EZH2 Inhibitor Tazemetostat in Pediatric Subjects With Relapsed or Refractory INI1-Negative Tumors or Synovial Sarcoma

Inclusion Criteria

• Age (at the time of consent/assent): ≥6 months to 50%
• If ≥12 years of age: Karnofsky Performance Status >50% NOTE: If subject is unable to walk due to paralysis, but is mobile in a wheelchair, subject is considered to be ambulatory for the purpose of assessing their performance status.
• Has provided signed written informed consent/assent
• Has a life expectancy of >3 months
• Has relapsed or refractory disease and no standard treatment options as determined by locally or regionally available standards of care and treating physician's discretion
• Is ineligible or inappropriate for other treatment regimens known to have effective potential
• Has a documented local diagnostic pathology of original biopsy confirmed by a Clinical Laboratory Improvement Amendments (CLIA)/College of American Pathologists (CAP) or equivalent laboratory certification
• Has all prior treatment (i.e., chemotherapy, immunotherapy, radiotherapy) related clinically significant toxicities resolve to ≤ Grade 1 per CTCAE, version 4.03 or are clinically stable and not clinically significant, at time of enrollment
• Has completed a prior therapy (ies) according to the criteria below:
• Other investigational study agent (any medicinal product that is not approved in the country of treatment for any indication, adult or pediatric) (At least 30 days or five half-lives, whichever is longer, since last dose prior to the first dose of tazemetostat)
• Chemotherapy: cytotoxic (At least 14 days since last dose of chemotherapy prior to first dose of tazemetostat)
• Chemotherapy: nitrosoureas (At least 6 weeks since last dose of nitrosoureas prior to first dose of tazemetostat)
• Chemotherapy: non-cytotoxic (e.g., small molecule inhibitor) (At least 14 days since last dose of non-cytotoxic chemotherapy prior to first dose of tazemetostat)
• Monoclonal antibody (ies) (At least 28 days since the last dose of any monoclonal antibody prior to first dose of tazemetostat)
• Immunotherapy (e.g., tumor vaccine) At least 6 weeks since last dose of immunotherapy agent(s) prior to first dose of tazemetostat)
• Radiotherapy (RT) (At least 14 days from last local site RT prior to first dose of tazemetostat/At least 21 days from stereotactic radiosurgery prior to first dose of tazemetostat/At least 12 weeks from craniospinal, ≥ 50% radiation of pelvis, or total body irradiation prior to first dose of tazemetostat)
• Hematopoietic growth factor (At least 14 days from last dose of hematopoietic growth factor prior to first dose of tazemetostat)
• Hematopoietic cell transplantation (At least 60 days from infusion of hematopoietic cells prior to first dose of tazemetostat)
• Has adequate hematologic (bone marrow and coagulation factors), renal and hepatic function as defined by criteria below:
• Hematologic (BM Function):
• Hemoglobin ≥ 8 g/dL
• Platelets ≥100,000/mm^3 (≥100 x 10^9/L)
• ANC ≥1,000/mm^3 (≥1.0 x 10^9/L)
• Hematologic (Coagulation Factors):
• INR/ PTd ≤1.5 ULN
• PTT ≤1.5 ULN
• Fibrinogen ≥0.75 LLN
• Renal Function (creatinine clearance or serum creatinine):
• Calculated creatinine clearance ≥50 mL/min/1.73m^2
• Serum creatinine 6 months to 1 year: male 0.6 mg/dL (53 µmol/L) female 0.5 mg/dL (44 µmol/L)
• Serum creatinine 1 to 27% or an ejection fraction of ≥50% by echocardiogram or multi-gated acquisition scan and New York Heart Association Class 450 msec)
• Is currently taking any prohibited medication(s) as described in Section 7.3.
• Is unwilling to exclude grapefruit juice, Seville oranges and grapefruit from the diet and all foods that contain those fruits from time of enrollment to while on study
• Has an active infection requiring systemic treatment
• Is immunocompromised (i.e. congenital immunodeficiencies), including subjects known history of infection with human immunodeficiency virus (HIV)
• Has known history of chronic infection with hepatitis B virus (hepatitis B surface antigen positive) or hepatitis C virus (dete