Predictive value of angiogenic proteins in patients with metastatic melanoma treated with bevacizumab monotherapy

uPAR+ extracellular vesicles: a robust biomarker of resistance to checkpoint inhibitor immunotherapy in metastatic melanoma patients

Background

Emerging evidence has highlighted the importance of extracellular vesicle (EV)-based biomarkers of resistance to immunotherapy with checkpoint inhibitors in metastatic melanoma. Considering the tumor-promoting implications of urokinase-type plasminogen activator receptor (uPAR) signaling, this study aimed to assess uPAR expression in the plasma-derived EVs of patients with metastatic melanoma to determine its potential correlation with clinical outcomes.

Methods

Blood samples from 71 patients with metastatic melanoma were collected before initiating immunotherapy. Tumor-derived and immune cell-derived EVs were isolated and analyzed to assess the relative percentage of uPAR⁺ EVs. The associations between uPAR and clinical outcomes, sex, BRAF status, baseline lactate dehydrogenase levels and number of metastatic sites were assessed.

Results

Responders had a significantly lower percentage of tumor-derived, dendritic cell (DC)-derived and CD8⁺ T cell-derived uPAR +EVs at baseline than non-responders. The Kaplan-Meier survival curves for the uPAR⁺EV quartiles indicated that higher levels of melanoma-derived uPAR⁺ EVs were strongly correlated with poorer progression-free survival (p<0.0001) and overall survival (p<0.0001). We also found a statistically significant correlation between lower levels of uPAR⁺ EVs from both CD8⁺ T cells and DCs and better survival.

Conclusions

Our results indicate that higher levels of tumor-derived, DC-derived and CD8⁺ T cell-derived uPAR⁺ EVs in non-responders may represent a new biomarker of innate resistance to immunotherapy with checkpoint inhibitors. Moreover, uPAR⁺ EVs represent a new potential target for future therapeutic approaches.

Alternative Vascularization Mechanisms in Tumor Resistance to Therapy

Simple Summary

Tumors rely on blood vessels to grow and metastasize. Malignant tumors can employ different strategies to create a functional vascular network. Tumor cells can use normal processes of vessel formation but can also employ cancer-specific mechanisms, by co-opting normal vessels present in tissues or by turning themselves into vascular cells. These different types of tumor vessels have specific molecular and functional characteristics that profoundly affect tumor behavior and response to therapies, including drugs targeting the tumor vasculature (antiangiogenic therapies). In this review, we discuss how vessels formed by different mechanisms affect the intrinsic sensitivity of tumors to therapy and, on the other hand, how therapies can affect tumor vessel formation, leading to resistance to drugs, cancer recurrence, and treatment failure. Potential strategies to avoid vessel-mediated resistance to antineoplastic therapies will be discussed.

Abstract

Blood vessels in tumors are formed through a variety of different mechanisms, each generating vessels with peculiar structural, molecular, and functional properties. This heterogeneity has a major impact on tumor response or resistance to antineoplastic therapies and is now emerging as a promising target for strategies to prevent drug resistance and improve the distribution and efficacy of antineoplastic treatments. This review presents evidence of how different mechanisms of tumor vessel formation (vasculogenesis, glomeruloid proliferation, intussusceptive angiogenesis, vasculogenic mimicry, and vessel co-option) affect tumor responses to antiangiogenic and antineoplastic therapies, but also how therapies can promote alternative mechanisms of vessel formation, contributing to tumor recurrence, malignant progression, and acquired drug resistance. We discuss the possibility of tailoring treatment strategies to overcome vasculature-mediated drug resistance or to improve drug distribution and efficacy.

Activin A: an emerging target for improving cancer treatment?

INTRODUCTION

Activin A is involved in the regulation of a surprisingly broad number of processes that are relevant for cancer development and treatment; it is implicated in cell autonomous functions and multiple regulatory functions in the tumor microenvironment.

AREAS COVERED

This article summarizes the current knowledge about activin A in cell growth and death, migration and metastasis, angiogenesis, stemness and drug resistance, regulation of antitumor immunity, and cancer cachexia. We explore the role of activin A as a biomarker and discuss strategies for using it as target for cancer therapy. Literature retrieved from Medline until 25 June 2020 was considered.

EXPERT OPINION

While many functions of activin A were investigated in preclinical models, there is currently limited experience from clinical trials. Activin A has growth- and migration-promoting effects, contributes to immune evasion and cachexia and is associated with shorter survival in several cancer types. Targeting activin A could offer the chance to simultaneously limit tumor growth and spreading, improve drug response, boost antitumor immune responses and improve cancer-associated or treatment-associated cachexia, bone loss, and anemia. Nevertheless, defining which patients have the highest likelihood of benefiting from these effects is challenging and will require further work.

Activin A triggers angiogenesis via regulation of VEGFA and its overexpression is associated with poor prognosis of oral squamous cell carcinoma

Poor prognosis associated with the dysregulated expression of activin A in a number of malignancies has been related to with numerous aspects of tumorigenesis, including angiogenesis. The present study investigated the prognostic significance of activin A immunoexpression in blood vessels and cancer cells in a number of oral squamous cell carcinoma (OSCC) cases and applied in vitro strategies to determine the impact of activin A on angiogenesis. In a cohort of 95 patients with OSCC, immunoexpression of activin A in both blood vessels and tumor cells was quantified and the association with clinicopathological parameters and survival was analyzed. Effects of activin A on the tube formation, proliferation and migration of human umbilical vein endothelial cells (HUVECs) were evaluated in gain‑of‑function (treatment with recombinant activin A) or loss‑of‑function [treatment with activin A‑antagonist follistatin or by stable transfection with short hairpin RNA (shRNA) targeting activin A] conditions. Conditioned medium from an OSCC cell line with shRNA‑mediated depletion of activin A was also tested. The profile of pro‑ and anti‑angiogenic factors regulated by activin A was assessed with a human angiogenesis quantitative PCR (qPCR) array. Vascular endothelial growth factor A (VEGFA) and its major isoforms were evaluated by reverse transcription‑qPCR and ELISA. Activin A expression in blood vessels demonstrated an independent prognostic value in the multivariate analysis with a hazard ratio of 2.47 [95% confidence interval (CI), 1.30‑4.71; P=0.006) for disease‑specific survival and 2.09 (95% CI, 1.07‑4.08l: P=0.03) for disease‑free survival. Activin A significantly increased tubular formation of HUVECs concomitantly with an increase in proliferation. This effect was validated by reduced proliferation and tubular formation of HUVECs following inhibition of activin A by follistatin or shRNA, as well as by treatment of HUVECs with conditioned medium from activin A‑depleted OSCC cells. Activin A‑knockdown increased the migration of HUVECs. In addition, activin A stimulated the phosphorylation of SMAD2/3 and the expression and production of total VEGFA, significantly enhancing the expression of its pro‑angiogenic isoform 121. The present findings suggest that activin A is a predictor of the prognosis of patients with OSCC, and provide evidence that activin A, in an autocrine and paracrine manner, may contribute to OSCC angiogenesis through differential expression of the isoform 121 of VEGFA.

Treatment patterns of malignant melanoma in the United States from 2011 to 2016: a retrospective cohort study

Background: Since 2011, the approval of several new agents has improved treatment options for malignant melanoma. We describe treatment patterns for malignant melanoma in the United States from the MarketScan database from 2011 to 2016.Methods: Treatments used for patients aged >18 years diagnosed with malignant melanoma after January 1, 2011 and enrolled in the Truven MarketScan database were analyzed. Patient data were collected for the 12-month period from the date of the first melanoma diagnosis to either death, the pre-specified study end date (August 31, 2016), or date of termination of health insurance. Treatment patterns from 2011-2013 and 2014-2016 were analyzed according to agent, year of drug administration, and line of therapy.Results: From 2011 to 2016, use of cytokines (63.8; 13.3%) and chemotherapy (19.6; 12.9%) decreased, and use of checkpoint inhibitors increased (2.0; 49.9%). Checkpoint inhibitor use also increased across all lines of therapy from 2011-2013 and 2014-2016. Use of BRAF/MEK inhibitors remained relatively stable from 2011 to 2016 (6.5-12.5%); however, the use of vemurafenib monotherapy decreased (6.5; 0.8%), and treatment with combination regimens increased (0; 10.9%) from 2011-2016. BRAF/MEK inhibitor use only increased in the first line setting from 2011-2013 (9.7%) to 2014-2016 (11.2%).Conclusion: With the approval of immune checkpoint inhibitors, BRAF/MEK inhibitors, and targeted therapies, the therapeutic landscape for the treatment of metastatic melanoma has shifted dramatically away from cytokines and chemotherapy. Treatment patterns will likely continue to evolve as scientific advances are made.

ctDNA detected by ddPCR reveals changes in tumour load in metastatic malignant melanoma treated with bevacizumab

Bevacizumab is included in an increasing number of clinical trials. To find biomarkers to predict and monitor treatment response, cancer and angiogenesis relevant mutations in tumour and circulating tumour DNA (ctDNA) were investigated in 26 metastatic melanoma patients treated with bevacizumab. Patients with >1% BRAF/NRAS ctDNA at treatment start had significantly decreased progression free survival (PFS) and overall survival (OS) (PFS: p = 0.019, median 54 vs 774 days, OS: p = 0.026, median 209 vs 1064 days). Patients with >1% BRAF/NRAS ctDNA during treatment showed similar results (PFS: p = 0.002, OS: p = 0.003). ≤1% BRAF/NRAS ctDNA and normal lactate dehydrogenase (LDH) levels both significantly predicted increased response to treatment, but BRAF/NRAS ctDNA was better at predicting response compared to LDH at treatment start (OR 16.94, p = 0.032 vs OR 4.57, p = 0.190), and at predicting PFS (HR 6.76, p = 0.002) and OS (HR 6.78, p = 0.002) during therapy. ctDNA BRAF p.V600D/E/K and NRAS p.G12V/p.Q61K/L/R were better biomarkers for response prediction than TERT promoter mutations (OR 1.50, p = 0.657). Next generation sequencing showed that all patients with ≥2 mutations in angiogenesis-relevant genes had progressive disease, but did not reveal other biomarkers identifying responders. To conclude, ctDNA and LDH are useful biomarkers for both monitoring and predicting response to bevacizumab.

Whole genome and biomarker analysis of patients with recurrent glioblastoma on bevacizumab: A subset analysis of the CABARET trial

The CABARET trial (ACTRN12610000915055) reported no difference in overall survival (OS) between patients with recurrent glioblastoma (GBM) randomized to either bevacizumab monotherapy or bevacizumab plus carboplatin. However, a subset of patients showed durable responses and prolonged survival, with recorded survival times of over 30 months in five of 122 patients (4%). Patient selection for bevacizumab therapy would be enhanced if a predictive biomarker of response or survival could be identified; this biomarker sub-study attempted to identify novel biomarkers. Patients who opted to participate in this sub-study and who had adequate biospecimens for analysis (n = 54) were retrospectively evaluated for the expression of a series of tumor proteins. Immunohistochemistry (IHC) was used to measure the expression of 19 proteins previously implicated in cancer treatment response to bevacizumab. MGMT promoter methylation was also assessed. Tumor DNA from five patients with outlying survival duration ('poor' and 'exceptional' survivors) was subjected to whole genome sequencing (WGS). No single protein expression level, including VEGF-A, predicted OS in the cohort. WGS of poor and exceptional survivors identified a gain in Chromosome 19 that was exclusive to the exceptional survivors. Validation of this finding requires examination of a larger independent cohort.