Including Vinca Alkaloids Research Articles

Peripheral Neuropathy in Children with High Risk Hodgkin Lymphoma (HL): The Role of Protocol-Stipulated Dose Modification in the Children's Oncology Group (COG) AHOD1331 Study

Background Peripheral neuropathy (PN) is commonly associated with several classes of chemotherapy, including vinca alkaloids and the novel anti-CD30-directed antibody-drug conjugate, Brentuximab vedotin (Bv). The drug moiety in Bv, monomethyl auristatin E, a potent microtubule tubulin inhibitor, is known to cause PN. In the 2018 Echelon-1 study, rates of PN among adults with advanced stage HL were 67% in the Bv arm as compared to 43% in the control arm (Connors, 2018) with dose modifications at the discretion of the treating physician of 66% for Bv and 57% for vinblastine (VBL). We examined rates of PN and use of protocol-stipulated dose modification in the COG AHOD1331, a Phase 3 randomized comparison of standard multi-agent chemotherapy (ABVE-PC) vs. Bv-AVE-PC among children and adolescents with high risk HL (Castellino, 2022). The combination of vincristine (VCR) with Bv warrants the formal study of PN in this trial. Methods Eligible patients (pts) ages 2-21 years with high risk HL were enrolled from 2015-2019 (NCT02166463). After randomization, pts received 5 cycles of chemotherapy. Pts in the standard (std) arm received VCR on Day 1 and 8 of each 21-day treatment cycle; pts in the experimental (exp) arm received Bv (1.8 mg/kg) on Day 1 and VCR on Day 8. Clinician grading of PN was required at each cycle, using the Balis PN Scale, with protocol-stipulated dose modifications of VCR preceding modification of Bv in cases of PN > grade 2. Rates of PN were calculated by treatment cycle by study arm. Dose modifications were summarized for each drug by treatment cycle. Median time to first dose modification was estimated by treatment arm. A Cox model estimated hazard ratios (HR) and 95% confidence intervals (CI) for dose modifications by treatment arm and pt and clinical characteristics. Progression-free survival (PFS) was compared with Log-rank test by study arms and within arm by presence or absence of PN. Results 587 pts were enrolled on the study. While the proportion of pts overall developing PN did not differ by study arm (19%, p=0.86), dose modification of Bv, VCR, or both occurred more frequently on the exp arm (50/298, 16.8%) than on the std arm (12/289, 4.2%). Among pts on the exp arm, Bv was dose modified in 8% of pts; VCR was dose modified in 13.4% of pts. The median time to first dose modification was 40.8 days (31.5-73.5) for the exp arm vs. 75.5 days (59.0-94.8) for the std arm (p=.0043). During cycle 5, the rate of any PN was 3.1% in the exp arm vs. 7.8% in the std arm. Compared to the std arm, the HR for dose modification was 5.4 in the exp arm (95% CI, 2.3-12.6, p<0.0001); none of the other pt or disease characteristics were significantly associated with dose modification of the tubulin inhibitors. PFS was significantly better in the exp arm and did not differ by PN status (Figure). Conclusions The rate of dose modifications for PN was consistent with protocol-specified dose modification among children and adolescents treated with known tubulin inhibitors as part of a multi-drug regimen for high risk HL. The strategy to preserve Bv dose in the experimental arm was successful. Overall rates of PN were substantially lower than previously reported in adults treated with Bv. While there were no significant differences in the rate of PN between study arms, we found shorter median time to dose modification in the exp arm, corresponding to the second treatment cycle, as compared to the 3rd cycle for the std arm. Despite dose modifications of vincristine and Bv as management strategies for PN in the experimental arm, patients treated with Bv-AVEPC had superior disease control in children with high-risk HL. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Insights on the structure-function relationship of human multidrug resistance protein 7 (MRP7/ABCC10) from molecular dynamics simulations and docking studies.

ATP‐binding cassette (ABC) transporters superfamily mediates multidrug resistance in cancer by extruding structurally distinct chemotherapeutic agents, causing failure in chemotherapy. Among the 49 ABC transporters, multidrug resistance protein 7 (MRP7 or ABCC10) is relatively new and has been identified as the efflux pump of multiple anticancer agents including Vinca alkaloids and taxanes. Herein, we construct and validate a homology model for human MRP7 based on the cryo‐EM structures of MRP1. Structure–function relationship of MRP7 was obtained from molecular dynamics simulations and docking studies and was in accordance with previous studies of ABC transporters. The motion patterns correlated with efflux mechanism were discussed. Additionally, predicted substrate‐ and modulator‐binding sites of MRP7 were described for the first time, which provided rational insights in understanding the drug binding and functional regulation in MRP7. Our findings will benefit the high‐throughput virtual screening and development of MRP7 modulators in the future.

Assessment Tools for Peripheral Neuropathy in Pediatric Oncology: A Systematic Review From the Children's Oncology Group.

Peripheral neuropathy is a known side effect of several chemotherapy agents, including vinca alkaloids and platinum-based chemotherapy. Early recognition and monitoring of this side effect is an important role of the pediatric oncology nurse. There are a variety of peripheral neuropathy assessment tools currently in use, but the usefulness of these tools in identifying and grading neuropathy in children varies, and there is currently no standardized tool in place to evaluate peripheral neuropathy in pediatric oncology. A systematic review was performed to identify the peripheral neuropathy assessment tools that best evaluate the early onset and progression of peripheral neuropathy in pediatric patients receiving vincristine. Because of the limited information available in pediatric oncology, this review was extended to any pediatric patient with neuropathy. A total of 8 studies were included in the evidence synthesis. Based on available evidence, the pediatric-modified Total Neuropathy Scale (ped-m TNS) and the Total Neuropathy Score-pediatric version (TNS-PV) are recommended for the assessment of vincristine-induced peripheral neuropathy in children 6 years of age and older. In addition, several studies demonstrated that subjective symptoms alone are not adequate to assess for vincristine-induced peripheral neuropathy. Nursing assessment of peripheral neuropathy should be an integral and regular part of patient care throughout the course of chemotherapy treatment.

PhytoNanotechnology: Enhancing Delivery of Plant Based Anti-cancer Drugs.

Natural resources continue to be an invaluable source of new, novel chemical entities of therapeutic utility due to the vast structural diversity observed in them. The quest for new and better drugs has witnessed an upsurge in exploring and harnessing nature especially for discovery of antimicrobial, antidiabetic, and anticancer agents. Nature has historically provide us with potent anticancer agents which include vinca alkaloids [vincristine (VCR), vinblastine, vindesine, vinorelbine], taxanes [paclitaxel (PTX), docetaxel], podophyllotoxin and its derivatives [etoposide (ETP), teniposide], camptothecin (CPT) and its derivatives (topotecan, irinotecan), anthracyclines (doxorubicin, daunorubicin, epirubicin, idarubicin), and others. In fact, half of all the anti-cancer drugs approved internationally are either natural products or their derivatives and were developed on the basis of knowledge gained from small molecules or macromolecules that exist in nature. Three new anti-cancer drugs introduced in 2007, viz. trabectedin, epothilone derivative ixabepilone, and temsirolimus were obtained from microbial sources. Selective drug targeting is the need of the current therapeutic regimens for increased activity on cancer cells and reduced toxicity to normal cells. Nanotechnology driven modified drugs and drug delivery systems are being developed and introduced in the market for better cancer treatment and management with good results. The use of nanoparticulate drug carriers can resolve many challenges in drug delivery to the cancer cells that includes: improving drug solubility and stability, extending drug half-lives in the blood, reducing adverse effects in non-target organs, and concentrating drugs at the disease site. This review discusses the scientific ventures and explorations involving application of nanotechnology to some selected plant derived molecules. It presents a comprehensive review of formulation strategies of phytoconstituents in development of novel delivery systems like liposomes, functionalized nanoparticles (NPs), application of polymer conjugates, as illustrated in the graphical abstract along with their advantages over conventional drug delivery systems supported by enhanced biological activity in in vitro and in vivo anticancer assays.

Abstract B190: Antitumor effects of ABC131, a novel diaminothiazole inhibitor of tubulin

Abstract Background: Several established chemotherapy drugs, including vinca alkaloids and paclitaxel, block tumor cell division by disrupting microtubule dynamics, ultimately leading to apoptosis. For decades, these drugs have remained central components for cancer therapy despite their limitations, which include hematologic and neurologic toxicities and the propensity for tumor cells to develop resistance to these agents. In characterizing a new series of diaminothiazoles, we focused on defining the mechanism of action and the antitumor activity of a novel compound (ABC131). Materials and Methods: A library of DATs was synthesized by reaction of substituted phenylisothiocyanates, tetramethylguanidine and substituted phenylacylbromides, and tested for cytotoxicity against several tumor cell lines. These compounds were further assessed for their mechanism(s) of action using a variety of cellular and biochemical assays, and selected compounds were tested in vivo for toxicity and antitumor activity in syngeneic allograft models using PAN02 (pancreatic), B16 (melanoma) or TRAMP (prostate) tumor cells. Results: A library of more than 90 diaminothiazoles was produced, and these compounds demonstrated IC50s for cytotoxicity against PAN02 cells ranging from 0.04 to &amp;gt;100 μM. Several of these compounds depolymerized microtubules in cells. One such compound, ABC131, was selected for detailed characterization because of the potent antiproliferative activity against a panel of murine and human tumor cells (IC50s ~30-300 nM). ABC131 caused dose-dependent microtubule depolymerization in cells, in parallel with G2/M cell cycle arrest and apoptosis. Kinome profiling demonstrated that ABC131 did not significantly inhibit any of more than 400 protein kinases, including cyclin-dependent kinases, which are inhibited by several compounds within this library. Importantly, transport studies demonstrated that ABC131 is not a substrate for P-glycoprotein, a well-established mechanism for resistance to many other anti-microtubule drugs. Oral administration of ABC131 at doses as low as 2 mg/kg/day inhibited tumor growth in all models tested (PAN02, B16, and TRAMP). Pharmacokinetic and biodistribution analyses of ABC131 demonstrated &amp;gt;10-fold IC50 levels in the plasma and tumors following oral dosing of mice. Although ABC131 was rapidly cleared from the plasma, liver, and brain, &amp;gt;IC50 levels of ABC131 persisted in tumors for at least 7 hours after oral dosing. No hematologic or major organ toxicity was observed in mice treated with ABC131 at 500 mg/kg/day for 7 days. A model of peripheral neuropathy in rats demonstrated markedly reduced toxicity for ABC131 compared with paclitaxel. Conclusions: ABC131 is a new potential anticancer agent with several advantages over established anti-microtubule drugs, including oral bioavailability, lack of sensitivity to P-glycoprotein, lack of hematologic toxicity, and reduced neuropathy. These properties of ABC131 are highly supportive of its development as an anticancer drug. Citation Format: Charles D. Smith, Randy S. Schrecengost, Yan Zhuang, Lynn W. Maines, Staci N. Keller, Ryan A. Smith, Cecelia L. Green. Antitumor effects of ABC131, a novel diaminothiazole inhibitor of tubulin [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B190.

Sensitivity of docetaxel-resistant MCF-7 breast cancer cells to microtubule-destabilizing agents including vinca alkaloids and colchicine-site binding agents.

IntroductionOne of the main reasons for disease recurrence in the curative breast cancer treatment setting is the development of drug resistance. Microtubule targeted agents (MTAs) are among the most commonly used drugs for the treatment of breaset cancer and therefore overcoming taxane resistance is of primary clinical importance. Our group has previously demonstrated that the microtubule dynamics of docetaxel-resistant MCF-7TXT cells are insensitivity to docetaxel due to the distinct expression profiles of β-tubulin isotypes in addition to the high expression of p-glycoprotein (ABCB1). In the present investigation we examined whether taxane-resistant breast cancer cells are more sensitive to microtubule destabilizing agents including vinca alkaloids and colchicine-site binding agents (CSBAs) than the non-resistant cells.MethodsTwo isogenic MCF-7 breast cancer cell lines were selected for resistance to docetaxel (MCF-7TXT) and the wild type parental cell line (MCF-7CC) to examine if taxane-resistant breast cancer cells are sensitive to microtubule-destabilizing agents including vinca alkaloids and CSBAs. Cytotoxicity assays, immunoblotting, indirect immunofluorescence and live imaging were used to study drug resistance, apoptosis, mitotic arrest, microtubule formation, and microtubule dynamics.ResultsMCF-7TXT cells were demonstrated to be cross resistant to vinca alkaloids, but were more sensitive to treatment with colchicine compared to parental non-resistant MCF-7CC cells. Cytotoxicity assays indicated that the IC50 of MCF-7TXT cell to vinorelbine and vinblastine was more than 6 and 3 times higher, respectively, than that of MCF-7CC cells. By contrast, the IC50 of MCF-7TXT cell for colchincine was 4 times lower than that of MCF-7CC cells. Indirect immunofluorescence showed that all MTAs induced the disorganization of microtubules and the chromatin morphology and interestingly each with a unique pattern. In terms of microtubule and chromain morphology, MCF-7TXT cells were more resistant to vinorelbine and vinblastine, but more sensitive to colchicine compared to MCF-7CC cells. PARP cleavage assay further demonstrated that all of the MTAs induced apoptosis of the MCF-7 cells. However, again, MCF-7TXT cells were more resistant to vinorelbine and vinblastine, and more sensitive to colchicine compared to MCF-7CC cells. Live imaging demonstrated that the microtubule dynamics of MCF-7TXT cells were less sensitive to vinca alkaloids, and more sensitive to colchicine. MCF-7TXT cells were also noted to be more sensitive to other CSBAs including 2MeOE2, ABT-751 and phosphorylated combretastatin A-4 (CA-4P).ConclusionDocetaxel-resistant MCF-7TXT cells have demonstrated cross-resistance to vinca alkaloids, but appear to be more sensitive to CSBAs (colchicine, 2MeOE2, ABT-751 and CA-4P) compared to non-resistant MCF-7CC cells. Taken together these results suggest that CSBAs should be evaluated further in the treatment of taxane resistant breast cancer.

Plant Anti-cancer Agents and their Biotechnological Production in Plant Cell Biofactories

Bioactive plant secondary metabolites have complex chemical structures, which are specific to each plant species/family, and accumulate in tiny amounts. The growing market demand for many phytochemicals can lead to the over-harvesting of medicinal plants in their natural habitat, endangering species in the process. An ongoing challenge for our society is therefore to develop a bio-sustainable production of phytochemicals, among other natural resources. Cancer is currently a major health problem, responsible for approximately 8.2 million deaths per year worldwide. We therefore focused this review on cancer therapeutic agents from plants and their biotechnological production. An extensive review of the literature shows that although a wide range of phytochemicals have demonstrated anti-proliferative activity in vitro, only a few examples of plant-based drugs are included in the Anatomical Therapeutic Chemical (ATC) classification as antineoplastic agents. These include vinca alkaloids and their derivatives (L01CA), podophyllotoxin derivatives (L01CB), and paclitaxel and its derivatives (L01CD), as well as camptothecin derivatives (L01XX). These compounds all have in common a complex chemical structure, a scarce distribution in nature, and a high added value. After describing the chemical structures, natural sources and biological activities of these anticancer compounds, we focus on the state of the art in their biotechnological production in plant cell biofactories. More in-depth studies are required on the biosynthesis of target plant metabolites and its regulation in order to increase their biotechnological production in plant cell factories and ultimately implement these biosustainable processes at an industrial level.

Novel mutations involving βI-, βIIA-, or βIVB-tubulin isotypes with functional resemblance to βIII-tubulin in breast cancer.

Tubulin is the target for very widely used anti-tumor drugs, including Vinca alkaloids, taxanes, and epothilones, which are an important component of chemotherapy in breast cancer and other malignancies. Paclitaxel and other tubulin-targeting drugs bind to the β subunit of tubulin, which is a heterodimer of α and β subunits. β-Tubulin exists in the form of multiple isotypes, which are differentially expressed in normal and neoplastic cells and differ in their ability to bind to drugs. Among them, the βIII isotype is overexpressed in many aggressive and metastatic cancers and may serve as a prognostic marker in certain types of cancer. The underpinning mechanisms accounting for the overexpression of this isotype in cancer cells are unclear. To better understand the role of β-tubulin isotypes in cancer, we analyzed over 1000 clones from 90 breast cancer patients, sequencing their β-tubulin isotypes, in search of novel mutations. We have elucidated two putative emerging molecular subgroups of invasive breast cancer, each of which involve mutations in the βI-, βIIA-, or βIVB isotypes of tubulin that increase their structural, and possibly functional, resemblance to the βIII isotype. A unifying feature of the first of the two subgroups is the mutation of the highly reactive C239 residue of βI- or βIVB-tubulin to L239, R239, Y239, or P239, culminating in probable conversion of these isotypes from ROS-sensitive to ROS-resistant species. In the second subgroup, βI, βIIA, and βIVB have up to seven mutations to the corresponding residues in βIII-tubulin. Given that βIII-tubulin has emerged as a pro-survival factor, overexpression of this isotype may confer survival advantages to certain cancer cell types. In this mini-review, we bring attention to a novel mechanism by which cancer cells may undergo adaptive mutational changes involving alternate β-tubulin isotypes to make them acquire some of the pro-survival properties of βIII-tubulin. These "hybrid" tubulins, combining the sequences and/or properties of two wild-type tubulins (βIII and either βI, βIIA, or βIVB), are novel isotypes expressed solely in cancer cells and may contribute to the molecular understanding and stratification of invasive breast cancer and provide novel molecular targets for rational drug development.

Abstract B54: Non-malignant cells from metastatic niches induce estrogen receptor-positive breast cancer cell resistance to therapy

Abstract Metastatic lesions remain the main cause of mortality in breast cancer (BrCa) and their resistance to systemic therapies has been mainly attributed to mutations in BrCa cells, while the non-mutually exclusive role of the metastatic microenvironment has been largely overlooked. To address the role of the local microenvironment of metastatic sites in conferring drug resistance to BrCa cells, we assembled heterotypic in vitro three-dimensional (3D) tissue cultures comprised of estrogen receptor-positive (ER+) BrCa cells and non-malignant cells from organs frequently targeted by metastatic disease. BrCa cells (MCF7, T47D, and ZR75-1) expressing the firefly luciferase gene were grown in extracellular matrices (collagen type I and Matrigel) alone or with nonmalignant cells from the respective metastatic target tissues, and exposed to clinically achievable concentrations of FDA-approved antineoplastic agents widely used for the treatment of BrCa. Interestingly, BrCa cell response to antiestrogens (hydroxytamoxifen (4-OHT), fulvestrant or raloxifene) in 3D conditions was marked by acinar differentiation of tumor spheroids into structures that resemble normal breast epithelium. Co-culture of BrCa cells with immortalized accessory cells from the bone (BMSCs and osteoblasts); brain (astrocytes); liver (hepatocytes); and lung (fibroblasts) in 3D (but not 2D) conditions, inhibited the antiestrogen-induced acinar differentiation and conferred resistance to 4-OHT, raloxifene, and fulvestrant at clinically relevant doses. The results obtained with immortalized human BMSCs were further confirmed in co-cultures of BrCa cells with primary human BMSCs isolated from bone metastatic site. MCF7 cells injected s.c. in nude mice together with BMSCs (heterotypic xenografts) had decreased response to tamoxifen compared with monotypic xenografts (MCF7 alone). Furthermore, immortalized BMSCs or metastatic patient-derived BMSCs induced MCF7 cell resistance to several chemotherapeutic agents including vinca alkaloids (vincristine, vinblastin and vinorelbin) and taxanes (docetaxel, paclitaxel, cabazitaxel). Notably, primary BMSCs from healthy donors and brain astrocytes isolated from cancer-free neurosurgical specimens did not induce BrCa cell resistance to anti-estrogens or chemotherapeutic agents. BMSCs induced in MCF7 cells downregulation of TGFβ2; upregulation of a transcriptional signature enriched for genes associated with high-grade tumors, including genes involved in IGF1R, IL6 and EGFR superfamily members; NF-kappaB and other antiapoptotic pathways; and elevated c-Myc protein levels. The co-cultures of MCF7 cells with BMSCs had increased sensitivity to inhibitors of c -myc, IGF1R, IL-6 and JAK/STAT pathways when compared to the respective mono-cultures. Our results indicate that local nonmalignant cells present in the metastatic niche can function as “accessories” to the tumor, conferring BrCa cell resistance to antiestrogens and chemotherapeutic agents in 3D tissue cultures and xenograft models. Preclinical modeling of the composition and 3D architecture of metastatic lesions can help elucidate the mechanisms of stroma-induced drug resistance and may reveal new therapeutic targets for refractory BrCa patients with metastatic disease. Citation Format: Eugen Dhimolea, Richard Groen, Culhane Aedin, Mitsiades Nicholas, Polyak Kornelia, Mitsiades Constantine. Non-malignant cells from metastatic niches induce estrogen receptor-positive breast cancer cell resistance to therapy. [abstract]. In: Abstracts: AACR Special Conference on Cellular Heterogeneity in the Tumor Microenvironment; 2014 Feb 26-Mar 1; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(1 Suppl):Abstract nr B54. doi:10.1158/1538-7445.CHTME14-B54

Effect of duloxetine on chemotherapy-induced painful peripheral neuropathy.

181 Background: Approximately 20% to 40% of patients with cancer who receive neurotoxic chemotherapy will develop painful chemotherapy-induced peripheral neuropathy. Smith et. al firstly reported that duloxetine was effective on above neuropathy after taxanes and platinums (JAMA 2013), so we planed to evaluate the duloxetine effect in Japanese patients after above drugs and more expanding drugs include vinca alkaloids and bortezomib. Methods: Patients were randomized to receive either duloxetine followed by vitamin(V)B12 or VB12 by duloxetine. The initial treatment consisted of 20 mg of duloxetine or 1.5g VB12 for the first week and 40mg of duloxetine or VB12 daily for 3 additional weeks (an open label, randomized, crossover). Dose reduction by the adverse effects was permitted. The primary hypothesis was that duloxetine would be more effective than VB12 in decreasing chemotherapy-induced peripheral neuropathic pain. Numbness and Pain severity were assessed weekly using visual analogue scale (VAS). This research was approved by the Research Ethics Committee of Higashi Sapporo Hospital and University Hospital Medical Information Network (UMIN) Center in Japan.Thirty-four cases (Breast cancer: taxanes 2, gastric cancer: taxane 5, colon cancer: oxaliplatin 6, Malignant lymphoma: vincristine 13, multiple myeloma: bortezomib 8) were made an entry in our institution. Five cases dropped out because of the adverse effect with sleepy and general malaise. Results: Obvious improvements of VAS scores of numbness and pain were observed in duloxetine group. Significant differences of delta VAS (pre VAS scale – 4 weeks VAS after drug administration) were observed between duloxetine group and VB12 group in the aspect of numbness (p=0.02) and pain (p=0.03). Conclusions: Among patients with painful chemotherapy-induced peripheral neuropathy, the use of duloxetine compared with VB12 for 4 weeks resulted in a reduction in numbness and pain, but there are many cases with drop out by the adverse effects. Clinical trial information: 000011554.

Abstract 5677: A comparative study of the interaction of the maytansinoid, DM1-Me, vinblastine, and taxol with human cells

Abstract The current interest in antimitotic compounds that interact with microtubules is caused, in part, by their clinical importance in oncology. Several microtubule-binding compounds, including Vinca alkaloids, taxanes, maytansinoids, and auristatins, are in clinical use, some additionally being evaluated as antibody conjugates. To better understand the factors that determine the potency of antibody-maytansinoid conjugates in killing cells, we examined the interaction of the maytansinoid, DM1-Me, with MCF7 cells, in comparison with vinblastine and taxol. DM1-Me was more potent in arresting mitosis than vinblastine or taxol (5- and 13-fold, respectively). We compared the levels of accumulation of these three compounds by MCF7 cells following a 24 hour exposure at the mitotic IC50 concentration and found that, at this concentration, cells accumulated comparable amounts of vinblastine and DM1-Me, but required more than a 10-fold greater concentration of taxol to achieve a similar effect. Additionally, cells exposed to each compound for 2 hours prior to being washed into drug free medium, retained most of the accumulated DM1-Me or taxol for at least 24 h, while most vinblastine was released into the medium within the first 2 h. DM1-Me and taxol had similar affinities for MCF7 cells, while that of vinblastine was 4-6-fold lower. These properties of DM1-Me, vinblastine and taxol suggest that maytansinoids are a better choice for antibody conjugates than vinblastine or taxol, a conclusion which is consistent with the experimental data and clinical experience with antibody conjugates made with compounds of these three classes. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5677. doi:1538-7445.AM2012-5677

Abstract 14: Role of Cdk1 and Bcl-2 proteins in mitotic cell death

Abstract Tumor cells exhibit variable responses to microtubule inhibitors (MTIs) and an understanding of the molecular basis of this variability and the determinants of resistance and sensitivity to these agents is critical for appropriate patient selection while minimizing associated toxicity. Our studies have focused on elucidation of the mechanism of action of MTIs including vinca alkaloids and taxanes. Using vinblastine-treated KB-3 cells, a HeLa subline, as a model system, we have shown previously that death in mitosis is associated with high levels of phosphorylation of anti-apoptotic Bcl-2 family proteins (Bcl-2, Bcl-xL and Mcl-1) catalyzed by cyclin dependent kinase-1 (Cdk1)/cyclin B. In this study, we sought to determine whether these results reflected a more general trend, and conversely, whether escape from mitotic arrest (mitotic slippage) was associated with defective Cdk1 activation and/or reduced levels of phosphorylation of anti-apoptotic Bcl-2 proteins. For this purpose, we used DLD-1 and HT-29 colon carcinoma cells lines that stably express GFP-tagged histone H2B which enable cell fate to be studied by examination of nuclear morphology by fluorescent microscopy and time lapse imaging. In confirmation of previous findings, DLD-1 cells on treatment with paclitaxel exhibited extensive mitotic slippage after mitotic arrest and then either survived or died in subsequent interphase. In contrast, the vast majority of HT29 cells upon paclitaxel treatment died in mitosis. To determine if a relationship existed between these different fate profiles and the extent/duration of Cdk1-mediated Bcl-2 protein phosphorylation, cells were synchronized by double thymidine block, treated with paclitaxel, and extracts made at 4-h intervals over a 48-h time-course for analysis by immunoblotting. In DLD-1 cells, both Mcl-1 and Bcl-xL were transiently and partially phosphorylated and PARP cleavage was incomplete, consistent with the majority of the cells surviving through mitotic arrest. In contrast, in HT-29 cells, paclitaxel induced robust phosphorylation and subsequent degradation of Mcl-1 as well as extensive Bcl-xL phosphorylation. In addition, PARP was completely cleaved consistent with widespread mitotic cell death. Interestingly, PARP cleavage was observed to occur in HT-29 cells only under conditions where Bcl-xL was phosphorylated and Mcl-1 was degraded, indicating that mitotic death requires simultaneous functional elimination of both these anti-apoptotic Bcl-2 proteins. (Note that Bcl-2 expression was low to undetectable in both DLD-1 and HT-29 cells compared to KB-3 cells.) These results support the hypothesis that death in mitosis results from sustained Cdk1 activation and high levels of phosphorylation and subsequent inactivation of anti-apoptotic Bcl-2 proteins. Further, our findings suggest that the robustness of these signaling events may be useful as a marker to define tumor cell susceptibility to anti-mitotic drugs. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 14. doi:10.1158/1538-7445.AM2011-14

Alkaloids derived from genus Veratrum and Peganum of Mongolian origin as multidrug resistance inhibitors of cancer cells

Alkaloids comprise one of the largest groups of plant secondary metabolites including vinca alkaloids. The ability of six alkaloids from Veratrum lobelianum, one from Veratrum nigrum and three from Peganum nigellastrum to modify transport activity of MDR1 was studied. Flow-cytometry in a multidrug-resistant human MDR1-gene-transfected mouse lymphoma cells (L5178Y) was applied. The inhibition of multidrug resistance was investigated by measuring the accumulation of rhodamine-123 in cancer cells. Veralosinine and veranigrine were the most effective resistance modifiers. In a checkerboard method veralosinine and veranigrine enhanced the antiproliferative effects of doxorubicin on MDR cells in combination. The structure–activity relationships were discussed.

Plant Derived Compounds Having Activity against P388 and L1210 Leukemia Cells

Cancer is a major cause of death and the number of new cases as well as the number of individuals living with cancer is expanding continuously. Due to the enormous propensity of plants that synthesize mixture of structurally derived bioactive compounds, the plant kingdom is potentially diverse source of chemical constituents with murine leukemia activity. Plant derived compounds have played an important role in the development of several clinically useful anticancer agents having activity against murine leukemia. These include vinca alkaloids, lignans, terpenoids, quinines and phytochemicals such as flavones, flavonoids, flavonol. The active compounds which have been isolated from various plant sources are listed, classified and discussed in terms of their activity against murine leukemia cells. Structure-activity relationship has been studied for further development of compounds which show activity against leukemia cells.

Abstract 579: Chinese herbal mixture LQ inhibits tumor growth and metastasis and increases survival in orthotopic and other mouse models of human and mouse cancer

Abstract Natural products have been used as sources of first-line cancer chemotherapeutic agents, including vinca alkaloids, taxanes, podophyllotoxin and camptothecin. However, Traditional Chinese Medicine (TCM) combinations (Fufang), which have been widely used in China for over 5000 years, are still poorly understood with regard to the types of cancer they are effective against as well as their mechanism of action. We report here on the use of patient-like orthotopic nude-mouse models of metastatic cancer and other mouse tumor models to obtain proof-of-concept that TCM (Fufang) combinations have anti-tumor and anti-metastatic activity. In the present study, human and mouse lung, pancreatic and prostate cancer cell lines (H460, Lewis lung carcinoma [LLC) MIA-PaCa-2 and PC-3, respectively), labeled with red fluorescent protein (RFP) or green fluorescent protein (GFP), were orthotopically implanted or injected subcutaneously, or injected in the tail vein in nude mice to evaluate anti-tumor and anti-metastatic efficacy of the Fufang LQ, which contains a mixture of herbs. Results showed that LQ (gavage, 600 mg/kg/day) significantly inhibited prostate, pancreatic and lung cancer tumor growth as measured by imaging, tumor size and weight, in both subcutaneous and metastatic models. LQ was efficacious against primary and metastatic cancer without weight loss in contrast to drugs such as doxorubicin and cisplatin, which caused significant weight loss. Survival of tumor-bearing mice was also prolonged by LQ treatment. Furthermore, in vitro experiments demonstrated that LQ inhibited proliferation of tumor cells (LLC, H460, PC-3 and MIA-PaCa-2) in a dose-dependent manner. Those results indicate that LQ has efficacy against metastatic pancreatic and lung and prostate cancer which demonstrates its clinical potential. The results also suggest that GFP- and RFP-expressing tumors in orthotopic and other nude mouse models can be widely used for in vivo evaluation of TCM. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 579.

Itraconazole, a Commonly Used Antifungal that Inhibits Hedgehog Pathway Activity and Cancer Growth

In a screen of drugs previously tested in humans we identified itraconazole, a systemic antifungal, as a potent antagonist of the Hedgehog (Hh) signaling pathway that acts by a mechanism distinct from its inhibitory effect on fungal sterol biosynthesis. Systemically administered itraconazole, like other Hh pathway antagonists, can suppress Hh pathway activity and the growth of medulloblastoma in a mouse allograft model and does so at serum levels comparable to those in patients undergoing antifungal therapy. Mechanistically, itraconazole appears to act on the essential Hh pathway component Smoothened (SMO) by a mechanism distinct from that of cyclopamine and other known SMO antagonists, and prevents the ciliary accumulation of SMO normally caused by Hh stimulation.

Syndrome of inappropriate antidiuresis (SIAD) in a patient with rectal carcinoma undergoing preoperative radiation

Dear Editor: We report a first case of the syndrome of inappropriate antidiuretic hormone secretion occurring following preoperative radiation for rectal carcinoma. The syndrome of inappropriate antidiuretic hormone secretion (SIADH) consists of hyponatremia, inappropriately elevated urine osmolality (>200 mOsm/kg), excessive urinary sodium excretion (>30 mEq/L) and decreased serum osmolality. SIADH is a known paraneoplastic syndrome, which may result from numerous types of cancer, including small cell lung cancer, gastrointestinal cancer and lymphoma. Small cell lung carcinoma alone accounts for 75% of all cases of SIAD caused directly by tumours. It has also been known to occur as a complication of chemotherapy use, including vinca alkaloids or cyclophosphamide. It has been described only once before in conjunction with rectal carcinoma. A 68-year-old male presented with constipation, rectal bleeding and a palpable low rectal mass on digital rectal examination. Biopsy-confirmed moderately differentiated adenocarcinoma and staging with computed tomography and magnetic resonance imaging demonstrated a large rectal mass abutting the dentate line. The tumour was staged as a T3N0M0 rectal adenocarcinoma as per the TNM (American Joint Committee on Cancer TNM Staging Handbook) staging system. He had a past history of hypertension which was well controlled on diltiazem, had no allergies and was an ex-smoker. At his initial oncology consultation, he had normal full blood count and electrolytes for the previous 6 months. Following multidisciplinary assessment, he was recommended to undergo short course preoperative three-dimensional conformal radiation therapy (25 Gray in five fractions, 15 MV photons). He was planned to undergo abdomino-perineal resection (APR) 1 week after completion of his radiation therapy, but at his anaesthetic assessment, he was found to have a serum sodium of 121mEq/L (normal range 135–145mEq/L). A repeat estimation was performed which showed a serum sodium of 123 mEq/L and a urinary spot sodium of 60 mEq/L. Serum ADH was 16 pg/mL and urinary osmolality was 703 mOsm/kg. Investigations included a normal serum cortisol and elevated C-reactive protein 45 IU/L. Following aggressive fluid restriction, serum sodium normalised long enough to permit APR to take place. The histological analysis demonstrated a ypT3N1(2/15) M0 mucinous adenocarcinoma. Postoperatively, serum ADH normalised to 5.4 pg/mL within 4 days of surgery. It was not possible to check ADH expression on the primary tumour, but the normalisation of serum sodium and the abrupt postoperative drop in serum ADH make us believe that this clinical course is consistent with synthesis and release of ADH from a primary rectal carcinoma. The patient was discharged on the 14th postoperative day and remains well, with normal serum sodium, and he is scheduled for adjuvant chemotherapy. This patient fulfilled all the criteria for SIAD, including high urinary sodium and urinary osmolality as well as inappropriately high ADH levels during the period of hyponatremia. The serum sodium normalised with aggressive fluid restriction long enough to permit APR to take place. There are a number of putative mechanisms for this, including aberrant secretion of ADH by adenocarcinoma cells and possible cytokine release as a consequence of Int J Colorectal Dis (2009) 24:861–862 DOI 10.1007/s00384-009-0650-1

Myeloid-Associated Antigen Expression Is an Adverse Factor for Complete Remission Following Induction Chemotherapy of Adult Precursor T-Lymphoblastic Leukemia/Lymphoma (T-ALL).

We retrospectively reviewed our experience of 63 adult T-ALL patients to identify clinical and pathologic prognostic factors and build a risk-stratification model for induction chemotherapy. At presentation, the patients' median age was 30, 49 were male and 14 female, 69% had lymphadenopathy, 38% a mediastinal mass, 24% CNS involvement and 21% splenomegaly. The median initial WBC was 17.9 x 109/L (range 0.10–510.0). Blasts expressed CD34 in 42% of cases, CD10 in 33% and at least one myeloid-associated antigen (CD13 or CD33) in 27%. Karyotypes were abnormal in 34% of cases. Fifty-three of 61 patients (87%) who underwent induction chemotherapy achieved complete remission (CR) on protocols including vinca alkaloids, anthracyclines and corticosteroids. On univariate analysis; age, gender, initial WBC, CD10, CD34 and abnormal karyotype did not predict CR but patients expressing at least one myeloid-associated antigen had a CR of 71% compared to 93% (P=0.03) for patients not expressing myeloid antigens. The median follow-up was 19.2 months (95% CI: 0.1–172.8). Twenty-three patients relapsed with a median relapse-free survival (RFS) of 41.6 months (95%CI: 21.6–55.9). The RFS was longer for patients with an initial WBC of 3–50 x 109 and for cases expressing CD10 but neither was statistically significant (P=0.19, P=0.14). On follow-up, 34 patients died with a median overall survival (OS) of 31.3 months (95%CI: 16.8–56.8). Patients with CD10 expression had a longer median OS at 44.7 months (versus 19.2 months for CD10 negative patients) but again, the difference was not statistically significant (P=0.11). Age, gender, CD34, myeloid-associated antigen expression and karyotype did not influence RFS or OS. Our study indicates that expression of myeloid-associated antigens is an adverse prognostic factor for complete remission of adult T-ALL and should be considered for induction chemotherapy risk-stratification.

Comparison of the antivascular and cytotoxic activities of TZT-1027 (Soblidotin) with those of other anticancer agents

TZT-1027 (Soblidotin), a microtubule-depolymerizing agent exerts both a direct cytotoxic activity against cancer cells and an indirect antivascular activity against tumor vascular endothelial cells. We compared both activities of TZT-1027 with those of various anticancer agents having different mechanisms of action, including vinca alkaloids, a vascular targeting agent, a taxane and nonmicrotubule-binding agents. In the MTT assay, TZT-1027 most potently inhibited the growth of both murine colon C26 cancer cells and human umbilical vein endothelial cells, implying its potent antivascular activity against tumor vasculature in addition to its cytotoxic activity against cancer cells. Treatment with 0.1 microg/ml TZT-1027 significantly enhanced vascular permeability in human umbilical vein endothelial cell monolayers and a single intravenous administration of 2 mg/kg TZT-1027 significantly reduced the perfusion of Colon26 tumors implanted into mice, with efficacies superior to vinca alkaloids and comparable to a known vascular targeting agent. These results strongly suggest that TZT-1027 exerts marked antivascular activity. Next, to clarify the mechanism of the antivascular activity, we have taken a novel approach, and analyzed the relationships among human umbilical vein endothelial cells cytotoxicity, vascular permeability and tumor perfusion, on the basis of efficacies of each agent. Analyses revealed strong and significant correlations, and indicated that the vascular endothelial cell damage leads to endothelial barrier dysfunction and, thereby, tumor vascular shutdown. In summary, TZT-1027 was verified to have not only an excellent cytotoxic activity, but also an attractive antivascular activity through the induction of damage to vascular endothelial cells. We believe that these dual activities may make TZT-1027 useful for treating solid tumors.

Cardiotoxicity of Cancer Chemotherapy

Many children and adolescents with cancer receive chemotherapeutic agents that are cardiotoxic. Thus, while survival rates in this population have improved for some cancers, many survivors may experience acute or chronic cardiovascular complications that can impair their quality of life years after treatment. In addition, cardiac complications of treatment lead to reductions in dose and duration of chemotherapy regimens, potentially compromising clinical efficacy. Anthracyclines are well known for their cardiotoxicity, and alkylating agents, such as cyclophosphamide, ifosfamide, cisplatin, busulfan, and mitomycin, have also been associated with cardiotoxicity. Other agents with cardiac effects include vinca alkaloids, fluorouracil, cytarabine, amsacrine, and asparaginase and the newer agents, paclitaxel, trastuzumab, etoposide, and teniposide. The heart is relatively vulnerable to oxidative injuries from oxygen radicals generated by chemotherapy. The cardiac effects of these drugs include asymptomatic electrocardiographic abnormalities, blood pressure changes, arrhythmias, myocarditis, pericarditis, cardiac tamponade, acute myocardial infarction, cardiac failure, shock, and long-term cardiomyopathy. These effects may occur during or immediately after treatment or may not be apparent until months or years after treatment. Mild myocardiocyte injury from chemotherapy may be of more concern in children than in adults because of the need for subsequent cardiac growth to match somatic growth and because survival is longer in children. Primary prevention is therefore important. Patients should be educated about the cardiotoxic risks of treatment and the need for long-term cardiac monitoring before chemotherapy is begun. Cardiotoxicity may be prevented by screening for risk factors, monitoring for signs and symptoms during chemotherapy, and continuing follow-up that may include electrocardiographic and echocardiographic studies, angiography, and measurements of biochemical markers of myocardial injury. Secondary prevention should aim to minimize progression of left ventricular dysfunction to overt heart failure. Approaches include altering the dose, schedule, or approach to drug delivery; using analogs or new formulations with fewer or milder cardiotoxic effects; using cardioprotectants and agents that reduce oxidative stress during chemotherapy; correcting for metabolic derangements caused by chemotherapy that can potentiate the cardiotoxic effects of the drug; and cardiac monitoring during and after cancer therapy. Avoiding additional cardiotoxic regimens is also important in managing these patients. Treating the adverse cardiac effects of chemotherapy will usually be dependent on symptoms or will depend on the anticipated cardiovascular effects of each regimen. Treatments include diuresis, afterload reduction, beta-adrenoceptor antagonists, and improving myocardial contractility.