Recent Patents on Anti-Cancer Drug Discovery - Volume 16, Issue 2, 2021

Background: Ciclopirox (CPX), a broad-spectrum fungicide, has been widely used to treat fungal infection on the skin and nails for decades. Recent preclinical and clinical studies have shown that CPX also possesses promising anticancer activity. Objective: The objective of this study is to summarize the patents, the pharmacological and toxicological properties, the anticancer activity, and the mechanisms of action of CPX and its derivatives as anticancer agents. Methods: PubMed and Google using the keywords “ciclopirox”, “cancer or tumor” and “patent” were searched, and the identified literature was reviewed. Results: Pharmacological and toxicological profiles from preclinical and clinical studies support that systemic administration of CPX and its derivatives is feasible and safe for cancer treatment. CPX exerts its anticancer activity by inhibiting cell proliferation, inducing apoptosis, suppressing cell migration and invasion, and inhibiting angiogenesis and lymphangiogenesis. Mechanistically, CPX impacts the expression or activities of multiple signaling molecules or pathways, such as ribonucleotide reductase, Myc, DJ-1, Wnt/β-catenin, DOHH/eIF5A/PEAK1, VEGFR-3/ERK1/2, ATR/Chk1/Cdc25A, and AMPK/TSC/mTORC1. Most of these effects are attributed to iron chelation by CPX. Five patents have been retrieved: four patents on the development of CPX prodrugs to improve the water solubility and bioavailability of CPX, and one patent on the methods of bladder cancer treatment with CPX, CPX-O, or a CPX prodrug. Conclusion: CPX has a great potential to be repositioned for cancer therapy.

Background: Cancer is a multistep process involving genetic and epigenetic changes in the somatic genome. Genetic mutations as well as environmental factors lead to the initiation, promotion, and progression of cancer. Metastasis allows cancer cells to spread via circulatory and lymphatic systems; secondary tumorigenesis typically leads to a fatal outcome. Recent experimental evidence suggests that Cancer Stem Cells (CSCs) play a pivotal role in tumor progression. A tumor is heterogeneous and composed of different cell types. CSCs are a subpopulation of tumor cells possessing abilities to self-renew and differentiate. Objective: The aim of this study was to present repurposed drugs, and potential candidates, that can serve as anticancer medications intended to target resistant cancer cells, i.e. CSCs. Methods: Research publications, FDA filings, and patents have been reviewed for repurposed drugs or drug combinations that can act to improve cancer treatment and care. Results: Drugs that act against CSCs include ones approved for treatment of diabetes (metformin & thiazolidinediones), parasitic diseases (chloroquine, niclosamide, mebendazole & pyrvinium), psychotic disorders (thioridazine, clomipramine & phenothiazines), alcoholism (disulfiram), lipid disorder (statins), inflammatory diseases (tranilast, auranofin, acetaminophen & celecoxib), antibiotics (azithromycin), and other disorders. Current research findings advocate the existence of beneficial effects by combining these repurposed drugs, and also through their complementary use with conventional cancer therapies. Conclusion: Repurposing FDA-approved medications towards cancer care, by targeting the resistant CSCs, will allow for a quicker, cheaper development and approval process. A larger drug library available to physicians will allow for increased efficacy during both first-line and recurrent cancer treatments.

Background: Over recent years, there has been an increasing focus on the repurposing of existing, well-known medications for new, novel usage. One such drug is metformin, typically utilized in the management of diabetes, which demonstrates a positive relationship between its administration and lower cancer morbidity and mortality. Based on this finding, numerous studies and clinical trials have been conducted to examine the potential usage of metformin as an anticancer agent. Objective: This article aims to summarize metformin’s anticancer effects through reviewing its literatures and patents, with a focus on its potential to be repurposed for cancer therapy. Methods: Various databases were examined using keywords, ‘Metformin’ and ‘Cancer’. Research articles were collected through the PubMed database, clinical trials were obtained from the Clinical Trials database, and patents were collected through the Google Patents database. Results: Metformin shows antineoplastic activity in various models. These anticancer properties appear to synergize with existing chemotherapeutics, which allows a reduction in drug dosage without losing potency while minimizing adverse effects. Numerous patents on metformin have been filed which claim various combination therapies, delivery methods, and uses for cancer therapy, displaying an increasing interest in metformin’s anticancer potential. Conclusion: Preclinical studies, along with early phase clinical trials, have examined the antitumor properties of metformin on a variety of cancers. Metformin’s anticancer effects are well documented, demonstrating a great promise in improving current cancer therapies. However, there is a significant lack of late phase clinical trials, specifically those involving nondiabetic cancer patients, and therefore further research in this area is required.

Background: Malignant Mesothelioma (MM), an orphan but aggressive malignancy of the mesothelial membrane, is a fatal tumour. Global epidemic related to malignant pleural mesothelioma is on the rise, so there is a need to explore novel biomarkers and ingenious therapeutic approaches to stalk this silent killer. Objective: The main aim of the present review is to provide a consolidated overview of the recent active patents related to diagnosis and therapy in the field of MM that will impact its future management. Methods: A search of existing literature was conducted from a PubMed database search. Recent patent information was fetched out from online free open-access databases. For related clinical trials, www.clinicaltrial.gov was searched. Results: Patent search data showed 72 active patents related to diagnosis and therapy in the field of MM, which we classified into eight broad categories. Of these, maximum 17 patents were attributed to immunotherapy and 13 were attributed to “Drug Repositioning” and “Biological / synthetic” based candidates. Relatively low number of patents accounts for gene signature (7), epigenetics (3) and microRNA (2) based diagnosis and therapy. Remaining 17 patents were distributed amongst virotherapy and various miscellaneous categories. Furthermore, our clinical trial based investigation revealed the futuristic impact of listed patents in MM patient management. Conclusion: This review article has provided an overview of patent based advancement in the field of MM, which might become apex in the clinical settings in future. Interestingly, immunotherapy and “drug repositioning” based therapy seems to be the front-runners in the race to provide relief.

Background: Drug repurposing is emerging as an attractive strategy with lower attrition rate, lower cost and shorter timeframe than traditional drug discovery methods. Chloroquine (CQ) and its analogs are old drugs originally indicated for malaria treatment. Serendipitous discovery in early years revealed its anti-inflammatory properties, thus allowing its repositioned use in autoimmune diseases. Recent evidence also suggested its potential therapeutic use for anticancer therapy. Objective: This article reviews the molecular mechanisms, clinical evaluation and recent patents of CQ analogs in cancer therapy. Methods: Literature and patent searches were conducted using PubMed database and Google Patent/ USPTO Patent Search database, respectively. The keywords including “chloroquine”, “hydroxychloroquine”, “chloroquine analogs”, “chloroquine derivatives”, “repurposing”, “autophagy”, and “cancer” were used. Results: CQ analogs have been reported to elicit their anticancer effects by modulating autophagy, inducing apoptosis, eliminating cancer stem cells, normalizing tumor vasculature and modulating antitumor immunity. As documented by recent patents and clinical trials, CQ analogs have been repurposed as an adjuvant therapy and combined with other anticancer agents for synergistic enhancement of treatment efficacy. However, most clinical trials on CQ only demonstrated modest improvement in anti-cancer efficacy. Conclusion: Given that CQ loses its anticancer activity in acidic and hypoxic environment within a tumor, novel CQ analogs and/or their formulations are under active investigation to improve their physicochemical properties and biological activity. On the other hand, identification of new biomarkers for better patient selection has been advocated in future trials in order to realize the repurposing of CQ analogs for cancer treatment in a personalized manner.

Background: To date, many compounds extracted from natural products have anti-tumor activity, such as citronellol, ellagitannin-containing pomegranate extract, etc. Evidence from clinical context shows that multidrug resistance is an obstacle that impedes the effectiveness of natural products, such as chemotherapeutic agents, paclitaxel and vincristine. Overexpression of ATP- Binding Cassette (ABC) transporters is the leading cause of MDR. Therefore, it is crucial to investigate whether these natural products are substrates of MDR-associated ABC transporters, which may benefit the development of their clinical usage. Objective: This review summarizes the latest insight on natural products possessing substrate profile and analyzes some possible directions for future drug discovery. Conclusion: The anti-tumor effects of natural products are constantly being explored, but the drug resistance issues cannot be ignored, which limits their prospects as anti-tumor drugs to a certain extent. At the same time, some natural products are taken as a daily diet, and their possible role in increasing the drug resistance of the substrate should arouse the attention of clinical cancer patients.

Hepatocellular Carcinoma (HCC) is one of the most common malignancies, and its incidence and mortality are increasing worldwide. Cancer immunotherapy has revolutionized cancer treatment in recent years. In particular, immune checkpoint inhibitors (ICIs), as new therapeutic tools, have demonstrated encouraging antitumor activity and manageable tolerability in HCC. Immune checkpoint blockade with antibodies targeting Programmed cell Death-1 (PD-1), Programmed cell Death Ligand-1 (PD-L1), and cytotoxic T lymphocyte-associated protein-4 (CTLA- 4) enhances tumor immunity by restoring exhausted T cells. Although the efficacy of combinational treatment strategies using ICIs combined with other ICIs, molecularly targeted agents, systemic therapy, or locoregional therapy has been well documented in numerous preclinical and clinical studies in several types of cancer, most HCC patients do not benefit from ICI treatment. This review highlights recent developments and potential opportunities related to ICIs and their combination in the management of HCC. The present article also reviews recent patents related to ICIs.

Background: Polymers are used in drug delivery systems to encapsulate and release the drug. Natural polymers have the advantages of biodegradability, biocompatibility, and recognizable biological moieties that maintain cellular functions as compared to synthetic polymers. Chitosan is a natural polycationic linear polysaccharide that originates from chitin. Its easy modification, release rate of drug, ability to cross-link with other polymers, gelling ability, immunostimulation, bioadhesion, biocompatibility, and biodegradability has increased its application in various drug delivery systems. Objective: The objective of the present study is to overview the recent patents of the application of chitosan in various drug delivery systems and their use in the prevention of cancer and other ailments. Methods: In this review, the patent application of chitosan in various drug delivery systems employed to cure mainly cancer has been covered with particular emphasis on their scientific impact and novelty. Results: Chitosan has proved its potential as a polymer to control and target the drug at the site of action. Conclusion: The potential of chitosan and its derivatives to deliver and target the drug may open new avenues for therapeutic interventions in different tumors.

Background: E2 (Camptothecin - 20 (S) - O- glycine - deoxycholic acid), and G2 (Camptothecin - 20 (S) - O - acetate - deoxycholic acid) are two novel bile acid-derived camptothecin analogues, modified deoxycholic acid at 20-position of CPT(camptothecin) with greater anticancer activity and lower systematic toxicity in vivo. Objective: We aimed to investigate the metabolism of E2 and G2 by Rat Liver Microsomes (RLM). Methods: Phase I and Phase II metabolism of E2 and G2 in rat liver microsomes were performed, respectively, and the mixed incubation of phase I and phase II metabolism of E2 and G2 was also processed. Metabolites were identified by liquid chromatographic/mass spectrometry. Results: The results showed that phase I metabolism was the major biotransformation route for both E2 and G2. The isoenzyme involved in their metabolism had some difference. The intrinsic clearance of G2 was 174.7 mL/min. mg protein, more than three times that of E2 (51.3 mL/min . mg protein), indicating a greater metabolism stability of E2. 10 metabolites of E2 and 14 metabolites of G2 were detected, including phase I metabolites (mainly via hydroxylations and hydrolysis) and their further glucuronidation products. Conclusion: These findings suggested that E2 and G2 have similar biotransformation pathways except for some differences in the hydrolysis ability of the ester bond and amino bond from the parent compounds, which may result in the diversity of their metabolism stability and responsible CYPs(Cytochrome P450 proteins).

Background: Breast Cancer (BC), a common fatal disease and the deadliest cancer next to lung cancer, is characterized by an abnormal growth of cells in the tissues of the breast. BC chemotherapy is marked by targeting the activities of some receptors such as Estrogen Receptor alpha (ER-α). At present, one of the most commonly used and approved marketed therapeutic drugs for BC is tamoxifen. Despite the short-term success of tamoxifen usage, its long time treatment has been associated with significant side effects. Therefore, there is a pressing need for the development of novel anti-estrogens for the prevention and treatment of BC. Objective: In this study, we evaluate the inhibitory effect of Cannabis sativa phytoconstituents on ER-α. Methods: Glide and induced fit docking followed by ADME, automated QSAR and binding free energy (ΔGbind) studies were used to evaluate anti-breast cancer and ER-α inhibitory activity of Cannabis sativa, which has been reported to be effective in inhibiting breast cancer cell proliferation. Results: Phyto-constituents of Cannabis sativa possess lower docking scores and good ΔGbind when compared to that of tamoxifen. ADME and AutoQSAR studies revealed that our lead compounds demonstrated the properties required to make them promising therapeutic agents. Conclusion: The results of this study suggest that naringenin, dihydroresveratrol, baicalein, apigenin and cannabitriol could have relatively better inhibitory activity than tamoxifen and could be a better and patent therapeutic candidate in the treatment of BC. Further research such as in vivo and/or in vitro assays could be conducted to verify the ability of these compounds.

Background: In recent years, there is an increasing interest in using Traditional Chinese Medicine (TCM) and their patents for the treatment of cancers. Qigefang (QGF) is a TCM formula and has been used for the treatment of metastatic esophageal cancer in China. However, its therapeutic effect on tumors and its mechanism of action is largely unknown. The aim of this study is to explore the role of QGF in the treatment of metastasis of Esophageal Squamous Cell Carcinoma( ESCC). Methods: Human esophageal carcinoma cell line KYSE150 was used for this study. CCK-8 assay was used to determine the cytotoxicity of QGF. The KYSE150 cells were treated with QGF to determine its effect on cell migration (cell scratch assay and imaging) and invasion (Transwell system based with Matrigel assay). Western blotting was used to investigate the effect of QGF on relevant molecules of signaling pathways. A mouse model of lung metastasis of esophageal cancer was established by injecting the KYSE150-Luc cells through the tail vein. A small animal imaging system was used to observe tumor metastasis in the mice. Results: QGF reduced cell migration and invasion of KYSE150 cells. QGF significantly inhibited lung metastasis in nude mice. Further study revealed that the expression of Growth arrest-specific 6 (Gas6), Anexelekto (Axl), N-Nuclear factor-kappa B (NF-ΚB) and matrix metalloproteinase-9 (MMP-9) proteins were decreased both in vitro and in vivo upon treatment with QGF. Conclusion: QGF could prevent invasion and metastasis of esophageal cancer by inhibiting the Gas6/Axl signaling pathway.