Phase 1 Dose-escalating Study of MM-398 (Irinotecan Sucrosofate Liposome Injection) Plus Intravenous Cyclophosphamide in Recurrent or Refractory Pediatric Solid Tumors

Inclusion Criteria:

* Histologically or cytologically-confirmed Ewing sarcoma, rhabdomyosarcoma, neuroblastoma, or osteosarcoma
* Disease progression after prior therapy in locally advanced or metastatic setting
* Measurable or evaluable disease based on the Response Evaluation Criteria in Solid Tumors (RECIST v1.1) criteria
* Age 12 months to \<21 years
* Adequate bone marrow reserves, hepatic function, and renal function
* Recovered from effects of any prior surgery or cancer therapy
* Patients 18 years or older will provide written consent. A parent or legal guardian of a patient \<18 years of age will provide informed consent and patients 11 to 18 years of age will provide written assent or as per participating institutional policy.

Exclusion Criteria:

* Clinically significant gastrointestinal disorders
* NYHA Class III or IV congestive heart failure, ventricular arrhythmias or uncontrolled blood pressure
* Active infection or unexplained fever
* Known hypersensitivity to any of the components of MM-398 or other liposomal products
* Recent Investigational therapy
* Pregnant or breast feeding; females of child-bearing potential must test negative for pregnancy at the time of enrollment