Anti-Cancer Agents in Medicinal Chemistry (v.14, #2)

Poxvirus-Based Vaccines for Cancer Immunotherapy: New Insights from Combined Cytokines/Co-Stimulatory Molecules Delivery and “Uncommon” Strains by Valerio Izzi, Marcin Buler, Laura Masuelli, Maria G. Giganti, Andrea Modesti, Roberto Bei (183-189).
Poxvirus-based vaccines have a long record of efficacy as both anti-tumour agents and vectors for gene therapy in differenthuman tumour models. Interestingly, several studies of these vaccines have now entered the clinical evaluation phase for safety andeffectiveness. A desirable outcome of antigen specific cancer immunotherapy is the disruption of host self-tolerance against endogenoustumour-associated antigens (TAAs). Nonetheless, recent studies have found reductions in vaccine efficacy due to host anti-vaccineimmune reactions. Thus, newer approaches bringing together poxvirus-based vaccination and immunostimulation are being developed,and new poxvirus strains are being examined in tumour therapy studies.;Our review summarizes the current knowledge on the efficacy of poxvirus-based vaccination on human tumours, with a particular focuson approaches aimed at increasing innate and specific immune responses. Special attention will be devoted to the new poxvirus strainsthat are currently under consideration for tumour therapy; the current knowledge on clinical trials and outcomes will also be reviewed.

The Need for Improvement of the Treatment of Advanced and Metastatic Cervical Cancer, the Rationale for Combined Chemo-Immunotherapy by Helene van Meir, Gemma G. Kenter, Jacobus Burggraaf, Judith R. Kroep, Marij J.P. Welters, Cornelis J.M. Melief, Sjoerd H. van der Burg, Mariette I.E. van Poelgeest (190-203).
The prognosis of patients with metastatic cervical cancer is poor with a median survival of 8-13 months. Despite the potencyof chemotherapeutic drugs, this treatment is rarely curative and should be considered palliative only. The last decades, targeted therapiessuch as immunotherapy have emerged as an attractive option for the treatment of these patients. Immunotherapy can consist of differentmodalities such as monoclonal antibodies, adoptive lymphocyte transfer and vaccines, which all are intended to augment the antitumorimmune responses in cancer patients. The available evidence indicates that both active and adoptive immunotherapeutical strategies arequite effective against small tumor burdens, but are usually insufficient to eradicate the disease in patients with advanced stages ofdifferent kinds of cancer, despite strong induction of tumor-specific immune responses. Although chemotherapy and immunotherapyhave not shown to be curative as single modalities, accumulating evidence suggests that combinations of these treatments hold potentialfor improved clinical outcomes in advanced stages of cancer. Therefore, the combination of chemotherapy and immunotherapy is nolonger considered incompatible, because of the emerging insight that certain chemotherapy-based cancer treatments may activate theimmune system against the tumor through several molecular and cellular mechanisms. Chemotherapeutic agents and immunotherapy maythus be synergistic and enhance the clinical response.;In this review, we show the rationale for combined chemo-immunotherapeutic strategies, and summarize recent data from clinical trialsperformed in patients with different types of cancer. Challenges such as the selection of the optimal dose and treatment schedule, will bediscussed as well as the identification of immune-specific biomarkers. Furthermore, we evaluated the long-term clinical outcomes ofpatients with advanced cervical cancer treated with HPV16 E6/E7 SLP vaccination with or without chemotherapy. Finally, the future ofvaccination therapy in combination with chemotherapy for the treatment of cervical cancer is discussed.

CCL21 and IFNγ Recruit and Activate Tumor Specific T cells in 3D Scaffold Model of Breast Cancer by Vy Phan-Lai, Forrest M. Kievit, Stephen J. Florczyk, Kui Wang, Mary L. Disis, Miqin Zhang (204-210).
Effective elicitation of endogenous immunity is associated with improved prognosis for cancer patients. Clinical evidence inhematological and solid cancers shows that intratumoral injection of immunostimulatory genes primes and augments endogenous T cellresponses. The ability of pro-inflammatory chemokines/cytokines to facilitate migration/activation of antigen-presenting cells (APC) andlymphocytes prompted our modeling of intratumoral delivery of a chemokine/cytokine combination for breast cancer treatment. Here, wedemonstrate that expression of chemokine ligand 21 (CCL21) and interferon gamma (IFNγ) in tumors improves tumor specific T cellrecruitment to tumor and activation in the tumor milieu. IFNγ and CCL21 were delivered into tumor cells via plasmids, and transfectedcells were seeded to form spheroids on three-dimensional (3D) chitosan-alginate (CA) scaffolds. Co-expression of CCL21 and IFNγ, asevidenced by qRT-PCR and ELISA, induced increased recruitment, binding, and infiltration of anti-neu (p98) peptide specific T cellsinto the breast tumors as determined by SEM and immunofluorescence assays. The co-expression promoted recruitment of only p98 Tcells, but not naïve T cells, demonstrating an antigen-restricted activation. Furthermore, the co-expression impacted T helper (Th) cellimmunity, promoting an increase in secretion of pro-inflammatory Th-associated cytokine, tumor necrosis factor alpha (TNFα), andcytotoxic T lymphocyte (CTL)-associated protease, Granzyme B (GzB). Therefore, 3D CA scaffolds may be a useful breast cancer tumormicroenvironment model to evaluate T cell function. Further characterization of CCL21-IFNγ mediated anti-tumor immunity willpotentially benefit the development of chemokine/cytokine combination platforms as anti-cancer agents.

Ex Vivo-Activated MHC-Unrestricted Immune Effectors for Cancer Adoptive Immunotherapy by Valeria Leuci, Giulia Mesiano, Loretta Gammaitoni, Maja Todorovic, Lidia Giraudo, Fabrizio Carnevale-Schianca, Massimo Aglietta, Dario Sangiolo (211-222).
Adoptive immunotherapy is considered a promising strategy for the treatment of metastatic tumors and current research effortsare directed to define the optimal approach and facilitate the transferability from preclinical to clinical settings. Among several approachesit is possible to schematically distinguish strategies based on either MHC-restricted or MHC-unrestricted immune effectors. The first aremainly based on the infusion of tumor-specific T lymphocytes capable of recognizing determined MHC-restricted tumor associatedantigens (TAA) through their T cell receptor. MHC-unrestricted approaches do not target specific tumor associated antigens and aremainly mediated by effectors of the innate immune system, like natural killer (NK) cells or NKT cells, first barrier against pathogens andtumorigenesis processes, or by ex vivo activated lymphocytes like cytokine-induced killer (CIK) cells. MHC-unrestricted effectors areusually more abundant than TAA-specific precursors and easier to expand. Furthermore their activity is not restricted to precise HLAhaplotypes,not limited to a single tumor histotype and could overcome downregulation of MHC molecules operated by tumor cells asimmune escape mechanism.;In this review we will discuss the main cancer immunotherapy strategies based on MHC-unrestricted immune effectors. The topic will beapproached from the angle of ex vivo expansion protocols in clinical prospective, as well as potential approaches to favorably modulatetheir functions.

Chemical Metabolic Inhibitors for the Treatment of Blood-Borne Cancers by Martin Villalba, Nuria Lopez-Royuela, Ewelina Krzywinska, Moeez G. Rathore, Robert A. Hipskind, Houda Haouas, Nerea Allende-Vega (223-232).
Tumor cells, including leukemic cells, remodel their bioenergetic system in favor of aerobic glycolysis. This process is called“the Warburg effect” and offers an attractive pharmacological target to preferentially eliminate malignant cells. In addition, recent resultsshow that metabolic changes can be linked to tumor immune evasion. Mouse models demonstrate the importance of this metabolicremodeling in leukemogenesis. Some leukemias, although treatable, remain incurable and resistance to chemotherapy produces anelevated percentage of relapse in most leukemia cases. Several groups have targeted the specific metabolism of leukemia cells inpreclinical and clinical studies to improve the prognosis of these patients, i.e. using L-asparaginase to treat pediatric acute lymphocyticleukemia (ALL). Additional metabolic drugs that are currently being used to treat other diseases or tumors could also be exploited forleukemia, based on preclinical studies. Finally, we discuss the potential use of several metabolic drugs in combination therapies,including immunomodulatory drugs (IMiDs) or immune cell-based therapies, to increase their efficacy and reduce side effects in thetreatment of hematological cancers.

Garlic (Allium sativum) has been used for centuries as a prophylactic and therapeutic medicinal agent. Importantly, garlic hasbeen suggested to have both cancer-preventive potential as well as significant enhancing effects on the immune system. While theseobservations are supported experimentally both in vitro and in vivo, the impact of garlic in assisting the immune system in the preventionof cancer still lacks experimental confirmation. Studies addressing the immunomodulatory effects of garlic reveal conflicting data as topro- or anti-inflammatory responses depending on the particular experimental set-ups and the garlic preparation used (i.e. garlic extractversus chemically pure garlic compounds). Here we provide an overview of the chemistry of the major garlic organosulfur compounds,summarize the current understanding and propose a link between the immunomodulating activity of garlic and the prevention of cancer.We hypothesize that garlic rather elicits anti-inflammatory and anti-oxidative responses that aid in priming the organism towardseradication of an emerging tumor.

Application of dsRNA in Cancer Immunotherapy: Current Status and Future Trends by Bo Jin, Liu-Fang Cheng, Kai Wu, Xiao-Hong Yu, Anthony E.T. Yeo (241-255).
Cancer cells create a microenvironment that prevents tumor rejection by the host's immune system. The activation of patternrecognition receptors (PRRs) can elicit an innate immune response and guide the adaptive immune response to overcome this. dsRNAanalogs can trigger TLR3, RIG-I, MDA5, NLRP3 and several other PRRs to induce not only robust immune response against cancer butalso programmed cell death. This review focuses on the signal pathways activated by dsRNA and examines examples of their clinicalapplication in cancer treatment.

Traditional anti-cancer therapies (surgery, radiotherapy and chemotherapy) have limited effectiveness in curbing progressionof advanced tumors. However, with advances in immunology and molecular biology in the last two decades, the prognosis of cancerimmunotherapy has improved. An emerging therapy is the cancer vaccine as adjunctive therapy. The purpose of this paper is to reviewthis therapeutic modality for non-small cell lung cancer.

HPV-Specific Immunotherapy: Key Role for Immunomodulators by Stephanie Van de Wall, Hans W Nijman, Toos Daemen (265-279).
Cervical cancer is the second most common malignancy among women worldwide. The prime causal factor of the disease is apersistent infection with human papillomavirus (HPV) with individuals failing to mount a sufficient immune response against the virus.Despite the current success of HPV16- and 18-specific prophylactic vaccination, established HPV infections and associated neoplasiarequire therapeutic vaccines with the induction of cellular immunity. The sustained expression of early proteins E6 and E7 from majoroncogenic HPV genotypes in cervical lesions are ideal targets for the design of immunotherapeutic strategies. These strategies,particularly subunit vaccines, may require additional help from immunomodulators to enhance HPV-specific cellular responses. Thisreview discusses recent studies, published since 2008, relating to immunotherapeutic strategies against HPV that includeimmunomodulators. These immunomodulators fall within the category of toll-like receptor adjuvants for innate immune activation,adjuvants directly contributing to adaptive immunity, such as cytokines and costimulatory molecules, and those that target tumor-inducedimmunosuppressive mechanisms. Using a combination of these strategies with delivery-based approaches may be most beneficial for thesuccess of therapeutic vaccines against HPV-induced neoplasia in the clinic.

Glucose-6-phosphate Dehydrogenase: a Biomarker and Potential Therapeutic Target for Cancer by Chunhua Zhang, Zheng Zhang, Yuechun Zhu, Suofu Qin (280-289).
Re-programming of metabolic pathways is a hallmark of pathological changes in cancer cells. The expression of certain genesthat directly control the rate of key metabolic pathways including glycolysis, lipogenesis and nucleotide synthesis is dysregulated for theadaptation and progression of tumor cells to become more aggressive phenotypes. The pentose phosphate pathway controlled by glucose-6-phosphate dehydrogenase (G6PD) has been appreciated largely to its role as a provider of reducing power and ribose phosphate to thecell for maintenance of redox balance and biosynthesis of nucleotides and lipids. Recently, G6PD has been revealed to be involved inapoptosis, angiogenesis, and the efficacy to anti-cancer therapy, making it as a promising target in cancer therapy. This reviewsummarizes the information about the latest progress relating the activity of the G6PD to cell proliferation, angiogenesis, and resistanceto therapy in cancer cells, and discusses the possibility of G6PD as a diagnostic biomarker of cancer and the therapeutic potentials ofG6PD inhibitors in cancer treatment. The available data show that G6PD plays a critical role in survival, proliferation, and metastasis ofcancer cells. Development of potent and selective G6PD inhibitors would provide novel opportunity for cancer therapy.

Recent data have shown strong chemopreventive and possibly cancer chemotherapeutic effects of green tea polyphenolsagainst cancer. Despite advances in breast cancer treatment, mortality from breast cancer is still high. Undoubtedly novel treatmentstrategies are needed for chemoprevention of high risk women and for the treatment of receptor negative breast cancer. Green teacatechins have been shown to inhibit proliferation of breast cancer cells and to block carcinogenesis. This review attempts a criticalpresentation of the mechanisms of action of green tea catechins in breast cancer. Several mechanisms of action of green tea catechins inbreast cancer have been proposed including modulation of extracellular signalling, induction of apoptosis through redox regulation, orthrough modulation of epigenetic alterations. A number of molecular targets of green tea catechins have been suggested i.e molecularchaperones, telomerase, apoptotic cascade. Although the molecular links among the proposed mechanisms of action of greentea catechins are often missing, it must be emphasized that all the proposed mechanisms indicate that green tea catechins inhibitgrowth and /or promote apoptosis. It would be interesting if future experimental trials could take into account that green tea catechins aremulti-target agents and attempt to link every novel proposed target with the other already proposed targets of green tea catechins.

Orai1 and Transient Receptor Potential Channels as Novel Molecular Targets to Impair Tumor Neovascularization in Renal Cell Carcinoma and other Malignancies by Francesco Moccia, Silvia Dragoni, Valentina Poletto, Vittorio Rosti, Franco Tanzi, Carlo Ganini, Camillo Porta (296-312).
The term “angiogenic switch” describes one of the earlier events of tumorigenesis, that occurs when the balance between proandanti-angiogenic factors shifts towards a pro-angiogenic outcome. This leads to the transition from a microscopic indolent lesion to amacroscopic and vascularised primary tumor, that may eventually metastasize and spread to distant sites. The molecular mechanismsunderlying such a critical step in the carcinogenetic process have been extensively investigated. Both local endothelial cells (ECs) andendothelial progenitor cells (EPCs), recruited from bone marrow, have been implicated in the angiogenic switch, which is ultimatelytriggered by a plethora of growth factors released by cancer cells, pivotal among which is vascular endothelial growth factor (VEGF);indeed, VEGF both activates ECs nearby the growing tumor, and leads to EPC mobilization into the circulation. In kidney, in particular,the frequent mutation of the Von Hippel Lindau tumor suppressor gene leads to an overproduction of pro-angiogenic factors whichmakes this neoplasm quite sensitive to antiangiogenic drugs. However, it is now evident that the use of VEGF(Rs) inhibitors in everydayclinical practice is not as effective as observed in murine models.;The investigation of alternative signaling pathways involved in the angiogenic switch is, therefore, imperative in order to induce tumorregression whereby preventing harmful drawback consequences. Ca2+ entry across the plasma membrane has long been known tostimulate mature ECs to undergo angiogenesis. Recent work from several groups worldwide has then outlined that members of theTransient Receptor Potential (TRP) super-family of cationic channels and Orai1 provide the pathway for such proangiogenic Ca2+ signal.In addition, Canonical TRP 1 (TRPC1) and Orai1 channels control proliferation and tubulogenesis in both normal EPCs and EPCsisolated from peripheral blood of tumor patients. As a consequence, TRP channels and Orai1 might serve as novel molecular targets todevelop alternative and more effective strategies of angiogenesis inhibition.

Artesunate Enhances the Antiproliferative Effect of Temozolomide on U87MG and A172 Glioblastoma Cell Lines by Georg Karpel-Massler, Mike-Andrew Westhoff, Richard E. Kast, Annika Dwucet, Lisa Nonnenmacher, C. Rainer Wirtz, Klaus-Michael Debatin, Marc-Eric Halatsch (313-318).
As chemotherapy with temozolomide is far from providing satisfactory clinical outcomes for patients with glioblastoma, moreefficient drugs and drug combinations are urgently needed. The anti-malarial artesunate was previously shown to exert a profoundcytotoxic effect on various tumor cell lines including those derived from glioblastoma. In the current study, we sought to examine theantiproliferative effect of a combination of temozolomide and artesunate on two different established human glioblastoma cell lines. TheIC50 and IC25 were determined for temozolomide and artesunate in U87MG and A172 glioblastoma cell lines after 144 h of continuousdrug exposure. The antiproliferative effect of combining both agents at IC50/IC50 and IC25/IC25 was determined by a cell viability assay.Moreover, necrosis and apoptosis were analyzed by annexin V/PI staining and flow cytometric analysis. In addition, cytostatic effectswere examined by carboxyfluorescein diacetate succinimidyl ester staining and subsequent flow cytometry. In both glioblastoma celllines, artesunate was found to enhance the antiproliferative effect exerted by temozolomide. Moreover, artesunate acted in concert withtemozolomide in terms of cytostatic and necrotizing effects. These observations suggest that a combination of artesunate andtemozolomide might result in increased cytotoxicity in glioblastoma.

A new series of N-substituted diarylidenepiperidin-4-ones was synthesized and screened for their possible anticancer activityat the NCI Developmental Therapeutic Program. Almost all the synthesized compounds showed more potent antiproliferative activitythan curcumin. The most active compound in this study was 3,5-bis(4-bromobenzylidene)-1-propanoylpiperidin-4-one (8a) with MGMIDGI50, TGI, and LC50 values of 0.35, 1.62 and 9.12 µM, respectively. Compound 8a displayed broad spectrum antiproliferativeactivity with GI50 values below 1 µM in 81% of the tested cell lines and was found to be two folds more potent than EF-24. A detailedstudy of the structure activity relationship of the N-substitution was also described.

Electrochemical Study of Ellipticine Interaction with Single and Double Stranded Oligonucleotides by Katerina Tmejova, Ludmila Krejcova, David Hynek, Vojtech Adam, Petr Babula, Libuse Trnkova, Marie Stiborova, Tomas Eckschlager, Rene Kizek (331-340).
Ellipticine (5,11-dimethyl-6H-pyrido[4,3-b]carbazole) is an alkaloid that has been isolated from plants of an Apocynaceaefamily. It is one of the simplest naturally occurring alkaloids with a planar structure. Over the past decades, ellipticine became a verypromising antitumor agent. Interaction with DNA is one of the most studied ellipticine effects on cell division. This phenomenon is notclearly explained so far. In our experiments we studied interaction of ellipticine with single-stranded and double-stranded oligonucleotides byelectrochemical methods on mercury electrode. Differential pulse voltammetry was applied for ellipticine (Elli) and CA peak detection.Square wave voltammetry was applied for G peak detection. The effect of the interaction time and ellipticine concentrations oninteractions of ellipticine with single- and double-stranded oligonucleotides was tested too.