Slow accrual and as a result, a strategic business decision was made to terminate enrollment.

The goal of this clinical trial was to compare participants with first relapse or refractory Ewing's sarcoma when treated with investigational product (Vigil) in addition to the standard treatment of irinotecan and temozolomide compared to the standard treatment of irinotecan and temozolomide alone. The main question it aimed to answer is "Will participants who receive Vigil in addition to irinotecan and temozolomide have a prolonged time to progression and improved quality of life compared to the participants who receive irinotecan and temozolomide alone?".

This was a multicenter, Phase III study in participants with metastatic Ewing's sarcoma Family of Tumors (ESFT) refractory/intolerant or recurrent to 1 prior line of chemotherapy. Participants who agreed to participation had tumor tissue harvested from a scheduled standard surgical procedure (e.g., tumor biopsy or palliative resection). The tumor tissue removed was shipped to Gradalis, Inc. to attempt to manufacture the investigational product, Vigil.

Subjects who met eligibility criteria including manufacture of a minimum of 4 doses of Vigil were randomized 1:1 to either Group A (Vigil + Irinotecan + Temozolomide (Tem/Iri)) or Group B (Irinotecan + Temozolomide). Screening for the main portion of the study occurred as early as one week but no later than 8 weeks following tumor procurement.

Subjects received repeat cycles of treatment until disease progression, unacceptable toxicity, withdrawal of consent or other criterion was met for discontinuation from study. Subjects randomized to Group A (Vigil + Tem/Iri) received up to 12 doses depending upon the quantity of Vigil manufactured from the surgical specimen. 1 cycle = 21 days. If irinotecan + temozolomide was administered beyond 12 cycles, it was administered off study. Subjects randomized to Group B (Tem/Iri) may have crossed over to receive single agent Vigil every 21 days following End of Treatment assessment and documented disease progression confirmed by central radiology vendor, for up to 12 doses of Vigil depending upon the quantity of Vigil manufactured.

Participants were managed in an outpatient setting. Hematologic function, liver enzymes, renal function and electrolytes will be monitored. Blood for immune function analyses including IFNγ-ELISPOT analysis of cytotoxic T cell activation in response to autologous tumor antigens will be collected at tissue procurement, post-procurement screening and Day 1 (prior to chemotherapy administration) at Cycles 2, 4, and 6, end of treatment (EOT), 3 months after EOT, and every 6 months thereafter. Blood for ctDNA analysis was collected at tissue procurement, prior to chemotherapy administration at baseline and on Day 1 prior to chemotherapy administration at Cycles 2, 3, 4, and 6, and EOT. After progression, participants were contacted quarterly for documentation of post study therapies and survival status information.

Tissue Procurement Inclusion Criteria:

1. Histologically confirmed Ewing's Sarcoma Family of Tumors (ESFT).
2. Age greater than or equal to 2 years.
3. Estimated survival greater than or equal to 6 months.
4. Evidence of EWS translocation by FISH or RT-PCR or Next Generation Sequencing (NGS). If available, NGS sequencing report should be submitted to Gradalis.
5. Recurrence or refractory to 1 line of systemic chemotherapy, including but not limited to doxorubicin, vincristine, and ifosfamide.
6. Planned standard of care surgical procedure (e.g., tumor biopsy or palliative resection or thoracentesis) and expected availability of a cumulative soft-tissue mass of ~10-30 grams tissue ("grape" to "golf-ball" size / approximately 2 cm total diameter on imaging) or pleural fluid estimated volume ≥ 500mL (from a primary or secondary thoracentesis, yielding in a high volume of tumor cells) for immunotherapy manufacture.
7. Tumor intended for immunotherapy manufacture is not embedded in bone and does not contain luminal tissue (e.g. bowel, ureter, bile duct).
8. Ability to understand and the willingness to sign a written protocol specific informed consent for tissue harvest or a parental/guardian informed consent and pediatric assent when appropriate.

Tissue Procurement Exclusion Criteria:

1. Medical condition requiring any form of chronic systemic immunosuppressive therapy (steroid or other) except physiologic replacement doses of hydrocortisone or equivalent (no more than 30 mg hydrocortisone or 10 mg prednisone equivalent daily) for < 30 days duration.
2. Known history of other malignancy unless having undergone curative intent therapy without evidence of that disease for ≥ 3 years except cutaneous squamous cell and basal cell skin cancer, superficial bladder cancer, in situ cervical cancer or other in situ cancers are allowed if definitively resected.
3. Brain metastases unless treated with curative intent (gamma knife or surgical resection) and without evidence of progression for ≥ 2 months.
4. Any documented history of autoimmune disease with exception of Type 1 diabetes on stable insulin regimen, hypothyroidism on stable dose of replacement thyroid medication, vitiligo, or asthma not requiring systemic steroids.
5. Known HIV or chronic Hepatitis B or C infection.
6. Known hypersensitivity to any temozolomide component or to dacarbazine (DTIC).
7. Known hypersensitivity to irinotecan or its excipients.
8. Known history of allergies or sensitivities to gentamicin.
9. History of or current evidence of any condition (including medical, psychiatric or substance abuse disorder), therapy, or laboratory abnormality that might confound the results of the study, interfere with the patient's participation for the full duration of the study, or is not in the best interest of the patient to participate, in the opinion of the treating Investigator.

Study Enrollment Inclusion Criteria:

1. Completed manufacture of at least 4 vials of Vigil.

2. Karnofsky performance status (KPS) / Lansky performance status (LS) ≥80 percent.

3. Normal organ and marrow function as defined below:

   Absolute granulocyte count ≥1,000/mm3, Absolute lymphocyte count ≥400/mm3, Platelets ≥75,000/mm3, Hemoglobin ≥ 8.0 mg/dL, Total bilirubin ≤ institutional upper limit of normal*, AST(SGOT)/ALT(SGPT) ≤2x institutional upper limit of normal, Creatinine <1.5 mg/dL

   * documented Gilbert's syndrome may be considered after medical monitor review

4. Subject has recovered to CTCAE Grade 1 (except for parameters noted in Item 3, above) or better from all adverse events associated with prior therapy or surgery. Pre-existing motor or sensory neurologic pathology or symptoms, or dermatologic must be recovered to CTCAE Grade 2 or better.

5. If female of childbearing potential, has a negative urine or serum pregnancy test. If the urine test is positive or cannot be confirmed as negative, a negative serum test will be required for study entry.

6. Ability to understand and the willingness to sign a written informed protocol specific consent or a parental/guardian informed consent and pediatric assent when appropriate.

Study Enrollment Exclusion Criteria:

In addition to the procurement exclusion criteria, subjects will NOT be eligible for study registration and randomization if meeting any of the following additional criteria:

1. Any anti-neoplastic therapy between tissue procurement for Vigil manufacture and start of study therapy.
2. Live vaccine used for the prevention of infectious disease administered < 30 days prior to the start of study therapy.
3. Post-surgery complication that in the opinion of the treating investigator would interfere with the patient's study participation or make it not in the best interest of the patient to participate.

Inclusion Criteria for Cross-Over:

Group B subjects will be eligible for cross-over, if they meet all of the following criteria:

1. Evidence of radiologic disease progression by RECIST 1.1 after enrollment into Group B.

2. Successful manufacturing of at least 4 vials of Vigil.

3. Karnofsky performance status (KPS) / Lansky performance status (LS) ≥70%.

4. Normal organ and marrow function as defined below:

   Absolute granulocyte count ≥1,000/mm3 Absolute lymphocyte count ≥400/mm3 Platelets ≥75,000/mm3 Total bilirubin ≤ institutional upper limit of normal AST(SGOT)/ALT(SGPT) ≤2x institutional upper limit of normal Creatinine <1.5 mg/dL

   *documented Gilbert's syndrome may be considered after medical monitor review.

5. Subject has recovered to CTCAE Grade 1 (except for parameters noted in Item 4, above) or better from all adverse events associated with prior therapy or surgery. Preexisting motor, sensory neurologic pathology or symptoms, or dermatologic toxicities must be recovered to CTCAE Grade 2 or better.

6. If female of childbearing potential, has a negative urine or serum pregnancy test. If the urine test is positive or cannot be confirmed as negative, a negative serum test will be required for study entry.

7. Ability to understand and the willingness to sign a written informed protocol specific consent or a parental/guardian informed consent and pediatric assent when appropriate.

Exclusion Criteria for Cross-Over:

In addition to the Procurement and Study Enrollment exclusion criteria, Subjects will not be eligible for cross-over if meeting any of the following criteria:

1. With the exception of irinotecan and temozolomide while on study, any anti-neoplastic therapy between tissue procurement for Vigil manufacture and start of study therapy.
2. Live vaccine used for the prevention of infectious disease administered < 30 days prior to the start of study therapy.