- To estimate the maximum-tolerated dose and/or recommended phase II dose of Seneca Valley virus-001 (NTX-010) when administered as a single infusion to pediatric patients with relapsed or refractory neuroblastoma, rhabdomyosarcoma, or rare tumors with neuroendocrine features (Wilms tumor, retinoblastoma, adrenocortical carcinoma, or carcinoid tumors). (Part A [completed])