Topics in Anti-Cancer Research

In recent years, antibody therapeutics have been widely and successfully used in treating cancer. Antibodies that specifically bind tumor surface antigens can also be used as therapeutics, and over 35 of them are in clinical use (e.g. trastuzumab, bevacizumab and cetuximab). However, some unmodified antibodies against tumorspecific antigens lack therapeutic activity. Conjugation to cytotoxic agents can increase the antibodies’ activity and, at the same time, enable extremely cytotoxic drugs to be used.

Antibody-delivered drugs and toxins are poised to become important classes of cancer therapeutics. These biopharmaceuticals have potential in this field, as they can selectively direct highly potent cytotoxic agents to cancer cells that present tumorassociated surface markers, thereby minimizing systemic toxicity. The activity of some conjugates is of particular interest receiving increasing attention, thanks to very promising clinical trial results in hematologic cancers. Over forty antibody-drug conjugates and six immunotoxins now in clinical trials, as well as some recently approved drugs, support the maturity of this approach.

This chapter focuses on recent advances in the development of these two classes of biopharmaceuticals: conventional toxins and anticancer drugs are described, together with their mechanisms of action. The processes of conjugation and purification, as reported in the literature and in several patents, are discussed and the most relevant results in clinical trials are listed. Innovative technologies and preliminary results on novel drugs and toxins, as reported in the literature and in recently-published patents (up to January 2015) are lastly examined.

Enhanced expression of the multi-functional protein nucleolin (NCL) is observed on the surface of activated lymphocytes, angiogenic endothelial and many different types of cancer cells. Translocation of NCL at the external side of the plasma membrane occurs via a secretory pathway independent of the endoplasmic reticulum- Golgi complex, requires intracellular intact actin cytoskeleton, and seems to be mediated by a variety of factors. Cell surface NCL serves as a binding partner of several molecules implicated in cell differentiation, adhesion and leukocyte trafficking, inflammation, angiogenesis and tumor development, mediating their biological activities and in some cases, leading to their internalization. Accumulating evidence validates cell surface NCL as a strategic target for treatment of cancer, while its property of tumor-specific uptake of targeted ligands seems to be useful for the development of non-invasive imaging tools for the diagnosis of cancer and for the targeted release of chemotherapeutic drugs. This chapter summarizes papers and patents related to the redistribution and the biological functions of cell surface NCL, with emphasis on the potential importance and advantages of developing efficient anticell surface NCL strategies.

Tubulin is one of the most useful and strategic molecular targets for anticancer drugs. The dynamic process of microtubule assembly and disassembly can be blocked by various agents that bind to distinct sites in the β-tubulin subunit. By interfering with microtubule function, these agents arrest cells in mitosis as well as interface, eventually leading to cell death, by both apoptosis and necrosis. So far, four binding domains have been identified a) the colchicine site close to the α/β interface, b) the area where the vinca alkaloids bind, c) the taxane-binding pocket and d) Laulimalide/Peloruside A Binding Site. This chapter compiles the patent literature up to 2015 and offers a detailed account of all the advances on anticancer agents targeting tubulin (lead molecules) along with in depth knowledge about the number of novel scaffolds, modified analogs and derivatives of the lead molecules. Colchicine binding site remains the most explored site indicated by the patent survey as majority of the patents revolve around phenstatins and combretastatins based molecules where the key structural feature for tubulin inhibition is an appropriate arrangement of the two aromatic rings at an appropriate distance and optimal dihedral angle maximizing interactions with tubulin. A brief account of promising microtubule destablizers/ stablizers in stages of clinical development and some strategies for the development of potent molecules overcoming the problem of drug resistance have also been discussed.

Resveratrol is a polyphenol with many beneficial effects: not only as an antioxidant, anti-inflammatory, and antiatherogenic agent, as well as a platelet aggregation inhibitor, but also as an antiproliferative and proapoptotic factor in various types of cancers. There are reviews about the mechanisms responsible for its effects in leukemia and lymphomas, emphasizing the chemosensitizing role of resveratrol, which allows overcoming the multidrug resistance of cancers. The action of resveratrol occurs preferentially on leukemic cells, and not on the normal ones. In addition, it is one of the few drugs that act on leukemic stem cells. If experimental results are promising, its application in humans encounters some difficulties. The paper presents the causes of its low bioavailability, as well as recent patents that allow improvement of its bioavailability, development of new extraction procedures, obtaining new formulae, and associating resveratrol with other drugs in order to increase its effects. These patents allow optimizing its effects in order to obtain an adjuvant agent for treatment of oncohematological disorders.

The response of the body to cancer is not a unique mechanism and has many parallels with inflammation and wound healing. Unresolved inflammation generates a microenvironment favorable for cellular transformation and the growth of cancer cells. Chronic tissue damage triggers a repair response that includes the production of growth factors, cytokines and chemokines. In particular, cytokines and chemokines have a crucial role in cancer-related inflammation with consequent direct and indirect effects on the proliferative and invasive properties of tumor cells. In view of the multifactorial functions of cytokines and chemokines in tumorigenesis, the elucidation of their roles will further advance our understanding of the pathological processes of cancer development and highlights potential innovative anti-cancer strategies.

Despite recent advances, the main anti-cancer therapies, namely surgery, radiation therapy and chemotherapy, are limited in their ability to treat minimal and metastatic residual disease. Furthermore, the benefit of conventional therapies is often limited by collateral damage to normal tissues. Immunotherapy is a new opportunity of cancer treatment being investigated by researchers and clinicians for different cancer types.

The aim of this chapter is to analyze the recent patents and scientific reviews on the major cytokine/chemokine pathways involved in cancer immunotherapy and discuss their basic biology, clinical relevance and potential directions for future anti-cancer therapeutic applications.

Molecular hybridization (MH) is a strategy of rational design of such ligands or prototypes based on the recognition of pharmacophoric sub-units in the molecular structure of two or more known bioactive derivatives which, through the adequate fusion of these sub-units, lead to the design of new hybrid architectures that maintain pre-selected characteristics of the original templates .The concept of molecular hybridization and the promises/challenges associated with these hybrid molecules along with recent advances in anticancer hybrids and critical discussions on the future aspects of the hybrid drugs have already been presented through number of reports. However, this chapter presents the structures of potent hybrids reported during the last two decades along with a detailed account of the patent literature from the year 1990 to 2014. Significant number of patents on the molecules designed through this valuable drug design technique clearly highlight the present focus of the researchers all around the globe towards hybrid molecules capable of amplifying the effect of individual functionalities through action on another bio target or to interact with multiple targets as one single molecule lowering the risk of drug-drug interactions and minimizing the drug resistance.

The Ehrlich tumor, derived from a mouse adenocarcinoma, has been used to investigate the bio-heat transfer and the effect of a gold macro-rod inserted into an Ehrlich tumor in white Mus musculus mice when irradiated with ultrasound. The in vitro measurements show that gold rods, when irradiated with ultrasound, not only confirm the bio heat transfer to tissue, as predicted by analytical calculations and in vitro measurements, but also prove to be a potential alternative to kill cancer cells. Several methods and apparatuses for cancer treatment with hyperthermia have been invented and are currently available. Out of the more than two hundred recent patents in the fields of hyperthermia and ultrasound, we mention some of them (at the introduction) that may relate to our proposed current cancer treatment methodology in future studies.

Literary data suggest apparently ambiguous interaction between menopausal status and obesity-associated breast cancer risk based on the principle of the carcinogenic capacity of estrogen. Before menopause, breast cancer incidence is relatively low and adiposity is erroneously regarded as a protective factor against this tumor conferred by the obesity associated defective estrogen-synthesis. By contrast, in postmenopausal cases, obesity presents a strong risk factor for breast cancer being mistakenly attributed to the presumed excessive estrogen-production of their adiposetissue mass. Obesity is associated with dysmetabolism and endangers the healthy equilibrium of sexual hormone-production and regular menstrual cycles in women, which are the prerequisites not only for reproductive capacity but also for somatic health. At the same time, literary data support that anovulatory infertility is a very strong risk for breast cancer in young women either with or without obesity. In the majority of premenopausal women, obesity associated insulin resistance is moderate and may be counteracted by their preserved circulatory estrogen level. Consequently, it is not obesity but rather the still sufficient estrogen-level, which may be protective against breast cancer in young adult females. In obese older women never using hormone replacement therapy (HRT), the breast cancer risk is high, which is associated with their continuous estrogen loss and increasing insulin-resistance. By contrast, obese postmenopausal women using HRT, have a decreased risk for breast cancer as the protective effect of estrogen-substitution may counteract to their obesity associated systemic alterations. Increased local estrogen synthesis in the microenvironment of breast malignancies may be regarded as defensive counteraction against tumor spread. The revealed inverse correlation between estrogen-levels and breast cancer risk in obese women should advance our understanding of breast cancer etiology and promotes primary prevention measures. New patents recommend various methods for the prevention and treatment of obesity-related systemic disorders and the associated breast cancer.

Nano-sized drug delivery systems might well be a fundamental tool to overcome some of the major challenges for future treatment of cancer, optimizing drug effectiveness while simultaneously reducing systemic side effects. This chapter is an update on patents related to nanosystems applications to anticancer drug delivery published in the last five years (2010-2015); the chapter focuses on polymeric nanosystems (nanospheres, nanocapsules, hydrogel based nanosystems, dendrimers and polymeric micelles).

The advent of nanomedicines allows a diversity of drugs with unfavorable biopharmaceutical properties and safety issues to be accessible as pharmaceutical products. The expectations are particularly high in the field of cancer therapeutics, where nanotechnology promises to enhance treatment selectivity, solving or ameliorating off-target toxicity issues. The biocompatible nature of lipid-based nanosystems and their scalable production make them especially auspicious for therapeutic applications.

Here, we present an update on recent patents on lipid-based nanosystems (liposomes, solid lipid nanoparticles and nano-structured lipid carriers) applications to cancer therapy.

Transforming growth factor beta1 (TGF-β1) plays different roles in health and disease. TGF-β1 has been assumed as a dual factor in tumor growth, since it can repress epithelial tumor development in early stages, while it acts as a tumor promoter in the late stages of tumor progression. Cancer cells, during carcinogenesis, acquire migration and invasion capacity which enables them to metastasize. The urokinase type plasminogen activator (uPA) system, comprised of uPA, the cell surface receptor (uPAR) and plasminogen-plasmin, is involved in the proteolytic degradation of the extracellular matrix and it also regulates several critical cellular events by its capacity to trigger the activation of intracellular signaling pathways. This enables the cancer cell survival, its dissemination, and enhancement of cell malignancy during tumor progression. The expression of both uPA and uPAR is finely regulated in normal development, but their expression is deregulated in cancer. TGF-β regulates uPA expression in cancer cells while uPA, by conversion of plasminogen to active form, plasmin, may release TGF-β1 from its latent state. Thus, these pathways cross-regulate each other by mutual feedback contributing to tumor progression. Here, we review the specific roles and the interplay between TGF-β1 and uPA system in cancer cells, the current cancer therapies and the novel patents focused mainly on uPA and TGF-β ligands and their cell surface receptors. Finally, with regard to the mutual activity of uPA and TGF-β1 in tumorigenesis, the aim of this chapter is to expose the potential of TGF-β1 and uPA systems to become combinatorial targets for therapies and patents.

Lung cancer affecting the majority of patients is usually present with advanced stage and contributes in killing more people than any other malignancy in the world. The discovery of a number of lung cancer-molecular alterations contributes to uniquely targeted therapies with specific inhibitors for non-small cell lung cancer such as erlotinib, gefitinib and crizotinib.

Pemetrexed has statistically shown significantly reduced adverse-side effects of drug compared with docetaxel. V1801, an analog of gefitinib may overcome gefitinib resistance in patients with non-small cell lung cancer. Thymosin α1, an immunomodulator, significantly improves patient’s quality of life by enhancing T-cell function, stimulation of T-cell maturation and differentiation. Various novel compounds and chemotherapeutics were introduced in 2013 patents such as taxane, quinazoline, arylamino purine, benzodiazepine, pyrrolopyrimidine, nitrobenza-mide, cyclopropane amide, 4-iodo-3-nitrobenzamide, heteroaryl (alkyl) dithiocarba-mate, and histone deacetylase in treating non-small-cell lung cancer and piperidine, piperazine, picoplatin, and arsenic trioxide in treating small-cell lung cancer. Currently, new drugs such as alectinib, AP26113, crizotinib, etc. are in the pipeline.

A variety of clinical trials for vaccines against cancer have provided evidence that DNA vaccines are well tolerated and have an excellent safety profile.

DNA vaccines require much improvement to make them sufficiently effective against cancer in the clinic. Nowadays, it is clear that an increased antigen expression correlates with improved immunogenicity and it is critical to vaccine performance in large animals and humans. Similarly, additional strategies are required to activate effective immunity against poorly immunogenic tumor antigens.

This chapter discusses very recent scientific references focused on the development of sophisticated DNA vaccines against cancer.

We report a selection of novel and relevant patented inventions employed to improve DNA vaccine immunogenicity through several strategies such as the use of tissuespecific transcriptional elements, nuclear localisation signalling, codon-optimisation and by targeting antigenic proteins to secretory pathway.

Recent patents validating portions or splice variants of tumor antigens as candidates for cancer DNA vaccines with improved specificity, such as mesothelin and hTERT, are also discussed.

Lastly, we review novel scientific references and patents on the use of genetic immunomodulators, such as “universal” T helper epitopes derived from tetanus toxin, Escherichia coli heat labile enterotoxin and vegetable proteins, as well as cytokines, chemokines or costimulatory molecules such as IL-6, IL-15, IL-21 to amplify immunity against cancer.