A phase I pharmacokinetic and pharmacodynamic study of CKD-732, an antiangiogenic agent, in patients with refractory solid cancer

The Chemotherapeutic Potentials of Compounds Isolated from the Plant, Marine, Fungus, and Microorganism: Their Mechanism of Action and Prospects

Research on natural products mainly focuses on developing a suitable drug to treat human disease. There has been a sharp increase in the development of drugs from natural products. Most of the drugs that are available are from the terrestrial origin. Marine natural products are less explored. Oceans are considered as a vast ecosystem with a wide variety of living organisms and natural products that are unexplored. Large numbers of antitumor drugs are from natural sources such as plants, marine, and microorganisms. 80% new chemical entities that were launched over the past 60 decades were from a natural source. In this article, the anticancer potential from the natural source such as plants, fungi, microorganisms, marine, and endophytes has been reviewed. Emphasis is given on the compound from the marine, plant, and of bacterial origin. Finally, we consider the future and how we might achieve better sustainability to alleviate human cancer suffering while having fewer side effects, more efficacies, and causing less harm than the present treatments.

Newly synthesized methionine aminopeptidase 2 inhibitor hinders tumor growth

Methionine aminopeptidase 2 (MetAp2) inhibition has been recognized as a promising approach for suppressing angiogenesis and cancer progression. Small molecule fumagillol derivatives with adamantane side groups were synthesized and evaluated for MetAp2 inhibition activity, and a lead molecule with superior abilities to inhibit the enzymatic activity of MetAp2 was identified. The compound, referred to as AD-3281, effectively suppressed proliferation of cancer and endothelial cells and impaired tube formation of endothelial cells in vitro. When administered systemically, AD-3281 was well tolerated and led to a significant suppression of human melanoma and mammary tumor xenografts grown in mice. The activity in vivo was associated with reduced angiogenesis and tumor proliferation as detected histologically. In order to develop a formulation that can solubilize AD-3281 with a minimal content of organic solvents, biodegradable nanoparticles comprised of poly-lactic-co-glycolic acid (PLGA) were fabricated and characterized. Compared with the free compound, AD-3281-loaded nanoparticles showed an advantageous cellular availability and uptake, leading to higher activity in cells and better transport in three-dimensional (3D) cultures. Taken together, we introduce a novel MetAp2 inhibitor with high anti-cancer activity and a stable nano-formulation with a high potential for future clinical translation.

Targeting methionine aminopeptidase 2 in cancer, obesity, and autoimmunity

For over three decades, methionine aminopeptidase 2 (MetAP2) has been a tentative drug target for the treatment of cancer, obesity, and autoimmune diseases. Currently, no MetAP2 inhibitors (MetAP2i) have reached the clinic yet, despite considerable investment by major pharmaceutical companies. Here, we summarize the key series of MetAP2i developed to date and discuss their clinical development, progress, and issues. We coalesce the currently disparate knowledge regarding MetAP2i mechanism of action and discuss discrepancies across varied studies. Finally, we highlight the current knowledge gaps that need to be addressed to enable successful development of MetAP2 inhibitors in clinical settings.

Using Target Engagement Biomarkers to Predict Clinical Efficacy of MetAP2 Inhibitors

Target-engagement pharmacodynamic (PD) biomarkers are valuable tools in the prioritization of drug candidates, especially for novel, first-in-class mechanisms whose robustness to alter disease outcome is unknown. Methionine aminopeptidase 2 (MetAP2) is a cytosolic metalloenzyme that cleaves the N-terminal methionine from nascent proteins. Inhibition of MetAP2 leads to weight loss in obese rodents, dogs and humans. However, there is a need to develop efficacious compounds that specifically inhibit MetAP2 with an improved safety profile. The objective of this study was to identify a PD biomarker for selecting potent, efficacious compounds and for predicting clinical efficacy that would result from inhibition of MetAP2. Here we report the use of NMet14-3-3γ for this purpose. Treatment of primary human cells with MetAP2 inhibitors resulted in an approx. 10-fold increase in NMet14-3-3γ levels. Furthermore, treatment of diet-induced obese mice with these compounds reduced body weight (approx. 20%) and increased NMet14-3-3γ (approx. 15-fold) in adipose tissues. The effects on target engagement and body weight increased over time and were dependent on dose and administration frequency of compound. The relationship between compound concentration in plasma, NMet14-3-3γ in tissue, and reduction of body weight in obese mice was used to generate a pharmacokinetic-pharmacodynamic-efficacy model for predicting efficacy of MetAP2 inhibitors in mice. We also developed a model for predicting weight loss in humans using a target engagement PD assay that measures inhibitor-bound MetAP2 in blood. In summary, MetAP2 target engagement biomarkers can be used to select efficacious compounds and predict weight loss in humans. SIGNIFICANCE STATEMENT: The application of target engagement pharmacodynamic biomarkers during drug development provides a means to determine the dose required to fully engage the intended target and an approach to connect the drug target to physiological effects. This work exemplifies the process of using target engagement biomarkers during preclinical research to select new drug candidates and predict clinical efficacy. We determine concentration of MetAP2 antiobesity compounds needed to produce pharmacological activity in primary human cells and in target tissues from an appropriate animal model and establish key relationships between pharmacokinetics, pharmacodynamics, and efficacy, including the duration of effects after drug administration. The biomarkers described here can aid decision-making in early clinical trials of MetAP2 inhibitors for the treatment of obesity.

Spiroepoxytriazoles Are Fumagillin-like Irreversible Inhibitors of MetAP2 with Potent Cellular Activity

Methionine aminopeptidases (MetAPs) are responsible for the cotranslational cleavage of initiator methionines from nascent proteins. The MetAP2 subtype is up-regulated in many cancers, and selective inhibition of MetAP2 suppresses both vascularization and growth of tumors in animal models. The natural product fumagillin is a selective and potent irreversible inhibitor of MetAP2, and semisynthetic derivatives of fumagillin have shown promise in clinical studies for the treatment of cancer, and, more recently, for obesity. Further development of fumagillin derivatives has been complicated, however, by their generally poor pharmacokinetics. In an attempt to overcome these limitations, we developed an easily diversifiable synthesis of a novel class of MetAP2 inhibitors that were designed to mimic fumagillin's molecular scaffold but have improved pharmacological profiles. These substances were found to be potent and selective inhibitors of MetAP2, as demonstrated in biochemical enzymatic assays against three MetAP isoforms. Inhibitors with the same relative and absolute stereoconfiguration as fumagillin displayed significantly higher activity than their diastereomeric and enantiomeric isomers. X-ray crystallographic analysis revealed that the inhibitors covalently modify His231 in the MetAP2 active site via ring-opening of a spiroepoxide. Biochemically active substances inhibited the growth of endothelial cells and a MetAP2-sensitive cancer cell line, while closely related inactive isomers had little effect on the proliferation of either cell type. These effects correlated with altered N-terminal processing of the protein 14-3-3-γ. Finally, selected substances were found to have improved stabilities in mouse plasma and microsomes relative to the clinically investigated fumagillin derivative beloranib.

Aspergillus, angiogenesis, and obesity: the story behind beloranib

Fumagillin, an antimicrobial compound first isolated in 1949 from the fungus Aspergillus fumigatus, four decades later was unexpectedly found to inhibit angiogenesis. Interest in developing angiogenesis inhibitor drugs as possible treatments for cancer led to the synthesis of analogs of fumagillin. Preclinical studies of various analog drugs confirmed that they inhibited angiogenesis, but they also were associated with weight loss as an adverse effect. Because adipose tissue can grow and regress throughout adulthood, is highly vascularized, and has angiogenic properties, interest in investigating anti-angiogenic agents in animal models of obesity found that fumagillin analogs caused dose-dependent reversible weight reduction and adipose tissue loss. Beloranib, a fumagillin analog that is an angiogenesis inhibitor and associated with decreased adiposity in animals, has been studied in phase I clinical trials for cancer. It is currently being investigated for the treatment of obesity and related conditions. Three phase I and three phase II studies found significant degrees of weight loss and acceptable tolerability for beloranib compared to placebo, justifying further clinical development of the drug for obesity.

Toward a Cancer Drug of Fungal Origin

Although fungi produce highly structurally diverse metabolites, many of which have served as excellent sources of pharmaceuticals, no fungi-derived agent has been approved as a cancer drug so far. This is despite a tremendous amount of research being aimed at the identification of fungal metabolites with promising anticancer activities. This review discusses the results of clinical testing of fungal metabolites and their synthetic derivatives, with the goal to evaluate how far we are from an approved cancer drug of fungal origin. Also, because in vivo studies in animal models are predictive of the efficacy and toxicity of a given compound in a clinical situation, literature describing animal cancer testing of compounds of fungal origin is reviewed as well. Agents showing the potential to advance to clinical trials are also identified. Finally, the technological challenges involved in the exploitation of fungal biodiversity and procurement of sufficient quantities of clinical candidates are discussed, and potential solutions that could be pursued by researchers are highlighted.

Anticancer Agents from Diverse Natural Sources

This review attempts to portray the discovery and development of anticancer agents/drugs from diverse natural sources. Natural molecules from these natural sources including plants, microbes and marine organisms have been the basis of treatment of human diseases since the ancient times. Compounds derived from nature have been important sources of new drugs and also serve as templates for synthetic modification. Many successful anti-cancer drugs currently in use are naturally derived or their analogues and many more are under clinical trials. This review aims to highlight the invaluable role that natural products have played, and continue to play, in the discovery of anticancer agents.

Synthesis and antiproliferative activity of ligerin and new fumagillin analogs against osteosarcoma

Ligerin (1) is a natural chlorinated merosesquiterpenoid related to fumagillin (2) exhibiting a selective antiproliferative activity against osteosarcoma cell lines and an in vivo antitumor activity in a murine model. Semisynthesis of ligerin analogs was performed in order to study the effects of the C3-spiroepoxide substitution by a halogenated moiety together with the modulation of the C6 chain. Results showed that all derivatives exhibited an in vitro antiproliferative activity against osteosarcoma cell lines and that chlorohydrin compounds were equally or more active than their spiroepoxy analogs. Among semisynthetic analogs, the parent compound 1 was the best candidate for further studies since it exhibited higher or equivalent activity compared to TNP470 (3) against SaOS2 and MG63 human osteosarcoma cells with a four times weaker toxicity against HFF2 human fibroblasts. Quantitative videomicroscopy analysis was conducted and allowed a better understanding of the mechanism of its antiproliferative activity.

Natural product and natural product derived drugs in clinical trials

The 25 Natural Product (NP)-derived drugs launched since 2008 and the 100 NP-derived compounds and 33 Antibody Drug Conjugates (ADCs) in clinical trials or in registration at the end of 2013 are reviewed.

Ascending dose-controlled trial of beloranib, a novel obesity treatment for safety, tolerability, and weight loss in obese women

OBJECTIVE

Evaluate the safety and tolerability of beloranib, a fumagillin-class methionine aminopetidase-2 (MetAP2) inhibitor, in obese women over 4 weeks.

DESIGN AND METHODS

Thirty-one obese (mean BMI 38 kg/m2) women were randomized to intravenous 0.1, 0.3, or 0.9 mg/m2 beloranib or placebo twice weekly for 4 weeks (N = 7, 6, 9, and 9).

RESULTS

The most frequent AEs were headache, infusion site injury, nausea, and diarrhea. Nausea and infusion site injury occurred more with beloranib than placebo. The most common reason for discontinuation was loss of venous access. There were no clinically significant abnormal laboratory findings. In subjects completing 4 weeks, median weight loss with 0.9 mg/m2 beloranib was -3.8 kg (95% CI -5.1, -0.9; N = 8) versus -0.6 kg with placebo (-4.5, -0.1; N = 6). Weight change for 0.1 and 0.3 mg/m2 beloranib was similar to placebo. Beloranib (0.9 mg/m2) was associated with a significant 42 and 18% reduction in triglycerides and LDL-cholesterol, as well as improvement in C-reactive protein and reduced sense of hunger. Changes in β-hydroxybutyrate, adiponectin, leptin, and fibroblast growth factor-21 were consistent with the putative mechanism of MetAP2 inhibition. Glucose and blood pressure were unchanged.

CONCLUSIONS

Beloranib treatment was well tolerated and associated with rapid weight loss and improvements in lipids, C-reactive protein, and adiponectin.

A Phase Ib pharmacokinetic study of the anti-angiogenic agent CKD-732 used in combination with capecitabine and oxaliplatin (XELOX) in metastatic colorectal cancer patients who progressed on irinotecan-based chemotherapy

BACKGROUND

We conducted a Phase I clinical trial to evaluate the safety, tolerability, and pharmacokinetics (PK) of CKD-732 [6-O-(4-dimethylaminoethoxy) cinnamoyl fumagillol hemioxalate] in combination with capecitabine and oxaliplatin (XELOX) in nine metastatic colorectal cancer patients who had progressed on irinotecan-based chemotherapy.

METHODS

Using a dose-escalation schedule, CKD-732 doses of 2, 5, or 10 mg/m(2)/d were administered twice weekly for 2 weeks, followed by a 1-week rest. Oxaliplatin (130 mg/m(2)) was administered on day 1, and capecitabine (1,000 mg/m(2) twice a day) was orally administered for 14 days of a 3-week cycle.

RESULTS

In the group given the 10 mg/m(2)/d dose, two patients experienced dose limiting toxicities (one had grade 3 nausea, insomnia, and fatigue; the other had grade 3 insomnia). The maximum tolerated dose was 10 mg/m(2)/d, and the clinically recommended dose was 5 mg/m(2)/d for CKD-732 in combination with XELOX. Frequently encountered non-hematological grade 3/4 adverse events included insomnia (22.2%), fatigue (11.1%), sensory neuropathy (11.1%), hyperbilirubinemia (11.1%), and dyspnea (11.1%). The area under the concentration-time curve and maximum concentration of CKD-732 increased in a dose-dependent manner. There were no notable effects of CKD-732 on the PK of capecitabine and oxaliplatin-derived platinum.

CONCLUSION

The Phase II recommended dose of CKD-732 was determined to be 5 mg/m(2)/d, and this dose was safely combined with a conventional dose of capecitabine and oxaliplatin in this patient population. Further studies on the effects of CKD-732 in combination with XELOX and other chemotherapies using a larger study population are warranted.