Treatment of refractory osteosarcoma with fractionated cyclophosphamide and etoposide

Standard multiagent chemotherapy for osteosarcoma may include platinum compounds, doxorubicin, and high-dose methotrexate. By identifying new chemotherapeutic strategies, the outcome of these patients can be improved and the toxicity of treatment regimens decreased.

The authors evaluated the activity of the combination of cyclophosphamide (500 mg/m2 per day for 5 days) and etoposide (100 mg/m2 per day for 5 days) given with granulocyte colony-stimulating factor (G-CSF) to children with osteosarcoma unresponsive to conventional treatment.

Fourteen patients with refractory osteosarcoma were treated with this combination. Twelve patients had been previously treated with a multiagent regimen that included carboplatin, ifosfamide, methotrexate, and doxorubicin. Seven of 11 evaluable patients had a poor histologic response in their primary tumor at the time of definitive surgery (Huvos grade 1 or 2). Sites of relapse included lung, bone, and brain. A total of 47 courses were given. An overall response rate of 28.5% was achieved. A complete response was obtained in one patient (7.1%), a partial response was obtained in three patients (21.4%), and stable disease for 1 to 4 months was achieved in five patients (35.7%). Five patients (35.7%) had progressive disease. Grade 4 neutropenia was the primary form of toxicity observed; the median duration of absolute neurophil count less than 500/microL was 4 days.

The combination of cyclophosphamide and etoposide resulted in a response rate of 28.5% in patients with refractory or relapsed osteosarcoma, and its incorporation into front-line therapies deserves further evaluation.