The US Food and Drug Administration (FDA) has issued a complete response letter (CRL) regarding the biologics license application (BLA) for omburtamab for the treatment of central nervous system (CNS)/leptomeningeal metastasis from neuroblastoma.

Omburtamab is a radiolabeled monoclonal antibody designed to target tumor cells that express B7-H3. The BLA submission included data from 2 clinical studies, Study 101 ( Identifier: NCT03275402) and Study 03-133 ( Identifier NCT00089245). The studies were designed to evaluate the efficacy and safety of omburtamab in children and adults with neuroblastoma and CNS/leptomeningeal metastasis. 

In October 2022, the FDA’s Oncologic Drugs Advisory Committee (ODAC) met to discuss the application and identified 3 key efficacy issues. According to the CRL, the FDA could not approve the application in its current form as additional data would be required to substantiate the effectiveness and safety of the product.

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“We are disappointed by the CRL but not surprised based on the outcome of the ODAC meeting on October 28,” said Thomas Gad, president and interim chief executive officer of Y-mAbs Therapeutics, the company developing omburtamab. “We want to express our gratitude to all the patients, their families, and investigators who have participated in our clinical trials and advocated for the advancement of omburtamab.”


Y-mAbs announces complete response letter for omburtamab biologics license application. News release. Y-mAbs. December 1, 2022. Accessed December 5, 2022.

This article originally appeared on MPR