<br>        Participants must be<br><br>          -  >=12 months to less than or equal to (<=) 25 years old at the time of consent [no more<br>             than 25 percent (%) of participants between the ages of 18 and 25 years will be<br>             enrolled in this study].<br><br>          -  >6 months and <12 months at the time of consent (Phase 1 and Schedule A only)<br>             participants will be enrolled one dose level behind the dose level at which the >=12<br>             months to <18 years old group are enrolled.<br><br>        Inclusion Criteria:<br><br>          -  Phase 1: Participants must be diagnosed with histologically confirmed solid tumors<br>             (excluding CNS tumors), which is relapsed or refractory, and for which there are no<br>             currently available therapies.<br><br>          -  Phase 2: Participants must be diagnosed with histologically confirmed RMS, NRSTS or<br>             EWS which is relapsed or refractory having received at least 1 prior therapy,<br>             including primary treatment.<br><br>          -  Phase 1: Participants must have either measurable or evaluable disease as per RECIST<br>             1.1.<br><br>          -  Phase 2: Participants must have measurable disease as per RECIST 1.1.<br><br>          -  Participant's current disease state must be one for which there is no known curative<br>             therapy.<br><br>          -  Participant's performance score must be >=50% Karnofsky (for participants >16 years of<br>             age) or Lansky (for participants <=16 years of age).Participants who are unable to<br>             walk because of paralysis and/or previous surgeries, but who are in a wheelchair, will<br>             be considered ambulatory for the purpose of assessing the performance score.<br><br>          -  Participants must have fully recovered from the acute toxic effects of all prior<br>             anticancer treatments prior to study drug administration:<br><br>               -  Must not have received myelosuppressive chemotherapy within 21 days prior to<br>                  study drug administration (42 days if prior nitrosourea).<br><br>               -  Must not have received a long-acting growth factor (eg, Neulasta) within 14 days<br>                  or a short-acting growth factor within 7 days.<br><br>               -  Must not have received an antineoplastic targeted therapy within 14 days.<br><br>               -  Must not have received immunotherapy, eg, tumor vaccines, within 42 days.<br><br>               -  Must not have received monoclonal antibodies within at least 3 half-lives of the<br>                  antibody after its last dose.<br><br>               -  Must not have received radiotherapy (XRT) within 14 days prior to study drug<br>                  administration (small field) or 42 days for craniospinal XRT, or if >=50%<br>                  radiation of pelvis.<br><br>               -  At least 84 days must have elapsed after stem cell infusion prior to study drug<br>                  administration<br><br>               -  No evidence of active graft-versus-host disease (GVHD) and at least 100 days must<br>                  have elapsed after allogeneic bone marrow transplant or stem cell infusion prior<br>                  to study drug administration<br><br>          -  Participants must have adequate bone marrow function, defined as:<br><br>               -  Peripheral absolute neutrophil count (ANC) >=1.0*10^9/liter (L).<br><br>               -  Platelet count >=100*10^9/L (not receiving platelet transfusions within a 7-day<br>                  period prior to study drug administration).<br><br>               -  Hemoglobin (Hb) at least 8.0 grams per deciliter (g/dL) at baseline (blood<br>                  transfusions are allowed during the screening period to correct Hb values less<br>                  than 8.0 g/dL).<br><br>          -  Participants must have adequate renal function, defined as:<br><br>               -  A serum creatinine based on age/gender, derived from the Schwartz formula for<br>                  estimating glomerular filtration rate (GFR), per protocol-specified criteria.<br><br>               -  Serum creatinine clearance or GFR >=50 milliliters/minute/1.73 m^2, based on a 12<br>                  or 24 hours (h) urine creatinine collection.<br><br>          -  Participants must have adequate liver function, defined as:<br><br>               -  Bilirubin (sum of conjugated + unconjugated) <=1.5 times the upper limit of<br>                  normal (ULN) for age.<br><br>               -  Alkaline phosphatase, alanine aminotransferase (ALT) and aspartate<br>                  aminotransferase (AST) <=3*ULN (in the case of liver metastases <=5*ULN), unless<br>                  there are bone metastases, in which case liver-specific alkaline phosphatase must<br>                  be separated from the total and used to assess the liver function instead of the<br>                  total alkaline phosphatase.<br><br>               -  Serum albumin >=2 g/dL.<br><br>          -  All participants and/or their parents or guardians must sign a written informed<br>             consent.<br><br>          -  Participants must be willing to comply with all aspects of the protocol.<br><br>        Exclusion Criteria:<br><br>          -  Females who are breastfeeding or pregnant at Screening or Baseline. A separate<br>             baseline assessment is required if a negative screening pregnancy test was obtained<br>             more than 72 h before the first dose of study drug.<br><br>          -  Females of childbearing potential who:<br><br>               -  Do not agree to use a highly effective method of contraception for the entire<br>                  study period and for 6 months after study drug discontinuation, ie:<br><br>               -  Total abstinence (if it is their preferred and usual lifestyle)<br><br>               -  An intrauterine device (IUD) or intrauterine system (IUS)<br><br>               -  A contraceptive implant<br><br>               -  An oral contraceptive OR<br><br>               -  Do not have a vasectomized partner with confirmed azoospermia.<br><br>          -  Males who have not had a successful vasectomy (confirmed azoospermia) or they and<br>             their female partners do not meet the criteria above (ie, not of childbearing<br>             potential or practicing highly effective contraception throughout the study period or<br>             for 3 months after study drug discontinuation). No sperm donation is allowed during<br>             the study period or for 3 months after study drug discontinuation.<br><br>          -  Concomitant Medications:<br><br>               -  Participants receiving corticosteroids who have not been on a stable dose for at<br>                  least 7 days prior to study drug administration.<br><br>               -  Participants who are currently receiving other anticancer agents.<br><br>               -  Participants who are receiving cyclosporine, tacrolimus or other agents to<br>                  prevent GVHD post bone marrow transplant.<br><br>               -  Participants who are receiving strong cytochrome P450 3A4 (CYP3A4) inhibitors and<br>                  inducers including traditional herbal medicinal products (eg St. John's Wort).<br><br>          -  Phase 1: Received prior therapy with eribulin mesilate within 6 months prior to study<br>             drug administration.<br><br>          -  Phase 2: Received prior therapies with eribulin mesilate or irinotecan hydrochloride<br>             (for prior irinotecan hydrochloride, participants can be included if there was no<br>             tumor progression during irinotecan therapy).<br><br>          -  Any other malignancy that required trea