HER-2 targeted treatment of osteosarcoma: The challenges of developing targeted therapy and prognostic factors for rare malignancies

Importance of the field: Despite the substantial success realized treating osteosarcoma with chemotherapy, metastatic disease or refractory/recurrent disease continue to frustrate patients and clinicians. The failure to improve outcomes with treatment intensification indicates the need for new approaches, such as the introduction of targeted therapy. The application of trastuzumab (Herceptin^®) in the setting of HER-2 positive osteosarcoma is reflective of this concept. Areas covered in this review: This review summarizes reports from 1996 to the present which focus on HER-2 expression and its prognostic relevance in the setting of osteosarcoma. What the reader will gain: The prognostic value of HER-2 remains controversial, and both standard methodologies for assessing expression and the effectiveness of HER-2 directed therapy in this patient population have yet to be established. Take home message: The relative rarity of the disease makes larger prospective studies difficult in terms of both time and coordination. The feasibility of defining therapy specifically for a subpopulation of patients afflicted with a rare cancer, such as osteosarcoma, can be conceptually questioned.