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Omburtamab I-131

Phase 2

Recurrent Medulloblastoma | Small molecule | Oncology |Y-mAbs Therapeutics, Inc.|Last Updated: Feb 5, 2026

Success Probability
Approval Probability 71%
TA Base Rate26%
Adjusted LOA41%
ML RiskLOW_RISK
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Market & Valuation
rNPV $3.2B
Market Size $9.4B
Revenue Basis $1.6B
Competitors 6
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Trial Design
CONTROLLEDDMCBiomarker
Total Trials1
Total Enrollment62
FDA Designations
No designations recorded
Clinical Trials (1)
NCT IDTitlePhaseStatusEnrollmentVelocityDesignStartCompletionLast UpdatedSitesCountries
NCT04743661131I-Omburtamab, in Recurrent Medulloblastoma and EpendymomaPHASE2 ACTIVE NOT_RECRUITING 62Apr 4, 2022Sep 30, 2027Feb 5, 20263 United States
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Study Endpoints
Primary Endpoints
2-year event free survival (EFS) in the Recurrent Medulloblastoma Cohort
2 years

Using the Kaplan Meier method, estimate of event-free survival (EFS) of patients with relapsed medulloblastoma treated with the study regimen. EFS is defined as the interval of time between enrollment on the study and the minimum date of documentation of progressive disease, death due to any cause, subsequent malignancy or date of last follow-up.

Percentage of Patients who met feasibility criteria in the Recurrent Ependymoma Cohort
3 months

Percentage of patients who met feasibility criteria of incorporating cRIT 131I-omburtamab treatment for patients with recurrent ependymoma. Patients who meet both of the following criteria will be counted as feasibility successes: 1) Administration of the first therapeutic dose of the antibody at the treating institution within 6 days of labeling. 2) Successful acquisition of all 3 SPECT scans during the Dosimetry Course prior to Radioimmunotherapy.

Secondary Endpoints
Overall survival (OS) in in Recurrent Medulloblastoma Cohort
5 years
Percentage of Recurrent Ependymoma patients with B7H3 reactivity
1 month
Event free survival (EFS) for Recurrent Ependymoma
5 years from enrollment completion
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Study Design & Arms
AllocationNON_RANDOMIZED
MaskingNONE
ModelPARALLEL
PurposeTREATMENT
Treatment Arms
ArmTypeDescription
Recurrent MedulloblastomaEXPERIMENTALThis arm aims to estimate event-free survival (EFS) and overall survival (OS) following therapy with irinotecan, temozolomide, bevacizumab, and compartmental (intraOmmaya) radioimmunotherapy (cRIT) 131I-omburtamab in patients with recurrent medulloblastoma. Patients with recurrent medulloblastoma will undergo surgery if feasible prior to study entry, followed by Induction Chemotherapy with irinotecan, temozolomide, and bevacizumab on study as per the Children's Oncology Group (COG) trial ACNS0821. Following 2 or 4 courses of chemotherapy and if radiographic disease status is stable or improved, patients will receive 2 therapeutic doses of 50 mCi cRIT 131I-omburtamab during Radioimmunotherapy. Following Radioimmunotherapy, patients may resume to Maintenance Chemotherapy with irinotecan, temozolomide, and bevacizumab for up to 12 total courses of chemotherapy or until disease progression, whichever occurs sooner.
Recurrent EpendymomaEXPERIMENTALThis is a feasibility cohort. The primary objective is to assess feasibility of incorporating cRIT 131I-omburtamab for patients with recurrent ependymoma and to assess dosimetry. Patients must have progressed after initial surgery, radiation therapy, or other therapies. Patients will undergo surgery (if feasible) prior to study entry with the goal of achieving stable or better disease. Tumor tissue (archived or new) will be tested for B7H3 prior to enrollment. If positive, patients will enroll on Stratum 2 and receive one dosimetry dose (2 mCi) of cRIT 131I-omburtamab with nuclear medicine scintigraphy using SPECT during the Dosimetry Course (14 days in length). Following the Dosimetry Course and within 2 weeks of the dosimetry dose, patients may continue to Radioimmunotherapy to receive 2 therapeutic doses (50 mCi) of cRIT 131I-omburtamab.
Interventions
NameTypeDescription
IrinotecanDRUGIrinotecan is a semisynthetic water-soluble analog of camptothecin (a plant alkaloid isolated from Camptotheca acuminata). Irinotecan is available in single-dose amber glass vials in 40 mg (2 mL) and 100 mg (5 mL), 300 mg (15 mL), and 500 mg (25 mL). Patients on Stratum 1 will be given irinotecan at 50 mg/m2/day IV on Days 1 through 5 of each chemotherapy course.
TemozolomideDRUGAn orally administered alkylating agent, a second generation imidazotetrazine. A prodrug of MTIC, temozolomide spontaneously decomposes to MTIC at physiologic pH. Exerts its effect by cross-linking DNA. Temozolomide capsules are available in six different strengths (5, 20, 100, 140, 180, 250 mg). The capsules vary in size, color, and imprint according to strength. In the US, capsules are packaged in 5-count and 14-count bottles. Patients on Stratum 1 will be given temozolomide at 150 mg/m2/dose PO on Days 1-5 of each chemotherapy course.
BevacizumabDRUGBevacizumab is a recombinant humanized anti-vascular endothelial growth factor (anti-VEGF) monoclonal antibody. Bevacizumab is supplied as a clear to slightly opalescent, sterile liquid ready for parenteral administration. Each 400 mg (25 mg/mL, 16 mL fill) glass vial contains bevacizumab with phosphate, trehalose, polysorbate 20, and Sterile Water for Injection. Patients on Stratum 1 will be given bevacizumab at 10 mg/kg/day IV on Days 1 and 15 of each chemotherapy course, with the exception of the last course of Induction Chemotherapy (i.e., Course 2 or 4) where it will be administered on Day 1 only.
Omburtamab I-131DRUGOmburtamab is a murine IgG1 monoclonal antibody (mAb) against B7-H3 (CD276) manufactured by in vivo growth of the hybridoma cell line without the use of animal-derived components. Omburtamab will be radiolabeled with iodine-131 at a designated radiolabeling facility. 131I-omburtamab is supplied as a sterile, injectable, radioactive product in a vial. Each supplied vial will contain enough radioactivity to prepare 50 mCi of 131I-omburtamab, formulated in 3.5-4 mL of solution. 131I-omburtamab should be administered via an intraventricular access device (i.e., Ommaya catheter or programmable VP shunt). Radioimmunotherapy consists of 56 days. Patients on Stratum 1 will receive a therapeutic dose of 50 mCi cRIT 131I-omburtamab on Days 8 and 36 of Radioimmunotherapy. Patients on Stratum 2 will receive a therapeutic dose of 50 mCi cRIT 131I-omburtamab on Days 1 and 29 of Radioimmunotherapy.
LiothyronineDRUGLiothyronine (or equivalent) will be given as premedication for 131I-omburtamab to prevent thyroid accumulation. Liothyronine (or equivalent) will be administered at 25 µg PO, NG, or G-tube (if weight \< 25 kg) or 50 µg PO, NG, or G-tube (if weight ≥ 25 kg) daily starting on Day 1 of Radioimmunotherapy (for Stratum 1 patients) or Day 1 of Dosimetry (for Stratum 2 patients), with a mandated minimum of 7 days before each 131I-omburtamab injection and 14 days after each 131I-omburtamab injection. On the day of the 131I-omburtamab injection, administer any time before the injection.
SSKIDRUGSSKI (potassium iodide) will be given as premedication for 131I-omburtamab to prevent thyroid accumulation. SSKI (potassium iodide) will be administered as 7 drops (\~0.35 mL) PO, NG, or G-tube daily starting on Day 1 of Radioimmunotherapy (for Stratum 1 patients) or Day 1 of Dosimetry (for Stratum 2 patients), with a mandated minimum of 7 days before each 131I-omburtamab injection and 14 days after each 131I-omburtamab injection. On the day of the 131I-omburtamab injection, administer any time before the injection.
DexamethasoneDRUGDexamethasone will be given as premedication for 131I-omburtamab to prevent possible meningeal inflammatory reaction. Starting within 24 hours prior to each 131I-omburtamab injection, dexamethasone will be administered orally at 0.5 mg (if weight \< 15 kg) or 1 mg (if weight ≥ 15 kg) twice-daily doses for a total of 6 doses to alleviate infusion-related AEs: Two doses starting 24 hours pre-131I-omburtamab injection, two doses on the day of the injection (can be given before or after), and two doses 24 hours post-131I-omburtamab injection.
AntipyreticDRUGAn antipyretic (e.g., oral acetaminophen \[15 mg/kg, 650 mg maximum\] or equivalent) will be given as premedication for 131I-omburtamab within 1 to 3 hours before each 131I-omburtamab injection.
AntihistamineDRUGAn antihistamine (e.g., IV diphenhydramine \[1 mg/kg, 50 mg maximum\] or equivalent) will be given as premedication for 131I-omburtamab within 1 to 3 hours before each 131I-omburtamab injection.
anti-emeticsDRUGAn anti-emetic (e.g., IV ondansetron \[0.25 mg/kg, 16 mg maximum\] or equivalent) will be given as premedication for 131I-omburtamab within 1 to 3 hours before each 131I-omburtamab injection.
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Eligibility Criteria
Age RangeN/A — 21 Years
SexALL
Healthy VolunteersNo
Study Sites3

INCLUSION CRITERIA: Stratum 1 * Patients with histologically confirmed diagnosis of medulloblastoma that is recurrent, progressive, or refractory to standard therapy. All tumors must have histologic verification at either time of initial diagnosis or recurrence. Note: For this study, refractory dis...

Countries:United States
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Recent Changes (Last 90 Days)
LOWMay 24, 2026NCT04743661studyFirstPostDate: changed