Oral etoposide in relapsed or refractory Ewing sarcoma: a monoinstitutional experience in children and adolescents.

Aims: To assess the efficacy and toxicity of low-dose oral etoposide (VP) 16 in relapsing/refractory Ewing sarcoma.
Methods: The records of all patients treated at our department between 1989 and 2012 for relapsing/refractory Ewing sarcoma who received oral VP-16 were analyzed. The dose was 40 mg/m2 daily for 21 consecutive days in every 28. Response was assessed after 2/3 cycles according to Response Evaluation Criteria in Solid Tumors 1.0.
Results: A total of 46 of 58 patients completed at least 2 cycles; 12 suspended the treatment earlier due to rapid disease progression. The patients' median age at diagnosis was 14 years and 25/58 had metastatic disease. All patients received intensive polychemotherapy including VP-16 IV as first- (n = 53) or second-line (n = 5) treatment; 21/58 had myeloablative regimens with peripheral blood stem cell rescue, and 1 underwent allogeneic stem cell transplantation. Oral VP-16 was prescribed as 2nd-, 3rd-, and 4th-line treatment for 19, 27, and 12 patients, respectively. The cycles administered totaled 241 (median 3, mean 4 per patient; range 1-14). A total of 46 of 58 patients were evaluable: 11 responded (9 partial remission, 1 very good partial remission, 1 complete remission) and 10 were stable, the response lasting a mean of 8 months. Hematologic toxicity G3/G4 (in 164/241 evaluable cycles) occurred in 15%, 16%, and 11% of cycles for leukocytes, hemoglobin, and platelets, respectively. There were 5 cases of pneumonia. Two patients developed secondary leukemia after receiving 12 and 14 cycles.
Conclusions: Low-dose oral VP-16 may be suitable in a palliative setting with an acceptable toxicity. The risk of secondary leukemia is in line with reports in the literature.