A phase I study of MN-029 (denibulin), a novel vascular-disrupting agent, in patients with advanced solid tumors

Antiproliferative and Pro-Apoptotic Activity and Tubulin Dynamics Modulation of 1H-Benzimidazol-2-yl Hydrazones in Human Breast Cancer Cell Line MDA-MB-231

(1) Background: The aim of the work is the evaluation of in vitro antiproliferative and pro-apoptotic activity of four benzimidazole derivatives containing colchicine-like and catechol-like moieties with methyl group substitution in the benzimidazole ring against highly invasive breast cancer cell line MDA-MB-231 and their related impairment of tubulin dynamics. (2) Methods: The antiproliferative activity was assessed with the MTT assay. Alterations in tubulin polymerization were evaluated with an in vitro tubulin polymerization assay and a docking analysis. (3) Results: All derivatives showed time-dependent cytotoxicity with IC50 varying from 40 to 60 μM after 48 h and between 13 and 20 μM after 72 h. Immunofluorescent and DAPI staining revealed the pro-apoptotic potential of benzimidazole derivatives and their effect on tubulin dynamics in living cells. Compound 5d prevented tubulin aggregation and blocked mitosis, highlighting the importance of the methyl group and the colchicine-like fragment. (4) Conclusions: The benzimidazole derivatives demonstrated moderate cytotoxicity towards MDA-MB-231 by retarding the initial phase of tubulin polymerization. The derivative 5d containing a colchicine-like moiety and methyl group substitution in the benzimidazole ring showed potential as an antiproliferative agent and microtubule destabilizer by facilitating faster microtubule aggregation and disrupting cellular and nuclear integrity.

Triazolo-linked benzimidazoles as tubulin polymerization inhibitors and DNA intercalators: Design, synthesis, cytotoxicity, and docking studies

A simple "click" protocol was employed in the quest of synthesizing 1,2,3-triazole-linked benzimidazoles as promising anticancer agents on various human cancer cell lines such as A549, HCT116, SK-Mel-28, HT-29, and MCF-7. Compound 12j demonstrated significant cytotoxic potential towards SK-Mel-28 cancer cells (IC₅₀ : 4.17 ± 0.09 µM) and displayed no cytotoxicity (IC₅₀ : > 100 µM) against normal human BEAS-2B cells inferring its safety towards normal healthy cells. Further to comprehend the underlying apoptosis mechanisms, AO/EB, dichlorodihydrofluorescein diacetate (DCFDA), and 4',6-diamidino-2-phenylindole (DAPI) staining were performed, which revealed the nuclear and morphological alterations. Compound 12j displayed impairment in cellular migration and inhibited colony formation. The annexin V binding assay and JC-1 were implemented to evaluate the scope of apoptosis and the loss of the mitochondrial transmembrane potential in SK-Mel-28 cells. Cell-cycle analysis revealed that compound 12j arrested the cells at the G2/M phase in a dose-dependent manner. Target-based assays established the inhibition of tubulin polymerization by 12j at an IC₅₀ value of 5.65  ± 0.05 μM and its effective binding with circulating tumor DNA as a DNA intercalator. The detailed binding interactions of 12j with tubulin and DNA were examined by docking studies on PDB ID: 3E22 and DNA hexamer (PDB ID: 1NAB), respectively.

Non-Invasive Evaluation of Acute Effects of Tubulin Binding Agents: A Review of Imaging Vascular Disruption in Tumors

Tumor vasculature proliferates rapidly, generally lacks pericyte coverage, and is uniquely fragile making it an attractive therapeutic target. A subset of small-molecule tubulin binding agents cause disaggregation of the endothelial cytoskeleton leading to enhanced vascular permeability generating increased interstitial pressure. The resulting vascular collapse and ischemia cause downstream hypoxia, ultimately leading to cell death and necrosis. Thus, local damage generates massive amplification and tumor destruction. The tumor vasculature is readily accessed and potentially a common target irrespective of disease site in the body. Development of a therapeutic approach and particularly next generation agents benefits from effective non-invasive assays. Imaging technologies offer varying degrees of sophistication and ease of implementation. This review considers technological strengths and weaknesses with examples from our own laboratory. Methods reveal vascular extent and patency, as well as insights into tissue viability, proliferation and necrosis. Spatiotemporal resolution ranges from cellular microscopy to single slice tomography and full three-dimensional views of whole tumors and measurements can be sufficiently rapid to reveal acute changes or long-term outcomes. Since imaging is non-invasive, each tumor may serve as its own control making investigations particularly efficient and rigorous. The concept of tumor vascular disruption was proposed over 30 years ago and it remains an active area of research.

Cinnamide derived pyrimidine-benzimidazole hybrids as tubulin inhibitors: Synthesis, in silico and cell growth inhibition studies

An approach in modern medicinal chemistry to discover novel bioactive compounds is by mimicking diverse complementary pharmacophores. In extension of this strategy, a new class of piperazine-linked cinnamide derivatives of benzimidazole-pyrimidine hybrids have been designed and synthesized. Their in vitro cytotoxicity profiles were explored on selected human cancer cell lines. Specifically, structural comparison of target hybrids with tubulin-DAMA-colchicine and tubulin-nocodazole complexes has exposed a deep position of benzimidazole ring into the αT5 loop. All the synthesized compounds were demonstrated modest to interesting cytotoxicity against different cancer cell lines. The utmost cytotoxicity has shown with an amine linker of benzimidazole-pyrimidine series, with specificity toward A549 (lung cancer) cell line. The most potent compound in this series was 18i, which inhibited cancer cell growth at micromolar concentrations ranging 2.21-7.29 µM. Flow cytometry studies disclosed that 18i inhibited the cells in G2/M phase of cell cycle. The potent antitumor activity of 18i resulted from enhanced microtubule disruption at a similar level as nocodazole on β-tubulin antibody, explored using immunofluorescence staining. The most active compound 18i also inhibited tubulin polymerization with an IC₅₀ of 5.72 ± 0.51 µM. In vitro biological analysis of 18i presented apoptosis induction on A549 cells with triggering of ROS generation and loss of mitochondrial membrane potential, resulting in DNA injury. In addition, 18i displayed impairment in cellular migration and inhibited the colony formation. Notably, the safety profile of most potent compound 18i was revealed by screening against normal human pulmonary epithelial cells (L132: IC₅₀: 69.25 ± 5.95 μM). The detailed binding interactions of 18i with tubulin was investigated by employing molecular docking, superimposition and free energy analyses. Thus remarks made in this study established that pyrimidine-benzimidazole hybrids as a new class of tubulin polymerization inhibitors with significant anticancer activity.

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.

Recent Advancements of Nanomedicine towards Antiangiogenic Therapy in Cancer

Angiogenesis is a process of generation of de-novo blood vessels from already existing vasculature. It has a crucial role in different physiological process including wound healing, embryonic development, and tumor growth. The methods by which therapeutic drugs inhibit tumor angiogenesis are termed as anti-angiogenesis cancer therapy. Developments of angiogenic inhibiting drugs have various limitations causing a barrier for successful treatment of cancer, where angiogenesis plays an important role. In this context, investigators developed novel strategies using nanotechnological approaches that have demonstrated inherent antiangiogenic properties or used for the delivery of antiangiogenic agents in a targeted manner. In this present article, we decisively highlight the recent developments of various nanoparticles (NPs) including liposomes, lipid NPs, protein NPs, polymer NPs, inorganic NPs, viral and bio-inspired NPs for potential application in antiangiogenic cancer therapy. Additionally, the clinical perspectives, challenges of nanomedicine, and future perspectives are briefly analyzed.

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.

Magnetic resonance imaging of the hand and wrist in a randomized, double-blind, multicenter, placebo-controlled trial of infliximab for rheumatoid arthritis: Comparison of dynamic contrast enhanced assessments with semi-quantitative scoring

The objective of this study was to compare the scope and the discriminative power of Dynamic Contrast Enhanced Magnetic Resonance Imaging (DCE-MRI) to those of semi-quantitative MRI scoring for evaluating treatments for rheumatoid arthritis (RA) in multicenter randomized clinical trials (RCTs). Sixty-one patients with active RA participated in a double-blind, parallel group, randomized, multicenter methodology study receiving infliximab or placebo through 14 weeks. The most symptomatic wrist and metacarpophalangeal joints (MCPs) were imaged using MRI. In addition to clinical assessments with DAS28(CRP), the severity of inflammation was measured as synovial leak of gadolinium based contrast agent (GBCA) using DCE-MRI (K_trans, primary endpoint) at weeks 0, 2, 4, and 14. Two radiologists independently scored synovitis, osteitis and erosion using RA MRI Score (RAMRIS) and cartilage loss using a 9-point MRI scale (CARLOS). Infliximab showed greater decrease from baseline in DAS28(CRP), DCE-MRI K_trans of wrist and MCP synovium, and RAMRIS synovitis and osteitis at all visits compared with placebo (p<0.001). Treatment effect sizes of infliximab therapy were similar for DAS28(CRP) (1.08; 90% CI (0.63–1.53)) and MRI inflammation endpoints: wrist K_trans (1.00 (0.55–1.45)), RAMRIS synovitis (0.85 (0.38–1.28)) and RAMRIS osteitis (0.99 (0.52–1.43)). Damage measures of bone erosion (RAMRIS) and cartilage loss (CARLOS) were reduced with infliximab compared to with placebo at 14 weeks (p≤0.025). DCE-MRI and RAMRIS were equally sensitive and responsive to the anti-inflammatory effects of infliximab. RAMRIS and CARLOS showed suppression of erosion and cartilage loss, respectively, at 14 weeks. (ClinicalTrials.gov registration: NCT01313520)

Multimodal imaging guided preclinical trials of vascular targeting in prostate cancer

The high mortality rate associated with castration-resistant prostate cancer (CRPC) underscores the need for improving therapeutic options for this patient population. The purpose of this study was to examine the potential of vascular targeting in prostate cancer. Experimental studies were carried out in subcutaneous and orthotopic Myc-CaP prostate tumors implanted into male FVB mice to examine the efficacy of a novel microtubule targeted vascular disrupting agent (VDA), EPC2407 (Crolibulin™). A non-invasive multimodality imaging approach based on magnetic resonance imaging (MRI), bioluminescence imaging (BLI), and ultrasound (US) was utilized to guide preclinical trial design and monitor tumor response to therapy. Imaging results were correlated with histopathologic assessment, tumor growth and survival analysis. Contrast-enhanced MRI revealed potent antivascular activity of EPC2407 against subcutaneous and orthotopic Myc-CaP tumors. Longitudinal BLI of Myc-CaP tumors expressing luciferase under the androgen response element (Myc-CaP/ARE-luc) revealed changes in AR signaling and reduction in intratumoral delivery of luciferin substrate following castration suggestive of reduced blood flow. This reduction in blood flow was validated by US and MRI. Combination treatment resulted in sustained vascular suppression, inhibition of tumor regrowth and conferred a survival benefit in both models. These results demonstrate the therapeutic potential of vascular targeting in combination with androgen deprivation against prostate cancer.

Therapeutic application of anti-angiogenic nanomaterials in cancers

Angiogenesis, the formation of new blood vessels from pre-existing vasculature, plays a vital role in physiological and pathological processes (embryonic development, wound healing, tumor growth and metastasis). The overall balance of angiogenesis inside the human body is maintained by pro- and anti-angiogenic signals. The processes by which drugs inhibit angiogenesis as well as tumor growth are called the anti-angiogenesis technique, a most promising cancer treatment strategy. Over the last couple of decades, scientists have been developing angiogenesis inhibitors for the treatment of cancers. However, conventional anti-angiogenic therapy has several limitations including drug resistance that can create problems for a successful therapeutic strategy. Therefore, a new comprehensive treatment strategy using antiangiogenic agents for the treatment of cancer is urgently needed. Recently researchers have been developing and designing several nanoparticles that show anti-angiogenic properties. These nanomedicines could be useful as an alternative strategy for the treatment of various cancers using anti-angiogenic therapy. In this review article, we critically focus on the potential application of anti-angiogenic nanomaterial and nanoparticle based drug/siRNA/peptide delivery systems in cancer therapeutics. We also discuss the basic and clinical perspectives of anti-angiogenesis therapy, highlighting its importance in tumor angiogenesis, current status and future prospects and challenges.

Intravoxel incoherent motion diffusion-weighted MR imaging for monitoring the therapeutic efficacy of the vascular disrupting agent CKD-516 in rabbit VX2 liver tumors

PURPOSE

To evaluate the diagnostic value of intravoxel incoherent motion (IVIM) diffusion-weighted (DW) magnetic resonance (MR) imaging in the quantitative assessment of the therapeutic efficacy of a vascular disrupting agent (VDA) (CKD-516) in rabbit VX2 liver tumors.

MATERIALS AND METHODS

The institutional animal care and use committee approved this study. In 21 VX2 liver tumor-bearing rabbits, IVIM DW imaging examinations were serially performed with a 3.0-T imaging unit by using 12 b values from 0 to 800 sec/mm(2). The apparent diffusion coefficient (ADC), true diffusion coefficient (D), pseudodiffusion coefficient (D*), perfusion fraction (f), and blood flow-related parameter (fD*) of tumors at different time points (baseline, 4 hours, 24 hours, 3 days, and 7 days after CKD-516 administration) were compared within the treated group (n = 15) by using the Friedman test as well as between the control (n = 6) and treated groups by using the Mann-Whitney test. Correlation between the change in tumor size and IVIM DW imaging parameters was analyzed by using the Spearman rank test.

RESULTS

In the treated group, D* and f significantly decreased at 4 hours and then recovered to baseline at 24 hours, while D significantly increased at 24 hours (P < .005). All IVIM-derived parameters showed no significant differences between the control and treated groups at 3- and at 7-day follow-up. The greater decrease observed in f and fD* at 4 hours correlated with the smaller increase in tumor size during the 7 days of follow-up (ρ = 0.53 and 0.65, respectively; P < .05 for both).

CONCLUSION

The therapeutic effect induced by a VDA could be effectively evaluated by using IVIM DW imaging, and f and fD* may be early predictive indicators of tumor response.

Indole molecules as inhibitors of tubulin polymerization: potential new anticancer agents

Agents that interfere with tubulin function have a broad anti-tumor spectrum and they represent one of the most significant classes of anticancer agents. In the past few years, several small synthetic molecules that have an indole nucleus as a core structure have been identified as tubulin inhibitors. Among these, several aroylindoles, arylthioindoles, diarylindoles and indolylglyoxyamides have shown good inhibition towards the tubulin polymerization. This article reviews the synthesis, biological activities and SARs of these main classes of indoles. Brief mention has also been made about the fused indole analogs as tubulin inhibitors.

An overview of tubulin inhibitors that interact with the colchicine binding site

Tubulin dynamics is a promising target for new chemotherapeutic agents. The colchicine binding site is one of the most important pockets for potential tubulin polymerization destabilizers. Colchicine binding site inhibitors (CBSI) exert their biological effects by inhibiting tubulin assembly and suppressing microtubule formation. A large number of molecules interacting with the colchicine binding site have been designed and synthesized with significant structural diversity. CBSIs have been modified as to chemical structure as well as pharmacokinetic properties, and tested in order to find a highly potent, low toxicity agent for treatment of cancers. CBSIs are believed to act by a common mechanism via binding to the colchicine site on tubulin. The present review is a synopsis of compounds that have been reported in the past decade that have provided an increase in our understanding of the actions of CBSIs.

Recent Advances in CT and MR Imaging for Evaluation of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide. Accurate diagnosis and assessment of disease extent are crucial for proper management of patients with HCC. Imaging plays a crucial role in early detection, accurate staging, and the planning of management strategies. A variety of imaging modalities are currently used in evaluating patients with suspected HCC; these include ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), nuclear medicine, and angiography. Among these modalities, dynamic MRI and CT are regarded as the best imaging techniques available for the noninvasive diagnosis of HCC. Recent improvements in CT and MRI technology have made noninvasive and reliable diagnostic assessment of hepatocellular nodules possible in the cirrhotic liver, and biopsy is frequently not required prior to treatment. Until now, the major challenge for radiologists in imaging cirrhosis has been the characterization of small cirrhotic nodules smaller than 2 cm in diameter. Further technological advancement will undoubtedly have a major impact on liver tumor imaging. The increased speed of data acquisition in CT and MRI has allowed improvements in both spatial and temporal resolution, which have made possible a more precise evaluation of the hemodynamics of liver nodules. Furthermore, the development of new, tissue-specific contrast agents such as gadoxetic acid has improved HCC detection on MRI. In this review, we discuss the role of CT and MRI in the diagnosis and staging of HCC, recent technological advances, and the strengths and limitations of these imaging modalities.