A Study of Trabectedin or Dacarbazine for the Treatment of Patients With Advanced Liposarcoma or Leiomyosarcoma

Inclusion Criteria

• Histologically proven, unresectable, locally advanced or metastatic liposarcoma (dedifferentiated, myxoid round cell, or pleomorphic) or leiomyosarcoma. Participants must have a pathology report indicating the diagnosis of liposarcoma or leiomyosarcoma that has been reviewed by the sponsor before randomization may occur
• Treated in any order with at least: an anthracycline and ifosfamide containing regimen, or an anthracycline containing regimen and 1 additional cytotoxic chemotherapy regimen
• Measurable disease at baseline in accordance with RECIST Version 1.1
• Pathology specimens (example [e.g.], tumor blocks or unstained slides) for potential centralized pathology review and biomarker studies
• ECOG Performance Status score of 0 or 1
• Adequate recovery from prior therapy, all side effects (except alopecia) have resolved to Grade 1 or less according to the National Cancer Institute - Common Terminology Criteria of Adverse Events (NCI-CTCAE) Version 4.0
• Adequate organ function as evidenced by the following peripheral blood counts or serum chemistry values: hemoglobin 9 gram per deciliters (g/dL), absolute neutrophil count (ANC) 1,500/L, platelet count 100,000/L, serum creatinine 1.5*the upper limit of normal (ULN), creatine phosphokinase (CPK) 2.5 Upper Limit of Normal [ULN]
• Adequate hepatic function as evidenced by the following serum chemistry values: total bilirubin, ULN. If total bilirubin is greater than (>) ULN, measure indirect bilirubin to evaluate for Gilbert's syndrome (if direct bilirubin is within normal range, participant may be eligible) ALP 2.5 x ULN; Trabectedin: if the ALP is >2.5 x ULN, then an ALP liver fraction or 5-nucleotidase must be obtained and ULN, AST and ALT 2.5 ULN
• Negative pregnancy test (urinary or serum beta-HCG) at screening (applicable to women of child bearing potential who are sexually active)
• Female participants must be postmenopausal (no spontaneous menses for at least 2 years), surgically sterile (have had a hysterectomy or bilateral oophorectomy, tubal ligation, or otherwise be incapable of pregnancy), abstinent (at the discretion of the investigator), or if sexually active, be practicing an effective method of birth control. Male participants must agree to use an adequate contraception method as deemed appropriate by the investigator (e.g., vasectomy, double-barrier, partner using effective contraception) and to not donate sperm for a minimum of 5 months after treatment discontinuation

Optional Extension Phase (OEP) Phase:

• Documentation for inclusion criteria histologically proven, unresectable, locally advanced or metastatic liposarcoma (dedifferentiated, myxoid round cell, or pleomorphic) or leiomyosarcoma. Participants must have a pathology report indicating the diagnosis of liposarcoma or leiomyosarcoma that has been reviewed by the sponsor before randomization may occur and treated in any order with at least: an anthracycline and ifosfamide containing regimen, or an anthracycline containing regimen and 1 additional cytotoxic chemotherapy regimen do not need to be reviewed by the Sponsor
• Collection of the specimen: Pathology specimens (example (e.g.), tumor blocks or unstained slides) for potential centralized pathology review and biomarker studies is not applicable
• Documentation of inclusion criteria adequate organ function as evidenced by the following peripheral blood counts or serum chemistry values: hemoglobin 9 gram per deciliters (g/dL), absolute neutrophil count (ANC) 1,500/L, platelet count 100,000/L, serum creatinine 1.5*the upper limit of normal (ULN), creatine phosphokinase (CPK) 2.5*ULN and adequate hepatic function as evidenced by the following serum chemistry values: total bilirubin, ULN. If total bilirubin is greater than (>) ULN, measure indirect bilirubin to evaluate for Gilbert's syndrome (if direct bilirubin is within normal range, participant may be eligible) ALP 2.5*ULN, then an ALP liver fraction or 5-nucleotidase mu