Objective YKL-40 is a proangiogenic glycoprotein that is secreted by cancer cells and inflammatory cells. The expression of YKL-40 is induced by vascular endothelial growth factor inhibition. We tested the hypothesis that low baseline plasma YKL-40 is associated with improved outcomes in patients with ovarian cancer treated with bevacizumab.

Methods One hundred forty patients with chemotherapy-refractory epithelian ovarian cancer were treated with single-agent bevacizumab 10 mg/kg every 3 weeks in a prospective trial. Plasma YKL-40 was determined by enzyme-linked immunosorbent assay before and during treatment. Both raw YKL-40 concentrations and age-corrected percentiles of normal YKL-40 level were used. Associations between plasma YKL-40 level and progression-free survival (PFS) and overall survival were tested using univariate and multivariate Cox proportional hazards models.

Results Baseline plasma YKL-40 levels were higher in patients with poor performance status, less differentiated tumors, residual disease after primary surgery, higher than the median serum CA-125 level, and higher than the median serum vascular endothelial growth factor level. Age-corrected percentile of normal plasma YKL-40 greater than the lowest quartile (Q1, 85th percentile) was associated with shorter PFS in univariate (hazard ratio, 1.83; 95% confidence interval, 1.15–2.89; P = 0.010) and multivariate analyses and shorter overall survival in univariate analysis (hazard ratio, 1.96; 95% confidence interval, 1.27–3.03; P = 0.003). Increase in plasma YKL-40 during bevacizumab treatment, with correction for baseline plasma YKL-40, was a predictor of shorter PFS. Using normal versus elevated plasma YKL-40 as a cutoff did not provide the same discriminative value.

Conclusions Low plasma YKL-40 at baseline and during treatment is associated with improved outcomes in patients with chemotherapy-refractory advanced ovarian cancer treated with single-agent bevacizumab.