What treatment do you offer to a pediatric patient with metastatic ewing sarcoma who has completed VDC/IE chemotherapy?

The most important treatment to offer would be local control of metastatic sites (usually by radiation therapy); by convention, this therapy is usually delivered after completion of chemotherapy. This would be critical for any chance of prolonged disease remission.

In terms of systemic therapy, at this point there is no good prospective evidence to support any sort of maintenance chemotherapy for metastatic Ewing sarcoma. The question of the benefit of maintenance chemotherapy for metastatic Ewing sarcoma is being considered for study by the Bone Tumor committee of the Children's Oncology Group; but at this point, a large prospective (hopefully randomized) trial would be necessary to recommend any further systemic treatment.

That does not, however, mean that it hasn't been utilized before. The overall outcomes of metastatic Ewing sarcoma are so poor that it is reasonable to question what else can be offered and to want to do something else for your patient. Regimens I have seen or heard of being used include: irinotecan/temozolomide, regorafanib or cabozantinib, and metronomic chemotherapy (such as PO cyclophosphamide x3 weeks alternating with PO etoposide x3 weeks, daily celocoxib, and weekly vinblastine). But, again, prospective evidence is lacking for any of these, and any use of such regimens would necessitate a clear and open discussion with the patient and family about lack of good evidence of benefit and real chance for side effects. It has not been my practice to offer such therapies, though I have been tempted for those who have a good response to upfront therapy.