FDA Decides Not to Approve 131I-Omburtamab for Neuroblastoma With CNS/Leptomeningeal Metastases


The FDA has followed the recommendation of its Oncologic Drugs Advisory Committee and issued a complete response letter denying approval to 131I-omburtamab as a treatment for central nervous system and leptomeningeal metastases stemming from neuroblastoma.

131I-omburtamab, a potential treatment for patients with neuroblastoma who have developed central nervous system or leptomeningeal metastases, has been issued a complete response letter from the FDA, according to a press release from Y-mAbs Therapeutics.1

After reviewing omburtamab’s biologics license application, the FDA stated that they were not able to grant approval in its current state. The regulatory organization’s decision was consistent with a vote from the Oncologic Drugs Advisory Committee (ODAC) in October 2022, in which the group voted 16-to-0 against omburtamab in the aforementioned indication.2

The complete response letter further recommended a meeting with the FDA to determine an adequate and well controlled clinical trial design that can notably highlight evidence supporting the efficacy and risk/benefit profile of omburtamab.

“We are disappointed by the [complete response letter] but not surprised based on the outcome of the ODAC meeting on October 28,” Thomas Gad, president and interim chief executive officer at Y-mAbs Therapeutics, said in the press release.

The ODAC’s vote was based on findings from the phase 1 study 03-133 (NCT00089245), which assessed omburtamab in a population with relapsed, recurrent, or advanced CNS or leptomeningeal cancer, as well as the phase 1/2 study 101 (NCT03275402) examining omburtamab in neuroblastoma with CNS or leptomeningeal metastases. Members of ODAC concluded that there was not enough evidence to support omburtamab’s overall survival benefit in this patient population.

The biologics license application for omburtamab was submitted to the FDA in April 2022.3 The application for the monoclonal antibody targeted to B7-H3 was created for a population of pediatric patients diagnosed with CNS or leptomeningeal metastases stemming from neuroblastoma and were based on safety/efficacy data from study 101 and 03-133.


  1. Y-mAbs announces complete response letter for omburtamab biologics license application. News release. Y-mAbs. December 1, 2022. Accessed December 5, 2022. https://bit.ly/3HbVSJm
  2. Y-mAbs announces outcome of FDA Advisory Committee Meeting on omburtamab. News release. Y-mAbs Therapeutics. October 28, 2022. Accessed November 2, 2022. http://bit.ly/3h70aab
  3. Y-mAbs announces submission of omburtamab biologics license application to FDA. News release. Y-mAbs Therapeutics. April 1, 2022. Accessed December 5, 2022. https://bit.ly/3h06sYZ
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