A Study of the Drug I131-Omburtamab in People With Desmoplastic Small Round Cell Tumors and Other Solid Tumors in the Peritoneum

Phase II Combination of 131I-Omburtamab Radioimmunotherapy and External Beam Radiotherapy for Desmoplastic Small Round Cell Tumor

The purpose of this study is to test any good and bad effects of the study drug 131I-omburtamab. 131I-omburtamab could prevent the cancer from returning, or delay the cancer from getting worse, but it could also cause side effects. Researchers hope to learn more about how 131I-omburtamab works in the body, and how effective it is in treating cancer. 131I-Omburtamab is not approved by the FDA to treat DSRCT or other cancers of the peritoneum.

Inclusion Criteria:

• Have the diagnosis of DSRCT confirmed at MSKCC

• Age >1 year and able to cooperate with radiation safety restrictions during therapy period.

• Prior to intraperitoneal catheter placement

  • At least 1 weeks must have elapsed since prior chemotherapy
  • At least 2 weeks must have elapsed since biologic therapy
  • Toxicities of prior therapy must have resolved to grade 1 or less or to the patient's baseline

At the completion of surgery, patients must fulfill all of the additional following criteria:

• Have no definitive radiological evidence of disease active in liver or outside the abdomen/pelvic OR have had GTR of this disease at the time of catheter placement

Exclusion Criteria:

• Prior progression of disease
• Prior hypothermic intraperitoneal chemotherapy (HIPEC)
• Cardiac, pulmonary, and neurologic toxicities are greater grade 1 per NCI CTCAE version 5
• Renal, gastrointestinal, and hepatic, toxicities are greater than grade 2 (per NCI CTCAE version 5)
• History of allergy to mouse proteins
• Patients with grade 4 hypersensitivity reaction to radiolabeled iodine