[Extracellular domain of HER-2 as a prognostic factor in osteosarcoma. A pilot study]

The expression of Human Epidermal Growth Factor Receptor 2 (HER-2) in tissue and the level of its extracellular domain (ECD/HER-2) in serum have been found to be helpful prognostic factors in many malignancies. THE AIM of this study was to assess the prognostic value of baseline level of ECD/HER-2 in patients with primary osteosarcoma.

26 newly-diagnosed osteosarcoma patients aged 6-18 years (median 15 years) were included in the study. Disease localised at presentation (16 patients) and dissemination--stage IV (10 patients).

13-44 months (median 23 months). The serum samples were collected before initial chemotherapy. The serum baseline level of ECD/HER-2 was measured using immunoenzymatic method.

The level of ECD/HER-2 in serum ranged 3.8-14.4 ng/ml; median 5 ng/ml. Disease progression occurred statistically significantly more often in patients with ECD/HER-2 > 5 ng/ml (7/12 patients) than in patients with ECD/HER-2 < or = 5 ng/ml (1/14 patient), P=0.005. High concentration of ECD/HER-2 was also related to decreased overall survival: ECD/HER-2 > 5 ng/ml vs ECD/HER-2 < or = 5 ng/ml: 50% vs 93%; P=0.057.

The preliminary results from this study indicate that the serum concentration of ECD/HER-2 in patients with osteosarcoma may be a useful marker for predicting course of disease, in particular for detecting early disease progression. However, it is mandatory to make further studies to determine the prognostic role of elevated serum concentrations ECD/HER-2 in osteosarcoma, which also may be a step towards target therapies with monoclonal antibodies against the HER-2 receptor.