Inhibition of human leukemia in an animal model with human antibodies directed against vascular endothelial growth factor receptor 2. Correlation between antibody affinity and biological activity

Foretinib Is Effective in Acute Myeloid Leukemia by Inhibiting FLT3 and Overcoming Secondary Mutations That Drive Resistance to Quizartinib and Gilteritinib

FLT3 internal tandem duplication (FLT3-ITD) mutations are one of the most prevalent somatic alterations associated with poor prognosis in patients with acute myeloid leukemia (AML). The clinically approved FLT3 kinase inhibitors gilteritinib and quizartinib improve the survival of patients with AML with FLT3-ITD mutations, but their long-term efficacy is limited by acquisition of secondary drug-resistant mutations. In this study, we conducted virtual screening of a library of 60,411 small molecules and identified foretinib as a potent FLT3 inhibitor. An integrated analysis of the BeatAML database showed that foretinib had a lower IC50 value than other existing FLT3 inhibitors in patients with FLT3-ITD AML. Foretinib directly bound to FLT3 and effectively inhibited FLT3 signaling. Foretinib potently inhibited proliferation and promoted apoptosis in human AML cell lines and primary AML cells with FLT3-ITD mutations. Foretinib also significantly extended the survival of mice bearing cell-derived and patient-derived FLT3-ITD xenografts, exhibiting stronger efficacy than clinically approved FLT3 inhibitors in treating FLT3-ITD AML. Moreover, foretinib showed potent activity against secondary mutations of FLT3-ITD that confer resistance to quizartinib and gilteritinib. These findings support the potential of foretinib for treating patients with AML with FLT3-ITD mutations, especially for those carrying secondary mutations after treatment failure with other FLT3 inhibitors.

SIGNIFICANCE

Foretinib exhibits superior efficacy to approved drugs in AML with FLT3-ITD mutations and retains activity in AML with secondary FLT3 mutations that mediate resistance to clinical FLT3 inhibitors.

Pharmacokinetic considerations for angiogenesis inhibitors used to treat hepatocellular carcinoma: an overview

INTRODUCTION

Hepatocellular carcinoma (HCC) is the fifth malignancy in terms of frequency and the fourth malignancy in terms of cancer-related death worldwide. Systemic therapy of advanced HCC has probably gone through the greatest wave of change in the last decade, with the introduction of several anti-angiogenic drugs and immune checkpoint inhibitors, able to significantly improve patients' prognosis.

AREAS COVERED

In this review, we summarize the pharmacokinetic characteristic of the antiangiogenic drugs currently approved for the treatment of HCC, from oral tyrosine kinase inhibitors (sorafenib, lenvatinib, regorafenib and cabozantinib) to monoclonal antibodies (bevacizumab and ramucirumab), focusing on the main aspects that differ among compounds from the same class, on factors that can exert an influence on pharmacokinetic parameters and the main issues that could limit their clinical use.

EXPERT OPINION

Anti-angiogenic drugs have different profiles in terms of bioavailability, metabolism, elimination and interindividual variability in their pharmacokinetics and effectiveness. More studies should be developed to address the intrinsic and extrinsic factors influencing pharmacokinetics parameters to improve the individual therapeutic response and, furthermore, to evaluate the benefit and the harm of systemic therapy for advanced HCC in selected patients with liver impairment.

Association of Kinase-Insert-Domain-Containing Receptor Polymorphisms with Glioma Susceptibility in a Chinese Population: A Hospital-Based Case-Control Study

Background

Gliomas are the most common malignant tumors of the central nervous system. However, the inherited genetic variation in gliomas is presently unclear. Therefore, this study investigated the association of the rs2071559 and rs2239702 gene polymorphisms with glioma susceptibility in Chinese patients.

Methods

In this study, a case-control approach was used to compare and analyze whether two genes, rs2071559 and rs2239702, were associated with the risk of glioma formation.

Results

The cases and controls were matched for sex, smoking status, and family history of cancer using single nucleotide polymorphisms. Specific rs2071559 and rs2239702 alleles were found much more frequently in the glioma group than in the control group (P < 0.001 and P = 0.014, respectively).

Conclusions

These findings suggest that specific rs2071559 and rs2239702 polymorphisms are associated with a higher risk of glioma development; the risk allele is C in rs2071559 or A in rs2239702. Moreover, the kinase-insert-domain-containing receptor may act as a suppressor of tumor progression.

Novel hKDR mouse model depicts the antiangiogenesis and apoptosis-promoting effects of neutralizing antibodies targeting vascular endothelial growth factor receptor 2

Vascular endothelial growth factor receptor 2 (VEGFR2)/KDR plays a critical role in tumor growth, diffusion, and invasion. The amino acid sequence homology of KDR between mouse and human in the VEGF ligand-binding domain was low, thus the WT mice could not be used to evaluate Abs against human KDR, and the lack of a suitable mouse model hindered both basic research and drug developments. Using the CRISPR/Cas9 technique, we successfully inserted different fragments of the human KDR coding sequence into the chromosomal mouse Kdr exon 4 locus to obtain an hKDR humanized mouse that can be used to evaluate the marketed Ab ramucirumab. In addition, the humanized mAb VEGFR-HK19 was developed, and a series of comparative assays with ramucirumab as the benchmark revealed that VEGFR-HK19 has higher affinity and superior antiproliferation activity. Moreover, VEGFR-HK19 selectively inhibited tumor growth in the hKDR mouse model but not in WT mice. The most important binding epitopes of VEGFR2-HK19 are D257, L313, and T315, located in the VEGF binding region. Therefore, the VEGFR2-HK19 Ab inhibits tumor growth by blocking VEGF-induced angiogenesis, inflammation, and promoting apoptosis. To our best knowledge, this novel humanized KDR mouse fills the gaps both in an animal model and the suitable in vivo evaluation method for developing antiangiogenesis therapies in the future, and the newly established humanized Ab is expected to be a drug candidate possibly benefitting tumor patients.

Aptamer-Functionalized Carbon Nanotube Field-Effect Transistor Biosensors for Alzheimer's Disease Serum Biomarker Detection

Blood-biomarker-based tests are highly important for the early clinical diagnosis of Alzheimer's disease (AD) and the treatment and care of AD patients, but the complex serum environment and extremely low abundance of AD blood protein biomarkers present challenges. Nanomaterials are promising for constructing highly sensitive transistor-based biosensors due to their small size. However, such biosensors are difficult to fabricate on a large scale and suffer from the lack of combined optimization of reproducibility and sensitivity in complex physiological fluids. In this work, field-effect transistor (FET) biosensors based on highly uniform semiconducting carbon nanotube (CNT) thin films are mass produced to achieve highly sensitive and selective detection of the AD core blood biomarkers of β-amyloid (Aβ). The combination of the mass-produced CNT FET sensors and oligonucleotide aptamers as efficient bioreceptors enables reliable and reproducible sub-femtomolar detection in full human serum for Aβ₄₂ and Aβ₄₀ peptides and has outperformed other methods reported to date. The adsorption of biological substrates to the sensor was significantly reduced by multiple blocking steps, resulting in selectivity ratios of up to 730% (Aβ₄₀) and 800% (Aβ₄₂). The aptamer-functionalized CNT FET biosensor exhibits a large dynamic range (>10⁴), rapid response time (several minutes), and low variation (<10%) and can be delivered as a low-cost and rapid clinical detection technology for the early diagnosis and mass screening of AD. This platform will help bring complex laboratory-based and expensive diagnostic tools to the point of care.

Efficacy and safety of weekly paclitaxel with or without ramucirumab as second-line therapy for the treatment of advanced gastric or gastroesophageal junction adenocarcinoma (RAINBOW-Asia): a randomised, multicentre, double-blind, phase 3 trial

BACKGROUND

In the global phase 3 RAINBOW study, ramucirumab plus paclitaxel significantly improved overall survival compared with placebo plus paclitaxel in patients with advanced gastric or gastro-oesophageal junction (GEJ) adenocarcinoma. RAINBOW-Asia, a bridging study with similar design to RAINBOW, aimed to evaluate the efficacy and safety of ramucirumab plus paclitaxel for advanced gastric or GEJ adenocarcinoma in Asian, predominantly Chinese, patients.

METHODS

RAINBOW-Asia was a randomised, double-blind, placebo-controlled, phase 3 trial done at 32 centres in China, Malaysia, the Philippines, and Thailand. Adult patients (≥18 years) with metastatic or locally advanced, unresectable gastric or GEJ adenocarcinoma who previously received fluoropyrimidine-platinum-based chemotherapy were randomly assigned with a centralised interactive web response system in a 2:1 ratio to receive ramucirumab 8 mg/kg or placebo intravenously on days 1 and 15 plus paclitaxel 80 mg/m2 intravenously on days 1, 8, and 15 of every 28-day cycle. Randomisation was stratified by Eastern Cooperative Oncology Group performance status and presence of peritoneal metastases. The co-primary endpoints were progression-free survival and overall survival. Efficacy analyses were done in the intention-to-treat population, and safety analysis included patients who received at least one dose of study treatment. This trial is registered with ClinicalTrials.gov, NCT02898077, and has been completed.

FINDINGS

Between March 2, 2017, and June 30, 2020, 440 patients were randomly assigned to receive ramucirumab plus paclitaxel (n=294) or placebo plus paclitaxel (n=146). Median progression-free survival was 4·14 months (95% CI 3·71-4·30) in the ramucirumab plus paclitaxel group compared with 3·15 months (2·83-4·14) in the placebo plus paclitaxel group (hazard ratio [HR] 0·765, 95% CI 0·613-0·955, p=0·0184). Median overall survival was 8·71 months (95% CI 7·98-9·49) in the ramucirumab plus paclitaxel group and 7·92 months (6·31-9·10) in the placebo plus paclitaxel group (HR 0·963, 95% CI 0·771-1·203, p=0·7426). The most common grade 3 or worse treatment-emergent adverse events were decreased neutrophil count (159 [54%] of 293 patients in the ramucirumab plus paclitaxel group vs 56 [39%] of 145 in the placebo plus paclitaxel group), decreased white blood cell count (127 [43%] vs 42 [29%]), anaemia (46 [16%] vs 24 [17%]), hypertension (21 [7%] vs nine [6%]), and febrile neutropenia (18 [6%] vs one [<1%]).

INTERPRETATION

These findings, along with the results from RAINBOW, support the use of ramucirumab plus paclitaxel as second-line therapy in a predominantly Chinese population with advanced gastric or GEJ adenocarcinoma.

FUNDING

Eli Lilly and Company, USA.

TRANSLATION

For the Chinese translation of the abstract see Supplementary Materials section.

Preclinical assessment of intravitreal ramucirumab: in vitro and in vivo safety profile

Background

Anti-angiogenic drugs remain the mainstay therapy for several vascular retinal pathologies. The repurposing of approved anti-angiogenic drugs for use in ophthalmology can increase therapeutic options and reduce costs. The purpose of this study was to investigate the ocular safety profile of intravitreal (IVT) ramucirumab, an approved anti-vascular endothelial growth factor molecule for systemic treatment, using cell culture and animal models.

Methods

The cytotoxicity of ramucirumab at different concentrations was evaluated in human retinal pigment epithelial cells (ARPE-19) using the MTT assay. In addition, 250 or 500 µg of ramucirumab or vehicle was injected in the eye of 16 chinchilla rabbits. The eyes were evaluated by ophthalmoscopy, electroretinography, spectral-domain optical coherence tomography (SD-OCT) and by light and transmission electron microscopy.

Results

Electroretinography or SD-OCT did not detect functional or morphological alterations at 24 h or one week after injection. Light and transmission electron microscopy confirmed the absence of major signs of toxicity, although we found a statistically significant reduction in ganglion cell number between the controls and the eyes that received 500 µg of ramucirumab after 7 days. Compared to lower concentrations, 500 µg of ramucirumab caused reduction in cell viability and changes in morphology in ARPE-19 cells. Compared to the baseline, ocular and serum osmolarity showed no difference after IVT injection at all timepoints.

Conclusion

In conclusion, IVT injection of ramucirumab in rabbits is safe and does not cause functional damage to the retina. At the lower dose tested in vivo (250 µg), the morphology and ultrastructural anatomy were normal at 24 h and 1 week after the injection. However, the 500 µg dose can cause a decrease in ganglion cell number seven days after the injection.

The promising role of monoclonal antibodies for gastric cancer treatment

Gastric cancer (GC) is the second leading cause of cancer-related death world-wide. Despite improvements in prevention, early detection and various therapeutic options, the prognosis is still poor. GC is often diagnosed at an advanced stage with survivals less than 1 year. Chemotherapy as the mainstay of treatment in advanced stage is not of notable advantages, underlining the need for novel more effective therapeutic options. Based on current knowledge of molecular and cellular mechanisms, a number of novel biologic approaches such as monoclonal antibodies have been recently introduced for cancer treatment that mainly affect the immune system or target signaling pathways playing role in cancer and metastasis development. In this review, various monoclonal antibodies for GC therapy were explained.

Ramucirumab: A Review in Hepatocellular Carcinoma

Ramucirumab (Cyramza®), a fully human anti-VEGFR-2 monoclonal antibody, has been approved as monotherapy for the treatment of patients with hepatocellular carcinoma (HCC) and α-fetoprotein levels ≥ 400 ng/mL who have been treated with sorafenib. Ramucirumab significantly prolonged overall survival (OS) and progression-free survival (PFS) relative to placebo in this population in the randomized, double-blind phase 3 REACH 2 trial. These benefits were seen in key prespecified subgroups based on demographic and disease characteristics. Ramucirumab had an acceptable tolerability profile and manageable safety profile in these patients, with the majority of treatment-related adverse events being mild or moderate in severity. The safety profile of ramucirumab was consistent with that expected for agents targeting the VEGF/VEGFR axis. Currently, ramucirumab is the only therapy specifically tested in patients with α-fetoprotein levels ≥ 400 ng/mL, which is associated with an aggressive disease and poor prognosis. Therefore, ramucirumab is an important treatment option for patients with HCC and α-fetoprotein levels ≥ 400 ng/mL who have been treated with sorafenib.

Anti-VEGF/VEGFR2 Monoclonal Antibodies and their Combinations with PD-1/PD-L1 Inhibitors in Clinic

The vascular endothelial growth factor (VEGF)/VEGF receptor 2 (VEGFR2) signaling pathway is one of the most important pathways responsible for tumor angiogenesis. Currently, two monoclonal antibodies, anti-VEGF-A antibody Bevacizumab and anti-VEGFR2 antibody Ramucizumab, have been approved for the treatment of solid tumors. At the same time, VEGF/VEGFR2 signaling is involved in the regulation of immune responses. It is reported that the inhibition of this pathway has the capability to promote vascular normalization, increase the intra-tumor infiltration of lymphocytes, and decrease the number and function of inhibitory immune cell phenotypes, including Myeloid-derived suppressor cells (MDSCs), regulatory T cells (Tregs) and M2 macrophages. On this basis, a number of clinical studies have been performed to investigate the therapeutic potential of VEGF/VEGFR2-targeting antibodies plus programmed cell death protein 1 (PD-1)/ programmed cell death ligand 1 (PD-L1) inhibitors in various solid tumor types. In this context, VEGF/VEGFR2- targeting antibodies, Bevacizumab and Ramucizumab are briefly introduced, with a description of the differences between them, and the clinical studies involved in the combination of Bevacizumab/ Ramucizumab and PD-1/PD-L1 inhibitors are summarized. We hope this review article will provide some valuable clues for further clinical studies and usages.

Ramucirumab for the treatment of gastric or gastro-esophageal junction cancer

Introduction: Gastric cancer remains one of the most lethal malignancy, accounting for an estimated 783,000 deaths worldwide in 2018. Although there are several approved drugs for the treatment of gastric cancer, the survival of patients with advanced disease remains dismal. Ramucirumab, a vascular endothelial growth factor receptor-2 inhibitor, is an important new targeted drug approved for gastric and gastroesophageal adenocarcinoma (GEJ) in second-line setting. Areas covered: In this article, we have reviewed the role of ramucirumab in the management of gastric and GEJ adenocarcinoma. A comprehensive review of various clinical trials is presented that support the use of ramucirumab in gastric cancer. Expert opinion: In our opinion, ramucirumab should be considered as a standard of care option, either alone or with paclitaxel, after progression on first-line therapy for advanced or metastatic disease. The results of large, randomized phase III clinical trials show benefit of ramucirumab on median overall survival (OS). However, the benefit is limited, with only about two months OS benefit of using ramucirumab with paclitaxel compared to paclitaxel alone. Novel combination therapies, such as ramucirumab with other targeted agents and immune checkpoint inhibitors in ongoing clinical trials, may provide important information to further improve the patient outcomes.

Avian leukosis virus subgroup J induces VEGF expression via NF-κB/PI3K-dependent IL-6 production

Avian leukosis virus subgroup J (ALV-J) is an oncogenic virus causing hemangiomas and myeloid tumors in chickens. Interleukin-6 (IL-6) is a multifunctional pro-inflammatory interleukin involved in many types of cancer. We previously demonstrated that IL-6 expression was induced following ALV-J infection in chickens. The aim of this study is to characterize the mechanism by which ALV-J induces IL-6 expression, and the role of IL-6 in tumor development. Our results demonstrate that ALV-J infection increases IL-6 expression in chicken splenocytes, peripheral blood lymphocytes, and vascular endothelial cells. IL-6 production is induced by the ALV-J envelope protein gp85 and capsid protein p27 via PI3K- and NF-κB-mediated signaling. IL-6 in turn induced expression of vascular endothelial growth factor (VEGF)-A and its receptor, VEGFR-2, in vascular endothelial cells and embryonic vascular tissues. Suppression of IL-6 using siRNA inhibited the ALV-J induced VEGF-A and VEGFR-2 expression in vascular endothelial cells, indicating that the ALV-J-induced VEGF-A/VEGFR-2 expression is mediated by IL-6. As VEGF-A and VEGFR-2 are important factors in oncogenesis, our findings suggest that ALV-J hijacks IL-6 to promote tumorigenesis, and indicate that IL-6 could potentially serve as a therapeutic target in ALV-J infections.

Inhibition of Siah2 Ubiquitin Ligase by Vitamin K3 Attenuates Chronic Myeloid Leukemia Chemo-Resistance in Hypoxic Microenvironment

BACKGROUND A hypoxic microenvironment is associated with resistance to tyrosine kinase inhibitors (TKIs) and a poor prognosis in chronic myeloid leukemia (CML). The E3 ubiquitin ligase Siah2 plays a vital role in the regulation of hypoxia response, as well as in leukemogenesis. However, the role of Siah2 in CML resistance is unclear, and it is unknown whether vitaminK3 (a Siah2 inhibitor) can improve the chemo-sensitivity of CML cells in a hypoxic microenvironment. MATERIAL AND METHODS The expression of Siah2 was detected in CML patients (CML-CP and CML-BC), K562 cells, and K562-imatinib-resistant cells (K562-R cells). We measured the expression of PHD3, HIF-1α, and VEGF in both cell lines under normoxia and hypoxic conditions, and the degree of leukemic sensitivity to imatinib and VitaminK3 were evaluated. RESULTS Siah2 was overexpressed in CML-BC patients (n=9) as compared to CML-CP patients (n=13). Similarly, K562-imatinib-resistant cells (K562-R cells) showed a significantly higher expression of Siah2 as compared to K562 cells in a hypoxic microenvironment. Compared to normoxia, under hypoxic conditions, both cell lines had lower PHD3, higher HIF-1α, and higher VEGF expression. Additionally, Vitamin K3 (an inhibitor of Siah2) reversed these changes and promoted a higher degree of leukemic sensitivity to imatinib. CONCLUSIONS Our findings indicate that the Siah2-PHD3- HIF-1α-VEGF axis is an important hypoxic signaling pathway in a leukemic microenvironment. An inhibitor of Siah2, combined with TKIs, might be a promising therapy for relapsing and refractory CML patients.

Isoprenaline/β2-AR activates Plexin-A1/VEGFR2 signals via VEGF secretion in gastric cancer cells to promote tumor angiogenesis

Background

The role of stress signals in regulating gastric cancer initiation and progression is not quite clear. It is known that stress signals modulate multiple processes such as immune function, cell migration and angiogenesis. However, few studies have investigated the mechanisms of how stress signals contribute to gastric cancer angiogenesis.

Methods

Here, we used β2-adrenergic receptor (β2-AR) agonist isoprenaline to imitate a stress signal and demonstrated the molecular mechanism underlying stress’s influence on tumor angiogenesis.

Results

We found that isoprenaline stimulated vascular endothelial growth factor (VEGF) secretion in gastric cancer cells and plexin-A1 expression was induced by human recombinant VEGF165 in both gastric cancer cells and vascular endothelial cells. Furthermore, interfere with plexin-A1 expression in gastric cancer cells influence HUVEC tube formation, migration and tumor growth in vivo.

Conclusions

These findings suggest that isoprenaline stimulate VGEF secretion and subsequently up-regulate the expression of plexin-A1 and VEGFR2 in gastric cancer cells, which form a positive impetus to promote tumor angiogenesis. This study reveals a novel molecular mechanism that a stress signal like isoprenaline may enhance angiogenesis via activating plexin-A1/VEGFR2 signaling pathway in gastric cancer, which may be a potential target in development of an anti-angiogenic therapy for gastric cancer.

Population pharmacokinetic meta-analysis of ramucirumab in cancer patients

AIMS

Ramucirumab is a human IgG1 monoclonal antibody that specifically binds vascular endothelial growth factor receptor-2 (VEGFR-2) and blocks binding of VEGF-A, VEGF-C and VEGF-D. The objective of the analysis was to characterize the clinical pharmacology profile of ramucirumab using a population pharmacokinetic approach.

METHODS

A total of 1639 patients with 6427 serum concentrations from 11 Phase 1b, 2 and 3 clinical trials in patients with various cancer indications were included in the analysis. Ramucirumab was administered as an intravenous infusion over 1 h at 8 mg kg-1 every 2 weeks or 10 mg kg-1 every 3 weeks. A series of pharmacostatistical models were developed to describe the concentration data. The best model was used to evaluate patient factors for their effect on ramucirumab pharmacokinetics.

RESULTS

The pharmacokinetics of ramucirumab were well characterized by a two-compartment model. Mean population estimates of clearance, volume of distribution and half-life for a typical 68-kg patient were 0.0148 l h-1 , 5.30 l and 13.4 days, respectively. A modest relationship was observed between body weight and ramucirumab disposition; clearance and central compartment volume increased with body weight. No other patient characteristics were shown to influence the disposition of ramucirumab in this patient population.

CONCLUSIONS

The final model adequately described the concentration-time profile of ramucirumab in patients with a range of cancer indications. The model confirmed that a weight-normalized dosing regimen is appropriate for ramucirumab therapy. Dose adjustment was not required for patients with mild to moderate renal impairment or mild hepatic impairment.

Evolution of ramucirumab in the treatment of cancer - A review of literature

Ramucirumab is a recombinant human monoclonal antibody and is used in the treatment of advanced malignancies. Its mechanism of action is by inhibiting angiogenesis in tumor cells by targeting the vascular endothelial growth factor receptor 2. United States Food and Drug Administration (FDA) approved it initially in 2014 for the treatment of advanced gastric or gastro-esophageal junction adenocarcinoma and metastatic non-small cell lung carcinoma. It was approved by FDA in 2015 for the treatment of advanced colorectal cancer. This manuscript consolidates pre-clinical trials to phase I, II, and III trial data indicating the effects of ramucirumab on different cancer types, which led to its approval. By comparing these clinical trials alongside each other, we can more easily examine the studies that have already been completed, along with currently ongoing studies and potential further areas of interest for this newly approved treatment. This approach makes it convenient to compare dosages, overall survival, adverse events, as well as possible routes for combination therapy with ramucirumab. By compiling results for various oncological malignancies, we can differentiate between treatments that are effective and have the highest incidence of stable disease, and those that do not seem promising. Ramucirumab has been effective in the treatment of various carcinomas and this article outlines other tumors in which this treatment option may be successful.

Increased Vascular Permeability in the Bone Marrow Microenvironment Contributes to Disease Progression and Drug Response in Acute Myeloid Leukemia

The biological and clinical behaviors of hematological malignancies can be influenced by the active crosstalk with an altered bone marrow (BM) microenvironment. In the present study, we provide a detailed picture of the BM vasculature in acute myeloid leukemia using intravital two-photon microscopy. We found several abnormalities in the vascular architecture and function in patient-derived xenografts (PDX), such as vascular leakiness and increased hypoxia. Transcriptomic analysis in endothelial cells identified nitric oxide (NO) as major mediator of this phenotype in PDX and in patient-derived biopsies. Moreover, induction chemotherapy failing to restore normal vasculature was associated with a poor prognosis. Inhibition of NO production reduced vascular permeability, preserved normal hematopoietic stem cell function, and improved treatment response in PDX.

Anti-Vascular Endothelial Growth Factor Effects of Sorafenib and Arsenic Trioxide in Acute Myeloid Leukemia Cell Lines

Acute myeloid leukemia (AML), is a clonal disorder caused by acquired somatic mutations and chromosomal rearrangements. According to some evidence, progression of hematolymphoid malignancies depends on the induction of new blood vessel formation under the influence of acute leukemia. Various factors are produced by cancer cells under hypoxic conditions to increase vascular formation. Among these, vascular endothelial growth factor (VEGF) plays a crucial role. Cytotoxicity and anticancer effects of arsenic trioxide (ATO) have been reported in many cancers. Sorafenib, known as an angiogenic inhibitor, decreases leukemic cell survival. The aim of this study was to indicate combination effects of ATO and sorafenib in two AML cell lines, KG-1 and U937. Effective doses was determined by MTT assay for both single and combination treatments. Percentages of apoptotic cells were evaluated by Annexin V FITC staining and mRNA levels of VEGF isoforms and receptor expression were investigated by Real-Time PCR. Our data show that sorafenib (5μM and 7μM in KG-1 and U937 cell lines respectively), ATO (1.618μM and 1μM in KG-1 and U937 cell lines respectively), and also their combination significantly increased the percentage of apoptotic cells. In addition the mRNA level of VEGF isoforms was downregulated in the U937 cell line while upregulated in KG-1 cells. Taken together, our results suggest that the VEGF autocrine loop may have an influence on AML development and progression and could be consider as a therapeutic target. The combination of sorafenib as a VEGF inhibitor with ATO synergistically inhibits cell proliferation and promotes apoptosis.

A phase 1 study of ramucirumab in Japanese patients with advanced solid tumors

OBJECTIVE

Ramucirumab is a recombinant human immunoglobulin G1 monoclonal antibody targeting the vascular endothelial growth factor receptor-2. The aim of this phase 1 study was to evaluate the safety and tolerability of ramucirumab monotherapy in Japanese patients with advanced solid tumors.

METHODS

Patients with solid tumors who had not responded to standard therapy or for whom no standard therapy was available received escalating doses of ramucirumab, administered once every 2 (Q2W) or 3 (Q3W) weeks. The primary objective was to establish the safety and pharmacokinetic profiles of ramucirumab. Secondary and exploratory objectives included assessment of immunogenicity and antitumor activity. ClinicalTrials.gov: NCT01005355.

RESULTS

Fifteen patients were treated with ramucirumab at a dose of 6 mg/kg Q2W (N = 3), 8 mg/kg Q2W (N = 6) or 10 mg/kg Q3W (N = 6). There were no dose-limiting toxicities and the maximum tolerated dose was not reached. The most common ramucirumab-related adverse events were headache, pyrexia, hypertension and increased aspartate aminotransferase. Following single-dose administration of ramucirumab, there appeared to be a dose-proportional increase in maximum observed drug concentration but not in area under the curve. Treatment-emergent anti-ramucirumab antibodies were not detected in any patient.

CONCLUSIONS

Ramucirumab monotherapy was well tolerated and feasible at the doses and schedules used in this study population of Japanese patients with advanced solid tumors.

Randomized Phase II Study of Ramucirumab or Icrucumab in Combination with Capecitabine in Patients with Previously Treated Locally Advanced or Metastatic Breast Cancer

BACKGROUND

Icrucumab (ICR) and ramucirumab (RAM) bind vascular endothelial growth factor (VEGF) receptors 1 and 2 (VEGFR-1 and -2), respectively. This open-label, randomized phase II study evaluated their efficacy and safety in combination with capecitabine (CAP) in patients with previously treated unresectable, locally advanced or metastatic breast cancer.

METHODS

Patients were randomly assigned (1:1:1) to receive CAP (1,000 mg/m2 orally twice daily, days 1-14) alone or in combination with RAM (10 mg/kg intravenously [IV], days 1 and 8) (RAM + CAP) or ICR (12 mg/kg IV, days 1 and 8) (ICR + CAP) every 21 days. The primary endpoint was progression-free survival (PFS). Secondary endpoints included overall survival (OS), tumor response, safety, and pharmacokinetics.

RESULTS

Of 153 patients randomized, 150 received treatment. Median PFS (95% confidence interval) was 22.1 (12.1-36.1) weeks on RAM + CAP, 7.3 (6.3-13.0) weeks on ICR + CAP, and 19.0 (12.1-24.3) weeks on CAP (hazard ratios [HRs]: 0.691, p = .1315, RAM + CAP versus CAP; 1.480, p = .0851, ICR + CAP versus CAP). Median OS was 67.4 weeks on RAM + CAP, 62.1 weeks on ICR + CAP, and 71.6 weeks on CAP (HRs: 1.833, p = .0283, RAM + CAP versus CAP; 1.468, p = .1550, ICR + CAP versus CAP). There was no statistically significant difference in PFS or OS between either combination arm and CAP. Treatment-related adverse events more frequent (by ≥10%) on RAM + CAP than on CAP were constipation, decreased appetite, headache, epistaxis, and hypertension. Those more frequent (by ≥10%) on ICR + CAP than CAP were anemia, increased lacrimation, periorbital edema, nausea, vomiting, peripheral edema, facial edema, dehydration, and dyspnea.

CONCLUSION

Combining RAM or ICR with CAP did not improve PFS in the targeted study population. The Oncologist 2017;22:245-254 IMPLICATIONS FOR PRACTICE: Icrucumab and ramucirumab are recombinant human IgG1 monoclonal antibodies that bind vascular endothelial growth factor (VEGF) receptors 1 and 2 (VEGFR-1 and -2), respectively. VEGFR-1 activation on endothelial and tumor cell surfaces increases tumor vascularization and growth and supports tumor growth via multiple mechanisms, including contributions to angiogenesis and direct promotion of cancer cell proliferation. Strong preclinical and clinical evidence suggests key roles for VEGF and angiogenesis in breast cancer growth, invasion, and metastasis. This randomized phase II study evaluated the efficacy and safety of each antibody in combination with capecitabine in patients with previously treated unresectable, locally advanced or metastatic breast cancer.

The safety and efficacy of ramucirumab in combination with docetaxel in the treatment of lung cancer

INTRODUCTION

Angiogenesis is critical for tumor growth, proliferation and metastasis with the crucial role of Vascular Endothelial Growth factor (VEGF) pathway. Ramucirumab is a monoclonal antibody that specifically targets the extracellular domain of Vascular Endothelial Growth Factor Receptor 2. Areas covered: We performed a search on Medline to browse the current literature on Ramucirumab and anti-angiogenic agents, for the treatment of NSCLC. The REVEL study demonstrated a significant improvement of response rate, progression-free survival and overall survival by adding ramucirumab to docetaxel compared to docetaxel plus a placebo in second-line treatment of advanced non-small cell lung cancer, irrespective of histology, with an acceptable safety profile. This article has for objective to summarize efficacy and safety data of the use of ramucirumab in combination with docetaxel in second line in NSCLC. Expert commentary: REVEL constitutes the first significant advance in second-line setting for patients eligible to anti-angiogenic therapy. The landscape of post-platinum therapy in NSCLC is considerably evolving and the role of ramucirumab or other anti-angiogenic agents as nintedanib in this setting has to be discussed for each patient with other available treatment options, among which immune checkpoints inhibitors, as well as the best treatment sequence.

Ramucirumab Clinical Development: an Emerging Role in Gastrointestinal Tumors

Ramucirumab (IMC-1121B, LY3009806) is a fully human G1 monoclonal antibody that specifically targets vascular endotelial growth factor receptor 2 (VEGFR-2) with a substantially greater binding affinity than that of its natural ligands. Early clinical trials in patients with advanced solid tumors demonstrated that biologically relevant blood target concentrations are achievable with tolerable doses, and also showed some preliminary evidence of clinical activity. Several pivotal phase III trials have now been concluded and have led regulatory agencies to grant marketing authorization to ramucirumab for use as second line therapy in patients with advanced gastric or gastroesophageal junction (GEJ) adenocarcinoma (as single agent or in combination with paclitaxel), in patients with advanced colorectal carcinoma (CRC) (in combination with infusional fluorouracil and irinotecan (FOLFIRI regimen)) and in patients with advanced non-small cell lung cancer (NSCLC) (in combination with docetaxel). In contrast, ramucirumab failed to significantly improve survival versus placebo as second line therapy in patients with advanced hepatocellular carcinoma (HCC). The aim of this review is to summarize the clinical development and emerging role of ramucirumab in gastrointestinal (GI) tumors, including relevant aspects of its mechanism of action, pharmacology, safety profile, and antitumor activity in gastric, HCC, and CRC carcinomas.

Antagonist antibodies to vascular endothelial growth factor receptor 2 (VEGFR-2) as anti-angiogenic agents

Interaction of numerous signaling pathways in endothelial and mesangial cells results in exquisite control of the process of physiological angiogenesis, with a central role played by vascular endothelial growth factor receptor 2 (VEGFR-2) and its cognate ligands. However, deregulated angiogenesis participates in numerous pathological processes. Excessive activation of VEGFR-2 has been found to mediate tissue-damaging vascular changes as well as the induction of blood vessel expansion to support the growth of solid tumors. Consequently, therapeutic intervention aimed at inhibiting the VEGFR-2 pathway has become a mainstay of treatment in cancer and retinal diseases. In this review, we introduce the concepts of physiological and pathological angiogenesis, the crucial role played by the VEGFR-2 pathway in these processes, and the various inhibitors of its activity that have entered the clinical practice. We primarily focus on the development of ramucirumab, the antagonist monoclonal antibody (mAb) that inhibits VEGFR-2 and has recently been approved for use in patients with gastric, colorectal, and lung cancers. We examine in-depth the pre-clinical studies using DC101, the mAb to mouse VEGFR-2, which provided a conceptual foundation for the role of VEGFR-2 in physiological and pathological angiogenesis. Finally, we discuss further clinical development of ramucirumab and the future of targeting the VEGF pathway for the treatment of cancer.

The safety and efficacy of ramucirumab for the treatment of metastatic colorectal cancer

INTRODUCTION

Ramucirumab (IMC-1121B, LY3009806) is a fully humanized monoclonal antibody that targets the extracellular domain of vascular endothelial growth factor receptor 2 (VEGFR2), the principal mediator of VEGF-A downstream effects in cancer angiogenesis. Ramucirumab has been recently approved for use in combination with FOLFIRI for the treatment of patients with metastatic colorectal cancer (mCRC) whose disease has progressed on a first line bevacizumab-, oxaliplatin- and fluoropyrimidine-containing regimen. This approval was based on the results of the RAISE phase III placebo-controlled trial. This study demonstrated that the addition of ramucirumab to irinotecan-based chemotherapy significantly improved progression-free and overall survival of patients with mCRC, with manageable toxicity.

AREAS COVERED

The aim of this drug profile is to briefly summarize the pharmacology, clinical efficacy, safety and tolerability of ramucirumab in the context of metastatic colorectal cancer, and to provide some perspective regarding the role of the drug in clinical practice. Expert commentary: Pending issues that shall be addressed in the upcoming years include the optimization of ramucirumab dosing schedule, assessment of its role with other chemotherapy regimens or in other treatment settings, comparative evaluation of this agent with other antiangiogenics, and identification of predictive biomarkers to improve the therapeutic index and cost-effectiveness of this drug.

Angiogenesis in Liquid Tumors: An In Vitro Assay for Leukemic-Cell-Induced Bone Marrow Angiogenesis

The critical role of angiogenesis for solid tumor growth and metastatic spread has been well established. In contrast, even though increased vascularity has been commonly observed in bone marrows of patients with hematological malignancies (liquid tumors), the pathophysiology of leukemia-induced angiogenesis in the bone marrow remains elusive. This paper demonstrates the usage of a microengineered 3D biomimetic model to study leukemic-cell-induced bone marrow angiogenesis. Rational design of the 3D angiogenesis chip incorporating endothelial cells (ECs), leukemic cells, and bone marrow stromal fibroblasts provide an efficient biomimetic means to promote and visualize early angiogenic processes. Morphological features of angiogenesis induced by three different leukemic cell lines (U937, HL60, and K562) are investigated and compared. Quantitative measurements of angiogenic factors secreted from monocultures and cocultures of leukemic cells with bone marrow stromal fibroblasts suggest a synergistic relationship between ECs, leukemic cells, and bone marrow stromal fibroblasts for angiogenic induction, and also confirm the necessity of conducting functional angiogenic assays in proper 3D biomimetic cell culture systems like the one developed in this work.

Clinical pharmacokinetics and pharmacodynamics of ramucirumab in the treatment of colorectal cancer

INTRODUCTION

Colorectal cancer is the third most common cancer worldwide. The prognosis of colorectal cancer patients still remains dismal and half of them will develop metastatic disease. Angiogenesis plays an essential role in colorectal tumorigenesis, and the VEGF pathway is one of the targets that has been validated up to now. The use of antiangiogenics along with chemotherapy has become an accepted standard for colorectal cancer.

AREAS COVERED

This review discusses the efficacy and safety profile of ramucirumab, a fully human immunoglobulin G1 monoclonal antibody against the vascular endothelial growth factor receptor-2 (VEGFR-2), for the treatment of second-line metastatic colorectal cancer upon progression to first-line chemotherapy including anti-angiogenics.

EXPERT OPINION

Ramucirumab in combination with chemotherapy represents a valid option in second-line treatment of advanced colorectal cancer patients, who progressed on previous bevacizumab-based combinations. This agent demonstrates a similar benefit in terms of overall survival to other angiogenesis inhibitors (bevacizumab and ziv-aflibercept) used in this setting.

Membrane-proximal TRAIL species are incapable of inducing short circuit apoptosis signaling: Implications for drug development and basic cytokine biology

TRAIL continues to garner substantial interest as a recombinant cancer therapeutic while the native cytokine itself serves important tumor surveillance functions when expressed in membrane-anchored form on activated immune effector cells. We have recently developed the genetically stabilized TRAIL platform TR3 in efforts to improve the limitations associated with currently available drug variants. While in the process of characterizing mesothelin-targeted TR3 variants using a single chain antibody (scFv) delivery format (SS-TR3), we discovered that the membrane-tethered cytokine had a substantially increased activity profile compared to non-targeted TR3. However, cell death proceeded exclusively via a bystander mechanism and protected the mesothelin-positive targets from apoptosis rather than leading to their elimination. Incorporation of a spacer-into the mesothelin surface antigen or the cancer drug itself-converted SS-TR3 into a cis-acting phenotype. Further experiments with membrane-anchored TR3 variants and the native cytokine confirmed our hypothesis that membrane-proximal TRAIL species lack the capacity to physically engage their cognate receptors coexpressed on the same cell membrane. Our findings not only provide an explanation for the “peaceful” coexistence of ligand and receptor of a representative member of the TNF superfamily but give us vital clues for the design of activity-enhanced TR3-based cancer therapeutics.

Angiogenesis inhibitors in gastric and gastroesophageal junction cancer

Despite significant improvements in systemic chemotherapy during the past two decades, the prognosis of patients with advanced gastric and gastroesophageal junction adenocarcinoma remains poor. Because of molecular heterogeneity, it is essential to classify tumors based on the underlying oncogenic pathways and to develop targeted therapies acting on individual tumors. Unfortunately, although a number of molecular targets have been studied, very few of these agents can be used in a clinical setting. In this review, we summarize the available data on anti-angiogenic agents in advanced/metastatic gastric cancer.

Monoclonal antibodies-based treatment in gastric cancer: current status and future perspectives

Gastric cancer (GC) is the second leading cause of cancer-related death, and despite having improved treatment modalities over the last decade, for most patients, only modest improvements have been seen in overall survival. Recent progress in understanding the molecular biology of GC and the related signaling pathways offers, from the clinical point of view, promising advances for selected groups of patients. In the past, targeted therapies have significantly impacted the treatment strategy of several common solid tumors such as breast, colorectal, and lung cancers. Unfortunately, translational and clinical research shows fewer encouraging targeted treatments with regards to the GC. To date, only two monoclonal antibodies (mAb), named trastuzumab and ramucirumab, are approved for the treatment of advanced GC, suggesting that in GC, maybe more than in other cancers, effective targeted therapy requires patient selection based on precise predictive molecular biomarkers. The aim of this review is to summarize the available data on the clinical advantages offered by the use of mAbs in the treatment of advanced/metastatic GC. Future perspective is also discussed.

Targeting VEGFR1- and VEGFR2-expressing non-tumor cells is essential for esophageal cancer therapy

Increasing appreciation of tumor heterogeneity and the tumor-host interaction has stimulated interest in developing novel therapies that target both tumor cells and tumor microenvironment. Bone marrow derived cells (BMDCs) constitute important components of the tumor microenvironment. In this study, we aim to investigate the significance of VEGFR1- and VEGFR2-expressing non-tumor cells, including BMDCs, in esophageal cancer (EC) progression and in VEGFR1/VEGFR2-targeted therapies. Here we report that VEGFR1 or VEGFR2 blockade can significantly attenuate VEGF-induced Src and Erk signaling, as well as the proliferation and migration of VEGFR1⁺ and VEGFR2⁺ bone marrow cells and their pro-invasive effect on cancer cells. Importantly, our in vivo data show for the first time that systemic blockade of VEGFR1⁺ or VEGFR2⁺ non-tumor cells with neutralizing antibodies is sufficient to significantly suppress esophageal tumor growth, angiogenesis and metastasis in mice. Moreover, our tissue microarray study of human EC clinical specimens showed the clinicopathological significance of VEGFR1 and VEGFR2 in EC, which suggest that anti-VEGFR1/VEGFR2 therapies may be particularly beneficial for patients with aggressive EC. In conclusion, this study demonstrates the important contributions of VEGFR1⁺ and VEGFR2⁺ non-tumor cells in esophageal cancer progression, and substantiates the validity of these receptors as therapeutic targets for this deadly disease.

U.S. Food and Drug Administration Approval Summary: Ramucirumab for the Treatment of Metastatic Non-Small Cell Lung Cancer Following Disease Progression On or After Platinum-Based Chemotherapy

On December 12, 2014, the U.S. Food and Drug Administration (FDA) approved ramucirumab for use in combination with docetaxel for the treatment of patients with metastatic non-small cell lung cancer (NSCLC) with disease progression on or after platinum-based chemotherapy. Patients with epidermal growth factor receptor or anaplastic lymphoma kinase genomic tumor aberrations should have disease progression on FDA-approved therapy for these aberrations prior to receiving ramucirumab. This approval was based on an improvement in overall survival (OS) with an acceptable toxicity profile in a randomized, multicenter, double-blinded, placebo-controlled trial of 1,253 patients with metastatic NSCLC previously treated with a platinum-based combination therapy. Patients were randomized 1:1 to receive either ramucirumab in combination with docetaxel or placebo in combination with docetaxel. The primary endpoint was OS. Patients who received ramucirumab in combination with docetaxel had improved OS (hazard ratio [HR]: 0.86; 95% confidence interval [CI]: 0.75, 0.98). Median OS was 10.5 months on the ramucirumab plus docetaxel arm versus 9.1 months on the placebo plus docetaxel arm. The most frequent (≥ 30%) adverse reactions in ramucirumab-treated patients were fatigue, neutropenia, and diarrhea. The most frequent (≥ 5%) grade 3 and 4 adverse reactions in the ramucirumab arm were fatigue, neutropenia, febrile neutropenia, leukopenia, and hypertension.

IMPLICATIONS FOR PRACTICE

This report presents key information on the U.S. Food and Drug Administration approval of ramucirumab, a monoclonal antibody targeting vascular endothelial growth factor receptor-2, given in combination with docetaxel for the treatment of patients with metastatic non-small cell lung cancer whose disease has progressed on or after platinum-based chemotherapy. This report specifically addresses the issues of safety in patients with squamous cell tumors, effect of treatment in elderly patients, and uncertainties regarding effects in patients with tumors harboring epidermal growth factor receptor or anaplastic lymphoma kinase genomic tumor aberrations.

Critical evaluation of ramucirumab in the treatment of advanced gastric and gastroesophageal cancers

Gastric (GC) and gastroesophageal junction (GEJ) cancers are two global health problems with a relatively high mortality, particularly in the advanced stage. Inhibition of angiogenesis is now contemplated as a classic treatment preference for myriad tumor types encompassing renal cell carcinoma, non-small cell lung cancer, colorectal cancer, glioblastoma, and ovarian cancer, among others. Bevacizumab and ramucirumab have been widely investigated in GC and GEJ cancer, with some controversy about their therapeutic role. Ramucirumab is a monoclonal antibody for vascular endothelial growth factor receptor-2, with demonstrated activity both as a monotherapy and as a part of combination strategy in the management of advanced GC/GEJ cancer. In this review article, we present a critical evaluation of the preclinical and clinical data underlying the use of this drug in this indication. Moreover, we provide a spotlight on the future perspectives in systemic therapy for advanced GC/GEJ cancer.

TTAC-0001, a human monoclonal antibody targeting VEGFR-2/KDR, blocks tumor angiogenesis

Angiogenesis is one of the most important processes for cancer cell survival, tumor growth and metastasis. Vascular endothelial growth factor (VEGF) and its receptor, particularly VEGF receptor-2 (VEGFR-2, or kinase insert domain-containing receptor, KDR), play critical roles in tumor-associated angiogenesis. We developed TTAC-0001, a human monoclonal antibody against VEGFR-2/KDR from a fully human naïve single-chain variable fragment phage library. TTAC-0001 was selected as a lead candidate based on its affinity, ligand binding inhibition and inhibition of VEGFR-2 signal in human umbilical vein endothelial cells (HUVEC). TTAC-0001 inhibited binding of VEGF-C and VEGF-D to VEGFR-2 in addition to VEGF-A. It binds on the N-terminal regions of domain 2 and domain 3 of VEGFR-2. It could inhibit the phosphorylation of VEGFR-2/KDR and ERK induced by VEGF in HUVEC. TTAC-0001 also inhibited VEGF-mediated endothelial cell proliferation, migration and tube formation in vitro, as well as ex vivo vessel sprouting from rat aortic rings and neovascularization in mouse matrigel model in vivo. Our data indicates that TTAC-0001 blocks the binding of VEGFs to VEGFR-2/KDR and inhibits VEGFR-induced signaling pathways and angiogenesis. Therefore, these data strongly support the further development of TTAC-0001 as an anti-cancer agent in the clinic.

Anti-angiogenic therapies for advanced esophago-gastric cancer

Neo-vascularization is a vital process for tumor growth and development which involves the interaction between tumor cells and stromal endothelial cells through several growth factors and membranous receptors which ultimately activate pro-angiogenic intracellular signaling pathways. Inhibition of angiogenesis has become a standard treatment option for several tumor types including colorectal cancer, glioblastoma and ovarian cancer. In gastric cancer, the therapeutic role of anti-angiogenic agents is more controversial. Bevacizumab and ramucirumab, two monoclonal antibodies, which target vascular endothelial growth factor-A and vascular endothelial growth factor receptor-2, respectively, have been demonstrated antitumor activity in patients with tumors of the stomach or esophagogastric junction. However, especially for bevacizumab, this antitumor activity has not consistently translated into a survival advantage over standard treatment in randomized trials. In this article, we provide an overview of the role of angiogenesis in gastric cancer and discuss the results of clinical trials that investigated safety and effectiveness of antiangiogenic therapies in this disease. A review of the literature has been done using PubMed, ClinicalTrials.gov website and the ASCO Annual Meeting Library.

Ramucirumab: preclinical research and clinical development

Ramucirumab (IMC-1121B, LY3009806), a fully humanized monoclonal antibody directed against the extracellular domain of vascular endothelial growth factor receptor 2 (VEGFR-2), is a new therapeutic option that selectively inhibits the human VEGFR-2 with a much greater affinity than its natural ligands. Based on the promising results of both preclinical and early clinical studies, ramucirumab has been tested in different tumor types either alone or in combination with chemotherapy. While it has recently been granted its first US Food and Drug Administration approval for use as a single agent in patients with advanced or metastatic gastric cancer or gastroesophageal junction carcinoma, its role for metastatic breast cancer or advanced non-small-cell lung cancer is still debated. The aims of this review are to recall and discuss the most significant preclinical and clinical studies that led to the development of ramucirumab and to present the results of the randomized clinical trials that have tested its efficacy in different malignancies, including gastric and lung cancer.

Drugs derived from phage display: from candidate identification to clinical practice

Phage display, one of today’s fundamental drug discovery technologies, allows identification of a broad range of biological drugs, including peptides, antibodies and other proteins, with the ability to tailor critical characteristics such as potency, specificity and cross-species binding. Further, unlike in vivo technologies, generating phage display-derived antibodies is not restricted by immunological tolerance. Although more than 20 phage display-derived antibody and peptides are currently in late-stage clinical trials or approved, there is little literature addressing the specific challenges and successes in the clinical development of phage-derived drugs. This review uses case studies, from candidate identification through clinical development, to illustrate the utility of phage display as a drug discovery tool, and offers a perspective for future developments of phage display technology.

Molecular targeting to treat gastric cancer

Trastuzumab that targets human epidermal growth factor receptor 2 (HER2) protein is the only approved molecular targeting agent for treating gastric cancer in Japan and the outcomes have been favorable. However, trastuzumab is effective for only 10% to 20% of the population with gastric cancer that expresses HER2 protein. Molecular targeting therapy with bevacizumab against vascular endothelial growth factors (VEGF) and with cetuximab and panitumumab against the epidermal growth factors pathway that have been approved for treating colorectal cancer are not considered effective for treating gastric cancer according to several clinical trials. However, ramucirumab that targets VEGF receptor-2 prolonged overall survival in a large phase III clinical trial and it might be an effective molecular targeting therapy for gastric cancer. The significance of molecular targeting therapy for gastric cancer remains controversial. A large-scale randomized clinical trial of novel molecular targeting agents with which to treat gastric cancer is needed.

A phase II study of ramucirumab (IMC-1121B) in the treatment of persistent or recurrent epithelial ovarian, fallopian tube or primary peritoneal carcinoma

OBJECTIVE

Vascular endothelial growth factor (VEGF) receptor-mediated signaling contributes to ovarian cancer pathogenesis. Elevated VEGF expression is associated with poor clinical outcomes. We investigated ramucirumab, a fully human anti-VEGFR-2 antibody, in patients with persistent or recurrent epithelial ovarian, fallopian tube, or primary peritoneal carcinoma. Primary endpoints were progression-free survival at 6 months (PFS-6) and confirmed objective response rate (ORR).

METHODS

Women who received ≥ 1 platinum-based chemotherapeutic regimen and had a platinum-free interval of <12 months with measurable disease were eligible. Patients received 8 mg/kg ramucirumab intravenously every 2 weeks.

RESULTS

Sixty patients were treated; one patient remained on study as of September 2013. The median age was 62 years (range: 27-80), and median number of prior regimens was 3. Forty-five (75%) patients had platinum refractory/resistant disease. Thirty-nine patients (65.0%) had serous tumors. PFS-6 was 25.0% (n=15/60, 95% CI: 14.7-37.9%). Best overall response was: partial response 5.0% (n=3/60), stable disease 56.7% (n=34/60), and progressive disease 33.3% (n=20/60). The most common treatment-emergent adverse events possibly related to study drug were headache (65.0%; 10.0% Grade ≥ 3), fatigue (56.7%; 3.3% Grade ≥ 3), diarrhea (28.3%; 1.7% Grade ≥ 3), hypertension (25.0%; 3.3% Grade ≥ 3), and nausea (20.0%; no Grade ≥ 3). Two patients experienced intestinal perforations (3.3% Grade ≥ 3). Pharmacodynamic analyses revealed changes in several circulating VEGF proteins following initial ramucirumab infusion, including increased VEGF-A, PlGF and decreased sVEGFR-2.

CONCLUSIONS

Although antitumor activity was observed, the predetermined efficacy endpoints were not met.

Preparation and antitumor effect of a toxin-linked conjugate targeting vascular endothelial growth factor receptor and urokinase plasminogen activator

The aberrant signaling activation of vascular endothelial growth factor receptor (VEGFR) and urokinase plasminogen activator (uPA) is a common characteristic of many tumors, including lung cancer. Accordingly, VEGFR and uPA have emerged as attractive targets for tumor. KDR (Flk-1/VEGFR-2), a member of the VEGFR family, has been recognized as an important target for antiangiogenesis in tumor. In this study, a recombinant immunotoxin was produced to specifically target KDR-expressing tumor vascular endothelial cells and uPA-expressing tumor cells and mediate antitumor angiogenesis and antitumor effect. Based on its potent inhibitory effect on protein synthesis, Luffin-beta (Lβ) ribosome-inactivating protein was selected as part of a recombinant fusion protein, a single-chain variable fragment against KDR (KDRscFv)-uPA cleavage site (uPAcs)-Lβ-KDEL (named as KPLK). The KDRscFv-uPAcs-Lβ-KDEL (KPLK) contained a single-chain variable fragment (scFv) against KDR, uPAcs, Lβ, and the retention signal for endoplasmic reticulum proteins KDEL (Lys-Asp-Glu-Leu). The KPLK-expressing vector was expressed in Escherichia coli, and the KPLK protein was isolated with nickel affinity chromatography and gel filtration chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis test demonstrated KPLK was effectively expressed. Result of in vitro cell viability assay on non-small cell lung cancer (NSCLC) H460 cell line (uPA-positive cell) revealed that KPLK significantly inhibited cell proliferation, induced apoptosis, and accumulated cells in S and G2/M phases, but the normal cell line (human submandibular gland cell) was unaffected. These effects were enhanced when uPA was added to digest KPLK to release Lβ. For in vivo assay of KPLK, subcutaneous xenograft tumor model of nude mice were established with H460 cells. Growth of solid tumors was significantly inhibited in animals treated with KPLK up to 21 days, tumor weights were decreased, and the expression of angiogenesis marker CD31 was downregulated; meanwhile, the apoptosis-related protein casspase-3 was upregulated. These results suggested that the recombinant KPLK may have therapeutic applications on tumors, especially uPA-overexpressing ones.

Critical appraisal of ramucirumab (IMC-1121B) for cancer treatment: from benchside to clinical use

Although antiangiogenic treatments have produced milestone advances in the treatment of several diseases, and have significantly extended the median survival of cancer patients, these agents share some weaknesses, including a limited impact on the overall cure rate, a fleeting effect because of redundant pathways or early appearance of resistance mechanisms, and the lack of predictive factors for treatment selection. Recent data suggest that antibodies targeting the vascular endothelial growth factor axis exert their activity through the inhibition of vascular endothelial growth factor receptor-2 phosphorylation, which has a pivotal role in the neoangiogenic process. Ramucirumab, a fully humanized monoclonal antibody specifically directed against the extracellular domain of the receptor, administered intravenously every 2 or 3 weeks, is emerging as a novel antiangiogenic opportunity. Starting with preclinical data and early clinical results, this concise review focuses on the development of the novel compound across multiple cancers (including gastrointestinal malignancies, breast cancer, lung carcinoma, and genitourinary tumors), and presents available data from randomized phase II and phase III trials. REGARD was the first phase III study to report on the efficacy of single-agent ramucirumab in patients with advanced cancer. Many other ongoing phase III trials are testing the efficacy of this interesting antiangiogenic compound as a single agent or in combination with chemotherapy in different cancer types.

Expression and significance of vascular endothelial growth factor A and C in leukemia central nervous system metastasis

Metastasis to the central nervous system (CNS) is an obstacle for leukemia treatment, the mechanisms of which remain to be elucidated. VEGF-A and VEGF-C are suspected to participate in this process. Paired of cerebrospinal fluid (CSF) and serum samples were collected from leukemia and control cases. Levels of VEGF-A and VEGF-C in both CSF (VEGF-ACSF, VEGF-CCSF) and serum (VEGF-ASerum, VEGF-CSerum) were detected by ELISA. Our data show that higher levels of VEGF-ACSF are closely related to CNS leukemia (CNSL), and VEGF-ACSF may be a better predictor than the other risk factors elucidating the pathogenesis and development of CNSL.

A novel rabbit immunospot array assay on a chip allows for the rapid generation of rabbit monoclonal antibodies with high affinity

Antigen-specific rabbit monoclonal antibodies (RaMoAbs) are useful due to their high specificity and high affinity, and the establishment of a comprehensive and rapid RaMoAb generation system has been highly anticipated. Here, we present a novel system using immunospot array assay on a chip (ISAAC) technology in which we detect and retrieve antigen-specific antibody-secreting cells from the peripheral blood lymphocytes of antigen-immunized rabbits and produce antigen-specific RaMoAbs with 10^–12 M affinity within a time period of only 7 days. We have used this system to efficiently generate RaMoAbs that are specific to a phosphorylated signal-transducing molecule. Our system provides a new method for the comprehensive and rapid production of RaMoAbs, which may contribute to laboratory research and clinical applications.

Human ESC-derived hemogenic endothelial cells undergo distinct waves of endothelial to hematopoietic transition

Several studies have demonstrated that hematopoietic cells originate from endotheliumin early development; however, the phenotypic progression of progenitor cells during human embryonic hemogenesis is not well described. Here, we define the developmental hierarchy among intermediate populations of hematopoietic progenitor cells (HPCs) derived from human embryonic stem cells (hESCs). We genetically modified hESCs to specifically demarcate acquisition of vascular (VE-cadherin) and hematopoietic (CD41a) cell fate and used this dual-reporting transgenic hESC line to observe endothelial to hematopoietic transition by real-time confocal microscopy. Live imaging and clonal analyses revealed a temporal bias in commitment of HPCs that recapitulates discrete waves of lineage differentiation noted during mammalian hemogenesis. Specifically, HPCs isolated at later time points showed reduced capacity to form erythroid/ megakaryocytic cells and exhibited a tendency toward myeloid fate that was enabled by expression of the Notch ligand Dll4 on hESC-derived vascular feeder cells. These data provide a framework for defining HPC lineage potential, elucidate a molecular contribution from the vascular niche in promoting hematopoietic lineage progression, and distinguish unique subpopulations of hemogenic endothelium during hESC differentiation.

KEY POINTS

Live imaging of endothelial to hematopoietic conversion identifies distinct subpopulations of hESC-derived hemogenic endothelium. Expression of the Notch ligand DII4 on vascular ECs drives induction of myeloid fate from hESC-derived hematopoietic progenitors.

Angiogenesis in metastatic colorectal cancer and the benefits of targeted therapy

The diverse pathways and molecules involved in angiogenesis, the formation of new blood vessels, have been targeted for the treatment of colorectal and other cancers. Vascular endothelial growth factor (VEGF)-A binding to VEGF receptor (VEGFR)-2 is believed to be the key signaling pathway mediating angiogenesis. Other VEGF pathways involved in angiogenesis include VEGF-A, VEGF-B, and placental growth factor binding to VEGFR-1, and VEGF-C and VEGF-D binding to VEGFR-2 and VEGFR-3. VEGF signaling also intersects with other pathways, including angiopoietin/Tie, Notch, hypoxia-inducible factor, and integrin pathways. The roles of these pathways in tumor angiogenesis and in various human cancers will be explored in this article. In addition, preclinical and clinical data on bevacizumab, aflibercept (known as ziv-aflibercept in the US), and investigational antiangiogenic agents in development for the treatment of colorectal and other cancers will be reviewed.

Role of VEGF/VEGFR in the pathogenesis of leukemias and as treatment targets (Review)

Angiogenesis plays an important role in solid tumor growth, progression and metastasis. Evidence suggests that the progression of hematolymphoid malignancies also depends on the induction of new blood vessel formation under the influence of acute leukemia, myelodysplastic syndromes, myeloproliferative neoplasms, multiple myeloma and lymphomas. The vascular endothelial growth factor (VEGF) is the most important proangiogenic agent that activates receptors on vascular endothelial cells and promotes blood vessel regeneration. It has been demonstrated that VEGF/VEGF receptor (VEGFR) expression is upregulated in several types of hematolymphoid tumor cells accompanied with angiogenesis. The levels of VEGF/VEGFR are correlated with the treatment, relapse and prognosis of hematolymphoid tumors. In order for VEGF family and their receptors as antiangiogenic targets to treat solid tumors, several antiangiogenic agents targeting VEGF-related pathways have been used for the treatment of hematolymphoid malignancies in clinical trials. The results demonstrate a promising therapeutic intervention in multiple types of hematolymphoid tumors. This review aims to summarize recent advances in understanding the role of VEGF and angiogenesis in leukemias, mainly focusing on their upstream transcriptors, downstream targets and the correlation of VEGF/VEGFR with the treatment, relapse or prognosis of leukemia. The progress of VEGF and its receptors as attractive targets for therapies are also discussed in clinical application.