Phase I Safety, Pharmacokinetic and Pharmacodynamic Evaluation of the Vascular Disrupting Agent Ombrabulin (AVE8062) in Patients with Advanced Solid Tumors

A phase I study of docetaxel plus synthetic lycopene in metastatic prostate cancer patients

PURPOSE

Our preclinical studies showed that lycopene enhanced the anti-prostate cancer efficacy of docetaxel in animal models. A phase I trial (NCT0149519) was conducted to identify an optimum dose of synthetic lycopene in combination with docetaxel (and androgen blockade [androgen deprivation therapy, ADT]), and to evaluate its effect on the safety and pharmacokinetics of docetaxel in men with metastatic prostate cancer.

METHODS

Subjects were treated with 21-day cycles of 75 mg/m2 docetaxel (and ADT), plus lycopene at 30, 90 or 150 mg/day. A Bayesian model averaging continual reassessment method was used to guide dose escalation. Pharmacokinetics of docetaxel and multiple correlative studies were carried out.

RESULTS

Twenty-four participants were enrolled, 18 in a dose escalation cohort to define the maximum tolerated dose (MTD), and six in a pharmacokinetic cohort. Docetaxel/ADT plus 150 mg/day synthetic lycopene resulted in dose-limiting toxicity (pulmonary embolus) in one out of 12 participants with an estimated probability of .106 and thus was chosen as the MTD. Lycopene increased the AUCinf and Cmax of plasma docetaxel by 9.5% and 15.1%, respectively. Correlative studies showed dose-related changes in circulating endothelial cells and vascular endothelial growth factor A, and reduction in insulin-like growth factor 1R phosphorylation, associated with lycopene therapy.

CONCLUSIONS

The combination of docetaxel/ADT and synthetic lycopene has low toxicity and favourable pharmacokinetics. The effects of lycopene on biomarkers provide additional support for the toxicity-dependent MTD definition.

HIGHLIGHTS

The maximum tolerated dose was identified as 150 mg/day of lycopene in combination with docetaxel/ADT for the treatment of metastatic prostate cancer patients. Small increases in plasma exposure to docetaxel were observed with lycopene co-administration. Mechanistically significant effects were seen on angiogenesis and insulin-like growth factor 1 signalling by lycopene co-administration with docetaxel/ADT.

Discovery, synthesis, activities, structure-activity relationships, and clinical development of combretastatins and analogs as anticancer drugs. A comprehensive review

Covering: 1982 to up to the end of 2022Bioassay guided purification of the extracts of Combretum caffrum led to the discovery of six series of combretastatins A-D with cytotoxic activities ranging from sub nM to >50 μM ED50's against a wide variety of cancer cell lines. Of these, cis-stilbenes combretastatins A-4 and A-1 were the most potent, exhibiting in vivo efficacy against a wide variety of tumor types in murine models. These antimitotic agents inhibited tubulin polymerization by reversibly binding to the colchicine binding sites. They inhibited tumor growth by a novel antivascular and antineogenesis mechanism in which they stopped blood flows to the blood vessels causing necrosis. Over 20 clinical trials of the phosphate prodrugs of combretastatin A-4 (CA4P) and A-1 (CA1P) showed objective and stable responses against many tumor types, with increased survival times of many patients along with the confirmed cure of certain patients inflicted with anaplastic thyroid cancers. Medicinal chemistry efforts led to the identification of three new leads (AVE8062, BNC105P, SCB01A) with improved in vitro and in vivo potency and an often-improved cellular spectrum. Unfortunately, these preclinical improvements did not translate clinically in any meaningful way. Objectively, CA4P remained the best compound and has garnered many Orphan drug designations by FDA. Clinical trials with tumor genetic mapping, particularly from previous responders, may help boost the success of these compounds in future studies. A comprehensive review of combretastatin series A-D, including bioassay guided discovery, total syntheses, and structure-activity relationship (SAR) studies, biological and mechanistic studies, and preclinical and clinical evaluations of the isolated combretastatins and analogs, along with the personal perspective of the author who originated this project, is presented.

Discovery of novel N-benzylarylamide-dithiocarbamate based derivatives as dual inhibitors of tubulin polymerization and LSD1 that inhibit gastric cancers

In this work, N-benzylarylamide-dithiocarbamate based derivatives were designed, synthesized, and their biological activities as anticancer agents were explored. Some of the 33 target compounds displayed significant antiproliferative activities with IC₅₀ values at the double-digit nanomolar level. The representative compound I-25 (also named MY-943) not only showed the most effective inhibitory effects on three selected cancer cells MGC-803 (IC₅₀ = 0.017 μM), HCT-116 (IC₅₀ = 0.044 μM) and KYSE450 (IC₅₀ = 0.030 μM), but also exhibited low nanomolar IC₅₀ values from 0.019 to 0.253 μM against the other 11 cancer cells. Compound I-25 (MY-943) effectively inhibited tubulin polymerization and suppressed LSD1 at the enzymatic levels. Compound I-25 (MY-943) could act on the colchicine binding site of β-tubulin, thus disrupting the construction of cell microtubule network and affecting the mitosis. In addition, compound I-25 (MY-943) could dose-dependently induce the accumulation of H3K4me1/2 (MGC-803 and SGC-7091 cells) and H3K9me2 (SGC-7091 cells). Compound I-25 (MY-943) could induce G2/M phase arrest and cell apoptosis, and suppress migration in MGC-803 and SGC-7901 cells. In addition, compound I-25 (MY-943) significantly modulated the expression of apoptosis- and cycle-related proteins. Furthermore, the binding modes of compound I-25 (MY-943) with tubulin and LSD1 were explored by molecular docking. The results of in vivo anti-gastric cancer assays using in situ tumor models showed that compound I-25 (MY-943) effectively reduced the weight and volume of gastric cancer in vivo without obvious toxicity. All these findings suggested that the N-benzylarylamide-dithiocarbamate based derivative I-25 (MY-943) was an effective dual inhibitor of tubulin polymerization and LSD1 that inhibited gastric cancers.

Mechanistic Insights and Docking Studies of Phytomolecules as Potential Candidates in the Management of Cancer

BACKGROUND

Cancer is a leading risk of death globally. According to the World Health Organization, it is presently the second most important disease that causes death in both developing and developed countries. Remarkable progress has been made in the war against cancer with the development of numerous novel chemotherapy agents. However, it remains an immense challenge to discover new efficient therapeutic potential candidates to combat cancer.

OBJECTIVES

The majority of the currently used anticancer drugs are of natural origins, such as curcumin, colchicine, vinca alkaloid, paclitaxel, bergenin, taxols, and combretastatin. Concerning this, this review article presents the structure of the most potent molecules along with IC50 values, structure-activity relationships, mechanistic studies, docking studies, in silico studies of phytomolecules, and important key findings on human cancer cell lines.

METHODS

A viewpoint of drug design and development of antiproliferative agents from natural phytomolecules has been established by searching peer-reviewed literature from Google Scholar, PubMed, Scopus, Springer, Science Direct, and Web of Science over the past few years.

RESULTS

Our analysis revealed that this article would assist chemical biologists and medicinal chemists in industry and academia in gaining insights into the anticancer potential of phytomolecules.

CONCLUSION

In vitro and in silico studies present phytomolecules, such as curcumin, colchicine, vinca alkaloids, colchicine, bergenin, combretastatin, and taxol encompassing anticancer agents, offerings abundant sanguinity and capacity in the arena of drug discovery to inspire the investigators towards the continual investigations on these phytomolecules. It is extremely expected that efforts in this track will strengthen and grant some budding cancer therapeutics candidates in the near future.

Destruction of tumor vasculature by vascular disrupting agents in overcoming the limitation of EPR effect

Nanomedicine greatly improves the efficiency in the delivery of antitumor drugs into the tumor, but insufficient tumoral penetration impairs the therapeutic efficacy of most nanomedicines. Vascular disrupting agent (VDA) nanomedicines are distributed around the tumor vessels due to the low tissue penetration in solid tumors, and the released drugs can selectively destroy immature tumor vessels and block the supply of oxygen and nutrients, leading to the internal necrosis of the tumors. VDAs can also improve the vascular permeability of the tumor, further increasing the extravasation of VDA nanomedicines in the tumor site, markedly reducing the dependence of nanomedicines on the enhanced permeability and retention effect (EPR effect). This review highlights the progress of VDA nanomedicines in recent years and their application in cancer therapy. First, the mechanisms of different VDAs are introduced. Subsequently, different strategies of delivering VDAs are described. Finally, multiple combination strategies with VDA nanomedicines in cancer therapy are described in detail.

Design, synthesis and biological evaluation of combretastatin A-4 sulfamate derivatives as potential anti-cancer agents

A series of combretastatin A-4 (CA-4) sulfamate derivatives were synthesized and their structure-activity relationship on tubulin, arylsulfatase and tumor cell antiproliferation inhibition was studied. Among them, compound 16a showed excellent potency as well as CA-4 under the same conditions against six tumor cells including HTC-116, HeLa, HepG2, MGC803, MKN45 and MCF-7 cells, respectively. Molecular docking revealed that several important hydrogen bond interactions were formed between the sulfamate group of 16a and the colchicine binding site of tubulin and steroid sulfatase respectively. Although compound 16a was less active than CA-4 in regard to its in vitro activity as an inhibitor of tubulin polymerization, it was effective as an inhibitor of arylsulfatase. This novel combretastatin A-4 sulfamate derivative has the potential to be developed as a dual inhibitor of tubulin polymerization and arylsulfatase for cancer therapy.

Phase I and pharmacokinetic study of the vascular-disrupting agent CKD-516 (NOV120401) in patients with refractory solid tumors

We report a phase I pharmacological study of an oral formulation of CKD‐516, a vascular‐disrupting agent, in patients with refractory solid tumors. Twenty‐seven patients (16 in the dose‐escalation cohort and 11 in the expansion cohort) received a single daily dose (5‐25 mg) of CKD‐516 five days per week. Nausea (67%) and diarrhea (63%) were the most common treatment‐related adverse events. The recommended phase II dose of oral CKD‐516 was 20 mg/d (15 mg/d with a body surface area (BSA) <1.65 m²). Notably, S‐516 half‐lives in patients receiving 15‐20 mg CKD‐516/d significantly differed between patients with and without splenomegaly that is suggestive of portal hypertension associated with liver cirrhosis (6.1 vs 4.6 hours, respectively). Of 11 patients without splenomegaly who completed at least one cycle of a daily CKD‐516 dose of either 15 or 20 mg, only one patient (9.1%) suffered from any dose‐limiting toxicity. We conclude that a daily oral dose of 15 or 20 mg CKD‐516 five days per week could be tolerable in patients without liver cirrhosis.

Design, synthesis, and biological evaluation of 3',4',5'-trimethoxy evodiamine derivatives as potential antitumor agents

A series of compounds bearing 3',4',5'-trimethoxy module into the core structure of evodiamine were designed and synthesized. The synthesized compounds were screened in vitro for their antitumor potential. MTT results showed that compounds 14a-14c and 14i-14j had significant effects, with compound 14h being the most prominent, with an IC₅₀ value of 3.3 ± 1.5 μM, which was lower than evodiamine and 5-Fu. Subsequent experiments further confirmed that compound 14h could inhibit cell proliferation and migration, and induce G2/M phase arrest to inhibit the proliferation of HGC-27 cells, which is consistent with the results of the cytotoxicity experiment. Besides, 14h could inhibit microtubule assembly and might kill tumor cells by inhibiting VEGF and glycolysis. All experimental results indicate that compound 14h might be a potential drug candidate for the treatment of gastric cancer and was worthy of further study.

Dose-response assessment by quantitative MRI in a phase 1 clinical study of the anti-cancer vascular disrupting agent crolibulin

The vascular disrupting agent crolibulin binds to the colchicine binding site and produces anti-vascular and apoptotic effects. In a multisite phase 1 clinical study of crolibulin (NCT00423410), we measured treatment-induced changes in tumor perfusion and water diffusivity (ADC) using dynamic contrast-enhanced MRI (DCE-MRI) and diffusion-weighted MRI (DW-MRI), and computed correlates of crolibulin pharmacokinetics. 11 subjects with advanced solid tumors were imaged by MRI at baseline and 2–3 days post-crolibulin (13–24 mg/m²). ADC maps were computed from DW-MRI. Pre-contrast T₁ maps were computed, co-registered with the DCE-MRI series, and maps of area-under-the-gadolinium-concentration-curve-at-90 s (AUC_90s) and the Extended Tofts Model parameters k^trans, v_e, and v_p were calculated. There was a strong correlation between higher plasma drug \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${C}^{max}$$\end{document}Cmax and a linear combination of (1) reduction in tumor fraction with \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${AUC}_{90s}>15.8$$\end{document}AUC90s>15.8 mM s, and, (2) increase in tumor fraction with \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${v}_{e}<0.3$$\end{document}ve<0.3. A higher plasma drug AUC was correlated with a linear combination of (1) increase in tumor fraction with \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{ADC}} < 1.1 \times 10^{ - 3} \;{\text{mm}}^{2} /{\text{s}}$$\end{document}ADC<1.1×10-3mm2/s, and, (2) increase in tumor fraction with \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$v_{e}<0.3$$\end{document}ve<0.3. These findings are suggestive of cell swelling and decreased tumor perfusion 2–3 days post-treatment with crolibulin. The multivariable linear regression models reported here can inform crolibulin dosing in future clinical studies of crolibulin combined with cytotoxic or immune-oncology agents.

Discovery of tertiary amide derivatives incorporating benzothiazole moiety as anti-gastric cancer agents in vitro via inhibiting tubulin polymerization and activating the Hippo signaling pathway

On the basis and continuation of our previous studies on anti-tubulin and anti-gastric cancer agents, novel tertiary amide derivatives incorporating benzothiazole moiety were synthesized and the antiproliferative activity was studied in vitro. Preliminary structure activity relationships (SARs) were explored according to the in vitro antiproliferative activity results. Some of compounds could significantly inhibit the proliferation of three cancer cells (HCT-116, MGC-803 and PC-3 cells) and compound F10 exhibited excellent antiproliferative activity against HCT-116 cells (IC₅₀ = 0.182 μM), MGC-803 cells (IC₅₀ = 0.035 μM), PC-3 cells(IC₅₀ = 2.11 μM) and SGC-7901 cells (IC₅₀ = 0.049 μM). Compound F10 effectively inhibited tubulin polymerization (IC₅₀ = 1.9 μM) and bound to colchicine binding site of tubulin. Molecular docking results suggested compound F10 could bind tightly into the colchicine binding site of β-tubulin. Moreover, compound F10 could regulate the Hippo/YAP signaling pathway. Compound F10 activated Hippo signaling pathway from its very beginning MST1/2, as the result of Hippo cascade activation YAP were inhibited. And then it led to a decrease of c-Myc and Bcl-2 expression. Further molecular experiments showed that compound F10 arrested at G2/M phase, inhibited cell colony formatting and induced extrinsic and intrinsic apoptosis in MGC-803 and SGC-7901 cells. Collectively, compound F10 was the first to be reported as a new anticancer agent in vitro via inhibiting tubulin polymerization and activating the Hippo signaling pathway.

Vascular Disrupting Agents in cancer treatment: Cardiovascular toxicity and implications for co-administration with other cancer chemotherapeutics

Destruction of the established tumour vasculature by a class of compound termed Vascular Disrupting Agents (VDAs) is showing considerable promise as a viable approach for the management of solid tumours. VDAs induce a rapid shutdown and collapse of tumour blood vessels, leading to ischaemia and consequent necrosis of the tumour mass. Their efficacy is hindered by the persistence of a viable rim of tumour cells, supported by the peripheral normal vasculature, necessitating their co-administration with additional chemotherapeutics for maximal therapeutic benefit. However, a major limitation for the use of many cancer therapeutics is the development of life-threatening cardiovascular toxicities, with significant consequences for treatment response and the patient's quality of life. The aim of this review is to outline VDAs as a cancer therapeutic approach and define the mechanistic basis of cardiovascular toxicities of current chemotherapeutics, with the overall objective of discussing whether VDA combinations with specific chemotherapeutic classes would be good or bad in terms of cardiovascular toxicity.

The arrival of predictive biomarkers for monitoring therapy response to natural compounds in cancer drug discovery

Intrinsic or acquired drug resistance, adverse drug reactions and tumor heterogeneity between and within cancer patients limit the efficacy of clinical management of advanced cancers. To overcome these barriers, predictive biomarkers have recently emerged to guide medical oncologists in the selection of cancer patients who will respond to various anticancer treatments and to improve the toxicity to benefit ratio. Notably, targeted therapy has significantly benefited from these advances, but the application of predictive biomarkers have been a bit slower with some drugs derived from natural sources such as trabectedin, cabazitaxel and alvocidib. In this paper, we discuss some recent advances regarding the use of cancer biomarkers to predict efficacy of some selected natural compounds with a focus on human clinical studies.

Combretastatin-Inspired Heterocycles as Antitubulin Anticancer Agents

Combretastatin (CA-4) and its analogues are undergoing several clinical trials for treating different types of tumors. In this work, the antiproliferative activity of a series of 2-aminoimidazole-carbonyl analogs of clinically relevant combretastatins A-4 (CA-4) and A-1 was evaluated using a cell-based assay. Among the compounds tested, C-13 and C-21 displayed strong antiproliferative activities against HeLa cells. C-13 inhibited the proliferation of lung carcinoma (A549) cells more potently than combretastatin A-4. C-13 also retarded the migration of A549 cells. Interestingly, C-13 displayed much stronger antiproliferative effects against breast carcinoma and skin melanoma cells compared to noncancerous breast epithelial and skin fibroblast cells. C-13 strongly disassembled cellular microtubules, perturbed the localization of EB1 protein, inhibited mitosis in cultured cells, and bound to tubulin at the colchicine site and inhibited the polymerization of reconstituted microtubules in vitro. C-13 treatment increased the level of reactive oxygen species and induced apoptosis via poly(ADP-ribose) polymerase-cleavage in HeLa cells. The results revealed the importance of the 2-aminoimidazole-carbonyl motif as a double bond replacement in combretastatin and indicated a pharmacodynamically interesting pattern of H-bond acceptors/donors and requisite syn-templated aryls.

Starvation tactics using natural compounds for advanced cancers: pharmacodynamics, clinical efficacy, and predictive biomarkers

The high mortality associated with oncological diseases is mostly due to tumors in advanced stages, and their management is a major challenge in modern oncology. Angiogenesis is a defined hallmark of cancer and predisposes to metastatic invasion and dissemination and is therefore an important druggable target for cancer drug discovery. Recently, because of drug resistance and poor prognosis, new anticancer drugs from natural sources targeting tumor vessels have attracted more attention and have been used in several randomized and controlled clinical trials as therapeutic options. Here, we outline and discuss potential natural compounds as salvage treatment for advanced cancers from recent and ongoing clinical trials and real-world studies. We also discuss predictive biomarkers for patients' selection to optimize the use of these potential anticancer drugs.

Recent advances in trimethoxyphenyl (TMP) based tubulin inhibitors targeting the colchicine binding site

Microtubules (composed of α- and β-tubulin heterodimers) play a pivotal role in mitosis and cell division, and are regarded as an excellent target for chemotherapeutic agents to treat cancer. There are four unique binding sites in tubulin to which taxanes, vinca alkaloids, laulimalide and colchicine bind respectively. While several tubulin inhibitors that bind to the taxane or vinca alkaloid binding sites have been approved by FDA, currently there are no FDA approved tubulin inhibitors targeting the colchicine binding site. Tubulin inhibitors that bind to the colchicine binding site have therapeutic advantages over taxanes and vinca alkaloids, for example, they can be administered orally, have less drug-drug interaction potential, and are less prone to develop multi-drug resistance. Typically, tubulin inhibitors that bind to the colchicine binding site bear the trimethoxyphenyl (TMP) moiety which is essential for interaction with tubulin. Over the last decade, a variety of molecules bearing the TMP moiety have been designed and synthesized as tubulin inhibitors for cancer treatment. In this review, we focus on the TMP analogs that are designed based on CA-4, indole, chalcone, colchicine and natural product scaffolds which are known to interact with the colchicine binding site in tubulin. The challenges and future direction of the TMP based tubulin inhibitors are also discussed in detail.

Drug-Clinical Agent Molecular Hybrid: Synthesis of Diaryl(trifluoromethyl)pyrazoles as Tubulin Targeting Anticancer Agents

Twenty-three combretastatin A-4 (CA-4) analogues were synthesized by judiciously incorporating a functional N-heterocyclic motif present in Celecoxib (a marketed drug) while retaining essential pharmacophoric features of CA-4. Combretastatin-(trifluoromethyl)pyrazole hybrid analogues, i.e., 5-trimethoxyphenyl-3-(trifluoromethyl)pyrazoles with a variety of relevantly substituted aryls and heteroaryls at 1-position were considered as potential tubulin polymerization inhibitors. The cytotoxicity of the compounds was evaluated using MCF-7 cells. Analog 23 (C-23) was found to be the most active among the tested compounds. It showed pronounced cytotoxicity against HeLa, B16F10, and multidrug-resistant mammary tumor cells EMT6/AR1. Interestingly, C-23 displayed significantly lower toxicity toward noncancerous cells, MCF10A and L929, than their cancerous counterparts, MCF-7 and B16F10, respectively. C-23 depolymerized interphase microtubules, disrupted mitotic spindle formation, and arrested MCF-7 cells at mitosis, leading to cell death. C-23 inhibited the assembly of tubulin in vitro. C-23 bound to tubulin at the colchicine binding site and altered the secondary structures of tubulin. The data revealed the importance of (trimethoxyphenyl)(trifluoromethyl)pyrazole as a cis-restricted double bond-alternative bridging motif, and carboxymethyl-substituted phenyl as ring B for activities and interaction with tubulin. The results indicated that the combretastatin-(trifluoromethyl)pyrazole hybrid class of analogues has the potential for further development as anticancer agents.

Desacetylvinblastine Monohydrazide Disrupts Tumor Vessels by Promoting VE-cadherin Internalization

Vinca alkaloids, the well-known tubulin-binding agents, are widely used for the clinical treatment of malignant tumors. However, little attention has been paid to their vascular disrupting effects, and the underlying mechanisms remain largely unknown. This study aims to investigate the vascular disrupting effect and the underlying mechanisms of vinca alkaloids.

Methods: The capillary disruption assay and aortic ring assay were performed to evaluate the in vitro vascular disrupting effect of desacetylvinblastine monohydrazide (DAVLBH), a derivate of vinblastine, and the in vivo vascular disrupting effect was assessed on HepG2 xenograft model using magnetic resonance imaging, hematoxylin and eosin staining and immunohistochemistry. Tubulin polymerization, endothelial cell monolayer permeability, western blotting and immunofluorescence assays were performed to explore the underlying mechanisms of DAVLBH-mediated tumor vascular disruption.

Results: DAVLBH has potent vascular disrupting activity both in vitro and in vivo. DAVLBH disrupts tumor vessels in a different manner than classical tubulin-targeting VDAs; it inhibits microtubule polymerization, promotes the internalization of vascular endothelial cadherin (VE-cadherin) and inhibits the recycling of internalized VE-cadherin to the cell membrane, thus increasing endothelial cell permeability and ultimately resulting in vascular disruption. DAVLBH-mediated promotion of VE-cadherin internalization and inhibition of internalized VE-cadherin recycling back to the cell membrane are partly dependent on inhibition of microtubule polymerization, and Src activation is involved in DAVLBH-induced VE-cadherin internalization.

Conclusions: This study sheds light on the tumor vascular disrupting effect and underlying mechanisms of vinca alkaloids and provides new insight into the molecular mechanism of tubulin-targeting VDAs.

Phase 1 study of ombrabulin in combination with cisplatin (CDDP) in Japanese patients with advanced solid tumors

OBJECTIVE

In clinical studies in Western countries, the recommended dose of combination ombrabulin a vascular disrupting agent, with cisplatin is 25 mg/m2 ombrabulin with 75 mg/m2 cisplatin every 3 weeks. Here, we report the first Phase 1 study of this treatment regimen in Japanese patients with advanced solid tumors.

METHODS

This was an open-label, multicenter, sequential cohort, dose-escalation Phase 1 study of ombrabulin with cisplatin administered once every 3 weeks. The study used a 3 + 3 design without intrapatient dose escalation. The investigated dose levels of ombrabulin were 15.5 and 25 mg/m2 combined with cisplatin 75 mg/m2. The latter dose level was regarded as the maximum administered dose if more than one patient experienced dose-limiting toxicities.

RESULTS

Ten patients were treated, but no dose-limiting toxicity was observed at both dose levels. Ombrabulin 25 mg/m2 with cisplatin 75 mg/m2 was the maximum administered dose and regarded as the recommended dose in the combination regimen for Japanese patients with cancer. The most frequently reported drug-related adverse events were neutropenia, decreased appetite, constipation, nausea and fatigue. One partial response and five cases of stable disease were reported as the best overall responses. Pharmacokinetic parameters of ombrabulin and cisplatin were comparable with those in non-Japanese patients.

CONCLUSIONS

Ombrabulin 25 mg/m2 with cisplatin 75 mg/m2 once every 3 weeks was well tolerated and established as the recommended dose in Japanese patients with advanced solid tumors. The safety and pharmacokinetic profiles were comparable between Japanese and Caucasian patients.

Early investigational tubulin inhibitors as novel cancer therapeutics

INTRODUCTION

Microtubules represent one of the most logical and strategic molecular targets amongst the current targets for chemotherapy, alongside DNA. In the past decade, tubulin inhibitors as cancer therapeutics have been an area of focus due to the improved understanding and biological relevance of microtubules in cellular functions. Fueled by the objective of developing novel chemotherapeutics and with the aim of establishing the benefits of tubulin inhibition, several clinical trials have been conducted with others ongoing.

AREA COVERED

At present, the antitubulin development pipeline contains an armful of agents under clinical investigation. This review focuses on novel tubulin inhibitors as cancer therapeutics. The article covers the agents which have completed the phase II studies along with the agents demonstrating promising results in phase I studies.

EXPERT OPINION

Countless clinical trials evaluating the efficacy, safety and pharmacokinetics of novel tubulin inhibitors highlights the scientific efforts being paid to establish their candidature as cancer therapeutics. Colchicine binding site inhibitors as vascular disrupting agents (VDAs) and new taxanes appear to be the most likely agents for future clinical interest. Numerous agents have demonstrated clinical benefits in terms of efficacy and survival in phase I and II studies. However conclusive benefits can only be ascertained on the basis of phase III studies.

A cooperative polymeric platform for tumor-targeted drug delivery

A tumor-targeted drug delivery system with small-molecule vascular disrupting agents inducing coagulation environment inside tumor and coagulation-targeted nanoparticles accumulating there.

In the pursuit of effective treatments for cancer, an emerging strategy is “active targeting”, where nanoparticles are decorated with targeting ligands able to recognize and bind specific receptors overexpressed by tumor cells or tumor vasculature so that a greater fraction of the administered drugs are selectively trafficked to tumor sites. However, the implementation of this strategy has faced a major obstacle. The interpatient, inter- and intra-tumoral heterogeneity in receptor expression can pose challenges for the design of clinical trials and result in the paucity of targetable receptors within a tumor, which limits the effectiveness of “active targeting” strategy in cancer treatment. Here we report a cooperative drug delivery platform that overcomes the heterogeneity barrier unique to solid tumors. The cooperative platform comprises a coagulation-inducing agent and coagulation-targeted polymeric nanoparticles. As a typical small-molecule vascular disrupting agent (VDA), DMXAA can create a unique artificial coagulation environment with additional binding sites in a solid tumor by locally activating a coagulation cascade. Coagulation-targeted cisplatin-loaded nanoparticles, which are surface-decorated with a substrate of activated blood coagulation factor XIII, can selectively accumulate in the solid tumor by homing to the VDA-induced artificial coagulation environment through transglutamination. In vivo studies show that the cooperative tumor-selective platform recruits up to 7.5-fold increases in therapeutic cargos to the tumors and decreases tumor burden with low systemic toxicity as compared with non-cooperative controls. These indicate that the use of coagulation-targeted nanoparticles, in conjunction with free small-molecule VDAs, may be a valuable strategy for improving standard chemotherapy.

Pharmacokinetic strategies to improve drug penetration and entrapment within solid tumors

Despite the discovery of a large number of anticancer agents, cancer still remains among the leading causes of death since the middle of the twentieth century. Solid tumors possess a high degree of genetic instability and emergence of treatment resistance. Tumor resistance has emerged for almost all approved anticancer drugs and will most probably emerge for newly discovered anticancer agents as well. The use of pharmacokinetic approaches to increase anticancer drug concentrations within the solid tumor compartment and prolong its entrapment might diminish the possibility of resistance emergence at the molecular pharmacodynamic level and might even reverse tumor resistance. Several novel treatment modalities such as metronomic therapy, angiogenesis inhibitors, vascular disrupting agents and tumor priming have been introduced to improve solid tumor treatment outcomes. In the current review we will discuss the pharmacokinetic aspect of these treatment modalities in addition to other older treatment modalities, such as extracellular matrix dissolving agents, extracellular matrix synthesis inhibitors, chemoembolization and cellular efflux pump inhibition. Many of these strategies showed variable degrees of success/failure; however, reallocating these modalities based on their influence on the intratumoral pharmacokinetics might improve their understanding and treatment outcomes.

Coadministration of Vascular Disrupting Agents and Nanomedicines to Eradicate Tumors from Peripheral and Central Regions

A strategy for enhancing the treatment efficacy of nanomedicines within the central region of solid tumors is developed by combining nanomedicines and free small-molecule vascular disrupting agents (VDAs). The nanomedicines (cis-diamminedichloroplatinum-loaded nanoparticles) primarily target cells at the tumor periphery whereas the free small-molecule VDA (combretastatin A4 disodium phosphate) efficiently kills the cancer cells within the central regions of the tumor.

Angiogenic inhibitors in gastric cancers and gastroesophageal junction carcinomas: A critical insight

Advanced gastric cancer ranks second as the global leading cause of cancer-related death and improvements in systemic chemotherapy have reached a plateau. Advanced molecular sequencing techniques help identifying patients more likely to respond to targeted agents; nevertheless we are still far from major breakthroughs. Although antiangiogenic drugs have produced notable advances, redundant pathways or mechanisms of resistance may limit their efficacy. Novel compounds have been recently developed to specifically target VEGF receptors, PlGF, FGF, MET, and angiopoietin. Ramucirumab, a monoclonal antibody specifically directed against the VEGFR-2, has emerged as a novel therapeutic opportunity. REGARD and RAINBOW were the first phase III studies to report the value of this strategy in gastric cancer patients, and other ongoing trials are testing novel antiangiogenic compounds. The aim of our review is to present the state-of-the-art of novel antiangiogenic compounds in advanced gastric cancer, underlying the biology, their mechanism of action, and their clinical results.

Recent advances in vascular disrupting agents in cancer therapy

Vascular disrupting agents (VDAs) are an important class of compounds that exhibit selective activity against pre-existing tumor vasculature, causing rapid shutdown of the tumor blood flow and consequent necrosis of the tumor mass. The VDAs can be divided into flavonoid compounds, which are related to flavone acetic acid, and tubulin-binding agents. Tubulin-binding agents represent the largest group of VDAs and are characterized by different chemical structures, although most of them are derivatives of the lead compound combretastatin (CA-4). They demonstrated clinical activity, although recent findings have established that they have insufficient activity as single agents. Several resistance mechanisms occur, such as the resistance of the tumor rim cells, while promising results have been described in combination with other chemotherapeutics.

Ombrabulin plus cisplatin versus placebo plus cisplatin in patients with advanced soft-tissue sarcomas after failure of anthracycline and ifosfamide chemotherapy: a randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

Ombrabulin (AVE8062) disrupts the vasculature of established tumours and has shown preclinical synergistic anti-tumour activity when combined with cisplatin. In this phase 3 trial, we aimed to assess the efficacy and safety of ombrabulin plus cisplatin compared with placebo plus cisplatin in patients with advanced soft-tissue sarcomas.

METHODS

We did this multinational, randomised, double-blind, placebo-controlled phase 3 study at 44 centres in ten countries. Patients aged 18 years and older with metastatic soft-tissue sarcomas, an Eastern Cooperative Oncology Group performance status of 0-2, and who had previously received treatment with anthracycline and ifosfamide were randomly assigned (1:1) to intravenous infusion of ombrabulin 25 mg/m(2) plus cisplatin 75 mg/m(2) or intravenous infusion of placebo plus cisplatin 75 mg/m(2) every 3 weeks. Patients were allocated to treatment using a permuted blocks randomisation scheme (block size of four) via an interactive voice-response system, and stratified by histological subtype. Patients, medical staff, study investigators, and individuals who handled and analysed the data were masked to treatment assignment. Our primary endpoint was median progression-free survival in the intention-to-treat population. Safety analyses were done on all randomised patients who received at least one dose of study drug. This trial is now closed, and is registered with ClinicalTrials.gov, number NCT00699517.

FINDINGS

Between June 13, 2008, and April 26, 2012, we randomly assigned 355 patients to ombrabulin plus cisplatin (n=176) or placebo plus cisplatin (n=179). Median duration of follow-up was 27·9 (IQR 20·9-33·2) in the placebo group and 30·5 months (20·7-37·6) in the ombrabulin group. Progression-free survival was slightly, but significantly, improved in the ombrabulin group compared with the placebo group (median 1·54 months [95% CI 1·45-2·69] vs 1·41 [1·38-1·58] months; hazard ratio 0·76 [95% CI 0·59-0·98]; p=0·0302). Grade 3 or 4 adverse events occurred more frequently in individuals in the ombrabulin group than in those in the placebo group and included neutropenia (34 [19%] in the ombrabulin group vs 14 [8%] in the placebo group) and thrombocytopenia (15 [8%] vs six [3%] for placebo). Adverse events leading to death occurred in 18 patients in the ombrabulin group and 10 patients in the placebo group.

INTERPRETATION

The combination of ombrabulin and cisplatin significantly improved progression-free survival; however, it did not show a sufficient clinical benefit in patients with advanced soft-tissue sarcomas to support its use as a therapeutic option. Predictive biomarkers are needed for the rational clinical development of tumour vascular-disrupting drugs for soft-tissue sarcomas.

FUNDING

Sanofi.

Phase I Study of CKD-516, a Novel Vascular Disrupting Agent, in Patients with Advanced Solid Tumors

PURPOSE

CKD-516 is a newly developed vascular disrupting agent. This phase I dose-escalation study of CKD-516 was conducted to determine maximum-tolerated dose (MTD), safety, pharmacokinetics, and preliminary antitumor efficacy in patients with advanced solid tumors.

MATERIALS AND METHODS

Patients received CKD-516 intravenously on D1 and D8 every 3 weeks, in a standard 3+3 design. Safety was evaluated by National Cancer Institute Common Terminology Criteria for Adverse Events ver. 4.02 and response was assessed by Response Evaluation Criteria in Solid Tumor ver. 1.1.

RESULTS

Twenty-three patients were treated with CKD-516 at seven dosing levels: 1 mg/m(2)/day (n=3), 2 mg/m(2)/day (n=3), 3.3 mg/m(2)/day (n=3), 5 mg/m(2)/day (n=3), 7 mg/m(2)/day (n=3), 9 mg/m(2)/day (n=6), and 12 mg/m(2)/day (n=2). Mean age was 54 and 56.5% of patients were male. Two dose-limiting toxicities, which were both grade 3 hypertension, were observed in two patients at 12 mg/m(2)/day. The MTD was determined as 12 mg/m(2)/day. Most common adverse events were gastrointestinal adverse events (diarrhea, 34.8% [30.4% grade 1/2, 13.0% grade 3]; nausea, 21.7% [all grade 1/2]; vomiting, 21.7% [all grade 1/2]), myalgia (17.4%, all grade 1/2), and abdominal pain (21.7% [21.7% grade 1/2, 4.3% grade 3]). The pharmacokinetic study showed the dose-linearity of all dosing levels. Among 23 patients, six patients (26.1%) showed stable disease. Median progression-free survival was 39 days (95% confidence interval, 37 to 41 days).

CONCLUSION

This study demonstrates feasibility of CKD-516, novel vascular disrupting agent, in patients with advanced solid tumor. MTD of CKD-516 was defined as 12 mg/m(2)/day on D1 and D8 every 3 weeks.

Novel drugs against non-small-cell lung cancer

PURPOSE OF REVIEW

Important therapeutic advances for patients with advanced non-small-cell lung cancer (NSCLC) with focus on individualized therapy have recently occurred and are summarized in this review.

RECENT FINDINGS

Cetuximab added to first-line chemotherapy has been shown to improve survival in patients with high epidermal growth factor receptor (EGFR) expression in their tumors. Afatinib has shown improved progression-free survival and better quality of life compared to chemotherapy in patients with EGFR-mutation-positive adenocarcinomas. Several other EGFR-directed agents are in clinical development. Crizotinib improved progression-free survival compared to second-line chemotherapy with docetaxel or pemetrexed in patients with advanced anaplastic lymphoma kinase-positive NSCLC. Selumetinib added to docetaxel has improved outcome compared with docetaxel in a randomized phase II trial in patients with advanced KRAS-mutant NSCLC and this combination is currently studied in a phase III trial. Nintedanib added to docetaxel improved progression-free survival in the second-line therapy of patients with advanced NSCLC but many other angiogenesis inhibitors failed to improve clinical outcome in phase III trials. Several other targeted therapies are currently evaluated in phase III trials in patients with advanced NSCLC.

SUMMARY

Recent trials have led to the approval of afatinib and crizotinib for subsets of patients with advanced NSCLC.

Phase I clinical and pharmacokinetic study of ombrabulin (AVE8062) combined with cisplatin/docetaxel or carboplatin/paclitaxel in patients with advanced solid tumors

PURPOSE

Preclinical evidence supports synergy between the vascular disrupting agent ombrabulin and various chemotherapy agents. Ombrabulin was combined with two standard taxane/platinum doublets in a phase I study to determine the recommended combination doses.

METHODS

Ombrabulin (30-min infusion, day 1 every 3 weeks) was escalated from 15.5 to 35 mg/m(2) with two chemotherapy doublets; OCD, 75 mg/m(2) cisplatin (C), day 1 (cohort 1) or day 2 (cohort 2) with 60/75 mg/m(2) docetaxel (D), day 2; and OCP, AUC5/6 carboplatin (C) and paclitaxel (P) 175 mg/m(2) (cohort 3) or 200 mg/m(2) (cohort 4), day 2. Safety, pharmacokinetics, and tumor response were evaluated.

RESULTS

Sixty-nine patients were treated (32 OCD, 37 OCP). Four had DLTs in cycle 1, two in cohort 1 (grade 4 febrile neutropenia, grade 4 pulmonary embolism) and one each in cohorts 2 (grade 3 ALT elevation) and 4 (grade 3 peripheral ischemia). Ombrabulin escalation in cohorts 2, 3 and 4 was halted at the highest planned dose (35 mg/m(2)). Asthenia, nausea, paresthesia, alopecia, vomiting, and stomatitis were common, as was grade 3-4 neutropenia. Ombrabulin clearance was high with a short terminal half-life and a medium volume of distribution. Pharmacokinetic analysis showed no clinically relevant drug interactions between the taxane-platinum doublet and ombrabulin or its active metabolite RPR258063, however docetaxel and carboplatin pharmacokinetics were slightly altered. One complete and 15 partial responses (10 OCD, 5 OCP; median duration 5.5 and 4.4 months, respectively) were reported.

CONCLUSIONS

The addition of ombrabulin to standard doses of cisplatin/docetaxel or carboplatin/paclitaxel proved feasible with manageable overlapping toxicities but appears to have limited impact on the efficacy of these doublets. Recommended combination doses are 35 mg/m(2) ombrabulin with 75 mg/m(2) cisplatin/75 mg/m(2) docetaxel or 200 mg/m(2) paclitaxel/AUC6 carboplatin, every 3 weeks.

A phase I pharmacokinetic study of the vascular disrupting agent ombrabulin (AVE8062) and docetaxel in advanced solid tumours

BACKGROUND

The vascular disrupting agent ombrabulin shows synergy with docetaxel in vivo. Recommended phase II doses were determined in a dose escalation study in advanced solid tumours.

METHODS

Ombrabulin (30-min infusion, day 1) followed by docetaxel (1-h infusion, day 2) every 3 weeks was explored. Ombrabulin was escalated from 11.5 to 42 mg m(-2) with 75 mg m(-2) docetaxel, then from 30 to 35 mg m(-2) with 100 mg m(-2) docetaxel. Recommended phase II dose cohorts were expanded.

RESULTS

Fifty-eight patients were treated. Recommended phase II doses were 35 mg m(-2) ombrabulin with 75 mg m(-2) docetaxel (35/75 mg m(-2); 13 patients) and 30 mg m(-2) ombrabulin with 100 mg m(-2) docetaxel (30/100 mg m(-2); 16 patients). Dose-limiting toxicities were grade 3 fatigue (two patients; 42/75, 35/100), grade 3 neutropaenic infection (25/75), grade 3 headache (42/75), grade 4 febrile neutropaenia (30/100), and grade 3 thrombosis (35/100). Toxicities were consistent with each agent; mild nausea/vomiting, asthaenia/fatigue, alopecia, and anaemia were common, as were neutropaenia and leukopaenia. Diarrhoea, nail disorders and neurological symptoms were frequent at 100 mg m(-2) docetaxel. Pharmacokinetic analyses did not show any relevant drug interactions. Ten patients had partial responses (seven at 30 mg m(-2) ombrabulin), eight lasting >3 months.

CONCLUSIONS

Sequential administration of ombrabulin with 75 or 100 mg m(-2) docetaxel every 3 weeks is feasible.

An open-label, dose-escalation, safety, and pharmacokinetics phase I study of ombrabulin, a vascular disrupting agent, administered as a 30-min intravenous infusion every 3 weeks in Japanese patients with advanced solid tumors

PURPOSE

To determine ombrabulin's maximum tolerated dose and dose recommended for Japanese patients with advanced solid tumors and to assess its antitumor activity and overall safety and pharmacokinetic profiles.

METHODS

This was a multi-center, open-label, sequential-cohort, dose-escalation phase I study of ombrabulin, a vascular disrupting agent, administered once every 3 weeks. Patients were treated with 15.5, 25, 35, or 50 mg/m(2) ombrabulin over a 30-min intravenous infusion. The recommended dose was the highest dose at which <33 % of all evaluable patients experienced dose-limiting toxicities (DLTs) during the first treatment cycle or 50 mg/m(2) (recommended in Caucasian patients) if the previous definition was not met.

RESULTS

Fifteen patients were treated. No DLT occurred with 15.5, 25, or 35 mg/m(2) ombrabulin. In the 50 mg/m(2) group, one patient had Grade 3 lymphopenia, and another experienced Grade 2 hypertension and Grade 3 diarrhea judged as DLTs. The most frequent related adverse events in this group were diarrhea, nausea, and hypertension. Two patients had Grade 3 anemia, one at the 15.5 mg/m(2) and the other at the 50 mg/m(2). No AEs necessitating dose reduction or Grade 4 AEs were observed. Overall, five patients had stable disease. Pharmacokinetic parameters were comparable to those in non-Japanese patients.

CONCLUSIONS

Ombrabulin treatment once every 3 weeks was well tolerated in Japanese patients with advanced solid tumors. The dose recommended is 50 mg/m(2), as in Caucasian patients. The safety and pharmacokinetic profiles were comparable between Japanese and Caucasian patients (funded by Sanofi; ClinicalTrials.gov number, NCT00968916).