Abstract

No validated biological markers (or biomarkers) currently exist for appropriately selecting patients with cancer for antiangiogenic therapy. Nor are there biomarkers identifying escape pathways that should be targeted after tumors develop resistance to a given antiangiogenic agent. A number of potential systemic, circulating, tissue and imaging biomarkers have emerged from recently completed phase I–III studies. Some of these are measured at baseline (for example VEGF polymorphisms), others are measured during treatment (such as hypertension, MRI-measured K^trans, circulating angiogenic molecules or collagen IV), and all are mechanistically based. Some of these biomarkers might be pharmacodynamic (for example, increase in circulating VEGF, placental growth factor) while others have potential for predicting clinical benefit or identifying the escape pathways (for example, stromal-cell-derived factor 1, interleukin-6). Most biomarkers are disease and/or agent specific and all of them need to be validated prospectively. We discuss the current challenges in establishing biomarkers of antiangiogenic therapy, define systemic, circulating, tissue and imaging biomarkers and their advantages and disadvantages, and comment on the future opportunities for validating biomarkers of antiangiogenic therapy.

Author affiliations

1. Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
2. Division of Abdominal Imaging and Intervention, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
3. T. Gosnell Center for Gastrointestinal Cancers, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
4. Division of Hematology and Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
5. A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
6. Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA.

Correspondence to: R. K. Jain, Steele Laboratory, Department of Radiation Oncology, Massachusetts General Hospital, 100 Blossom Street, Cox-7, Boston, MA 02114, USA
Email: jain@steele.mgh.harvard.edu