Multifaceted Mechanism Of Action Research Articles

Abstract 3334: GSTP1-activated nitric oxide-releasing/PARP inhibitor hybrid prodrugs induce cancer cell death through ROS/RNS, DNA damage, ER stress, and apoptosis.

Abstract Poly [ADP-ribose] polymerase (PARP) has been recognized as a potential molecular target in cancer therapy. PARP inhibitors have been evaluated in clinical trials, both in combination with DNA damaging chemotherapy, and also as single agents in patients with BRCA deficiencies. However, there are problems associated with the clinical applicability of PARP inhibitors that include theoretical genotoxicity of these DNA damage repair inhibitors, and increased toxicity in combination with chemotherapy. Therefore targeted delivery of PARP inhibitors selectively to cancer cells would be clinically beneficial. Diazeniumdiolate-based nitric oxide (NO)-releasing prodrugs developed in our laboratory have proven effective as anticancer agents in a number of in vitro and in vivo models. The lead prodrug JS-K exhibits a multifaceted mechanism of action that includes generation of oxidative/nitrosative stress and DNA damage. We hypothesized that inhibiting PARP may increase effectiveness of JS-K. More importantly, creating a PARP inhibitor prodrug that is activated specifically in the cancer cell could diminish dose-limiting adverse events observed in clinical trials. Using structure-based molecular modeling approaches we have designed and synthesized novel diazeniumdiolate/PARP inhibitor hybrid prodrugs that are activated by glutathione S-transferase P1 (GSTP1), an enzyme frequently overexpressed by cancer cells. This GSTP1-catalyzed activation allows for the selective delivery of nitric oxide and PARP inhibitor simultaneously to the cancer cell. Biological evaluation of the prodrugs in vitro in lung adenocarcinoma and leukemia cells reveals that their mechanism of action involves oxidative/nitrosative stress associated with NO release and depletion of cellular GSH, leading to DNA strand break damage. The compounds induce aryl-mediated crosslinking glutathionylation of cellular thiols that is irreversible, and may lead to observed endoplasmic reticulum (ER) stress. The tumor suppressor p53 pathway is involved in cells bearing wildtype p53. We have also observed the activation of stress kinases p38 and SAPK/JNK. All of the above events led to initiation of apoptosis through both intrinsic and extrinsic pathways. Cancer cells often exhibit specific stress-related phenotypes, caused by insults such as reactive oxygen species, DNA damage, metabolic stress, or ER stress, and agents that further enhance these stresses could be developed as potential therapies. GSTP1-activated diazeniumdiolate/PARP inhibitor hybrid prodrugs selectively induce cancer cell death through ROS/DNA damage and ER stress overload, leading to apoptosis. Citation Format: Anna E. Maciag, Joseph E. Saavedra, Ryan J. Holland, Youseung Kim, Vandana Kumari, Christina E. Luthers, Waheed S. Sehareen, Xinhua Ji, Lucy M. Anderson, Larry K. Keefer. GSTP1-activated nitric oxide-releasing/PARP inhibitor hybrid prodrugs induce cancer cell death through ROS/RNS, DNA damage, ER stress, and apoptosis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3334. doi:10.1158/1538-7445.AM2013-3334

Real-World Efficacy and Safety of Bendamustine with or without Rituximab in Treatment-Naïve Patients with Chronic Lymphocytic Leukemia: Retrospective Analysis of a German Registry.

AbstractAbstract 2905 BackgroundBendamustine, a unique alkylating agent with a multifaceted mechanism of action is effective front-line therapy for chronic lymphocytic leukemia (CLL). In vitro studies showing that cytotoxic activity of bendamustine against CLL-derived cell lines is synergized by rituximab, an anti-CD20 monoclonal antibody, have led to investigation of combination bendamustine plus rituximab (BR) as first-line therapy and treatment of relapsed disease. This retrospective analysis assessed real-world efficacy and safety of bendamustine alone and combined with rituximab in treatment-naïve CLL patients from Projektgruppe Internistische Onkologie, the largest registry of treatment data from private medical oncology practices in Germany. MethodsRecords were obtained for all CLL patients in a registry from 57 German oncology practices from May 2008 to July 2011. Patients who received ≥3 cycles of first-line bendamustine monotherapy or BR were divided into the following age/treatment groups: ≤60 years treated with BR ± prednisone (P) [≤60 BR]; >60 to <70 years treated with bendamustine monotherapy [60–70 B]; >60 to <70 years treated with BR ± P [60–70 BR]; ≥70 years treated with bendamustine monotherapy [≥70 B]; and ≥70 years treated with BR ± P [≥70 BR].The primary efficacy measure was ORR (complete response [CR] plus partial response [PR]); secondary efficacy measures included CR, PR, progression-free survival (PFS), and overall survival (OS). Adverse events (AEs) were assessed. ResultsA total 217 patients (≥61.1% male in each group) were included in the analysis (Table). At diagnosis, all patients had an ECOG score of 0–2; most had RAI stage 0-II (16 had stage III/IV) and Binet stage A or B (29 had stage C). Mean number of treatment cycles (28 days/cycle) per group ranged from 5.1 to 5.9. Mean dose per cycle ranged from 133.6 to 165.9 mg/m2 for bendamustine and 391.1 to 412.1 mg/m2 for rituximab in those groups (Table). Median follow-up was 3 years (range 1–5).Observed ORRs were >83% in all groups (Table); 1 patient each in the 60–70 B and 60–70 BR groups had progressive disease, and 1 in the ≥70 BR group was not assessable. By Kaplan-Meier analysis, median PFS and OS have been reached in the 60–70 B (PFS: 14.8 months, OS: 41.0 months) and ≥70 B (PFS: 32.5 months, OS: 40.1 months) groups only. PFS results are shown in the Figure.There were 26 deaths at the time of analysis. The most common grade 3/4 hematologic AEs were febrile neutropenia (n=28) in the ≥70 BR group, leukopenia (n=15) in the ≤60 BR group, and leukopenia (n=25) in the ≥70 BR group. Depression was the most common grade 3/4 nonhematologic AE, affecting all patients in the ≤60 BR and 60–70 B groups, 48/50 patients in the 60–70 BR group, 35/36 in the ≥70 B, and 94/95 in the ≥70 BR. Other common grade 3/4 nonhematologic AEs included fatigue (2 patients in ≥70 BR and 1 patient each in 60–70 B and ≥70 B) and infections/infestations (2 patients in ≤60 BR and 3 in ≥70 BR). Thirty patients were hospitalized (Table). Dose reductions were most frequent in the ≥70 B group (67%) and least in the 60–70 B and 60–70 BR groups (17% and 12.0%, respectively) (Table). Dose delays occurred for 1 patient each in the ≤60 BR, 60–70 B, and ≥70 BR groups and 4 patients in the ≥70 B group. ConclusionsData from this real-world chart review indicate that bendamustine alone or with rituximab provides high response rates and an acceptable safety profile with low rates of dose delay in all patient age groups (≤60, 60–70, and ≥70) with previously untreated CLL. These findings are similar to those reported in large clinical trials.Table<60 BR n=2460–70 B n=1260–70 BR n=50>70 B n=36>70 BR n=95Mean (SD) ageAt diagnosis50.3 (6.4)62.6 (4.9)63.2 (4.3)74.5 (5.6)72.5 (5.5)Start of therapy53.1 (6.2)65.9 (2.1)65.7 (2.5)76.9 (4.8)75.5 (4.5)Mean dose (mg/m2) per cycleBendamustine154.0 (41.5)153.7 (32.5)165.9 (27.0)133.6 (39.0)147.7 (37.6)Rituximab412.1 (107.6)NA392.1 (100.4)NA402.5 (71.4)ResponseORR %10083889790CR5833441937PR4250447853Hospitalizations, patients (%)3 (13)2 (17)6 (12)5 (14)14 (15)Dose reductions, patients (%)9 (38)2 (17)9 (18)24 (67)30 (32)Dose delays, patients (%)1 (4)1 (8)04 (11)1 (1) [Display omitted] Support: Teva Pharmaceutical Industries Ltd. Disclosures:Günther:Mundipharma: Consultancy, Honoraria. Bartels:rgb Onkologisches Management GmbH, which received research funding from Teva Pharmaceuticals: Employment, Research Funding. Sterchele:Teva Pharmaceutical Industries Ltd.: Employment.

Plant-derived polyphenols regulate expression of miRNA paralogs miR-103/107 and miR-122 and prevent diet-induced fatty liver disease in hyperlipidemic mice

BackgroundMicroRNAs have the potential for clinical application. Probable modulation by plant-derived polyphenols might open preventive measures using simple dietary recommendations. MethodsWe assessed the ability of continuous administration of high-dose polyphenols to modulate hepatic metabolism and microRNA expression in diet-induced fatty liver disease in commercially available hyperlipidemic mice using well-established and accepted procedures that included the development of new antibodies against modified quercetin. ResultsWeight gain, liver steatosis, changes in the composition of liver tissue, and insulin resistance were all attenuated by the continuous administration of polyphenols. We also demonstrated that metabolites of polyphenols accumulate in immune cells and at the surface of hepatic lipid droplets indicating not only bioavailability but a direct likely action on liver cells. The addition of polyphenols also resulted in changes in the expression of miR-103, miR-107 and miR-122. ConclusionsPolyphenols prevent fatty liver disease under these conditions. The differential expression of mRNAs and miRNAs was also associated with changes in lipid and glucose metabolism and with the activation of 5′-adenosine monophosphate-activated protein kinase, effects that are not necessarily connected. miRNAs function via different mechanisms and miRNA–mRNA interactions are difficult to ascertain with current knowledge. Further, cell models usually elicit contradictory results with those obtained in animal models. General significanceOur data indicate that plant-derived polyphenols should be tested in humans as preventive rather than therapeutic agents in the regulation of hepatic fatty acid utilization. A multi-faceted mechanism of action is likely and the regulation of liver miRNA expression blaze new trails in further research.

Humic substances affect Arabidopsis physiology by altering the expression of genes involved in primary metabolism, growth and development

Humic substances (HS), as component of soil organic matter, have been widely studied. Their positive effects on plant physiology have been further demonstrated, but there are no clear evidences about the direct as well as indirect mechanisms regulating these processes. In this paper a transcriptomic approach based on the detection of cDNA-AFLP markers was used to identify candidate genes potentially involved in the regulation of the response to HS in Arabidopsis thaliana. Using 160 primer combinations, the cDNA-AFLP enabled to identify 133 genes putatively involved in plant–HS interaction. Sequence analysis and Gene Ontology classification indicated that a large number of genes involved in developmental and metabolic processes, as well as in transcription regulation or RNA metabolism were identified as HS-regulated. Real-Time PCR analyses confirmed transcription levels of 32 HS-regulated genes. This study demonstrates that HS exert their effects on plant physiology by means of complex transcriptional networks. From the overall transcriptomic results we may hypothesize that HS exert their function through a multifaceted mechanism of action, partially connected to their well demonstrated auxin activity, but involving also IAA-independent signalling pathways.

Bendamustine for the treatment of indolent non-Hodgkin’s lymphoma and chronic lymphocytic leukemia

The pharmacology, efficacy, safety, and dosage and administration of bendamustine and its use in indolent non-Hodgkin's lymphoma (NHL) and chronic lymphocytic leukemia (CLL) are reviewed. Bendamustine is an alkylating agent that has a unique, multifaceted mechanism of action. Compared with other alkylators, bendamustine produces more-extensive and long-lasting DNA damage. Bendamustine also inhibits cell-cycle checkpoints, leading to mitotic catastrophe and apoptosis. Bendamustine is approved for the treatment of CLL and for indolent B-cell NHL that has progressed during or within 6 months of treatment with rituximab or a rituximab-based regimen. In Phase II and III trials in patients with indolent NHL and CLL, bendamustine has demonstrated response rates of 67-84% as a single agent and median durations of response of 7-21 months. Additional clinical trials are examining bendamustine as a single agent and in combination therapy for the treatment of hematologic malignancies and solid tumors. Adverse events associated with bendamustine are typically mild to moderate and can usually be managed with supportive care. Myelosuppression is the most common grade 3 or 4 adverse event. Tumor lysis syndrome has been reported to occur in some patients, and preventive measures should be taken in at-risk patients. The dosage and administration differ for the treatment of NHL and CLL. Bendamustine is a well- tolerated and effective chemotherapeutic agent indicated for the treatment of rituximab-refractory, indolent NHL and CLL. It has demonstrated efficacy in patients whose disease is refractory to other therapies, including other alkylating agents.

Darinaparsin a Novel Organic Arsenic Molecule Active in Lymphoma: Development of An Oral Form.

Abstract 4759 IntroductionDarinaparsin is an organic arsenic molecule constructed of dimethylated arsenic linked to glutathione (N-[S-(dimethylarsino)-N-L-gamma-glutamyl-L-cysteinyl]-glycine). It has a multifaceted mechanism of action, inducing G2/M cell cycle arrest and apoptosis mediated through disruption of mitochondrial functions, increased reactive oxygen species production, and modulation of signal transduction pathways. In addition, darinaparsin has anti-angiogenic activity. It has significant activity in a broad spectrum of hematologic and solid tumors in preclinical models, including human cell lines resistant to arsenic trioxide. It is active in heavily treated patients with refractory lymphoma when administered IV 300 mg/m2 for 5 days on a 28 day cycle, and is very well tolerated. Preclinically it is orally highly bioavailable. Oral administration may be of importance in potential utility in lymphoma in continuous metronomic dosing. MethodsTwo Phase I studies of oral darinaparsin are being conducted in patients diagnosed with relapsed or refractory advanced tumors. The first protocol is a Phase I, dose-escalation, oral administration study designed to determine the MTD of darinaparsin capsules. The dosing schedule is a regimen of 2 doses per week for 3 weeks followed by 1 week of rest, starting at 300 mg twice weekly. A second Phase I study, having a similar design and objective, evaluates several dosing regimens, including dosing capsules three times per week increasing dosing frequency to daily dosing for 3 weeks, with 1 week of rest. For each study 28 days constitutes one cycle. Standard methods for evaluation of toxicity, escalation and efficacy are being used. ResultsThese two studies have thus far enrolled 19 and 17 patients, respectively. In total there are 24 male and 12 female patients. The median age is 59 years, with a range from 38 to 82 years. To date, MTD has not been reached in either study. The dose continues to be escalated and is currently at 900mg / day twice weekly in the 1st study, and 300 mg daily every day in the 2nd study. Bioavailability has been very high (>75%). All patients were heavily pretreated and refractory. Of 27 evaluable patients thus far in the two trials, 2 had a partial response and 15 had prolonged stable disease, including lymphoma (NHL), head and neck, colon, and pancreatic cancers. The duration of responses has been 3 – 8 + months. Safety and tolerability has been very good and comparable to that of IV darinaparsin. SAEs were atrial fibrillation and congestive heart failure, each occurring in one patient, and dyspnea, occurring in two patients. No QT prolongation has been observed. Dose escalation continues in both studies and updated results will be presented. ConclusionDarinaparsin is a novel organic arsenic molecule that has demonstrated clinical activity in refractory lymphoma when given IV. When given orally by capsule, the drug is well tolerated and demonstrates early signs of activity. Disclosures:Buck:ZIOPHARM Oncology: Employment. Wallner:ZIOPHARM Oncology: Employment. Lewis:ZIOPHARM Oncology: Employment, Membership on an entity's Board of Directors or advisory committees.

Proteomic and Functional Analyses Reveal a Dual Molecular Mechanism Underlying Arsenic-Induced Apoptosis in Human Multiple Myeloma Cells

Multiple myeloma (MM) is an incurable plasma cell malignancy with a terminal phase marked by increased proliferation and resistance to therapy. Arsenic trioxide (ATO), an antitumor agent with a multifaceted mechanism of action, displayed clinical activity in patients with late-stage multiple myeloma. However, the precise mechanism(s) of action of ATO has not been completely elucidated. In the present study, we used proteomics to analyze the ATO-induced protein alterations in MM cell line U266 and then investigated the molecular pathways responsible for the anticancer actions of ATO. Several clusters of proteins altered in expression in U266 cells upon ATO treatment were identified, including down-regulated signal transduction proteins and ubiquitin/proteasome members, and up-regulated immunity and defense proteins. Significantly regulated 14-3-3zeta and heat shock proteins (HSPs) were selected for further functional studies. Overexpression of 14-3-3zeta in MM cells attenuated ATO-induced cell death, whereas RNAi-based 14-3-3zeta knock-down or the inhibition of HSP90 enhanced tumor cell sensitivity to the ATO induction. These observations implicate 14-3-3zeta and HSP90 as potential molecular targets for drug intervention of multiple myeloma and thus improve our understanding on the mechanisms of antitumor activity of ATO.

Nociceptin-induced modulation of human T cell function

There is an accumulating evidence for the immunoregulatory role of the neuropeptide, nociceptin/orphanin FQ (N/OFQ) however its role on T cell function requires elucidation. This study has demonstrated an inhibitory role for N/OFQ on SEB-activated T cell function. N/OFQ decreases T cell proliferation, which is abrogated when the costimulatory receptors CD80 and CD86 are blocked. In addition, evidence suggests that the immunoregulatory cytokines TGF-β, IFN-γ and nitric oxide (NO) are involved in the N/OFQ effect. N/OFQ also, through involvement of IFN and NO, induces the expression of the immunosuppressive modulator indoleamine 2,3-dioxygenase (IDO), suggesting a central role for IDO in the N/OFQ effect on T cell proliferation. The data presented in this report indicate a multi-faceted mechanism of action used by N/OFQ to modulate T cell function.

Squalamine lactate for the treatment of age-related macular degeneration

Squalamine lactate (Evizon™, Genaera, PA, USA) is a systemically administered antiangiogenic compound that is among the group of drugs being investigated for the treatment of neovascular age-related macular degeneration (AMD). Squalamine lactate is the first drug candidate from the aminosterol class and has a unique and multifaceted mechanism of action. Both preclinical evaluations and clinical studies have demonstrated promise for the treatment of AMD and various cancers. In contrast to antibody-based antiangiogenic compounds, squalamine lactate has a more generalized effect on the cellular signaling cascades that are common to vascular endothelial growth factor and other growth factors, including basic fibroblast growth factor (FGF2), platelet-derived growth factor and thrombin. Due to its systemic (intravenous) mode of delivery, squalamine lactate avoids the severe potential complications (i.e., endophthalmitis, ocular inflammation, vitreous hemorrhage and traumatic cataract) associated with intraocular injections. In addition, hypertension, often severe, related to systemic use of antiangiogenic agents such as bevacizumab has been reported. To date, during therapy in clinical studies, squalamine has not demonstrated acute hypertension, any secondary effects on the cardiovascular system or any pattern of drug-related cardiovascular adverse events. In contrast to intravitreal agents, both eyes are treated simultaneously with a single infusion allowing for therapy in subjects with bilateral exudative AMD. The objective of this article is to summarize the basic science, pharmacokinetic, pharmacodynamic activity, safety and efficacy of squalamine lactate for the treatment of choroidal neovascularization associated with AMD.

The antihypertensive effect of angiotensin-converting enzyme inhibition: A multifaceted mechanism of action

The antihypertensive effect of angiotensin-converting enzyme inhibition: A multifaceted mechanism of action