Merus' Zenocutuzumab: FDA Extends PDUFA Goal Date

On November 5, 2024, Merus N.V. (Nasdaq: MRUS) announced that the United States Food and Drug Administration (FDA) has extended the Prescription Drug User Fee Act (PDUFA) goal date for zenocutuzumab (Zeno) Biologics License Application (BLA) currently under priority review. The US FDA has extended the PDUFA goal date to February 4, 2025 to enable sufficient time to review information recently submitted by the Company in response to a CMC information request. No additional clinical data have been requested.

Merus, a clinical-stage oncology company developing innovative, full-length multispecific antibodies (Biclonics® and Triclonics®), is focused on bringing Zeno to patients with NRG1+ cancer if approved. The extension of the PDUFA goal date allows Merus additional time to address the FDA's information request, ensuring a thorough review process. This extension does not impact the ongoing phase 1/2 eNRGy trial and Early Access Program (EAP), which have already treated over 175 patients with NRG1+ cancer.


Zenocutuzumab, a Biclonics® antibody, utilizes Merus' proprietary Dock & Block technology to bind to HER2 and disrupt the interaction between the HER3 receptor and neuregulin or NRG1-fusion proteins. Preclinical studies have confirmed that zenocutuzumab effectively blocks the formation of HER2/HER3 heterodimers, in turn preventing cancer cell proliferation and survival. The BLA submission for Zeno included results from the Phase I/II eNRGy study, which demonstrated a 37% objective response rate in NSCLC patients positive for NRG1 fusions and a 42% objective response rate in PDAC patients carrying the same biomarker status.


The extension of the PDUFA goal date for zenocutuzumab indicates additional review time is needed, potentially delaying its approval and market availability. This extension is due to Merus submitting new information in response to a CMC (Chemistry, Manufacturing, and Controls) information request, suggesting potential manufacturing or quality concerns. While no additional clinical data were requested, addressing CMC issues could impact the production and distribution of Zeno. This delay may affect Merus' plans to secure a commercialization partnership and bring Zeno to patients with NRG1+ cancer, if approved.

In conclusion, the FDA's PDUFA extension for zenocutuzumab allows Merus additional time to address the FDA's information request without the need for further clinical data. This extension is in line with recent trends in the biotechnology sector, where the FDA has granted extensions to facilitate more thorough reviews. Investors should monitor the situation closely, as the resolution of these CMC issues will be crucial in determining Zeno's regulatory and market timeline.