Recent Patents on Anti-Cancer Drug Discovery - Volume 11, Issue 2, 2016

Inhibitors of immune check-point molecule, programmed cell death 1 (PD-1) and its ligand, programmed cell death ligand 1 (PD-L1) have attracted much attention in cancer immunotherapy recently due to their durable antitumor effects in various malignances, especially the advanced ones. Unfortunately, only a fraction of patients with advanced tumors could benefit from anti-PD-1/PD-L1 therapy, while others still worsened. The key to this point is that there are no efficient biomarkers for screening anti-PD-1/PD-L1-sensitive patients. In this review, we aim at summarizing the latest advances of anti-PD-1/PDL1 immunotherapy and the potential predictive efficacy biomarkers to provide evidences for identifying anti-PD-1/PDL1- sensitive patients. The present article also includes the patent review coverage on this topic.

Background: Survivin is widely overexpressed in many forms of cancer and studies have related high survivin expression with poor survival rates. Although, there have been several attempts to target survivin, most therapeutics haven’t shown substantial success in clinical trials therefore, authors wish to attract the focus towards many recent therapeutic innovations to target survivin. Objective: Survivin plays an essential role in the cell cycle progression, apoptosis, cell stress response, drug resistance and angiogenesis therefore the prognostic and targeting benefits of survivin have been underestimated. An update on the current and existing therapeutic strategies implemented to target survivin is provided. Therefore, the reader will gain an insight into the recent patents targeting survivin. The review has emphasised on patents for quantification of survivin, survivin peptides as immunotherapeutics, application of survivin promoters, RNA interference of survivin, small molecules inhibitors of survivin and nanoparticles targeting survivin. The review also encompasses the survivin targeted therapeutics being implemented at clinical stages which include survivin targeted immunotherapeutics, peptide-based vaccines, antisense oligonucleotides and chemical inhibitors. Conclusion: We reviewed recent patents based on preclinical anti-survivin therapies reported to date and it was concluded that gataparsen has been most widely used for anti-survivin therapy in clinical trials. It was also concluded that most therapeutic patents were focussed on development of natural anti-survivin therapeutics such as anti-survivin peptides or survivin anti-sense oligonucleotides in the recent years therefore, proving that natural proteins and nucleic acids has an upper hand over chemicals and synthetic drugs.

Epidermal growth factor receptor (EGFR) is a tyrosine kinase receptor that activates downstream signaling pathways, including the Ras-MEK-Erk and PI3K-AKT pathways, leading to cell proliferation, resistance to apoptosis, angiogenesis and the ability to metastasize. EGFR overexpression is a significant finding in cancer, particularly in head and neck cancer, where it is also associated with a poor prognosis. In recent years, several molecules have been designed to inhibit EGFR activation. Among the many available anti-EGFR drugs, only cetuximab was approved for the treatment of head and neck cancers. However, no predictive biomarkers of cetuximab response are currently known. In the present review, we provide an updated assessment of EGFR biology and its clinical impact in head and neck cancers. A special emphasis is placed on novel patents of EGFR-inhibitors that are anticipated to diversify the anti-EGFR therapies available to treat head and neck cancers. In particular, we outline a new class of irreversible multi-target inhibitors (e.g. afatinib, icotinib, CUDC-101), which may significantly contribute to new head and neck cancer therapies.

Cytosolic NADPH-dependent reductase AKR1B10 is a member of the aldo-keto reductase (AKR) superfamily. This enzyme is normally expressed in the gastrointestinal tract. However, it is overexpressed in many solid tumors, such as hepatocarcinoma, lung cancer and breast cancer. AKR1B10 may play a role in the formation and development of carcinomas through multiple mechanisms including detoxification of cytotoxic carbonyls, modulation of retinoic acid level, and regulation of cellular fatty acid synthesis and lipid metabolism. Studies have suggested that AKR1B10 may be a useful biomarker for cancer diagnosis and a potential target for cancer treatment. Over the last decade, a number of AKR1B10 inhibitors including aldose reductase inhibitors (ARIs), endogenous substances, natural-based derivatives and synthetic compounds have been developed, which could be novel anticancer drugs. This review provides an overview on related articles and patents about AKR1B10 inhibitors, with a focus on their inhibition selectivity and mechanism of function.

Background: Apo2-ligand/TRAIL, a member of the TNF cytokine superfamily capable of inducing apoptosis on tumor cells while sparing normal cells, is a promising anti-tumor agent. However, about 50% of human cancer are TRAIL resistant. Consequently, future TRAIL-based therapies will require the use of novel highly bioactive forms of TRAIL and/or the addition of sensitizing agents to TRAIL-induced apoptosis. Recently, we demonstrated that artificial lipid nanoparticles coated with bioactive TRAIL (LUV-TRAIL) greatly improved TRAIL activity and were able to induce apoptosis in chemoresistant hematological tumor cells. Objective: In this study, we have tested LUV-TRAIL-pro-apoptotic potential in human breast cancer. Method: Comparative analysis of cytotoxicity induced by sTRAIL and LUV-TRAIL was performed using several human breast tumor cell lines with different sensitivity to TRAIL. In vivo anti-tumor activity of LUV-TRAIL was also studied using a xeno-graft tumor model. Results: LUV-TRAIL improved not only sTRAIL in vitro cytotoxicity in all breast tumor cell lines tested but also showed more anti-tumor activity than sTRAIL in an in vivo xeno-graft tumor model. On the other hand, the concomitant treatment of LUV-TRAIL with the sensitizing agent flavopiridol (FVP) induced a higher level of cell death in TRAIL-resistant cell lines. TRAIL-sensitization induced by FVP was mediated by DR5 up-regulation, and interestingly TRAIL-apoptotic signaling was completely shifted towards DR5 upon FVP treatment. LUV-TRAIL could especially take advantage of this DR5 up-regulation, while sTRAIL was not able. Conclusion: To date, no special attention had been paid to this aspect of FVP-induced TRAIL-sensitization, may be because sTRAIL used were not able to take advantage of this DR5 up-regulation. Hence, LUV-TRAIL could be a better choice than sTRAIL to be used in combination with anti-tumor drugs inducing DR5 over-expression, since LUV-TRAIL is especially effective activating this death-receptor.

Background: Isoliquiritigenin (ISL) is a licorice chalcone. According to CN104758274, CN101658513 and US009089546, it is claimed that ISL has anti-inflammatory, anti-oxidative, and anti-tumoral effects. Objective: This study aimed to investigate the potential therapeutic effect of ISL in mouse melanoma B16F10 cells. Methods: Sulforhodamine B (SRB) colorimetric assay was used to test the effects of ISL on proliferation. Commercial assay kits were applied to assess glucose uptake, lactate production and ATP levels. Measurement of apoptosis was involved with Hoechst 33258, JC-1 and annexin V-FITC/PI staining. H2DCFDA probe was employed to detect ROS generation. Quantitative RT-PCR and western blot were utilized to measure the mRNA and protein levels. Results: ISL abated hypoxia-inducible factor 1α (HIF-1α) stability and reduced a series of glycolysis-relevant enzymes expression, including glucose transporters 1/4 (GLUT 1/4), hexokinase 2 (HK2), pyruvate kinase M2 (PKM2) and lactate dehydrogenase A (LDHA). Exposure to ISL induced the mitochondrial membrane potential depolarization and increased intracellular reactive oxygen species (ROS) level. ISL could effectively inhibit proliferation and alleviate hypoxia in mouse melanoma B16F10 cells via inducing apoptosis and reducing the expression of significant enzymes in the glycolysis. ISL significantly inhibited B16F10 cell proliferation via inducing apoptosis, and alleviated hypoxia by recovering mitochondrial function and reversing high glycolysis. Conclusion: Our findings propose that ISL can be a promising therapeutic agent for the melanoma via reliving hypoxia of microenvironment and targeting energy metabolism system of cancer cells. Consistent with WO2015079213 and WO2014084494, targeting glycolysis can be an effective means to anti-cancer.

Background: The Anti-CD20 monoclonal antibody Rituximab suppresses B-lymphocytes and may induce hypogammaglobulinemia in treated patients. The incidence and clinical significance of rituximab induced hypogammaglobulinemia in lymphoma patients is underestimated. Methods: We retrospectively analyzed the rates of hypogammaglobulinemia, infection and infectionrelated mortality in 136 lymphoma patients who were treated with a combination of chemotherapy and rituximab. Results: Rituximab given in more than 8 doses (OR 6.05, 95% CI: 1.24-29.5), relative hypogammaglobulinemia at time of lymphoma diagnosis (OR 4.2, 95% CI: 1.26-14.1) and the combination of fludarabine with rituximab (OR 3.4, 95% CI: 1.24-9.47) were factors significantly associated with prolonged (more than 6 months) hypogammaglobulinemia. The combination of fludarabine and rituximab (OR 6.4, 95% CI: 1.49-27.0) and secondarily prolonged hypogammaglobulinemia (OR 4.5, 95% CI: 1.19-18.5) were found to be predictive factors for severe infections and infection-related mortality. Conclusion: These data suggest the importance of following serum immunoglobulin levels before and after combination immuno-chemotherapy, particularly in patients with recurrent infections or relapsed/refractory disease.

Background: Recent researches and relevant patents have been reported to prove the significant value of Caveolin-1 (Cav-1) in cancer diagnosis and treatment. Objective: Our study aimed to study the role of Cav-1 in gastric cancer progression and investigate the relationship between Cav-1/E-cadherin expression and the clinical status of gastric cancer. Method: Immunohistochemistry was applied to detect the expression of Cav-1 and E-cadherin in gastric cancer in a tissue microarray. Real-time PCR was used to further detect the mRNA expression of Cav-1 and E-cadherin in tumor-derived and peritumoral tissues and in different gastric cancer cell lines. The expression of E-cadherin was analyzed by Western Blot and the cell migration ability was examined by Transwell migration assays after downregulation of Cav-1 using siRNA. Results: The staining of Cav-1 and E-cadherin were both strong in all 5 of the normal gastric tissues, while in gastric cancer tissues the staining of Cav-1 and E-cadherin were downregulated (44&33 negative, 21&22weak and 5&15 strong). And their level was correlated with tumor clinical stage, pathological grade, and metastasis status. Moreover, there was a positive correlation between Cav-1 expression and E-cadherin expression in gastric cancer tissues(r = 0.42, P < 0.05). Knockdown of Cav-1 resulted in decreased expression of E-cadherin, cell morphology changes and elevated migration ability of gastric cancer cells. Conclusion: Decreased expression of Cav-1 and E-cadherin may play an important role in the progression of gastric cancer; Knockdown of Cav-1 may promote EMT of gastric cancer by targeting E-cadherin.