Mocetinostat With Vinorelbine in Children, Adolescents & Young Adults With Refractory and/or Recurrent Rhabdomyosarcoma

Inclusion Criteria: * Willing and able to provide written Institutional Review Board (IRB)/Independent Ethics Committee (IEC)-approved informed consent. For subjects \< 18 years of age, their parents or legal guardians must sign a written informed consent. Assent, when appropriate, will be obtained according to institutional guidelines * Have histologically or cytological confirmed diagnosis of rhabdomyosarcoma with locally advanced/unresectable, metastatic, refractory or relapsed disease who have failed standard therapy and for whom no known curative therapy exists * Measurable disease according to RECIST version 1.1 * Prior cancer therapy: Subjects may have received any number of prior therapy regimens. In the investigator's opinion, subjects must have tolerated prior cytotoxic therapies well and have adequate bone marrow reserve. At the time of treatment initiation, at least 3 weeks must have elapsed after prior cytotoxic chemotherapy. At least 7 days must have elapsed since completion of any prior non-cytotoxic cancer therapy and any associated AEs must have resolved * Prior radiotherapy is allowed if \>= 2 weeks have elapsed for local palliative radiation therapy (XRT) (small port); \>= 6 months must have elapsed if prior total body irradiation, craniospinal XRT or if \> 50% radiation of the pelvis; \> 6 weeks must have elapsed if other substantial bone marrow radiation (defined per principal investigator's \[PI's\] discretion). Subjects who have received brain irradiat…