A randomised, double-blind, placebo-controlled phase 2 study of trebananib (AMG 386) in combination with FOLFIRI in patients with previously treated metastatic colorectal carcinoma

Evaluating the efficacy and safety of trebananib in treating ovarian cancer and non-ovarian cancer patients: a meta-analysis and systematic review

OBJECTIVES

Due to its anti-angiogenic properties, trebananib is frequently employed in the treatment of cancer patients, particularly those with ovarian cancer. We conducted a meta-analysis to assess the efficacy and safety profile of trebananib in combination with other drugs for treating both ovarian and non-ovarian cancer patients.

METHODS

Our search encompassed PubMed, Medline, Cochrane, and Embase databases, with a focus on evaluating study quality. Data extraction was conducted from randomized controlled trials (RCTs), and RevMan 5.3 facilitated result analysis.

RESULTS

Combining trebananib with other drugs extended progression-free survival (PFS) [HR 0.81, (95%CI: 0.65, 0.99), p = 0.04] and overall survival (OS) [HR 0.88, (95%CI: 0.79, 1.00), p = 0.04] in ovarian cancer patients. Ovarian cancer patients exhibited a higher objective response rate (ORR) with trebananib compared to non-ovarian cancer cohorts. Moreover, the incorporation of trebananib into the standard treatment regimen for malignant tumors did not significantly elevate drug-related adverse events [RR 1.05, (95% CI: 1.00, 1.11), p = 0.05].

CONCLUSION

Trebananib plus other drugs can improve the PFS, OS and ORR in patients with cancer, especially ovarian cancer. Our recommendation is to use trebananib plus other drugs to treat advanced cancer, and to continuously monitor and manage drug-related adverse events.

REGISTRATION

PROSPERO (No. CRD42023466988).

Blood Vessel-Targeted Therapy in Colorectal Cancer: Current Strategies and Future Perspectives

The vasculature is a key player and regulatory component in the multicellular microenvironment of solid tumors and, consequently, a therapeutic target. In colorectal carcinoma (CRC), antiangiogenic treatment was approved almost 20 years ago, but there are still no valid predictors of response. In addition, treatment resistance has become a problem. Vascular heterogeneity and plasticity due to species-, organ-, and milieu-dependent phenotypic and functional differences of blood vascular cells reduced the hope of being able to apply a standard approach of antiangiogenic therapy to all patients. In addition, the pathological vasculature in CRC is characterized by heterogeneous perfusion, impaired barrier function, immunosuppressive endothelial cell anergy, and metabolic competition-induced microenvironmental stress. Only recently, angiocrine proteins have been identified that are specifically released from vascular cells and can regulate tumor initiation and progression in an autocrine and paracrine manner. In this review, we summarize the history and current strategies for applying antiangiogenic treatment and discuss the associated challenges and opportunities, including normalizing the tumor vasculature, modulating milieu-dependent vascular heterogeneity, and targeting functions of angiocrine proteins. These new strategies could open perspectives for future vascular-targeted and patient-tailored therapy selection in CRC.

Therapeutic targeting of angiopoietins in tumor angiogenesis and cancer development

The formation and progression of tumors in humans are linked to the abnormal development of new blood vessels known as neo-angiogenesis. Angiogenesis is a broad word that encompasses endothelial cell migration, proliferation, tube formation, and intussusception, as well as peri-EC recruitment and extracellular matrix formation. Tumor angiogenesis is regulated by angiogenic factors, out of which some of the most potent angiogenic factors such as vascular endothelial growth factor and Angiopoietins (ANGs) in the body are produced by macrophages and other immune cells within the tumor microenvironment. ANGs have a distinct function in tumor angiogenesis and behavior. ANG1, ANG 2, ANG 3, and ANG 4 are the family members of ANG out of which ANG2 has been extensively investigated owing to its unique role in modifying angiogenesis and its tight association with tumor progression, growth, and invasion/metastasis, which makes it an excellent candidate for therapeutic intervention in human malignancies. ANG modulators have demonstrated encouraging outcomes in the treatment of tumor development, either alone or in conjunction with VEGF inhibitors. Future development of more ANG modulators targeting other ANGs is needed. The implication of ANG1, ANG3, and ANG4 as probable therapeutic targets for anti-angiogenesis treatment in tumor development should be also evaluated. The article has described the role of ANG in tumor angiogenesis as well as tumor growth and the treatment strategies modulating ANGs in tumor angiogenesis as demonstrated in clinical studies. The pharmacological modulation of ANGs and ANG-regulated pathways that are responsible for tumor angiogenesis and cancer development should be evaluated for the development of future molecular therapies.

Predictive potential of angiopoietin-2 in a mCRC subpopulation treated with vanucizumab in the McCAVE trial

Introduction

Angiopoetin-2 (Ang-2) is a key mediator of tumour angiogenesis. When upregulated it is associated with tumour progression and poor prognosis. Anti-vascular endothelial growth factor (VEGF) therapy has been widely used in the treatment of metastatic colorectal cancer (mCRC). The potential benefit of combined inhibition of Ang-2 and VEGF-A in previously untreated patients with mCRC was evaluated in the phase II McCAVE study (NCT02141295), assessing vanucizumab versus bevacizumab (VEGF-A inhibitor), both in combination with mFOLFOX-6 (modified folinic acid [leucovorin], fluorouracil and oxaliplatin) chemotherapy. To date, there are no known predictors of outcome of anti-angiogenic treatment in patients with mCRC. In this exploratory analysis, we investigate potential predictive biomarkers in baseline samples from McCAVE participants.

Methods

Tumour tissue samples underwent immunohistochemistry staining for different biomarkers, including Ang-2. Biomarker densities were scored on the tissue images using dedicated machine learning algorithms. Ang-2 levels were additionally assessed in plasma. Patients were stratified by KRAS mutation status determined using next generation sequencing. Median progression-free survival (PFS) for each treatment group by biomarker and KRAS mutation was estimated using Kaplan-Meier plots. PFS hazard ratios (and 95% confidence intervals) were compared using Cox regression.

Results

Overall low tissue baseline levels of Ang-2 were associated with longer PFS, especially in patients with wild-type KRAS status. In addition, our analysis identified a new subgroup of patients with KRAS wild-type mCRC and high levels of Ang-2 in whom vanucizumab/mFOLFOX-6 prolonged PFS significantly (log-rank p=0.01) by ~5.5 months versus bevacizumab/mFOLFOX-6. Similar findings were seen in plasma samples.

Discussion

This analysis demonstrates that additional Ang-2 inhibition provided by vanucizumab shows a greater effect than single VEGF-A inhibition in this subpopulation. These data suggest that Ang-2 may be both a prognostic biomarker in mCRC and a predictive biomarker for vanucizumab in KRAS wild-type mCRC. Thus, this evidence can potentially support the establishment of more tailored treatment approaches for patients with mCRC.

Venous Thromboembolism in Cancer Patients Undergoing Chemotherapy: A Systematic Review and Meta-Analysis

Objective: Venous thromboembolism (VTE) is a life-threatening complication that may exacerbate cancer prognosis. Whilst some studies indicate an increased risk of VTE in cancer patients undergoing chemotherapy, the prevalence estimates on the pooled prevalence of VTE in cancer patients undergoing chemotherapy are not known. This study aims to calculate the pooled prevalence of VTE in chemotherapy-treated cancer patients. Methods: Studies on VTE occurrence in cancer patients undergoing chemotherapy were retrieved after database search. The terms used included “cancer”, “chemotherapy”, and “venous thromboembolism”. A random-effects meta-analysis was conducted to obtain a pooled estimate of VTE prevalence in cancer patients undergoing chemotherapy. Results: A total of 102 eligible studies involving 30,671 patients (1773 with VTE, 28,898 without) were included in the meta-analysis. The pooled estimate of VTE prevalence was found to be 6%, ranging from 6% to 7% (ES 6%; 95% CI 6−7%; z = 18.53; p < 0.001). Conclusions: The estimated pooled prevalence rate of VTEs was 6% in cancer patients undergoing CRT, which was higher than the overall crude prevalence rate (5.78%). Comprehensive cancer care should consider stratified VTE risk assessment based on cancer phenotype, given that certain phenotypes of cancer such as bladder, gastric and ovarian posing particularly high risks of VTE.

The Validity of Surrogate Endpoints in Sub Groups of Metastatic Colorectal Cancer Patients Defined by Treatment Class and KRAS Status

Background and Aim: Findings from the literature suggest that the validity of surrogate endpoints in metastatic colorectal cancer (mCRC) may depend on a treatments' mechanism of action. We explore this and the impact of Kirsten rat sarcoma (KRAS) status on surrogacy patterns in mCRC. Methods: A systematic review was undertaken to identify randomized controlled trials (RCTs) for pharmacological therapies in mCRC. Bayesian meta-analytic methods for surrogate endpoint evaluation were used to evaluate surrogate relationships across all RCTs, by KRAS status and treatment class. Surrogate endpoints explored were progression free survival (PFS) as a surrogate endpoint for overall survival (OS), and tumour response (TR) as a surrogate for PFS and OS. Results: 66 RCTs were identified from the systematic review. PFS showed a strong surrogate relationship with OS across all data and in subgroups by KRAS status. The relationship appeared stronger within individual treatment classes compared to the overall analysis. The TR-PFS and TR-OS relationships were found to be weak overall but stronger within the Epidermal Growth Factor Receptor + Chemotherapy (EGFR + Chemo) treatment class; both overall and in the wild type (WT) patients for TR-PFS, but not in patients with the mutant (MT) KRAS status where data were limited. Conclusions: PFS appeared to be a good surrogate endpoint for OS. TR showed a moderate surrogate relationship with PFS and OS for the EGFR + Chemo treatment class. There was some evidence of impact of the mechanism of action on the strength of the surrogacy patterns in mCRC, but little evidence of the impact of KRAS status on the validity of surrogate endpoints.

Novel Drugs with High Efficacy against Tumor Angiogenesis

Angiogenesis is involved in physiological and pathological processes in the body. Tumor angiogenesis is a key factor associated with tumor growth, progression, and metastasis. Therefore, there is great interest in developing antiangiogenic strategies. Hypoxia is the basic initiating factor of tumor angiogenesis, which leads to the increase of vascular endothelial growth factor (VEGF), angiopoietin (Ang), hypoxia-inducible factor (HIF-1), etc. in hypoxic cells. The pathways of VEGF and Ang are considered to be critical steps in tumor angiogenesis. A number of antiangiogenic drugs targeting VEGF/VEGFR (VEGF receptor) or ANG/Tie2, or both, are currently being used for cancer treatment, or are still in various stages of clinical development or preclinical evaluation. This article aims to review the mechanisms of angiogenesis and tumor angiogenesis and to focus on new drugs and strategies for the treatment of antiangiogenesis. However, antitumor angiogenic drugs alone may not be sufficient to eradicate tumors. The molecular chaperone heat shock protein 90 (HSP90) is considered a promising molecular target. The VEGFR system and its downstream signaling molecules depend on the function of HSP90. This article also briefly introduces the role of HSP90 in angiogenesis and some HSP90 inhibitors.

Vascular Normalization: A New Window Opened for Cancer Therapies

Preclinical and clinical antiangiogenic approaches, with multiple side effects such as resistance, have not been proved to be very successful in treating tumor blood vessels which are important targets for tumor therapy. Meanwhile, restoring aberrant tumor blood vessels, known as tumor vascular normalization, has been shown not only capable of reducing tumor invasion and metastasis but also of enhancing the effectiveness of chemotherapy, radiation therapy, and immunotherapy. In addition to the introduction of such methods of promoting tumor vascular normalization such as maintaining the balance between proangiogenic and antiangiogenic factors and targeting endothelial cell metabolism, microRNAs, and the extracellular matrix, the latest molecular mechanisms and the potential connections between them were primarily explored. In particular, the immunotherapy-induced normalization of blood vessels further promotes infiltration of immune effector cells, which in turn improves immunotherapy, thus forming an enhanced loop. Thus, immunotherapy in combination with antiangiogenic agents is recommended. Finally, we introduce the imaging technologies and serum markers, which can be used to determine the window for tumor vascular normalization.

Ang2 inhibitors and Tie2 activators: potential therapeutics in perioperative treatment of early stage cancer

Anti-angiogenic drugs targeting the VEGF pathway are most effective in advanced metastatic disease settings of certain types of cancers, whereas they have been unsuccessful as adjuvant therapies of micrometastatic disease in numerous phase III trials involving early-stage (resectable) cancers. Newer investigational anti-angiogenic drugs have been designed to inhibit the Angiopoietin (Ang)-Tie pathway. Acting through Tie2 receptors, the Ang1 ligand is a gatekeeper of endothelial quiescence. Ang2 is a dynamically expressed pro-angiogenic destabilizer of endothelium, and its upregulation is associated with poor prognosis in cancer. Besides using Ang2 blockers as inhibitors of tumor angiogenesis, little attention has been paid to their use as stabilizers of blood vessels to suppress tumor cell extravasation and metastasis. In clinical trials, Ang2 blockers have shown limited efficacy in advanced metastatic disease settings. This review summarizes preclinical evidence suggesting the potential utility of Ang2 inhibitors or Tie2 activators as neoadjuvant or adjuvant therapies in the prevention or treatment of early-stage micrometastatic disease. We further discuss the rationale and potential of combining these strategies with immunotherapy, including immune checkpoint targeting antibodies.

Angiopoietin inhibitors: A review on targeting tumor angiogenesis

Angiogenesis is the process of formation of new blood vessels from existing ones. Vessels serve the purpose of providing oxygen, nutrients and removal of waste from the cells. The physiological angiogenesis is a normal process and is required in the embryonic development, wound healing, menstrual cycle. For homeostasis, balance of pro angiogenic factors and anti angiogenic factors like is important. Their imbalance causes a process known as "angiogenic switch" which leads to various pathological conditions like inflammation, tumor and restenosis. Like normal cells, tumor cells also require oxygen and nutrients to grow which is provided by tumor angiogenesis. Hence angiogenic process can be inhibited to prevent tumor growth. This gives rise to study of anti angiogenic drugs. Currently approved anti angiogenic drugs are mostly VEGF inhibitors, but VEGF inhibitors have certain limitations like toxicity, low progression free survival (PFS), and resistance to anti VEGF therapy. This article focuses on angiopoietins as alternative and potential targets for anti angiogenic therapy. Angiopoietins are ligands of Tie receptor and play a crucial role in angiogenesis, their inhibition can prevent many tumor growths even on later stages of development. We present current clinical and preclinical stages of angiopoietin inhibitors. Drugs studied in the article are selective as well as non-selective inhibitors of angiopoietin 2 like Trebananib (AMG 386), AMG 780, REGN 910, CVX 060, MEDI 3617 and dual inhibitors of angiopoietin 2 and VEGF like Vanucizumab and RG7716. The angiopoietin inhibitors show promising results alone and in combination with VEGF inhibitors in various malignancies.

Monitoring cancer cell surface receptor expression during anti-angiogenesis therapy in vivo

Concurrent administration of cancer therapeutics with tumor vasculature targeting treatment has been shown to improve overall survival in multiple human cancer types, as such combinations aim to destroy different compartments of tumors. Anti-angiogenesis therapeutics designed to inhibit tumor induced vessel sprouting have also been shown to re-model the tumor vasculature through a transient vessel normalization effect, which leads to improved perfusion of oxygen and drug in tumor. However, the effects that this normalized vasculature has on the availability of cancer receptor, such as EGFR, is unknown. Herein, we examined the use of MRI-PAFT to estimate cancer surface receptor availability in response to anti-angiogenesis therapy, using MRI-coupled paired agent fluorescence tomography. Bevacizumab treated tumors showed increase in RA compared to control tumors, but this was not statistically significant.

Angiogenesis Inhibitors for Colorectal Cancer. A Review of the Clinical Data

Since the late 1990s, therapy for metastatic colorectal cancer (mCRC) has changed considerably, and the combination of doublet or triplet chemotherapy and a targeted agent are now routinely used. The targeting of angiogenesis, the development of new blood vessels, represents a key element in the overall treatment strategy. Since the approval in 2004 of the first anti-angiogenetic drug, multiple agents have been approved and others are currently under investigation. We present an overview of the recent literature on approved systemic treatment of mCRC, with a focus on anti-angiogenic drugs, and current treatment approaches, and elaborate on the future role of angiogenesis in colorectal cancer as seen from a clinical perspective. The treatment of mCRC, in general, has changed from "one strategy fits all" to a more personalized approach. This is, however, not entirely the case for anti-angiogenetic treatments, partly due to a lack of validated biomarkers. The anti-angiogenetic standard treatment at the present primarily includes monoclonal antibodies. The therapeutic field of angiogenesis, however, has received increased interest after the introduction of newer combinations. These approaches will likely change the current treatment strategy, once again, to the overall benefit of patients.

An appraisal of emerging second line therapies for metastatic colorectal cancer

INTRODUCTION

Despite a significant improvement in overall survival over the last 15 years, colorectal cancer remains a major public health problem worldwide. Much effort has been made to develop an optimal choice of first-line treatments, but after progression the therapeutic possibilities and the criteria for choice are different.

AREAS COVERED

The purpose of this literature review is to discuss the different possibilities of second-line treatment and to specify the criteria for choice. Biological subgroups requiring specific therapeutic decisions will be described. We conducted a systematic review for randomized controlled trials published since 1995. A non-exhaustive review of published phase II studies, cohort studies, and international guidelines was also given and future leads were discussed.

EXPERT OPINION

Some choices of second-line treatments are a direct result of the option chosen in the first line. Others are necessary because of the biological specificity of the tumor: immunotherapy for tumors with microsatellite instability, or the combination encorafenib cetuximab for mutated BRAF-V600E tumors. In many other circumstances, there are several options that require extensive involvement of multidisciplinary boards and the patient in the final therapeutic decision.

Dual Antiangiogenesis Agents Bevacizumab Plus Trebananib, without Chemotherapy, in First-line Treatment of Metastatic Colorectal Cancer: Results of a Phase II Study

PURPOSE

To assess the efficacy and safety of dual antiangiogenesis agents, bevacizumab plus trebananib, without chemotherapy, in first-line treatment of metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

This open-label phase II study enrolled patients with unresectable mCRC with no prior systemic treatment. All patients received bevacizumab 7.5 mg/kg 3-weekly and trebananib 15 mg/kg weekly. The primary endpoint was disease control [stable disease, partial response (PR), or complete response (CR)] at 6 months (DC6m). Secondary endpoints included toxicity, overall response rate (ORR), progression-free survival (PFS), and overall survival (OS). Exploratory biomarkers in plasma angiogenesis-related proteins, tumor gene expression, and plasma antibodies to tumor antigens were examined.

RESULTS

Forty-five patients were enrolled from four Australian sites. DC6m was 63% [95% confidence interval (CI), 47-77]. ORR was 17% (95% CI, 7-32), comprising of seven PRs. Median duration of response was 20 months (range, 10-48 months). Median PFS was 8.4 months and median OS 31.4 months. Grade 1-2 peripheral edema and joint-related symptoms were common. Overall incidence of grade 3-4 adverse events (AE) of any type was 33% (n = 15). Expected AEs of bevacizumab treatment did not appear to be increased by the addition of trebananib.

CONCLUSIONS

In a first-line mCRC population, the dual antiangiogenic combination, bevacizumab plus trebananib, without chemotherapy, was efficacious with durable responses. The toxicity profile of the combination was manageable and did not exceed that expected with bevacizumab +/- chemotherapy. Exploratory biomarker results raise the hypothesis that the antiangiogenic combination may enable the antitumor immune response in immunotolerant colorectal cancer.

The Angiopoietin-2 and TIE Pathway as a Therapeutic Target for Enhancing Antiangiogenic Therapy and Immunotherapy in Patients with Advanced Cancer

Despite significant advances made in cancer treatment, the development of therapeutic resistance to anticancer drugs represents a major clinical problem that limits treatment efficacy for cancer patients. Herein, we focus on the response and resistance to current antiangiogenic drugs and immunotherapies and describe potential strategies for improved treatment outcomes. Antiangiogenic treatments that mainly target vascular endothelial growth factor (VEGF) signaling have shown efficacy in many types of cancer. However, drug resistance, characterized by disease recurrence, has limited therapeutic success and thus increased our urgency to better understand the mechanism of resistance to inhibitors of VEGF signaling. Moreover, cancer immunotherapies including immune checkpoint inhibitors (ICIs), which stimulate antitumor immunity, have also demonstrated a remarkable clinical benefit in the treatment of many aggressive malignancies. Nevertheless, the emergence of resistance to immunotherapies associated with an immunosuppressive tumor microenvironment has restricted therapeutic response, necessitating the development of better therapeutic strategies to increase treatment efficacy in patients. Angiopoietin-2 (ANG2), which binds to the receptor tyrosine kinase TIE2 in endothelial cells, is a cooperative driver of angiogenesis and vascular destabilization along with VEGF. It has been suggested in multiple preclinical studies that ANG2-mediated vascular changes contribute to the development and persistence of resistance to anti-VEGF therapy. Further, emerging evidence suggests a fundamental link between vascular abnormalities and tumor immune evasion, supporting the rationale for combination strategies of immunotherapy with antiangiogenic drugs. In this review, we discuss the recent mechanistic and clinical advances in targeting angiopoietin signaling, focusing on ANG2 inhibition, to enhance therapeutic efficacy of antiangiogenic and ICI therapies. In short, we propose that a better mechanistic understanding of ANG2-mediated vascular changes will provide insight into the significance of ANG2 in treatment response and resistance to current antiangiogenic and ICI therapies. These advances will ultimately improve therapeutic modalities for cancer treatment.

The McCAVE Trial: Vanucizumab plus mFOLFOX-6 Versus Bevacizumab plus mFOLFOX-6 in Patients with Previously Untreated Metastatic Colorectal Carcinoma (mCRC)

Background

Bevacizumab, a VEGF‐A inhibitor, in combination with chemotherapy, has proven to increase progression‐free survival (PFS) and overall survival in multiple lines of therapy of metastatic colorectal cancer (mCRC). The angiogenic factor angiopoetin‐2 (Ang‐2) is associated with poor prognosis in many cancers, including mCRC. Preclinical models demonstrate improved activity when inhibiting both VEGF‐A and Ang‐2, suggesting that the dual VEGF‐A and Ang‐2 blocker vanucizumab (RO5520985 or RG‐7221) may improve clinical outcomes. This phase II trial evaluated the efficacy of vanucizumab plus modified (m)FOLFOX‐6 (folinic acid (leucovorin), fluorouracil (5‐FU) and oxaliplatin) versus bevacizumab/mFOLFOX‐6 for first‐line mCRC.

Patients and Methods

All patients received mFOLFOX‐6 and were randomized 1:1 to also receive vanucizumab 2,000 mg or bevacizumab 5 mg/kg every other week. Oxaliplatin was given for eight cycles; other agents were continued until disease progression or unacceptable toxicity for a maximum of 24 months. The primary endpoint was investigator‐assessed PFS.

Results

One hundred eighty‐nine patients were randomized (vanucizumab, n = 94; bevacizumab, n = 95). The number of PFS events was comparable (vanucizumab, n = 39; bevacizumab, n = 43). The hazard ratio was 1.00 (95% confidence interval, 0.64–1.58; p = .98) in a stratified analysis based on number of metastatic sites and region. Objective response rate was 52.1% and 57.9% in the vanucizumab and bevacizumab arm, respectively. Baseline plasma Ang‐2 levels were prognostic in both arms but not predictive for treatment effects on PFS of vanucizumab. The incidence of adverse events of grade ≥3 was similar between treatment arms (83.9% vs. 82.1%); gastrointestinal perforations (10.8% vs. 8.4%) exceeded previously reported rates in this setting. Hypertension and peripheral edema were more frequent in the vanucizumab arm.

Conclusion

Vanucizumab/mFOLFOX‐6 did not improve PFS and was associated with increased rates of antiangiogenic toxicity compared with bevacizumab/mFOLFOX‐6. Our results suggest that Ang‐2 is not a relevant therapeutic target in first‐line mCRC.

Implications for Practice

This randomized phase II study demonstrates that additional angiopoietin‐2 (Ang‐2) inhibition does not result in superior benefit over anti–VEGF‐A blockade alone when each added to standard chemotherapy. Moreover, the performed pharmacokinetic and pharmacodynamic analysis revealed that vanucizumab was bioavailable and affected its intended target, thereby strongly suggesting that Ang‐2 is not a relevant therapeutic target in the clinical setting of treatment‐naïve metastatic colorectal cancer. As a result, the further clinical development of the dual VEGF‐A and Ang‐2 inhibitor vanucizumab was discontinued.

This phase II trial evaluated the efficacy of vanucizumab plus mFOLFOX‐6 versus bevacizumab/mFOLFOX‐6 in the first‐line setting of metastatic colorectal cancer.

Safety and Tolerability of Anti-Angiogenic Protein Kinase Inhibitors and Vascular-Disrupting Agents in Cancer: Focus on Gastrointestinal Malignancies

Angiogenesis is an essential process for tumor growth and metastasis. Inhibition of angiogenesis as an anticancer strategy has shown significant results in a plethora of tumors. Anti-angiogenic agents are currently part of many standard-of-care options for several metastatic gastrointestinal cancers. Bevacizumab, aflibercept, ramucirumab, and regorafenib have significantly improved both progression-free and overall survival in different lines of treatment in metastatic colorectal cancer. Second-line ramucirumab and third-line apatinib are effective anti-angiogenic treatments for patients with metastatic gastric cancer. Unfortunately, the anti-angiogenic strategy has major practical limitations: resistance inevitably develops through redundancy of signaling pathways and selection for subclonal populations adapted for hypoxic conditions. Anti-angiogenic agents may be more effective in combination therapies, with not only cytotoxics but also other emerging compounds in the anti-angiogenic class or in the separate class of the so-called vascular-disrupting agents. This review aims to provide an overview of the approved and "under development" anti-angiogenic compounds as well as the vascular-disrupting agents in the treatment of gastrointestinal cancers, focusing on the actual body of knowledge available on therapy challenges, pharmacodynamic and pharmacokinetic mechanisms, safety profiles, promising predictive biomarkers, and future perspectives.

Angiopoietin-1 and Angiopoietin-2 Inhibitors: Clinical Development

PURPOSE OF REVIEW

The purpose of this review is to discuss the current understanding of the Tie2-angiopoietin system and its role in tumor growth and metastasis. This review also focuses on preclinical and clinical data published to date that have evaluated Tie2-angiopoietin inhibition.

RECENT FINDINGS

Tie2 inhibition has shown significant promise in preclinical models, notable for decreased tumor burden and fewer sites of metastatic disease across various malignancies. However, data from human clinical trials have shown more mixed results. Trebananib, rebastanib, and MEDI3617 are the three Tie2-angiopoietin inhibitors that have been most widely evaluated in phase I and II trials. Further investigation into these therapies is ongoing. The Tie2-angiopoietin pathway continues to show promise in preclinical and some clinical trials, including studies on recurrent or metastatic breast and renal cell carcinomas. Further evaluation of these therapies, however, is warranted to better understand their optimal clinical utility.

Phase 1b Study of Trebananib Plus Paclitaxel and Trastuzumab in Patients With HER2-Positive Locally Recurrent or Metastatic Breast Cancer

INTRODUCTION

Trebananib, a peptide-Fc fusion protein, blocks angiogenesis by inhibiting binding of angiopoietin-1/2 to the receptor tyrosine kinase Tie2. Trebananib plus trastuzumab and paclitaxel was evaluated in human epidermal growth factor receptor 2-positive breast cancer in an open-label phase 1b clinical study.

PATIENTS AND METHODS

Women with human epidermal growth factor receptor 2-positive breast cancer received weekly paclitaxel (80 mg/m²), trastuzumab (8 mg/m² then 6 mg/kg every 3 weeks), and intravenous trebananib (10 mg/kg or 30 mg/kg weekly) beginning week 2. The primary end point was the incidence of dose-limiting toxicities. Secondary end points included incidence of adverse events (AEs), pharmacokinetics, and tumor response (objective response and duration of response).

RESULTS

Forty women were enrolled; 2 experienced dose-limiting toxicities (grade 3 ocular transient ischemic attack [10 mg/kg cohort] and grade 3 elevation in γ-glutamyl transferase [30 mg/kg cohort]). The most common treatment-emergent AEs were peripheral edema (n = 28), diarrhea (n = 27), alopecia (n = 26), fatigue (n = 24), and nausea (n = 24). Maximum observed concentration and area under the concentration-time curve increased proportionally with the trebananib dose. Objective response was confirmed in 31 patients. In the 10 mg/kg cohort, 16 patients (80%) experienced partial response, and none experienced complete response. In the 30 mg/kg cohort, 12 patients (71%) experienced partial response and 3 (18%) experienced complete response. Median (95% confidence interval) duration of response in the 10 and 30 mg/kg cohorts was 12.6 (4.3-20.2) and 16.6 (8.2-not estimable) months, respectively.

CONCLUSION

This phase 1b study showed that trebananib was tolerated with manageable AEs at a dose up to 30 mg/kg weekly. Trebananib demonstrated anticancer activity, as indicated by objective response and duration of response.

A network meta-analysis on the efficacy of sixteen targeted drugs in combination with chemotherapy for treatment of advanced/metastatic colorectal cancer

OBJECTIVE

A network meta-analysis was conducted comparing the short-term efficacies of 16 targeted drugs in combination with chemotherapy for treatment of advanced/metastatic colorectal cancer (CRC).

RESULTS

Twenty-seven RCTs were ultimately incorporated into this network meta-analysis. Compared with chemotherapy alone, bevacizumab + chemotherapy, panitumumab + chemotherapy and conatumumab + chemotherapy had higher PR rate. Bevacizumab + chemotherapy, cetuximab + chemotherapy, panitumumab + chemotherapy, trebananib + chemotherapy and conatumumab + chemotherapy had higher ORR rate in comparison to chemotherapy alone. Furthermore, bevacizumab + chemotherapy had higher DCR rate than chemotherapy alone. The results of our cluster analysis showed that chemotherapy combined with bevacizumab, cetuximab, panitumumab, conatumumab, ganitumab, or brivanib + cetuximab had better efficacies for the treatment of advanced/metastatic CRC in comparison to chemotherapy alone.

MATERIALS AND METHODS

Electronic databases were comprehensively searched for potential and related randomized controlled trials (RCTs). Direct and indirect evidence were incorporated for evaluation of stable disease (SD), progressive disease (PD), complete response (CR), partial response (PR), disease control rate (DCR) and overall response ratio (ORR) by calculating odds ratio (OR) and 95% confidence intervals (CI), and using the surface under the cumulative ranking curve (SUCRA).

CONCLUSIONS

These results indicated that bevacizumab + chemotherapy, panitumumab + chemotherapy, conatumumab + chemotherapy and brivanib + cetuximab + chemotherapy may have better efficacies for the treatment of advanced/metastatic CRC.

Enhancing cancer immunotherapy using antiangiogenics: opportunities and challenges

Immunotherapy has emerged as a major therapeutic modality in oncology. Currently, however, the majority of patients with cancer do not derive benefit from these treatments. Vascular abnormalities are a hallmark of most solid tumours and facilitate immune evasion. These abnormalities stem from elevated levels of proangiogenic factors, such as VEGF and angiopoietin 2 (ANG2); judicious use of drugs targeting these molecules can improve therapeutic responsiveness, partially owing to normalization of the abnormal tumour vasculature that can, in turn, increase the infiltration of immune effector cells into tumours and convert the intrinsically immunosuppressive tumour microenvironment (TME) to an immunosupportive one. Immunotherapy relies on the accumulation and activity of immune effector cells within the TME, and immune responses and vascular normalization seem to be reciprocally regulated. Thus, combining antiangiogenic therapies and immunotherapies might increase the effectiveness of immunotherapy and diminish the risk of immune-related adverse effects. In this Perspective, we outline the roles of VEGF and ANG2 in tumour immune evasion and progression, and discuss the evidence indicating that antiangiogenic agents can normalize the TME. We also suggest ways that antiangiogenic agents can be combined with immune-checkpoint inhibitors to potentially improve patient outcomes, and highlight avenues of future research.

"Vessels in the Storm": Searching for Prognostic and Predictive Angiogenic Factors in Colorectal Cancer

High expectations are placed upon anti-angiogenic compounds for metastatic colorectal cancer (mCRC), the first malignancy for which such type of treatment has been approved. Indeed, clinical trials have confirmed that targeting the formation of new vessels can improve in many cases clinical outcomes of mCRC patients. However, current anti-angiogenic drugs are far from obtaining the desirable or expected curative results. Many are the factors probably involved in such disappointing results, but particular attention is currently focused on the validation of biomarkers able to improve the direction of treatment protocols. Because clinical studies have clearly demonstrated that serum or tissue concentration of some angiogenic factors is associated with the evolution of the disease of mCRC patients, they are currently explored as potential biomarkers of prognosis and of tumor response to therapy. However, the complex biology underlying CRC -induced angiogenesis is a hurdle in finding rapid solutions. The aim of this review was to explore molecular mechanisms that determine the formation of tumor-associated vessels during CRC progression, and to discuss the potential role of angiogenic factors as diagnostic, prognostic and predictive biomarkers in CRC.

Evaluation of short-term effectiveness of eight targeted agents combined with chemotherapy for treating esophageal-gastric junction adenocarcinoma: A network meta-analysis

This study aimed to evaluate the short-term effectiveness of eight targeted agents (ramucirumab, bevacizumab, rilotumumab, panitumumab, cetuximab, trebananib, trastuzumab, matuzumab) plus chemotherapy in esophageal-gastric junction adenocarcinoma (EGJA) by a network meta-analysis (NMA). PubMed, Embase, and Cochrane Library databases were systematically retrieved for randomized clinical trials (RCTs) concerning targeted agents plus chemotherapy in the treatment of EGJA. This NMA combined both direct and indirect evidence to evaluate odds ratio (OR) and to draw the surface under the cumulative ranking curve (SUCRA). In total 11 RCTs with 3649 EGJA patients (1907 patients treated with targeted agents plus chemotherapy were regarded as the case group, and 1742 patients with placebo plus chemotherapy were assigned into the control group) were enrolled in this study. Targeted agents in terms of stable disease (SD), partial response (PR), disease control rate (DCR), and overall response ratio (ORR) with the SUCRA values of 0.838, 0.807, 0.934, and 0.793, respectively. Cetuximab and trastuzumab, with the SUCRA values of 0.884 and 0.758, came on top as the best outcomes for treating EGJA in terms of progressive disease (PD) and complete response (CR). Cluster analysis results indicated that ramucirumab plus chemotherapy might be the optimal treatment for EGJA. Our findings indicated that ramucirumab plus chemotherapy might be the optimal treatment for EGJA amongst the nine treatment regimens, which provided clinical guidance for clinicians in the treatment of EGJA.

Peptibodies: An elegant solution for a long-standing problem

Chimeric proteins composed of a biologically active peptide and a fragment crystallizable (Fc) domain of immunoglobulin G (IgG) are known as peptibodies. They present an extended half-life due to neonatal Fc receptor (FcRn) salvage pathway, a decreased renal clearance rate owing to its increased size (≈70 kDa) and, depending on the peptide used in the design of the peptibody, an active-targeting moiety. Also, the peptides therapeutic activity is boosted by the number of peptides in the fusion protein (at least two peptides) and to some peptides' alterations. Peptibodies are mainly obtained through recombinant DNA technology. However, to improve peptide properties, "unnatural" changes have been introduced to the original peptides' sequence, for instance, the incorporation of D- or non-natural amino acid residues or even cyclization thus, limiting the application of genetic engineering in the production of peptibodies, since these peptides must be obtained via chemical synthesis. This constrains prompted the development of new methods for conjugation of peptides to Fc domains. Another challenge, subject of intense research, relates to the large-scale production of such peptibodies using these new techniques, which can be minimized by their proved value. To date, two peptibodies, romiplostim and dulaglutide, have been approved and stay as the standard of care in their areas of action. Furthermore, a considerable number of peptibodies are currently in preclinical and clinical development.

Phase 2 and biomarker study of trebananib, an angiopoietin-blocking peptibody, with and without bevacizumab for patients with recurrent glioblastoma

BACKGROUND

Angiopoietins contribute to tumor angiogenesis and may be upregulated as a compensatory factor after vascular endothelial growth factor (VEGF) blockade. The authors performed a phase 2 and biomarker study to evaluate trebananib, an angiopoietin 1 and angiopoietin 2 blocking peptibody, with and without bevacizumab in patients with recurrent glioblastoma.

METHODS

Forty-eight patients who had bevacizumab-naive, recurrent glioblastoma were treated with trebananib (30 mg/kg weekly) as single agent (n = 11) or combined with bevacizumab (n = 37). The primary endpoint was 6-month progression-free survival rate as determined by investigator review. Circulating biomarker levels were assessed before and after study therapy.

RESULTS

Trebananib was well tolerated as monotherapy and did not enhance bevacizumab-associated toxicity. Trebananib had no single-agent activity, and all treated patients exhibited progressive disease within 2 months. The 6-month progression-free survival rate for trebananib plus bevacizumab was 24.3% (95% confidence interval [CI], 12.1%-38.8%); whereas the median overall survival was 9.5 months (95% CI, 7.5-4.7 months), and the 12-month overall survival rate was 37.8% (95% CI, 22.6%-53.0%). Baseline and post-treatment changes in circulating vascular VEGF and interleukin-8 levels were correlated with survival among patients who received trebananib plus bevacizumab.

CONCLUSIONS

Angiopoietin 1 and angiopoietin 2 inhibition with trebananib was ineffective as monotherapy and did not enhance the ability of VEGF blockade with bevacizumab to improve the outcomes of patients with recurrent glioblastoma. Cancer 2018;124:1438-48. © 2017 American Cancer Society.

Efficacy and safety of FOLFIRI and biotherapy versus FOLFIRI alone for metastatic colorectal cancer patients: A meta-analysis

BACKGROUND

Previous randomized controlled trials (RCTs) and meta-analyses have demonstrated the useless of FOLFIRI alone for previously treated patients with metastatic colorectal cancer (mCRC). The role of FOLFIRI regimen combined with biological therapy is unknown. The purpose of this meta-analysis is to evaluate the efficacy and safety of combining biological therapy with chemotherapy in previously treated patients with mCRC.

METHODS

MEDLINE, EMBASE, Web of Science, Cochrane library, and ClinicalTrials.gov were searched. Eligible studies were RCTs that evaluated the efficacy and safety of the FOLFIRI regimen with or without biological therapy for previously treated patients with mCRC. The hazard ratio (HR) or risk ratio (RR) with 95% confidence interval was estimated. The Chi-squared and I-squared tests were used to assess the statistical heterogeneity.

RESULTS

The literature search identified 7 RCTs that met the inclusion criteria for the meta-analysis, and 3680 patients with mCRC were included. The meta-analysis showed that combined therapy was associated with a significant improved progression-free survival (PFS) (HR = 0.78, 95% CI = 0.72-0.85, P < .001), overall survival (OS) (HR = 0.84, 95% CI = 0.77-0.92, P < .001), and overall response rate (ORR) (RR = 1.70, 95% CI = 1.25-2.31, P = .001). Sensitivity analysis suggested that combined therapy versus FOLFIRI alone might increase the risk of Grade 3/4 AEs.

CONCLUSION

The addition of biological therapy to the FOLFIRI regimen improved the PFS, OS, and ORR compared with FOLFIRI alone for previously treated patients with mCRC. Long-term survival outcomes are warranted.

Angiopoietin-1 deficiency increases tumor metastasis in mice

Background

Angipoietin-1 activation of the tyrosine kinase receptor Tek expressed mainly on endothelial cells leads to survival and stabilization of endothelial cells. Studies have shown that Angiopoietin-1 counteracts permeability induced by a number of stimuli. Here, we test the hypothesis that loss of Angiopoietin-1/Tek signaling in the vasculature would increase metastasis.

Methods

Angiopoietin-1 was deleted in mice just before birth using floxed Angiopoietin-1 and Tek mice crossed to doxycycline-inducible bitransgenic ROSA-rtTA/tetO-Cre mice. By crossing Angiopoietin-1 knockout mice to the MMTV-PyMT autochthonous mouse breast cancer model, we investigated primary tumor growth and metastasis to the lung. Furthermore, we utilized B16F10 melanoma cells subcutaneous and experimental lung metastasis models in Angiopoietin-1 and Tek knockout mice.

Results

We found that primary tumor growth in MMTV-PyMT mice was unaffected, while metastasis to the lung was significantly increased in Angiopoietin-1 knockout MMTV-PyMT mice. In addition, angiopoietin-1 deficient mice exhibited a significant increase in lung metastasis of B16F10 melanoma cells, compared to wild type mice 3 weeks after injection. Additional experiments showed that this was likely an early event due to increased attachment or extravasation of tumor cells, since seeding of tumor cells was significantly increased 4 and 24 h post tail vein injection. Finally, using inducible Tek knockout mice, we showed a significant increase in tumor cell seeding to the lung, suggesting that Angiopoietin-1/Tek signaling is important for vascular integrity to limit metastasis.

Conclusions

This study show that loss of the Angiopoietin-1/Tek vascular growth factor system leads to increased metastasis without affecting primary tumor growth.

Surrogate Endpoints in Second-Line Trials of Targeted Agents in Metastatic Colorectal Cancer: A Literature-Based Systematic Review and Meta-Analysis

PURPOSE

The purpose of this study was to evaluate progression-free survival (PFS) and objective response rate (ORR) as surrogate endpoints of overall survival (OS) in modern clinical trials investigating the efficacy of targeted agents in the second-line treatment of metastatic colorectal cancer (mCRC).

MATERIALS AND METHODS

A systematic search of literature pertaining to randomized phase II and III trials evaluating targeted agents as second-line treatments for mCRC was performed. The strength of the correlation between both PFS and ORR and OS was assessed based on the Pearson's correlation coefficient (R) and the coefficient of determination (R2).

RESULTS

Twenty trials, including a total of 7,571 patients, met the search criteria. The median duration of post-progression survival (PPS) was 7.6 months. The median differences between experimental and control arms were 0.65 months (range, -2.4 to 3.4) for the median PFS and 0.7 months (range, -5.8 to 3.9) for the median OS. PFS and ORR showed moderate (R=0.734, R2=0.539, p < 0.001) and poor correlation (R=0.169, R2=0.029, p=0.476) with OS, respectively. No differences between anti-angiogenic agents and other drugs were evident.

CONCLUSION

Targeted agents investigated in the second-line treatment of mCRC provided minimal PFS gains translating into modest OS improvements. Considering both the moderate correlation between PFS and OS and the short duration of PPS, the OS should remain the preferred primary endpoint for randomized clinical trials in the second-line treatment of mCRC.

A Pharmacokinetic and Safety Study of Trebananib, an Fc-Fusion Peptibody, in Patients With Advanced Solid Tumors and Varying Degrees of Renal Dysfunction

Clearance of trebananib (AMG 386), a 64-kD antiangiogenic peptibody, has been associated with estimated glomerular filtration rate (eGFR). We prospectively evaluated trebananib pharmacokinetics and safety/tolerability in advanced solid tumor patients with varying degrees of renal function. Patients were assigned to normal renal function, mild, moderate, or severe renal dysfunction cohorts based on eGFR, received trebananib 15 mg/kg i.v. weekly, and underwent week 1 and week 5 pharmacokinetic and weekly safety assessments. For 28 patients, trebananib clearance decreased from normal renal function (1.52 mL/hr/kg), to mild (1.20 mL/hr/kg), moderate (0.79 mL/hr/kg), and severe (0.53 mL/hr/kg) renal dysfunction (P ≤ 0.001). Treatment-related adverse events showed no association with clearance. Trebananib clearance was proportional to eGFR and unrelated to pretreatment protein excretion. These data confirm a role for renal clearance of a recombinant peptibody with molecular weight <69 kD and support a longer dosing interval for patients with severe renal dysfunction.

Angiogenesis inhibition in the second-line treatment of metastatic colorectal cancer: A systematic review and pooled analysis

The last two decades have seen intensive efforts devoted to the development of compounds that target angiogenesis for the treatment of metastatic colorectal cancer (mCRC). In this review, we describe supporting evidence and ongoing development of angiogenesis inhibitors in the second-line treatment of mCRC, and summarize relevant randomized trials to help therapeutic decision-making in daily practice.

Second-line systemic therapy for metastatic colorectal cancer

BACKGROUND

The therapeutic management of people with metastatic colorectal cancer (CRC) who did not respond to first-line treatment represents a formidable challenge.

OBJECTIVES

To determine the efficacy and toxicity of second-line systemic therapy in people with metastatic CRC.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library 2016, Issue 4), Ovid MEDLINE (1950 to May 2016), Ovid MEDLINE In-process & Other Non-Indexed Citations (1946 to May 2016) and Ovid Embase (1974 to May 2016). There were no language or date of publication restrictions.

SELECTION CRITERIA

Randomized controlled trials (RCTs) assessing the efficacy (survival, tumour response) and toxicity (incidence of severe adverse effects (SAEs)) of second-line systemic therapy (single or combined treatment with any anticancer drug, at any dose and number of cycles) in people with metastatic CRC that progressed, recurred or did not respond to first-line systemic therapy.

DATA COLLECTION AND ANALYSIS

Authors performed a descriptive analysis of each included RCT in terms of primary (survival) and secondary (tumour response, toxicity) endpoints. In the light of the variety of drug regimens tested in the included trials, we could carry out meta-analysis considering classes of (rather than single) anticancer regimens; to this aim, we applied the random-effects model to pool the data. We used hazard ratios (HRs) and risk ratios (RRs) to describe the strength of the association for survival (overall (OS) and progression-free survival (PFS)) and dichotomous (overall response rate (ORR) and SAE rate) data, respectively, with 95% confidence intervals (CI).

MAIN RESULTS

Thirty-four RCTs (enrolling 13,787 participants) fulfilled the eligibility criteria. Available evidence enabled us to address multiple clinical issues regarding the survival effects of second-line systemic therapy of people with metastatic CRC.1. Chemotherapy (irinotecan) was more effective than best supportive care (HR for OS: 0.58, 95% CI 0.43 to 0.80; 1 RCT; moderate-quality evidence); 2. modern chemotherapy (FOLFOX (5-fluorouracil plus leucovorin plus oxaliplatin), irinotecan) is more effective than outdated chemotherapy (5-fluorouracil) (HR for PFS: 0.59, 95% CI 0.49 to 0.73; 2 RCTs; high-quality evidence) (HR for OS: 0.69, 95% CI 0.51 to 0.94; 1 RCT; moderate-quality evidence); 3. irinotecan-based combinations were more effective than irinotecan alone (HR for PFS: 0.68, 95% CI 0.60 to 0.76; 6 RCTs; moderate-quality evidence); 4. targeted agents improved the efficacy of conventional chemotherapy both when considered together (HR for OS: 0.84, 95% CI 0.77 to 0.91; 6 RCTs; high-quality evidence) and when bevacizumab was used alone (HR for PFS: 0.67, 95% CI 0.60 to 0.75; 4 RCTs; high-quality evidence).With regard to secondary endpoints, tumour response rates generally paralleled the survival results; moreover, higher anticancer efficacy was generally associated with worse treatment-related toxicity, with the important exception of bevacizumab-containing regimens, where the addition of the targeted agent to chemotherapy did not result in a significant increase in the rate of SAE. Finally, we found that oral (instead of intravenous) fluoropyrimidines significantly reduced the incidence of adverse effects (without compromising efficacy) in people treated with oxaliplatin-based regimens.We could not draw any conclusions on other debated aspects in this field of oncology, such as ranking of treatments (not all possible comparisons have been tested and many comparisons were based on single trials enrolling a small number of participants) and quality of life (virtually no data available).

AUTHORS' CONCLUSIONS

Systemic therapy offers a survival benefit to people with metastatic CRC who did not respond to first-line treatment, especially when targeted agents are combined with conventional chemotherapeutic drugs. Further research is needed to define the optimal regimen and to identify people who most benefit from each treatment.

Molecular Pathways: Deciphering Mechanisms of Resistance to Macrophage-Targeted Therapies

Tumor-associated macrophages (TAMs) are a major cellular component of numerous tumor types. TAM-targeted therapies include depletion strategies, inhibiting their effector functions or reprogramming toward an antitumorigenic phenotype, with varying degrees of efficacy. Here, we review preclinical and clinical strategies to target macrophages in cancer and discuss potential explanations for why some strategies are effective while other approaches have shown limited success. Clin Cancer Res; 23(4); 876-84. ©2016 AACR.

Cancer Tills the Premetastatic Field: Mechanistic Basis and Clinical Implications

A growing body of work has shown that cancer metastasis is not a random spontaneous event; rather, it is the culmination of a cascade of priming steps through which a subpopulation of the tumor cells acquires invasive traits while readying a permissive environment, termed the "premetastatic niche," in which distant metastases can occur. Signals from the primary tumor mobilize and adapt immune cells as well as directly communicating with distant niche cells to induce a broad spectrum of adaptations in target organs, including the induction of angiogenesis, inflammation, extracellular matrix remodeling, and metabolic reprogramming. Together, these interactions facilitate the formation of a premetastatic niche composed of a variable mix of resident and recruited immune cells, endothelial cells, and stromal cells connected through a complex signaling network that we are only beginning to understand. Here, we summarize the latest findings on how cancer induces and guides the formation of this premetastatic niche as well as potential prognostic markers and therapeutic targets that may lead to a better understanding and effective treatment of metastatic disease. Clin Cancer Res; 22(15); 3725-33. ©2016 AACR.

A Phase I, First-in-Human Study of AMG 780, an Angiopoietin-1 and -2 Inhibitor, in Patients with Advanced Solid Tumors

PURPOSE

To assess the toxicity, pharmacokinetics, tumor vascular response, tumor response, and pharmacodynamics of AMG 780, a mAb designed to inhibit the interaction between angiopoietin-1 and -2 and the Tie2 receptor.

EXPERIMENTAL DESIGN

This was a phase I dose-escalation study of patients with advanced solid tumors refractory to standard treatment without previous antiangiogenic treatment. AMG 780 was administered by intravenous infusion every 2 weeks in doses from 0.1 to 30 mg/kg. The primary endpoints were incidences of dose-limiting toxicity (DLT) and adverse events (AE), and pharmacokinetics. Secondary endpoints included tumor response, changes in tumor volume and vascularity, and anti-AMG 780 antibody formation.

RESULTS

Forty-five patients were enrolled across nine dose cohorts. Three patients had DLTs (0.6, 10, and 30 mg/kg), none of which prevented dose escalation. At 30 mg/kg, no MTD was reached. Pharmacokinetics of AMG 780 were dose proportional; median terminal elimination half-life was 8 to 13 days. No anti-AMG 780 antibodies were detected. At week 5, 6 of 16 evaluable patients had a >20% decrease in volume transfer constant (K(trans)), suggesting reduced capillary blood flow/permeability. The most frequent AEs were hypoalbuminemia (33%), peripheral edema (29%), decreased appetite (27%), and fatigue (27%). Among 35 evaluable patients, none had an objective response; 8 achieved stable disease.

CONCLUSIONS

AMG 780 could be administered at doses up to 30 mg/kg every 2 weeks in patients with advanced solid tumors. AMG 780 treatment resulted in tumor vascular effects in some patients. AEs were in line with toxicity associated with antiangiopoietin treatment. Clin Cancer Res; 22(18); 4574-84. ©2016 AACR.

Novel anti-angiogenic therapeutic strategies in colorectal cancer

INTRODUCTION

Anti-angiogenetic agents are currently the standard of care in metastatic CRC patients. Bevacizumab, aflibercept, regorafenib and recently ramucirumab have significantly improved both progression-free and overall survival in different lines of treatment. Since bevacizumab's approval, a number of novel anti-VEGF agents have been tested in preclinical and clinical models.

AREAS COVERED

This review is focused on the most recent clinical results of novel agents targeting VEGF and its receptors with a major focus on those investigated recently in clinical trials.

EXPERT OPINION

In the last 15 years, a number of new anti-angiogenetic agents have been tested. Unfortunately, most of them have demonstrated unacceptable toxicities or failed to show activity. When tested as single agents, encouraging preliminary results were reported with fruquintinib, famitinib, and nintedanib. Interesting novel mechanisms of action are also being explored: VGX-100 is a monoclonal antibody (mAb) which binds to VEGF-C, inhibiting activation of VEGFR-2 and VEGFR-3 when combined with bevacizumab; tanibirumab is a mAb which binds to VEGFR-2 and vanucizumab is a bispecific mAb binding both to VEGF-A and Angiopoietin-2. Data about the combination of these agents with chemotherapy are very encouraging, even though preliminary. However, the definition of specific predictive biomarkers remains a priority.

Vasculotide reduces endothelial permeability and tumor cell extravasation in the absence of binding to or agonistic activation of Tie2

Angiopoietin-1 (Ang1) activation of Tie2 receptors on endothelial cells (ECs) reduces adhesion by tumor cells (TCs) and limits junctional permeability to TC diapedesis. We hypothesized that systemic therapy with Vasculotide (VT)—a purported Ang1 mimetic, Tie2 agonist—can reduce the extravasation of potentially metastatic circulating TCs by similarly stabilizing the host vasculature. In vitro, VT and Ang1 treatments impeded endothelial hypermeability and the transendothelial migration of MDA-MB-231•LM2-4 (breast), HT29 (colon), or SN12 (renal) cancer cells to varying degrees. In mice, VT treatment inhibited the transit of TCs through the pulmonary endothelium, but not the hepatic or lymphatic endothelium. In the in vivo LM2-4 model, VT monotherapy had no effect on primary tumors, but significantly delayed distant metastatic dissemination to the lungs. In the post-surgical adjuvant treatment setting, VT therapeutically complemented sunitinib therapy, an anti-angiogenic tyrosine kinase inhibitor which limited the local growth of residual disease. Unexpectedly, detailed investigations into the putative mechanism of action of VT revealed no evidence of Tie2 agonism or Tie2 binding; alternative mechanisms have yet to be determined.

Antiangiogenic agents in gynecological cancer: State of art and perspectives of clinical research

Vascular endothelial growth factor [VEGF] pathway, which plays a key role in angiogenesis, may be blocked by either extracellular interference with VEGF itself (bevacizumab [BEV] or aflibercept), or intracytoplasmic inhibition of VEGF receptor (pazopanib, nintedanib, cediranid, sunitinib and sorafenib). An alternative approach is represented by trebananib, a fusion protein that prevents the interaction of angiopoietin [Ang]-1 and Ang-2 with Tie2 receptor on vascular endothelium. The combination of antiangiogenic agents, especially BEV, and chemotherapy is a rational therapeutic option for primary or recurrent ovarian carcinoma. However, it will be difficult to accept that it represents the new standard treatment, until biological characterization of ovarian carcinoma has not identified subsets of tumors with different responsiveness to BEV. Anti-angiogenesis is an interesting target also for recurrent cervical or endometrial cancer, but nowadays the use of anti-angiogenic agents in these malignancies should be reserved to patients enrolled in clinical trials.

Pharmacokinetic drug-drug interaction assessment of peptibody trebananib in combination with chemotherapies

PURPOSE

To provide the first evaluation of pharmacokinetic (PK) drug-drug interactions (DDIs) between trebananib and chemotherapies across tumor types.

METHODS

PK data of trebananib and chemotherapies (paclitaxel, carboplatin, pegylated liposomal doxorubicin, topotecan, capecitabine, lapatinib, 5-FU, irinotecan, or docetaxel) were collected from trials of ovarian cancer, metastatic breast cancer, colorectal carcinoma, and mixed solid tumor. A dedicated PK DDI study of trebananib and paclitaxel in patients with mixed solid tumors was also conducted. The geometric least squares mean (GLSM) ratios and corresponding 90 % confidence intervals (CI) of C max and AUC were estimated for DDI evaluations.

RESULTS

In the PK DDI study of trebananib and paclitaxel, the GLSM ratio (90 % CI) was 1.17 (1.10-1.25) for paclitaxel AUC and 1.30 (1.15-1.48) for paclitaxel C max. The GLSM ratio (90 % CI) for the effect of paclitaxel on trebananib PK was 0.92 (0.87-0.97) for trebananib AUC and 0.98 (0.92-1.05) for trebananib C max. In the remaining studies, the GLSM ratios (90 % CI) of C max and AUC generally ranged from 0.8 to 1.25 or exhibited less than twofold PK variabilities across chemotherapeutic agents. No dose-dependent DDIs were evident.

CONCLUSIONS

No PK DDI was deemed clinically meaningful between trebananib and the tested chemotherapeutic agents to warrant dose adjustments.

Pharmacokinetic drug-drug interaction study of the angiopoietin-1/angiopoietin-2-inhibiting peptibody trebananib (AMG 386) and paclitaxel in patients with advanced solid tumors

BACKGROUND

Trebananib is an anti-angiogenic peptibody under investigation in patients with advanced cancer. This study evaluated the pharmacokinetic (PK) drug-drug interaction of paclitaxel and trebananib.

PATIENTS AND METHODS

Patients with advanced solid tumors received weekly 80 mg/m(2) intravenous (IV) paclitaxel (3 weeks on/1 week off) with weekly 15 mg/kg IV trebananib starting at Week 2. Blood samples for PK analysis were collected at Week 1 (paclitaxel alone), Week 6 (paclitaxel and trebananib), and Week 8 (trebananib alone). An absence of interaction was to be concluded if the 90 % confidence intervals (CI) for the differences in paclitaxel exposure fell within the 0.80-1.25 interval.

RESULTS

The primary study was conducted between 7/2012 and 10/2013. Thirty-five patients were enrolled and 34 received both treatments. Most patients were white (91 %) and female (59 %); mean age was 61 years. The most common tumor types were ovarian (32 %) and bladder (27 %), 71 % of patients had stage IV disease, and all had Eastern Cooperative Oncology Group (ECOG) scores of 0 or 1. PK parameter analysis was done on patients with evaluable PK data at both assessments (with and without concomitant therapy; n = 28). The geometric least squares mean (GLSM) ratio (90 % CI) of paclitaxel AUCinf with and without trebananib was 1.17 (1.10, 1.25). The GLSM ratio (90 % CI) of trebananib AUCtau,ss with and without paclitaxel was 0.92 (0.87, 0.97). The most common adverse events were fatigue, local edema, peripheral edema, and nausea.

CONCLUSIONS

This study showed no evidence of clinically meaningful PK interaction between paclitaxel and trebananib.

Advances in anti-angiogenic agents for ovarian cancer treatment: The role of trebananib (AMG 386)

Ovarian cancer is a multifaceted and genomically complex disease and has emerged as leading cause of death among gynecological malignancies. Gold-standard treatment consisted of cytoreductive surgery and paclitaxel-carboplatin chemotherapy. Recently, promising results of randomized trials have definitively confirmed the importance of angiogenesis in oncogenesis and ovarian cancer behavior, by showing a significant prolongation of progression-free survival with the addiction of an angiogenesis inhibitor to standard treatment in the first and second line setting. Research over the years has sequentially provided a rapidly broadening signaling landscape and many drugs targeting different signaling pathways of angiogenesis have been developed and investigated. Recently accumulating scientific evidence has started to shed light on the efficacy of AMG 386, a new peptibody reported to neutralize the interaction between angiopoietins (Ang1/2) and their Tie2 receptors, thus representing a promising alternative, both in terms of efficacy and toxicity profile and is considerably under investigation. The aim of this review is to summarize the recent researches and clinical progresses of AMG 386 as a novel target agent in ovarian cancer.

Surrogate endpoints in second-line treatment for mCRC: a systematic literature-based analysis from 23 randomised trials

PURPOSE

To evaluate progression-free survival (PFS), overall response rate (ORR) and disease control rate (DCR) as potential surrogate endpoints (SEP) for overall survival (OS) in second-line treatment for metastatic colorectal cancer (mCRC).

METHODS

A systematic literature search of randomised trials of second-line chemotherapy for mCRC reported from January 2000 to July 2013 was performed. Correlation coefficients weighted by number of patients in the treatment arms between median PFS, ORR and DCR with median OS were estimated.

RESULTS

Twenty-three trials reflecting 10 800 patients met the inclusion criteria. Median PFS and OS across all trials were 4.5 months and 11.5 months and median ORR and DCR were 11.4% and 65%, respectively. PFS showed moderate correlation with OS [RPFS = 0.73; 95% confidence interval (CI) 0.61-0.82]. In contrast, ORR only weakly correlated with OS (RORR = 0.58; 95% CI 0.38-0.72, n = 22). Despite a small number of studies (n = 10) reporting on DCR, moderate correlation with OS was observed (RDCR = 0.74; 95% CI 0.56-0.86).

CONCLUSION

Based on the available trial-level data, PFS may serve as an appropriate SEP in second-line chemotherapy for mCRC. A small number of studies revealed moderate correlation of DCR with OS that justifies further investigation.

Angiogenesis and antiangiogenic agents in cervical cancer

Standard treatment of cervical cancer (CC) consists of surgery in the early stages and of chemoradiation in locally advanced disease. Metastatic CC has a poor prognosis and is usually treated with palliative platinum-based chemotherapy. Current chemotherapeutic regimens are associated with significant adverse effects and only limited activity, making identification of active and tolerable novel targeted agents a high priority. Angiogenesis is a complex process that plays a crucial role in the development of many types of cancer. The dominant role of angiogenesis in CC seems to be directly related to human papillomavirus-related inhibition of p53 and stabilization of hypoxia-inducible factor-1α. Both of these mechanisms are able to increase expression of vascular endothelial growth factor (VEGF). Activation of VEGF promotes endothelial cell proliferation and migration, favoring formation of new blood vessels and increasing permeability of existing blood vessels. Since bevacizumab, a recombinant humanized monoclonal antibody binding to all isoforms of VEGF, has been demonstrated to significantly improve survival in gynecologic cancer, some recent clinical research has explored the possibility of using novel therapies directed toward inhibition of angiogenesis in CC too. Here we review the main results from studies concerning the use of antiangiogenic drugs that are being investigated for the treatment of CC.

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.

Role of angiopoietin-2 in adaptive tumor resistance to VEGF signaling blockade

Angiopoietin-2 (ANG2/ANGPT2) is a context-dependent TIE2 receptor agonist/antagonist and proangiogenic factor. Although ANG2 neutralization improves tumor angiogenesis and growth inhibition by vascular endothelial growth factor (VEGF)-A signaling blockade, the mechanistic underpinnings of such therapeutic benefits remain poorly explored. We employed late-stage RIP1-Tag2 pancreatic neuroendocrine tumors (PNETs) and MMTV-PyMT mammary adenocarcinomas, which develop resistance to VEGF receptor 2 (VEGFR2) blockade. We found that VEGFR2 inhibition upregulated ANG2 and vascular TIE2 and enhanced infiltration by TIE2-expressing macrophages in the PNETs. Dual ANG2/VEGFR2 blockade suppressed revascularization and progression in most of the PNETs, whereas it had only minor additive effects in the mammary tumors, which did not upregulate ANG2 upon VEGFR2 inhibition. ANG2/VEGFR2 blockade did not elicit increased PNET invasion and metastasis, although it exacerbated tumor hypoxia and hematopoietic cell infiltration. These findings suggest that evasive tumor resistance to anti-VEGFA therapy may involve the adaptive enforcement of ANG2-TIE2 signaling, which can be reversed by ANG2 neutralization.

A phase 1b, open-label study of trebananib in combination with paclitaxel and carboplatin in patients with ovarian cancer receiving interval or primary debulking surgery

AIM

To evaluate the tolerability, pharmacokinetics and tumour response of first-line trebananib plus paclitaxel and carboplatin followed by trebananib maintenance in high-risk or advanced ovarian cancer.

METHODS

In this open-label phase 1b study, patients received intravenous (IV) trebananib 15 mg/kg administered weekly (QW) plus paclitaxel 175 mg/m(2) once every 3 weeks (Q3W) and carboplatin 6 mg/mL · min Q3W followed by trebananib 15 mg/kg QW monotherapy for 18 months. End-points were dose-limiting toxicities (DLTs; primary); treatment-emergent adverse events (AEs), anti-trebananib antibodies, pharmacokinetics and tumour response (secondary).

RESULTS

Twenty seven patients (interval debulking surgery [IDS], n=13) were enrolled. No DLTs occurred. During the combination therapy phase, AEs (>50%) in patients with IDS were nausea, diarrhoea, fatigue, decreased appetite and thrombocytopenia. In patients with primary debulking surgery (PDS), they were nausea, diarrhoea, fatigue and localised oedema. Grade 4 AEs were neutropenia (IDS, PDS; all n=3) and thrombocytopenia (IDS, PDS; all n=1). No deaths occurred. Toxicity results pertaining to trebananib maintenance were immature. The treatment combination did not markedly affect the pharmacokinetics across agents. In patients with IDS (n=14 after one patient was reassigned from PDS to IDS), 12 patients had a partial response (PR), two patients had stable disease. In patients with PDS (n=4), three patients had a complete response, one patient had a PR.

CONCLUSIONS

In women with ovarian cancer receiving IDS or PDS, IV trebananib 15 mg/kg QW plus paclitaxel and carboplatin appears tolerable. Results suggest that the treatment combination followed by trebananib 15 mg/kg monotherapy is associated with antitumour activity.

A phase 1b study of trebananib in combination with pegylated liposomal doxorubicin or topotecan in women with recurrent platinum-resistant or partially platinum-sensitive ovarian cancer

OBJECTIVE

To examine the tolerability and antitumor activity of trebananib plus pegylated liposomal doxorubicin (PLD) or topotecan in recurrent platinum-resistant or partially platinum-sensitive ovarian cancer.

METHODS

In this open-label phase 1b study, patients received trebananib 10 mg/kg or 15 mg/kg IV QW plus PLD 50 mg/m(2) (cohorts A1 and A3, respectively) or topotecan 4 mg/m(2) (cohorts B1 and B3, respectively). Endpoints were dose-limiting toxicity (DLT; primary); treatment-emergent adverse events (AEs), overall response rate, anti-trebananib antibodies, and pharmacokinetics (secondary).

RESULTS

103 patients were enrolled. One patient in A1 and B1 had DLTs. Across all cohorts, the most common AEs were nausea, fatigue, and peripheral edema. Across both trebananib plus PLD cohorts (A1/A3), grade 4 AEs were pulmonary embolism, disease progression, and anemia. Two patients had grade 5 intestinal perforation (n=1) and sudden death (n=1). Across both trebananib plus topotecan cohorts (B1/B3), grade 4 AEs were neutropenia, hypokalemia, decreased granulocyte count, chest pain, dyspnea, decreased neutrophil count, and pulmonary embolism. Two patients had grade 5 disease progression. One patient had grade 5 pleural effusion associated with progressive disease. Confirmed objective response rates were 36.0% (A1), 34.8% (A3), 16.7% (B1), and 0.0% (B3). Median progression-free survival duration (months) was 7.4 (A1), 7.1 (A3), 3.5 (B1), and 3.1 (B3), respectively. No drug-drug interactions were apparent.

CONCLUSIONS

Trebananib 10mg/kg and 15 mg/kg IV QW plus PLD or topotecan appear to have acceptable toxicity profiles in recurrent platinum-resistant or partially platinum-sensitive ovarian cancer. Antitumor activity was evident across all cohorts.

Anti-angiopoietin therapy with trebananib for recurrent ovarian cancer (TRINOVA-1): a randomised, multicentre, double-blind, placebo-controlled phase 3 trial

BACKGROUND

Angiogenesis is a valid target in the treatment of epithelial ovarian cancer. Trebananib inhibits the binding of angiopoietins 1 and 2 to the Tie2 receptor, and thereby inhibits angiogenesis. We aimed to assess whether the addition of trebananib to single-agent weekly paclitaxel in patients with recurrent epithelial ovarian cancer improved progression-free survival.

METHODS

For this randomised, double-blind phase 3 study undertaken between Nov 10, 2010, and Nov 19, 2012, we enrolled women with recurrent epithelial ovarian cancer from 32 countries. Patient eligibility criteria included having been treated with three or fewer previous regimens, and a platinum-free interval of less than 12 months. We enrolled patients with a computerised interactive voice response system, and patients were randomly assigned using a permuted block method (block size of four) in a 1:1 ratio to receive weekly intravenous paclitaxel (80 mg/m(2)) plus either weekly masked intravenous placebo or trebananib (15 mg/kg). Patients were stratified on the basis of platinum-free interval (≥0 and ≤6 months vs >6 and ≤12 months), presence or absence of measurable disease, and region (North America, western Europe and Australia, or rest of world). The sponsor, investigators, site staff, and patients were masked to the treatment assignment. The primary endpoint was progression-free survival assessed in the intention-to-treat population. The trial is registered with ClinicalTrials.gov, NCT01204749, and is no longer accruing patients.

FINDINGS

919 patients were enrolled, of whom 461 were randomly assigned to the trebananib group and 458 to the placebo group. Median progression-free survival was significantly longer in the trebananib group than in the placebo group (7·2 months [5·8-7·4] vs 5·4 months [95% CI 4·3-5·5], respectively, hazard ratio 0·66, 95% CI 0·57-0·77, p<0·0001). Incidence of grade 3 or higher adverse events was similar between treatment groups (244 [54%] of 452 patients in the placebo group vs 258 [56%] of 461 patients in the trebananib group). Trebananib was associated with more adverse event-related treatment discontinuations than was placebo (77 [17%] patients vs 27 [6%], respectively) and higher incidences of oedema (294 [64%] patients had any-grade oedema in the trebananib group vs 127 [28%] patients in the placebo group). Grade 3 or higher adverse events included ascites (34 [8%] in the placebo group vs 52 [11%] in the trebananib group), neutropenia (40 [9%] vs 26 [6%]), and abdominal pain (21 [5%] vs 22 [5%]). We recorded serious adverse events in 125 (28%) patients in the placebo group and 159 (34%) patients in the trebananib group. There was a difference of 2% or less in class-specific adverse events associated with anti-VEGF therapy (hypertension, proteinuria, wound-healing complications, thrombotic events, gastrointestinal perforations), except bleeding, which was more common in the placebo group than in the trebananib group (75 [17%] vs 46 [10%]).

INTERPRETATION

Inhibition of angiopoietins 1 and 2 with trebananib provided a clinically meaningful prolongation in progression-free survival. This non-VEGF anti-angiogenesis option for women with recurrent epithelial ovarian cancer should be investigated in other settings and in combination with additional agents. Although oedema was increased, typical anti-VEGF associated adverse events were not prominent.

FUNDING

Amgen.

The role of angiopoietins as potential therapeutic targets in renal cell carcinoma

Angiopoietin 2 (Ang2) is a secreted glycoprotein upregulated at sites of angiogenesis and has been implicated in cancer neovascularization. Recent studies have suggested efficacy of combined Ang and vascular endothelial growth factor receptor (VEGFR) inhibition for patients with metastatic renal cell carcinoma (mRCC). We measured Ang2 expression in human tissue and plasma, and tested the effect of dual Ang1/2 (trebananib; AMG386) or Ang2 alone (L1-7) inhibition with VEGFR inhibition on murine RCC growth and blood flow. Ang2 levels were higher in human tumors than normal tissues with RCC ranking highest for Ang2 expression across all tumor types tested. Plasma Ang2 was significantly higher in patients with mRCC compared to controls or patients with stage I disease. Plasma Ang2 decreased with sunitinib treatment and increased at time of disease progression. In the RCC mouse, dual Ang1/2 and Ang2 inhibition improved the activity of sunitinib. Combined Ang1/2 and VEGFR inhibition prevented the resumption of blood flow associated with sunitinib resistance. Thus, Ang2 inhibition, independent of Ang1 inhibition, improves the activity of sunitinib and plasma Ang2 increases in the setting of progression on sunitinib possibly contributing to resistance. Further, arterial spin-labeled perfusion magnetic resonance imaging might be a non-invasive marker of the antiangiogenic activity of Ang inhibitors.

Monoclonal antibodies as therapeutics in human malignancies

ABSTRACT: 

Monoclonal antibodies (mAbs) are a proven effective therapeutic modality in human malignancy. Several mAbs are approved to targets critical in aberrant oncogenic signaling within tumors and their microenvironment. These targets include secreted ligands (e.g., VEGF and HGH), their receptors (e.g., HER2 and VEGFR2), cell surface counter receptors and their receptor-bound ligands (e.g., PD1 and PD1L, respectively). The ability to genetically engineer the structure and/or functions of mAbs has significantly improved their effectiveness. Furthermore, advances in gene expression profiling, proteomics, deep sequencing and deciphering of complex signaling networks have revealed novel therapeutic targets. We review target selection, approved indications and the rationale for mAb utilization in solid and hematologic malignancies. We also discuss novel mAbs in early- and late-phase clinical trials that are likely to change the natural history of disease and improve survival. The future challenge is to design mAb-based novel trial designs for diagnostics and therapeutics for human malignancies.