FDA fingers tox assessment as cause of Denali clinical hold, leaving biotech with a to-do list to regain momentum

Denali Therapeutics now knows what it needs to do to get its Alzheimer’s disease drug DNL919 back on track. Almost one month after the FDA informed Denali of a clinical hold via email, the agency has sent a formal letter setting out what needs to happen before it OKs a study of the Takeda-partnered prospect.

San Francisco-based Denali shared a brief notice about the FDA’s clinical hold Jan. 13, precipitating a double-digit drop in its share price. At that time, little information was available publicly, with Denali only disclosing the FDA’s action and promising to provide additional updates after talking to the agency.

Today, with the FDA nearing the end of the 30-day window it had to send an official clinical hold letter, Denali revealed it has received the formal notice from the agency. Denali shared details of what the FDA said and what it will take to get clearance to run the study of the antibody transport vehicle, which is designed to activate the TREM2 receptor found on certain immune cells in the central nervous system.   

The FDA’s observations related to the preclinical toxicology assessment, Denali said. Denali is working to provide the FDA with the information needed to start the study, which include proposed changes to the clinical trial protocol, the informed consent form and the investigator brochure.

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It is unclear how long it will take Denali to get the FDA to lift the clinical hold. Denali is yet to share a  timeline but plans to post an update on the program “once a clear path forward has been established.” 

The delay affects a study that Denali identified as one of three trials that were supposed to post clinical data with “high impact potential” this year. Shortly before being hit with the clinical hold, Denali listed the delivery of first-in-human data that could confirm pathway engagement and validate its antibody transport vehicle as one of the highlights of 2022. Those data could now slip into 2023.