Biomarkers predicting tumor response and evasion to anti-angiogenic therapy
ABSTRACT No fully validated biological markers currently exist to predict responsiveness to or the development of evasion to anti-angiogenic therapy of cancer. The identification of such biomarkers is vital to move these therapies forward, as failure to respond to these treatments is often associated with rapid tumor progression that could have been averted had the intrinsic or acquired evasion to anti-angiogenic therapy been identified in a timely fashion. Furthermore, the high cost of antiangiogenic therapies makes it important to avoid utilizing them in the setting of lack of response or developing evasion, making the identification of biomarkers even more important. A number of potential physiologic, circulating, tissue, and imaging biomarkers have emerged from recently completed preclinical animal studies and clinical trials. In this review, we define 5 different types of biomarkers (physiologic, circulating, intratumoral, genetic polymorphisms, and radiographic); discuss the challenges in establishing biomarkers of antiangiogenic therapy in animal models and in clinical trials; and discuss future strategies to identify and validate biomarkers of anti-angiogenic therapy.
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ABSTRACT: The mechanistic dissociation of 'tumor starvation' versus 'vascular normalization' following anti-angiogenic therapy is a subject of intense controversy in the field of experimental research. In addition, accurately evaluating changes of the tumor microenvironment after anti-angiogenic therapy is important for optimizing treatment strategy. Sorafenib has considerable anti-angiogenic effects that lead to tumor starvation and induce tumor hypoxia in the highly vascularized renal cell carcinoma (RCC) xenografts. 18F-fluoromisonidazole (18F‑FMISO) is a proven hypoxia imaging probe. Thus, to clarify early changes in the tumor microenvironment following anti-angiogenic therapy and whether 18F-FMISO imaging can detect those changes, we evaluated early changes in the tumor microenvironment after sorafenib treatment in an RCC xenograft by sequential histological analysis and 18F-FMISO autoradiography (ARG). A human RCC xenograft (A498) was established in nude mice, for histological studies and ARG, and further assigned to the control and sorafenib-treated groups (80 mg/kg, per os). Mice were sacrificed on Days 1, 2, 3 and 7 in the histological study, and on Days 3 and 7 in ARG after sorafenib treatment. Tumor volume was measured every day. 18F-FMISO and pimonidazole were injected intravenously 4 and 2 h before sacrifice, respectively. Tumor sections were stained with hematoxylin and eosin and immunohistochemically with pimonidazole and CD31. Intratumoral 18F-FMISO distribution was quantified in ARG. Tumor volume did not significantly change on Day 7 after sorafenib treatment. In the histological study, hypoxic fraction significantly increased on Day 2, mean vessel density significantly decreased on Day 1 and necrosis area significantly increased on Day 2 after sorafenib treatment. Intratumoral 18F-FMISO distribution significantly increased on Days 3 (10.2-fold, p<0.01) and 7 (4.1-fold, p<0.01) after sorafenib treatment. The sequential histological evaluation of the tumor microenvironment clarified tumor starvation in A498 xenografts treated with sorafenib. 18F-FMISO hypoxia imaging confirmed the tumor starvation. 18F-FMISO PET may contribute to determine an optimum treatment protocol after anti-angiogenic therapy.International Journal of Oncology 09/2012; 41(5):1593-600. DOI:10.3892/ijo.2012.1624 · 3.03 Impact Factor
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ABSTRACT: Introduction Anti-VEGF treatment has proven effective in recurrent ovarian cancer. However, the identification of the patients most likely to respond is still pending. It is well known that the angiogenesis is regulated by several other pro-angiogenic proteins, e.g. the platelet - derived growth factor (PDGF) system and the fibroblast growth factor (FGF) system. These other signaling pathways may remain active or become upregulated during anti-VEGF treatment. The aim of the present study was to investigate if potential changes of PDGF-BB, PDGF-AA, and FGF2 before and during bevacizumab treatment had predictive value for early progression or survival. Furthermore, we wanted to investigate the importance of serum VEGF in the same cohort. Methods This study included 106 patients with chemotherapy-resistant epithelial ovarian cancer who were treated with single agent bevacizumab as part of a biomarker protocol. Patients were evaluated for response by the Response Evaluation Criteria In Solid Tumors (RECIST) and/ or Gynecologic Cancer Intergroup (GCIG) CA125 criteria. Serum samples were collected at baseline and prior to each treatment. FGF2, PDGF-BB, PDGF-AA were quantified simultaneously using the Luminex system, and VEGF-A was measured by ELISA. Eighty-eight baseline samples were avaliable for FGF2, PDGF-BB, PDGF-AA analysis, and 93 baseline samples for VEGF. Results High baseline serum VEGF was related to poor overall survival. Furthermore, high serum PDGF-BB and FGF2 was of prognostic significance. None of the markers showed predictive value, neither at baseline level nor during the treatment.Journal of Ovarian Research 09/2012; 5(1):23. DOI:10.1186/1757-2215-5-23 · 2.03 Impact Factor
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ABSTRACT: Introduction: Angiogenesis, for its fundamental role in cancer growth and metastasis, has become an appealing target in cancer therapy. A number of angiogenesis-related microRNAs (miRNAs) are under investigation and they can affect the cancerous phenotype of malignant cells. Areas covered: The authors review the recent advances in angiogenesis-related miRNAs in human colon cancer. They also envisage future developments toward potential miRNA-based applications to cancer treatment. Expert opinion: Angiogenesis-related miRNAs may reasonably be considered as a valuable cancer therapeutic tool. More investigations should be performed to promote therapeutic-clinical research of miRNAs in patients with colon cancer.Expert opinion on biological therapy 11/2012; 13(1). DOI:10.1517/14712598.2013.727391 · 3.65 Impact Factor