Serum vascular endothelial growth factor and fibronectin predict clinical response to high-dose interleukin-2 therapy

Abstract

Purpose: High-dose interleukin-2 (IL-2) induces durable therapeutic responses in a small subset of patients with metastatic melanoma and renal cell carcinoma, but simple pretreatment predictors of response have not been identified.

Patients and methods: To identify predictive biomarkers of clinical response, sera from patients treated with high-dose IL-2 were collected for analysis using a customized, multiplex antibody-targeted protein array platform that surveyed expression of soluble factors associated with tumor immunobiology. Soluble factors associated with clinical responses were analyzed using a multivariate permutation test, and survival outcomes were determined using Kaplan-Meier and log-rank tests.

Results: A training set from 10 patients identified 68 potentially relevant soluble factors that were then tested in an independent validation set of 49 patients. Class comparison revealed a cluster of 11 biomarkers that were associated with therapeutic outcome. Vascular endothelial growth factor (VEGF) and fibronectin were identified as independent predictors of response. In particular, high levels of these proteins were correlated with lack of clinical response and decreased overall survival.

Conclusion: Serum VEGF and fibronectin are easily measured pretreatment biomarkers that could serve to exclude patients unlikely to respond to IL-2 therapy.

Conflict of interest statement

Authors' disclosures of potential conflicts of interest and author contributions are found at the end of this article.

Figures

Fig 1.

Unsupervised cluster analysis of serum proteins from interleukin-2 (IL-2)–treated patients. Dendrogram shows 59 serum samples (columns) and 65 soluble serum factors (rows). Serum samples obtained before IL-2 treatment are depicted as open circles, and serum samples obtained after IL-2 treatment are shown as closed circles. Patients with clinical responses (R) are shown in green, and nonresponders (NR) are shown in red.

Fig 2.

Supervised cluster analysis of serum proteins from interleukin-2 (IL-2)–treated patients before treatment. (A) Ten genes with significant variation in expression level among responders (R, green bars) and nonresponders (NR, red bars) from the validation set. (B) Cluster analysis of combined training and validation sets for vascular endothelial growth factor (VEGF) and fibronectin. MMP8, matrix metalloproteinase 8; PAI1, plasminogen activator inhibitor-1; TIMP1, tissue inhibitor of metalloproteinase 1; MPIF1, myeloid progenitor inhibitor factor-1; CRP, C-reactive protein; TNF-R1, tumor necrosis factor receptor 1; IFNα, interferon alpha.

Fig 3.

Serum vascular endothelial growth factor (VEGF) and fibronectin predict clinical response to interleukin-2 (IL-2) therapy. (A) VEGF and fibronectin levels from pretreatment sera are shown for responding (R) and nonresponding (NR) IL-2–treated patients as medians (central line), quartiles (boxes), and ranges (whiskers). (B) Receiver operating characteristic curve analysis for accuracy of VEGF as a biomarker for clinical responsiveness to IL-2 treatment.

Fig 4.

Serum vascular endothelial growth factor (VEGF) and fibronectin levels predict survival after interleukin-2 (IL-2) treatment. (A) Overall survival (OS) by pretreatment serum VEGF level median cutoff of 125 pg/mL (P < .007). (B) OS by fibronectin at cutoff of 8 × 106 pg/mL (P < .04). (C) OS by both VEGF (125 pg/mL) and fibronectin (8 × 106 pg/mL) concentrations (P < .01).

Fig A1.

(A) Pretreatment serum lactate dehydrogenase (LDH) levels in responder and nonresponder. (B) Pretreatment serum LDH and vascular endothelial growth factor (VEGF) levels.