycin C-induced cytotoxicity and induction of DNA interstrand cross-links could be inhibited by pretreatment of HT-29 cells with dicoumarol. Metabolism of mitomycin C by HT-29 cell cytosol was pH dependent and increased as the pH was lowered to 5.8, the lowest pH tested. Metabolism of mitomycin C by HT-29 cytosol was inhibited by prior boiling of cytosol or by the inclusion of dicoumarol. Little metabolism was detected in BE cytosols. When purified rat hepatic DT-diaphorase was used, metabolism of mitomycin C increased as the pH was decreased and could be detected at pH 5.8, 6.4, 7.0, 7.4, but not at 7.8. Metabolism of mitomycin C was NADH dependent and inhibited by dicoumarol or by prior boiling of enzyme. An approximate 1:1 stoichiometry between NADH and mitomycin C removal was demonstrated and no oxygen consumption could be detected. Metabolism of mitomycin C by purified HT-29 DT-diaphorase was also dicoumarol inhibitable and pH dependent. The major metabolite formed during metabolism of mitomycin C by HT-29 cytosol, purified HT-29, and rat hepatic DT-diaphorase was characterized as 2,7-diaminomitosene. These data suggest that two-electron reduction of mitomycin C by DT-diaphorase may be an important determinant of mitomycin C-induced genotoxicity and cytotoxicity.