Angiopoietin-2 May Be Involved in the Resistance to Bevacizumab in Recurrent Glioblastoma

Interleukin 6 and cancer resistance in glioblastoma multiforme

Despite unprecedented survival in patients with glioblastoma (GB), the aggressive primary brain cancer remains largely incurable and its mechanisms of treatment resistance have gained particular attention. The cytokine interleukin 6 (IL-6) and its receptor weave through the hallmarks of malignant gliomas and may represent a key vulnerability to GB. Known for activating the STAT3 pathway in autocrine fashion, IL-6 is amplified in GB and has been recognized as a negative biomarker for GB prognosis, rendering it a putative target of novel GB therapies. While it has been recognized as a biologically active component of GB for three decades only with concurrent advances in understanding of complementary immunotherapy has the concept of targeting IL-6 for a human clinical trial gained scientific footing.

Aqueous Humor Cytokine Analysis in Age-Related Macular Degeneration After Switching From Aflibercept to Faricimab

Purpose

To examine the changes in aqueous humor cytokine levels and clinical outcomes of switching from aflibercept to faricimab in eyes with neovascular age-related macular degeneration (nAMD).

Methods

Fifty-four eyes of 54 patients with AMD undergoing treatment with aflibercept under a treat-and-extend (TAE) regimen were switched to faricimab and studied prospectively. Best-corrected visual acuity (BCVA; in logarithm of the minimum angle of resolution), central retinal thickness (CRT), central choroidal thickness (CCT), and exudative status were analyzed using optical coherence tomography. Aqueous humor was collected before and after the switch, and angiopoietin-2 (Ang-2), placental growth factor (PlGF), and vascular endothelial growth factor (VEGF) A levels were measured.

Results

After switching from aflibercept to faricimab, exudative changes improved in 28 eyes (52%), remained stable in eight eyes (15%), and worsened in 18 eyes (33%). BCVA changed from 0.27 ± 0.31 to 0.26 ± 0.29 (P = 0.46), CRT decreased from 306.2 ± 147.5 µm to 278.6 ± 100.4 µm (P = 0.11), and CCT changed from 189.5 ± 92.8 µm to 186.8 ± 93.9 µm (P = 0.21). VEGF-A levels were below the detection sensitivity in many cases throughout the pre- and post-switching periods. Ang-2 significantly decreased from 23.8 ± 23.5 pg/mL to 16.4 ± 21.9 pg/mL (P < 0.001), and PlGF significantly increased from 0.86 ± 0.85 pg/mL to 1.72 ± 1.39 pg/mL (P < 0.001).

Conclusions

Switching from aflibercept to faricimab in patients with nAMD may not only suppress VEGF-A but also Ang-2 and reduce exudative changes.

A new perspective on antiangiogenic antibody drug resistance: Biomarkers, mechanisms, and strategies in malignancies

Drug resistance of malignant tumor leads to disease progression be the bottleneck in clinical treatment. Antiangiogenic therapy, which aims to "starve" the tumor by inhibiting angiogenesis, is one of the key strategies in clinical oncology treatments. Recently, dozens of investigational antibody drugs and biosimilars targeting angiogenesis have obtained regulatory approval for the treatment of various malignancies. Moreover, a new generation of bispecific antibodies based on the principle of antiangiogenesis are being advanced for clinical trial to overcome antiangiogenic resistance in tumor treatment or enhance the efficacy of monotherapy. Tumors often develop resistance to antiangiogenesis therapy, presenting as refractory and sometimes even resistant to new therapies, for which there are currently no effective management strategies. Thus, a detailed understanding of the mechanisms mediating resistance to antiangiogenesis antibodies is crucial for improving drug effectiveness and achieving a durable response to antiangiogenic therapy. In this review, we provide a novel perspective on the tumor microenvironment, including antibody structure, tumor stroma, and changes within tumor cells, to analyze the multifactorial reasons underlying resistance to antiangiogenesis antibodies. The review also enumerates biomarkers that indicate resistance and potential strategies for monitoring resistance. Furthermore, based on recent clinical and preclinical studies, we summarize potential strategies and translational clinical trials aimed at overcoming resistance to antiangiogenesis antibodies. This review provides a valuable reference for researchers and clinical practitioners involved in the development of new drugs or therapeutic strategies to overcome antiangiogenesis antibodies resistance.

Identification of established and novel extracellular matrix components in glioblastoma as targets for angiogenesis and prognosis

Glioblastomas (GBM) are aggressive tumors known for their heterogeneity, rapid proliferation, treatment resistance, and extensive vasculature. Angiogenesis, the formation of new vessels, involves endothelial cell (EC) migration and proliferation. Various extracellular matrix (ECM) molecules regulate EC survival, migration, and proliferation. Culturing human brain EC (HBMEC) on GBM-derived ECM revealed a decrease in EC numbers compared to controls. Through in silico analysis, we explored ECM gene expression differences between GBM and brain normal glia cells and the impact of GBM microenvironment on EC ECM transcripts. ECM molecules such as collagen alpha chains (COL4A1, COL4A2, p < 0.0001); laminin alpha (LAMA4), beta (LAMB2), and gamma (LAMC1) chains (p < 0.0005); neurocan (NCAN), brevican (BCAN) and versican (VCAN) (p < 0.0005); hyaluronan synthase (HAS) 2 and metalloprotease (MMP) 2 (p < 0.005); MMP inhibitors (TIMP1-4, p < 0.0005), transforming growth factor beta-1 (TGFB1) and integrin alpha (ITGA3/5) (p < 0.05) and beta (ITGB1, p < 0.0005) chains showed increased expression in GBM. Additionally, GBM-influenced EC exhibited elevated expression of COL5A3, COL6A1, COL22A1 and COL27A1 (p < 0.01); LAMA1, LAMB1 (p < 0.001); fibulins (FBLN1/2, p < 0.01); MMP9, HAS1, ITGA3, TGFB1, and wingless-related integration site 9B (WNT9B) (p < 0.01) compared to normal EC. Some of these molecules: COL5A1/3, COL6A1, COL22/27A1, FBLN1/2, ITGA3/5, ITGB1 and LAMA1/B1 (p < 0.01); NCAN, HAS1, MMP2/9, TIMP1/2 and TGFB1 (p < 0.05) correlated with GBM patient survival. In conclusion, this study identified both established and novel ECM molecules regulating GBM angiogenesis, suggesting NCAN and COL27A1 are new potential prognostic biomarkers for GBM.

REGOMA-OSS: a large, Italian, multicenter, prospective, observational study evaluating the efficacy and safety of regorafenib in patients with recurrent glioblastoma

BACKGROUND

In the randomized phase II REGOMA trial, regorafenib showed promising activity in patients with recurrent glioblastoma. We conducted a large, multicenter, prospective, observational study to confirm the REGOMA data in a real-world setting.

PATIENTS AND METHODS

The major inclusion criteria were histologically confirmed diagnosis of glioblastoma according to the World Health Organization (WHO) 2016 classification and relapse after radiotherapy with concurrent/adjuvant temozolomide treatment, good performance status [Eastern Cooperative Oncology Group performance status (ECOG PS 0-1)] and good liver function. Regorafenib was administered at the standard dose of 160 mg/day for 3 weeks on/1 week off. Brain magnetic resonance imaging was carried out within 14 days before starting regorafenib and every 8-12 weeks. The primary endpoint was overall survival (OS). The secondary endpoints were progression-free survival (PFS), objective response rate, disease control rate (DCR), safety and health-related quality of life. The Response Assessment in Neuro-Oncology (RANO) criteria were used for response evaluation and Common Terminology Criteria for Adverse Events (CTCAE) version 5 for assessment of adverse events (AEs).

RESULTS

From September 2020 to October 2022, 190 patients with recurrent glioblastoma were enrolled from 30 cancer centers in Italy: their median age was 58.5 years [interquartile range (IQR) 53-67 years], 68% were male and 85 (44.7%) were in optimal clinical condition (ECOG PS 0). The number of patients taking steroids at baseline was 113 (60%); the second surgery was carried out in 39 (20.5%). O6-methylguanine-DNA methyltransferase (MGMT) was methylated in 80 patients (50.3%) and 147 (92.4%) of the patients analyzed had isocitrate dehydrogenase (IDH) wild type. The median follow-up period was 20 months (IQR 15.6-25.5 months). The median OS was 7.9 months ([95% confidence interval (CI) 6.5-9.2 months] and the median PFS was 2.6 months (95% CI 2.3-2.9 months). Radiological response was partial response and stable disease in 13 (7.3%) and 26 (14.6%) patients, respectively, with a DCR of 21.9%. The median number of regorafenib cycles per patient was 3 (IQR 2.0-4.0). Grade 3-4 drug-related adverse events were reported in 22.6% of patients. A dose reduction due to AEs was required in 36% of patients. No deaths were considered as treatment-related AEs.

CONCLUSIONS

This large, real-world observational study showed similar OS with better tolerability of regorafenib in patients with relapsed glioblastoma compared with the REGOMA study.

The strange Microenvironment of Glioblastoma

Glioblastoma (GB) is the most common and aggressive primary brain tumor, with poor patient survival and lack of effective therapies. Late advances trying to decipher the composition of the GB tumor microenvironment (TME) emphasized its role in tumor progression and potentialized it as a therapeutic target. Many components participate critically to tumor development and expansion such as blood vessels, immune cells or components of the nervous system. Dysmorphic tumor vasculature brings challenges to optimal delivery of cytotoxic agents currently used in clinics. Also, massive infiltration of immunosuppressive myeloid cells and limited recruitment of T cells limits the success of conventional immunotherapies. Neuronal input seems also be required for tumor expansion. In this review, we provide a comprehensive report of vascular and immune component of the GB TME and their cross talk during GB progression.

Functional Graphene for Peritumoral Brain Microenvironment Modulation Therapy in Glioblastoma

Peritumoral brain invasion is the main target to cure glioblastoma. Chemoradiotherapy and targeted therapies fail to combat peritumoral relapse. Brain inaccessibility and tumor heterogeneity explain this failure, combined with overlooking the peritumor microenvironment. Reduce graphene oxide (rGO) provides a unique opportunity to modulate the local brain microenvironment. Multimodal graphene impacts are reported on glioblastoma cells in vitro but fail when translated in vivo because of low diffusion. This issue is solved by developing a new rGO formulation involving ultramixing during the functionalization with polyethyleneimine (PEI) leading to the formation of highly water-stable rGO-PEI. Wide mice brain diffusion and biocompatibility are demonstrated. Using an invasive GL261 model, an anti-invasive effect is observed. A major unexpected modification of the peritumoral area is also observed with the neutralization of gliosis. In vitro, mechanistic investigations are performed using primary astrocytes and cytokine array. The result suggests that direct contact of rGO-PEI_UT neutralizes astrogliosis, decreasing several proinflammatory cytokines that would explain a bystander tumor anti-invasive effect. rGO also significantly downregulates several proinvasive/protumoral cytokines at the tumor cell level. The results open the way to a new microenvironment anti-invasive nanotherapy using a new graphene nanomaterial that is optimized for in vivo brain delivery.

An agonistic anti-Tie2 antibody suppresses the normal-to-tumor vascular transition in the glioblastoma invasion zone

Tumor progression is intimately associated with the vasculature, as tumor proliferation induces angiogenesis and tumor cells metastasize to distant organs via blood vessels. However, whether tumor invasion is associated with blood vessels remains unknown. As glioblastoma (GBM) is featured by aggressive invasion and vascular abnormalities, we characterized the onset of vascular remodeling in the diffuse tumor infiltrating zone by establishing new spontaneous GBM models with robust invasion capacity. Normal brain vessels underwent a gradual transition to severely impaired tumor vessels at the GBM periphery over several days. Increasing vasodilation from the tumor periphery to the tumor core was also found in human GBM. The levels of vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2) showed a spatial correlation with the extent of vascular abnormalities spanning the tumor-invading zone. Blockade of VEGFR2 suppressed vascular remodeling at the tumor periphery, confirming the role of VEGF-VEGFR2 signaling in the invasion-associated vascular transition. As angiopoietin-2 (ANGPT2) was expressed in only a portion of the central tumor vessels, we developed a ligand-independent tunica interna endothelial cell kinase 2 (Tie2)-activating antibody that can result in Tie2 phosphorylation in vivo. This agonistic anti-Tie2 antibody effectively normalized the vasculature in both the tumor periphery and tumor center, similar to the effects of VEGFR2 blockade. Mechanistically, this antibody-based Tie2 activation induced VE-PTP-mediated VEGFR2 dephosphorylation in vivo. Thus, our study reveals that the normal-to-tumor vascular transition is spatiotemporally associated with GBM invasion and may be controlled by Tie2 activation via a novel mechanism of action.

Baseline Ang-2 Serum Levels as a Predictive Factor for Survival in NSCLC and SCLC

Angiopoietin-2 (Ang-2) has been implicated in the development of several types of cancer, including lung malignancy. In the present study, we examined the impact of Ang-2 serum concentration on the development, dissemination, and 5-year overall survival of NSCLC and SCLC. A total of 99 patients with lung cancer were tested. The OS of NSCLC and SCLC patients was estimated using Kaplan−Meier curves and compared through log-rank test. The median serum level of Ang-2 at baseline in both NSCLC and SCLC patients was significantly higher than that of controls (p < 0.0001). The Ang-2 serum concentration was not related to metastasis, neither in NSCLC nor in SCLC cases. The OS was found to be significantly shorter for stage IIIβ NSCLC patients with a high baseline Ang-2 serum concentration (p = 0.012), while Cox regression analysis showed that Ang-2 is a significant independent factor for poor prognosis for stage IIIβ NSCLC (hazard ratio = 2.97, 95% CI: 1.05−8.40, p = 0.04). The concentration of Ang-2 has no impact on the prognosis of SCLC. Ang-2 could be considered as a significant molecular marker that enables the prediction of NSCLC and SCLC development, and is involved in the poor prognosis of stage IIIβ NSCLC.

Wnt and PI3K/Akt/mTOR Survival Pathways as Therapeutic Targets in Glioblastoma

Glioblastoma (GBM) is a devastating type of brain tumor, and current therapeutic treatments, including surgery, chemotherapy, and radiation, are palliative at best. The design of effective and targeted chemotherapeutic strategies for the treatment of GBM require a thorough analysis of specific signaling pathways to identify those serving as drivers of GBM progression and invasion. The Wnt/β-catenin and PI3K/Akt/mTOR (PAM) signaling pathways are key regulators of important biological functions that include cell proliferation, epithelial–mesenchymal transition (EMT), metabolism, and angiogenesis. Targeting specific regulatory components of the Wnt/β-catenin and PAM pathways has the potential to disrupt critical brain tumor cell functions to achieve critical advancements in alternative GBM treatment strategies to enhance the survival rate of GBM patients. In this review, we emphasize the importance of the Wnt/β-catenin and PAM pathways for GBM invasion into brain tissue and explore their potential as therapeutic targets.

Efficacy and safety of bevacizumab in the treatment of adult gliomas: a systematic review and meta-analysis

OBJECTIVE

To assess the efficacy and safety of bevacizumab (BEV) in patients with glioma.

DESIGN

Systematic review and meta-analysis.

PARTICIPANTS

Adults aged 18 years and above, whose histology was confirmed to be malignant glioma.

PRIMARY AND SECONDARY OUTCOME MEASURES

The main indicators included progression-free survival (PFS) rate and overall survival (OS) rate, and the secondary indicators were adverse reactions.

RESULTS

A total of 11 clinical centre trials were included in this study for meta-analysis, including 2392 patients. The results of the meta-analysis showed that the median PFS rate of the BEV group was significantly higher than that of the non-BEV group (p<0.00001). When comparing PFS between two groups, we found that the PFS in the BEV group was higher than that in the non-BEV group at 6 months (OR 3.31, 95% CI 2.74 to 4.00, p<0.00001), 12 months (OR 2.05, 95% CI 1.70 to 2.49, p<0.00001) and 18 months (OR 1.31, 95% CI 1.02 to 1.69, p=0.03). But at 24 months (OR 0.83, 95% CI 0.50 to 1.37, p=0.47), there was no significant difference between the two groups. At 30 months (OR 0.62, 95% CI 0.39 to 0.97, p=0.04), the PFS of the BEV group was lower than that of the non-BEV group. Moreover, The results showed that BEV had no significant effect on improving OS, but the adverse reaction in BEV group was significantly higher than that in non-BEV group.

CONCLUSION

The evidence suggests that BEV can significantly prolong the PFS of patients with glioma within 18 months and shorten the PFS of patients after 30 months. This limitation may be related to the subgroup of patients, the change of recurrence mode, the optimal dose of drug, the increase of hypoxia, the enhancement of invasiveness and so on. Therefore, it is necessary to carry out more samples and higher quality large-scale research in the future.

Systemic counterregulatory response of angiopoietin-2 after aflibercept therapy for nAMD: a potential escape mechanism

Purpose

To analyse the effect of intravitreal aflibercept injections on systemic angiopoietin‐2 (Ang2) and vascular endothelial growth factor (VEGF)‐A levels in patients with neovascular age‐related macular degeneration (nAMD).

Methods

In a prospective, randomized study, aflibercept (2.0 mg/50 µl) or ranibizumab (0.5 mg/50 µl) was administered intravitreally to 38 treatment‐naive patients. Blood samples were taken before, 7 days after, and 28 days after the first intravitreal therapy. Cytokine levels were measured by enzyme‐linked immunosorbent assay. Twenty‐two age‐ and sex‐matched individuals served as controls.

Results

At baseline, there were no significant differences of systemic Ang2 and VEGF‐A levels among the treatment and control groups. After intravitreal aflibercept administration, median (interquartile range: IQR) systemic Ang2 was significantly upregulated from 1819 pg/ml (1262–3099) to 2123 pg/ml (1441–3769; p = 0.011) 7 days after the drug injection and remained non‐significantly elevated at 1944 pg/ml (1431–2546 pg/ml; p = 0.653) 28 days after the drug injection. Median (IQR) systemic VEGF‐A levels were significantly reduced from 43 pg/ml (30–57) to 8 pg/ml (8–8; p < 0.0001) 7 days and 16 pg/ml (8–26; p = 0.001) 28 days after the injection in the aflibercept group. There were no significant effects on systemic VEGF‐A and Ang2 levels in the ranibizumab group at any time point following the first injection.

Conclusion

In this study, we report significant systemic upregulation of Ang2 after intravitreal aflibercept administration. This counterregulatory response may represent a potential escape mechanism from antiangiogenic therapy.

Blood-Based Biomarkers for Glioma in the Context of Gliomagenesis: A Systematic Review

BACKGROUND

Gliomas are the most common and aggressive tumors of the central nervous system. A robust and widely used blood-based biomarker for glioma has not yet been identified. In recent years, a plethora of new research on blood-based biomarkers for glial tumors has been published. In this review, we question which molecules, including proteins, nucleic acids, circulating cells, and metabolomics, are most promising blood-based biomarkers for glioma diagnosis, prognosis, monitoring and other purposes, and align them to the seminal processes of cancer.

METHODS

The Pubmed and Embase databases were systematically searched. Biomarkers were categorized in the identified biomolecules and biosources. Biomarker characteristics were assessed using the area under the curve (AUC), accuracy, sensitivity and/or specificity values and the degree of statistical significance among the assessed clinical groups was reported.

RESULTS

7,919 references were identified: 3,596 in PubMed and 4,323 in Embase. Following screening of titles, abstracts and availability of full-text, 262 articles were included in the final systematic review. Panels of multiple biomarkers together consistently reached AUCs >0.8 and accuracies >80% for various purposes but especially for diagnostics. The accuracy of single biomarkers, consisting of only one measurement, was far more variable, but single microRNAs and proteins are generally more promising as compared to other biomarker types.

CONCLUSION

Panels of microRNAs and proteins are most promising biomarkers, while single biomarkers such as GFAP, IL-10 and individual miRNAs also hold promise. It is possible that panels are more accurate once these are involved in different, complementary cancer-related molecular pathways, because not all pathways may be dysregulated in cancer patients. As biomarkers seem to be increasingly dysregulated in patients with short survival, higher tumor grades and more pathological tumor types, it can be hypothesized that more pathways are dysregulated as the degree of malignancy of the glial tumor increases. Despite, none of the biomarkers found in the literature search seem to be currently ready for clinical implementation, and most of the studies report only preliminary application of the identified biomarkers. Hence, large-scale validation of currently identified and potential novel biomarkers to show clinical utility is warranted.

Angiopoietin-2 Combined with Radiochemotherapy Impedes Glioblastoma Recurrence by Acting in an Autocrine and Paracrine Manner: A Preclinical Study

Simple Summary

Glioblastoma (GB) is a highly aggressive brain tumor characterized by poor prognosis and high rate of recurrence in response to conventional treatments consisting of tumor resection and radiochemotherapy (RCT). The reasons for this therapeutic failure are mainly due to the complexity of GB biology and its environment. GB progression is highly dependent on its vascularization and inflammatory status. Besides, evidence showed that RCT also induces vascular change and inflammation. In GB patients, Angiopoietin-2 (Ang2), biomarker of poor prognosis is a crucial angiogenic factor also involved in inflammation. Our aim was to clarify the role of Ang2 in RCT-induced changes in the GB environment. To this end, we generated Ang2-overexpressing GL261 cells and characterized tumor progression, as well as inflammation and vascularization, in response to RCT. We showed that Ang2 delays tumor recurrence and makes a lasting improvement in animal survival when combined with conventional RCT.

Abstract

(1) We wanted to assess the impact of Ang2 in RCT-induced changes in the environment of glioblastoma. (2) The effect of Ang2 overexpression in tumor cells was studied in the GL261 syngeneic immunocompetent model of GB in response to fractionated RCT. (3) We showed that RCT combined with Ang2 led to tumor clearance for the GL261-Ang2 group by acting on the tumor cells as well as on both vascular and immune compartments. (4) In vitro, Ang2 overexpression in GL261 cells exposed to RCT promoted senescence and induced robust genomic instability, leading to mitotic death. (5) Coculture experiments of GL261-Ang2 cells with RAW 264.7 cells resulted in a significant increase in macrophage migration, which was abrogated by the addition of soluble Tie2 receptor. (6) Together, these preclinical results showed that, combined with RCT, Ang2 acted in an autocrine manner by increasing GB cell senescence and in a paracrine manner by acting on the innate immune system while modulating the vascular tumor compartment. On this preclinical model, we found that an ectopic expression of Ang2 combined with RCT impedes tumor recurrence.

Increased epithelial membrane protein 2 expression in glioblastoma after treatment with bevacizumab

Background

Antiangiogenic therapy with bevacizumab has failed to provide substantial gains in overall survival. Epithelial membrane protein 2 (EMP2) is a cell surface protein that has been previously shown to be expressed in glioblastoma, correlate with poor survival, and regulate neoangiogenesis in cell lines. Thus, the relationship between bevacizumab and EMP2 was investigated.

Methods

Tumor samples were obtained from 12 patients with newly diagnosed glioblastoma at 2 time points: (1) during the initial surgery and (2) during a subsequent surgery following disease recurrence post-bevacizumab treatment. Clinical characteristics and survival data from these patients were collected, and tumor samples were stained for EMP2 expression. The IVY Glioblastoma Atlas Project database was used to evaluate EMP2 expression levels in 270 samples by differing histological areas of the tumor.

Results

Patients with high EMP2 staining at initial diagnosis had decreased progression-free and overall survival after bevacizumab (median progression-free survival 4.6 months vs 5.9 months; log-rank P = .076 and overall survival 7.7 months vs 14.4 months; log-rank P = .011). There was increased EMP2 staining in samples obtained after bevacizumab treatment in both unpaired (mean H-score 2.31 vs 1.76; P = .006) and paired analyses (mean difference 0.571; P = .019). This expression increase correlated with length of bevacizumab therapy (R ²  = 0.449; Pearson P = .024).

Conclusions

Bevacizumab treatment increased EMP2 protein expression. This increase in EMP2 correlated with reduced mean survival time post-bevacizumab therapy. We hypothesize a role of EMP2 in clinical bevacizumab resistance and as a potential antiangiogenic therapeutic target in glioblastoma.

Blood Biomarkers of Glioma in Response Assessment Including Pseudoprogression and Other Treatment Effects: A Systematic Review

Imaging-based monitoring of disease burden in glioma patients is frequently confounded by treatment effects. Circulating biomarkers could theoretically augment imaging-based response monitoring. This systematic review aimed to present and evaluate evidence for differential expression and diagnostic accuracy of circulating biomarkers with respect to outcomes of tumor response, progression, stable disease, and treatment effects (pseudoprogression, radionecrosis, pseudoresponse, and pseudolesions) in patients undergoing treatment for World Health Organization grades II-IV diffuse astrocytic and oligodendroglial tumors. MEDLINE, EMBASE, Web Of Science, and SCOPUS databases were searched until August 18, 2019, for observational or diagnostic studies on multiple circulating biomarker types: extracellular vesicles, circulating nucleic acids, circulating tumor cells, circulating proteins, and metabolites, angiogenesis related cells, immune cells, and other cell lines. Methodological quality of included studies was assessed using an adapted Quality Assessment of Diagnostic Accuracy Studies-2 tool, and level of evidence (IA-IVD) for individual biomarkers was evaluated using an adapted framework from the National Comprehensive Cancer Network guidelines on evaluating tumor marker utility. Of 13,202 unique records, 58 studies met the inclusion criteria. One hundred thirty-three distinct biomarkers were identified in a total of 1,853 patients across various treatment modalities. Fifteen markers for response, progression, or stable disease and five markers for pseudoprogression or radionecrosis reached level IB. No biomarkers reached level IA. Only five studies contained data for diagnostic accuracy measures. Overall methodological quality of included studies was low. While extensive data on biomarker dysregulation in varying response categories were reported, no biomarkers ready for clinical application were identified. Further assay refinement and evaluation in larger cohorts with diagnostic accuracy study designs are required. PROSPERO Registration: CRD42018110658.

Adverse Events of Concurrent Immune Checkpoint Inhibitors and Antiangiogenic Agents: A Systematic Review

Background: Immune checkpoint blockade has revolutionized the treatment of multiple malignancies. Currently, however, the effect is not universal, with objective response rates (ORR) of about 15–25%, and even lower for some cancers. Abnormal vasculature is a hallmark of most solid tumors and plays a role in immune evasion. Growing body of evidence suggests that vascular normalization and immune reprogramming could operate synergistic effect, resulting in an enhanced therapeutic efficacy. However, the benefit of antitumor efficacy must be weighed against the risk of added toxicity. In this systematic review, we summarize severe toxicity observed in such a kind of combination regimen.

Methods: PubMed and Embase were searched for English references published up to May 31, 2019, with MeSH and keywords search terms of immune checkpoint inhibitors (ICIs) and antiangiogenic agents approved for using in solid tumors. Studies performing concomitant use of ICIs and antiangiogenic agents, and also reporting severe treatment-related adverse events (trAEs) (≥grade 3), were included for further analysis.

Results: A total of 32 studies including a total of 2,324 participants were analyzed. Limited available data suggests that both antiangiogenic monoclonal antibodies (mAbs) and tyrosine kinase inhibitors (TKIs) show potential risk of increasing treatment-related toxicity when combined with ICIs. Overall, the total incidence of severe adverse events (AEs) associated with ICIs plus mAbs (44.5%) is lower than that of ICIs plus TKIs (60.1%). However, the trAEs observed in combination therapy are mostly consistent with the known safety profiles of corresponding monotherapy, and they seem to be largely related to antiangiogenic agents, rather than a true immune-related adverse event (irAE) predominantly due to ICIs. The majority of trAEs are intervened by holding ICI treatment and adding corticosteroids, as well as reducing dose or adjusting administration frequency of the antiangiogenic drugs.

Conclusions: Concurrent use of ICIs and antiangiogenic agents shows potential treatment-related toxicity. Further research is required to compare the efficacy and safety of the combination regimen and corresponding monotherapy and identify predictive biomarkers, as well as explore dose, duration, and sequencing schedules of drugs.

The evolving role of antiangiogenic therapies in glioblastoma multiforme: current clinical significance and future potential

Introduction: Glioblastoma multiforme (GBM) is the most common primary malignant brain tumor in adults, but its prognosis remains poor despite significant advances in our understanding of its molecular biology and investigation of numerous treatment modalities. Despite conventional treatment consisting of surgical resection, radiotherapy, and temozolomide marginally prolonging survival, most GBM patients die within 2 years of initial diagnosis. Bevacizumab (Bev) is the best-studied antiangiogenic agent for GBM and currently the only FDA-approved second-line treatment. Areas covered: Areas covered in this review include the molecular pathways of angiogenesis in glioblastoma, specifically the overexpression of vascular endothelial growth factor (VEGF) and robust formation of tumor neovasculature. In addition, this review covers pharmacological targeting of this process as a longstanding attractive clinical strategy, specifically by Bev. Expert opinion: This review attempts to discuss the history of early studies of antiangiogenic treatment for GBM that eventually failed in subsequent studies and the evolving modern role of Bev in the course of treatment for a variety of indications, including symptom control, reduced glucocorticoid use, and improved quality of life.

Differential Effects of Ang-2/VEGF-A Inhibiting Antibodies in Combination with Radio- or Chemotherapy in Glioma

Antiangiogenic strategies have not shown striking antitumor activities in the majority of glioma patients so far. It is unclear which antiangiogenic combination regimen with standard therapy is most effective. Therefore, we compared anti-VEGF-A, anti-Ang2, and bispecific anti-Ang-2/VEGF-A antibody treatments, alone and in combination with radio- or temozolomide (TMZ) chemotherapy, in a malignant glioma model using multiparameter two-photon in vivo microscopy in mice. We demonstrate that anti-Ang-2/VEGF-A lead to the strongest vascular changes, including vascular normalization, both as monotherapy and when combined with chemotherapy. The latter was accompanied by the most effective chemotherapy-induced death of cancer cells and diminished tumor growth. This was most probably due to a better tumor distribution of the drug, decreased tumor cell motility, and decreased formation of resistance-associated tumor microtubes. Remarkably, all these parameters where reverted when radiotherapy was chosen as combination partner for anti-Ang-2/VEGF-A. In contrast, the best combination partner for radiotherapy was anti-VEGF-A. In conclusion, while TMZ chemotherapy benefits most from combination with anti-Ang-2/VEGF-A, radiotherapy does from anti-VEGF-A. The findings imply that uninformed combination regimens of antiangiogenic and cytotoxic therapies should be avoided.

IL-8 and thrombospondin-1 as prognostic markers in patients with metastatic colorectal cancer receiving bevacizumab

Purpose

Bevacizumab (B) plus chemotherapy (CT) is a common choice for first-line treatment of metastatic colorectal cancer. Molecular predictors of B efficacy have still not been identified. We analyzed the role of 22 angiogenesis-associated proteins in patient outcome.

Patients and methods

Serum samples collected at baseline and at the first clinical evaluation were available for 58 patients enrolled in the randomized multicenter ITACa trial and who received CT+ B. Serum protein levels were determined using multiplex ELISA.

Results

Patients with baseline ≥145 pg/mL IL-8 showed shorter median progression-free survival and overall survival (OS) than those with lower levels (6.5 vs 6. 12.6 months; HR 7.39, P<0.0001 and 8.7 vs 28.8 months, HR 7.68, P<0.001, respectively). Moreover, patients with baseline thrombospondin-1 levels ≥12,000 ng/mL had a better median OS than those with lower levels (34.5 vs 13.1 months, HR 0.43, P=0.007). Patients with a ≥20% reduction in IL-8 levels from baseline to first clinical evaluation showed a better progression-free survival and OS than the others (HR 0.41, P=0.005 and HR 0.43, P=0.007, respectively).

Conclusion

Baseline IL-8 and thrombospondin-1 levels and reduced IL-8 during B treatment could represent potential prognostic markers in metastatic colorectal cancer.

The role of interleukin-6-STAT3 signalling in glioblastoma

Glioblastoma is the most common type of malignant brain tumor among adults and is currently a non-curable disease due primarily to its highly invasive phenotype, and the lack of successful current therapies. Despite surgical resection and post-surgical treatment patients ultimately develop recurrence of the tumour. Several signalling molecules have been implicated in the development, progression and aggressiveness of glioblastoma. The present study reviewed the role of interleukin (IL)-6, a cytokine known to be important in activating several pro-oncogenic signaling pathways in glioblastoma. The current study particularly focused on the contribution of IL-6 in recurrent glioblastoma, with particular focus on glioblastoma stem cells and resistance to therapy.

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.

Identification of COL4A1 as a potential gene conferring trastuzumab resistance in gastric cancer based on bioinformatics analysis

Trastuzumab, the first targeted antibody against human epidermal growth factor receptor 2 (HER2), has been used to treat gastric cancer patients with HER2 overexpression. However, trastuzumab resistance often occurs following an initial period of benefits, and the underlying mechanisms remain largely unclear. The present study revealed that collagen type IV α1 chain (COL4A1), whose expression is upregulated in gastric cancer tissues and trastuzumab-resistant gastric cancer cells, may potentially confer trastuzumab resistance in gastric cancer. By performing bioinformatics analysis of 2 microarray datasets, the present study initially identified COL4A1, overexpressed in gastric cancer tissues and trastuzumab-resistant gastric cancer cells, as a potential candidate for inducing trastuzumab resistance. The drug resistance function of COL4A1 in gastric cancer was then validated by performing protein/gene interactions and biological process annotation analyses, and further validated by analyzing the functionality of microRNAs that target COL4A1 mRNA. Collectively, these data indicated that COL4A1 may confer trastuzumab resistance in gastric cancer.

IL-8 associates with a pro-angiogenic and mesenchymal subtype in glioblastoma

Glioblastoma (GBM) is a highly aggressive brain tumor characterized by a high rate of vascularization. However, therapeutic targeting of the vasculature through anti-vascular endothelial growth factor (VEGF) treatment has been disappointing, for which Angiopoietin-2 (Ang-2) upregulation has partly been held accountable. In this study we therefore explored the interplay of Ang-2 and VEGFA and their effect on angiogenesis in GBM, especially in the context of molecular subclasses. In a large patient cohort we identified that especially combined high expression of Ang-2 and VEGFA predicted poor overall survival of GBM patients. The high expression of both factors was also associated with increased IL-8 expression in GBM tissues, but in vitro stimulation with Ang-2 and/or VEGFA did not indicate tumor or endothelial cell-specific IL-8 responses. Glioblastoma stem cells (GSCs) of the mesenchymal (MES) subtype showed dramatically higher expression of IL8 when compared to proneural (PN) GSCs. Secreted IL-8 derived from MES GSCs induced endothelial proliferation and tube formation, and the MES GBMs had increased counts of proliferating endothelial cells. Our results highlight a critical pro-angiogenic role of IL-8 in MES GBMs.

Inhibition of VEGF-dependent angiogenesis and tumor angiogenesis by an optimized antibody targeting CLEC14a

The C‐type lectin‐like domain of CLEC14a (CLEC14a‐C‐type lectin‐like domain [CTLD]) is a key domain that mediates endothelial cell–cell contacts in angiogenesis. However, the role of CLEC14a‐CTLD in pathological angiogenesis has not yet been clearly elucidated. In this study, through complementarity‐determining region grafting, consecutive deglycosylation, and functional isolation, we generated a novel anti‐angiogenic human monoclonal antibody that specifically targets CLEC14a‐CTLD and that shows improved stability and homogeneity relative to the parental antibody. We found that this antibody directly inhibits CLEC14a‐CTLD‐mediated endothelial cell–cell contact and simultaneously downregulates expression of CLEC14a on the surface of endothelial cells. Using various in vitro and in vivo functional assays, we demonstrated that this antibody effectively suppresses vascular endothelial growth factor (VEGF)‐dependent angiogenesis and tumor angiogenesis of SNU182 human hepatocellular carcinoma, CFPAC‐1 human pancreatic cancer, and U87 human glioma cells. Furthermore, we also found that this antibody significantly inhibits tumor angiogenesis of HCT116 and bevacizumab‐adapted HCT116 human colorectal cancer cells. These findings suggest that antibody targeting of CLEC14a‐CTLD has the potential to suppress VEGF‐dependent angiogenesis and tumor angiogenesis and that CLEC14a‐CTLD may be a novel anti‐angiogenic target for VEGF‐dependent angiogenesis and tumor angiogenesis.

Bevacizumab in temozolomide refractory high-grade gliomas: single-centre experience and review of the literature

Background

Despite multidisciplinary treatment approaches, the prognosis for patients with high-grade glioma (HGG) is poor, with a median overall survival (OS) of 14.6 months for glioblastoma multiforme (GB). As high levels of vascular endothelial growth factor A (VEGF) are found in HGG, targeted anti-antiangiogenic therapy using the humanized monoclonal antibody bevacizumab (BEV) was studied in a series of clinical trials. Still, the discrepancy of BEV's efficacy with regard to initial clinical and radiological response and its reported failure to prolong survival remains to be explained. Here, we illustrate the effectiveness of BEV in recurrent HGG by summarizing our single-centre experience.

Methods

We have retrospectively investigated the effect of BEV in temozolomide refractory HGG in 39 patients treated at the University Hospital of Ulm, Germany.

Results

Median duration of BEV treatment was 12.5 weeks; 23% of patients received BEV for more than 6 months and 15% for more than 1 year, until clinical or radiological tumour progression led to discontinuation. Furthermore, Karnofsky performance status increased in 30.6% and steroid dose decreased in 39% of all patients.

Conclusions

The review of literature reveals that phase II and III studies support BEV as an effective therapy in recurrent HGG, at least with regard to progression-free survival (PFS), but landmark phase III trials failed to prove benefit concerning OS. Here, we discuss reasons that may account for this observation. We conclude that prolonging PFS with maintenance of neurological function and personal and economic independency justifies the off-label use of BEV.

Bevacizumab Injection in Patients with Neovascular Age-Related Macular Degeneration Increases Angiogenic Biomarkers

Purpose

To evaluate the expression of 19 angiogenic biomarkers in the aqueous humor before and after intravitreal bevacizumab injection (IVB) in eyes with neovascular age-related macular degeneration (AMD).

Design

Prospective, noncomparative, interventional case series.

Participants

Twenty-three eyes of 23 treatment-naïve patients with choroidal neovascularization (CNV) secondary to neovascular AMD.

Methods

Eyes were diagnosed with CNV secondary to neovascular AMD and were treated with 3 monthly IVBs. Aqueous humor samples were obtained by anterior chamber paracentesis at baseline and immediately before each intravitreal bevacizumab injection.

Main Outcome Measures

Aqueous humor levels of 19 angiogenic biomarkers (angiopoietin 2, bone morphogenetic protein 9 [BMP-9], epidermal growth factor [EGF], endoglin, endothelin 1, fibroblast growth factor [FGF]-1 and FGF-2, follistatin, granulocyte colony-stimulating factor [GCSF], heparin-binding EGF-like growth factor [HB-EGF], hepatocyte growth factor [HGF], interleukin 8, leptin, placental growth factor [PLGF], vascular endothelial growth factor [VEGF]-A, VEGF-C, VEGF-D, and tissue inhibitor of metalloproteinases [TIMP]-1 and TIMP-2) were measured. Best-corrected visual acuity (BCVA), spectral-domain OCT parameters, and intraocular pressure also were evaluated.

Results

Baseline aqueous VEGF-A expression was elevated in all study eyes before treatment initiation. A statistically significant decrease of VEGF-A was observed at the 1- and 2-month follow-ups. A statistically significant increased concentration was observed in 7 biomarkers: VEGF-C, angiopoietin 2, endothelin 1, follistatin, HB-EGF, HGF, and interleukin 8. The other 11 study biomarker levels (VEGF-D, BMP-9, EGF, endoglin, FGF-1, FGF-2, GCSF, leptin, PLGF, TIMP-1, and TIMP-2) did not show any significant difference during follow-up. The BCVA statistically improved significantly at 2 months. Spectral-domain OCT parameters improved significantly at all follow-ups. Mean intraocular pressure values were not statistically different during the study period.

Conclusions

Despite a decrease in VEGF-A, the aqueous levels of VEGF-C, angiopoietin 2, endothelin 1, follistatin, HB-EGF, HGF, and interleukin 8 increased significantly after intravitreal injection of bevacizumab. These upregulated angiogenic biomarkers may represent new therapeutic targets in exudative AMD.

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.

Bevacizumab for malignant gliomas: current indications, mechanisms of action and resistance, and markers of response

Vascular endothelial growth factor (VEGF) is an attractive target of antiangiogenic therapy in glioblastomas. Bevacizumab (Bev), a humanized anti-VEGF antibody, is associated with the improvement of progression-free survival and performance status in patients with glioblastoma. However, randomized trials uniformly suggest that these favorable clinical effects of Bev do not translate into an overall survival benefit. The mechanisms of action of Bev appear to include the inhibition of tumor angiogenesis, as well as indirect effects such as the depletion of niches for glioma stem cells and stimulation of antitumor immunity. Although several molecules/pathways have been reported to mediate adaptation and resistance to Bev, including the activation of alternative pro-angiogenic pathways, the resistance mechanisms have not been fully elucidated; for example, the mechanism that reinduces tumor hypoxia remains unclarified. The identification of imaging characteristics or biomarkers predicting the response to Bev, as well as the better understanding of the mechanisms of action and resistance, is crucial to improve the overall clinical outcome and optimize individual therapy. In this article, the authors review the results of important clinical trials/studies, the current understanding of the mechanisms of action and resistance, and the knowledge of imaging characteristics and biomarkers predicting the response to Bev.

Effectiveness of antiangiogenic drugs in glioblastoma patients: A systematic review and meta-analysis of randomized clinical trials

BACKGROUND

glioblastomas are highly vascularized tumors and various antiangiogenic drugs have been investigated in clinical trials showing unclear results. We performed a systematic review and a meta-analysis to clarify and evaluate their effectiveness in glioblastoma patients.

PATIENTS AND METHODS

we searched relevant published and unpublished randomized clinical trials analyzing antiangiogenic drugs versus chemotherapy in glioblastoma patients from January 2006 to January 2016 in MEDLINE, WEB of SCIENCE, ASCO, ESMO and SNO databases.

RESULTS

fourteen randomized clinical trials were identified (7 with bevacizumab, 2 cilengitide, 1 enzastaurin, 1 dasatinib, 1 vandetanib, 1 temsirolimus, 1 cediranib) including 4330 patients. Antiangiogenic drugs showed no improvement in overall survival with a pooled HR of 1.00, a trend for an inferior outcome, in terms of overall survival, was observed in the group of patients receiving antiangiogenic drug alone compared to cytotoxic drug alone (HR=1.24, p=0.056). Bevacizumab did not improve overall survival. Twelve trials (4113 patients) were analyzed for progression-free survival. Among antiangiogenic drugs, only bevacizumab demonstrated an improvement of progression-free survival (HR=0.63, p<0.001), both alone (HR=0.60, p=0.003) or in combination to chemotherapy (HR=0.63; p<0.001), both as first-line treatment (HR=0.70, p<0.001) or in recurrent disease (HR=0.52, p<0.001).

CONCLUSIONS

antiangiogenic drugs did not improve overall survival in glioblastoma patients, either as first or second-line treatment, and either as single agent or in combination with chemotherapy. Among antiangiogenic drugs, only bevacizumab improved progression-free survival regardless of treatment line, both as single agent or in combination with chemotherapy.