This is an open label, dose-seeking phase 1/2 study using escalating doses of TRABECTEDIN given intravenously with defined doses of IPILIMUMAB and NIVOLUMAB based on preliminary results of the Checkmate 012 trial for NSCLC (Hellman et al., 2016). For the Phase 1 Part of Study, only previously treated patients will be enrolled. For the Phase 2 Part of Study, previously treated patients will be enrolled.

I. Dose Escalation Phase 1 of Study: The study will employ the standard "Cohort of Three" design (Storer, 1989). Three patients are treated at each dose level with expansion to six patients per cohort if DLT is observed in one of the three initially-enrolled patients at each dose level. If no DLT occurs after 2 doses, escalation to the next dose level will be permitted. The maximum tolerated dose is defined as the highest safely tolerated dose, where not more than one patient experienced DLT, with the next higher dose level having at least two patients who experienced DLT. Patients in the dose escalation study may continue treatment at their designated dose levels until disease progression or unacceptable toxicity occurs or up to 9 six-week cycles (one year) of therapy (up 18 TRABECTEDIN doses). No intra-patient dose escalation will take place.

Dose of IPILIMUMAB: 1 mg/kg IV over 30 min. q 12 weeks, beginning 2 weeks after first dose of TRABECTEDIN, until disease progression or unacceptable toxicity, up to 5 doses

Dose of NIVOLUMAB: 3 mg/kg over 30 min. q 2 weeks, beginning 2 weeks after first dose of TRABECTEDIN, until disease progression or unacceptable toxicity, up to 26 doses

Dose of TRABECTEDIN: Escalating doses of TRABECTEDIN IV as continuous intravenous infusion (CIV) over 24 hrs) q 3 weeks:

Dose Level I: 1 mg/m2 (n = 3-6); Dose Level II: 1.2 mg/m2 (n=3-6); Dose Level III: 1.5 mg.m2 (n=3-6)

II. Expansion Phase 2 of Study: Following dose escalation, an additional 22-28 previously untreated patients will receive TRABECTEDIN at the MTD and defined doses of IPILIMUMAB and NIVOLUMAB to assess overall safety and potential efficacy in a greater number of patients. Patients in the expansion phase of the study may continue treatment until significant disease progression (see criteria for discontinuation of therapy) or unacceptable toxicity occurs up to 9 six-week cycles (one year) of therapy.

Surgical Resection: After one or more treatment cycles, the principal investigator may recommend surgical debulking, complete surgical removal or a biopsy. If residual disease is present either by histopathological examination or by CT scan/MRI, repeat treatment cycles may be given 4 weeks after surgery, if the surgical incision has healed, and if the patient has < grade I toxicity.

Resected or biopsied tumors will be analyzed for the effects of this triple therapy on response, and immune cell trafficking in the tumor microenvironment. Fresh and paraffin embedded tissue blocks will be analyzed by FACS for PD-L1 and other biomarkers, including Tregs, CD8+, CD4+ cells etc. Immunohistochemistry for cyclin G1, cyclin D1 and Ki67 will be conducted to determine the tumor's proliferative state. Histopathologic examination for tumor necrosis and mitotic index will also be determined.

Inclusion Criteria:

• Individuals must meet all of the inclusion criteria in order to be eligible to participate in the study, as follows:

  • Male or Female ≥ 18 years of age
  • Pathologically confirmed diagnosis of locally advanced unresectable or metastatic soft tissue sarcoma
  • For the Phase 1 Part of Study, previously treated patients will be enrolled. For the Phase 2 Part of Study, previously treated patients will be enrolled.
  • Ability to understand the purposes and risks of the study and has signed and dated a written informed consent form approved by the investigator's IRB/Ethics Committee
  • Willingness to comply with all study procedures and availability for the duration of the study.
  • Measurable disease by RECIST v1.1
  • ECOG performance status ≤1
  • Life expectancy of at least 3 months
  • Acceptable liver function: Bilirubin ≤ 1.5 times upper limit of normal (ULN; except subjects with Gilbert Syndrome who must have a total bilirubin level ≤ 3.0 ULN);AST (SGOT), ALT (SGPT) and alkaline phosphatase ≤ 3 x ULN (≤ 5 x ULN if liver metastases)
  • Acceptable renal function: Creatinine ≤1.5 times ULN or ≥ 60 mL/min (using the Cockcroft Gault formula)
  • Acceptable hematologic status (without hematologic support): WBC ≥2000/µL; ANC ≥ 1500 cells/μL; Platelet count ≥ 100,000/μL; Hemoglobin ≥ 9.0 g/dL; Normal PT, PTT, INR
  • All women of childbearing potential must have a negative pregnancy test and all subjects must agree to use highly effective means of contraception (surgical sterilization or the use of barrier contraception with either a condom or diaphragm in conjunction with spermicidal gel or an IUD) with their partner from entry into the study through 5 months for women and 7 months for men after the last dose.

Exclusion Criteria:

• All individuals meeting any of the exclusion criteria at baseline will be excluded from study participation, as follows:

  • Subjects with untreated CNS metastases. Subjects are eligible if CNS metastases have been adequately treated and have neurologically returned to baseline (except for residual signs or symptoms related to the CNS treatment) for at least 2 weeks prior to treatment initiation. In addition, subjects must be either off corticosteroids, or on a stable or decreasing dose of ≤10 mg daily prednisone (or equivalent) for at least 2 weeks prior to treatment initiation.
  • Subjects with carcinomatous meningitis
  • Anticancer treatment with radiation therapy, chemotherapy, targeted therapy or other antitumor treatment within 2 weeks prior to study entry
  • Subjects who participated in an investigational drug or device study within 14 days prior to study entry
  • Females who are pregnant or breast-feeding
  • Unwillingness or inability to comply with the study protocol for any reason
  • Non-oncology vaccine therapy used for prevention of infectious disease within 4 weeks of trial enrollment
  • • History of or known or suspected autoimmune disease (exception(s): patients with vitiligo, Type I diabetes, resolved childhood atopic dermatitis, hypothyroidism, or hyperthyroidism that is clinically euthyroid at Screening are allowed). Other exceptions may be allowed following discussion with the Sponsor Medical Monitor for patients who have not received treatment for their autoimmune disorder in the past 3 years.
  • Systemic immunosuppression, including HIV positive status with or without AIDS
  • Skin rash (psoriasis, eczema) affecting ≥ 25% body surface area
  • Inflammatory bowel disease (Crohn's or ulcerative colitis)
  • Ongoing or uncontrolled diarrhea within 4 weeks of trial enrollment
  • Recent history of acute diverticulitis, intraabdominal abscess or gastrointestinal obstruction within 6 months of trial enrollment, which are known risk factors for bowel perforation
  • Patients with congestive heart failure or recent cardiac event
  • Evidence of severe or uncontrolled systemic disease or any other concurrent condition, including psychiatric, which in the principal investigator's opinion makes it undesirable for the patient to participate in the trial or which would jeopardize compliance with the trial
  • Any positive test for hepatitis B virus or hepatitis C virus indicating acute or chronic infection
  • Known history of testing positive for human immunodeficiency virus (HIV) or known acquired immunodeficiency syndrome (AIDS).
  • Inadequate hematologic, renal or hepatic function defined by any of the following screening laboratory values: WBC ≤2000/µL; Neutrophils ≤1500/µL; Platelets ≤ 100,000/µL; hemoglobin ≤9.0 g/dL; Serum creatinine ≥1.5 x ULN or creatinine clearance ≤ 60 mL/min (using the Cockcroft Gault formula); AST/ALT ≥3 x ULN (≥ 5 x ULN if liver metastases); Total Bilirubin ≥1.5 x ULN (except subjects with Gilbert Syndrome who must have a total bilirubin level ≥ 3.0 ULN)
  • Current, active or previous history of heavy alcohol abuse
  • Pituitary endocrinopathy
  • Adrenal insufficiency or excess