Background: Annexin V staining has become a standard approach for identifying cells undergoing apoptosis in vitro and can be detected in plasma. We hypothesized that plasma annexin V levels might serve as a clinical marker of tumor burden and cell turnover in children and young adults with solid tumors.
Methods: Nine patients aged 4–22 with newly diagnosed solid tumors were enrolled. Plasma samples were obtained prior to and, in a subset of patients, after initiation of chemotherapy from which annexin V levels were determined by enzyme-linked immunosorbent assay (ELISA).
Results: Three of nine patients had elevated plasma annexin V levels (> 10 ng/mL) at diagnosis and there was poor correlation to LDH levels, a commonly used marker of cell turnover (r = 0.66). Of the five patients with annexin V levels obtained after starting chemotherapy, only one showed an increase over the time period assessed.
Conclusions: Plasma annexin V does not appear to be a useful marker of tumor burden or early response to chemotherapy in children with solid tumors.