Tumor angiogenic and hypoxic profiles predict radiographic response and survival in malignant astrocytoma patients treated with bevacizumab and irinotecan

Abstract

Purpose: The combination of a vascular endothelial growth factor (VEGF) -neutralizing antibody, bevacizumab, and irinotecan is associated with high radiographic response rates and improved survival outcomes in patients with recurrent malignant gliomas. The aim of these retrospective studies was to evaluate tumor vascularity and expression of components of the VEGF pathway and hypoxic responses as predictive markers for radiographic response and survival benefit from the bevacizumab and irinotecan therapy.

Patients and methods: In a phase II trial, 60 patients with recurrent malignant astrocytomas were treated with bevacizumab and irinotecan. Tumor specimens collected at the time of diagnosis were available for further pathologic studies in 45 patients (75%). VEGF, VEGF receptor-2, CD31, hypoxia-inducible carbonic anhydrase 9 (CA9), and hypoxia-inducible factor-2alpha were semiquantitatively assessed by immunohistochemistry. Radiographic response and survival outcomes were correlated with these angiogenic and hypoxic markers.

Results: Of 45 patients, 27 patients had glioblastoma multiforme, and 18 patients had anaplastic astrocytoma. Twenty-six patients (58%) had at least partial radiographic response. High VEGF expression was associated with increased likelihood of radiographic response (P = .024) but not survival benefit. Survival analysis revealed that high CA9 expression was associated with poor survival outcome (P = .016).

Conclusion: In this patient cohort, tumor expression levels of VEGF, the molecular target of bevacizumab, were associated with radiographic response, and the upstream promoter of angiogenesis, hypoxia, determined survival outcome, as measured from treatment initiation. Validation in a larger clinical trial is warranted.

Conflict of interest statement

Authors' Disclosures Of Potential Conflicts Of Interest: Although all authors completed the disclosure declaration, the following author(s) indicated a financial or other interest that is relevant to the subject matter under consideration in this article. Certain relationships marked with a “U” are those for which no compensation was received; those relationships marked with a “C” were compensated. For a detailed description of the disclosure categories, or for more information about ASCO's conflict of interest policy, please refer to the Author Disclosure Declaration and the Disclosures of Potential Conflicts of Interest section in Information for Contributors.

Employment or Leadership Position: None Consultant or Advisory Role: None Stock Ownership: None Honoraria: None Research Funding: Henry S. Friedman, Genentech Expert Testimony: None Other Remuneration: None

Figures

Fig 1

Semiquantitative image analysis. Representative images used to establish the optimal positive threshold for each marker: (A) vascular endothelial growth factor (VEGF) positive; (B) VEGF negative; (C) carbonic anhydrase 9 (CA9) positive; and (D) CA9 negative.

Fig 2

Representative immunostaining detection of angiogenic/hypoxic markers. (A and B) Vascular endothelial growth factor (VEGF) in tumor cytoplasm and stroma. (C and D) Kinase insert domain-containing receptor (KDR) on endothelial and tumor cell membrane and cytoplasm. (E and F) CD31 on vascular endothelial cells (arrows). (G and H) Carbonic anhydrase 9 (CA9) on tumor cell membrane and cytoplasm, adjacent to necrotic area (*) and relatively distant from blood vessels (arrows). (I and J) Hypoxia-inducible factor-2α (HIF-2α) in tumor cell nuclei and cytoplasm in a geographic distribution similar to that of CA9 reactivity.

Fig 3

Kaplan-Meier survival curves stratified by biomarker status. (A) Survival stratified by carbonic anhydrase 9 (CA9) status. (B) Survival stratified by CA9 and hypoxia-inducible factor-2α (HIF-2) status.