FDA delays decision on Merus' first-in-class cancer drug by 3 months

The FDA has scuttled Merus’ plans to win a speedy approval for its solid tumor drug zenocutuzumab. On the cusp of the priority review deadline, the agency has pushed back the decision date by three months to give its staff more time to assess recently submitted information.

Merus disclosed the FDA had accepted its zenocutuzumab filing for priority review on May 6. Benefiting from a six-month review, rather than the typical 10-month process, Merus was scheduled to learn if the FDA would approve the HER2xHER3 bispecific this week. Instead, the FDA delayed the decision date until Feb. 4.

The three-month delay relates to chemistry, manufacturing and controls (CMC) information, which the agency had requested from Merus. The Dutch biotech has provided the requested details but the FDA had too little time to review the submission by the original deadline. No additional clinical data have been requested, Merus said.

Merus’ management provided more details to William Blair analysts, revealing that the CMC information is related to a third-party manufacturer. The analysts said in a note to investors that “it appears the issue is between the FDA and the manufacturer, with Merus having less direct involvement,” adding that they are “encouraged by the fact that the issue is related to a third party.”

Delaying the decision could have implications for patients and Merus’ partnership plans. The biotech wants to find a partner to commercialize zenocutuzumab, although it recently softened its language on the topic. Previously, the biotech said signing up a partner was an “essential” step, although more recently it has begun calling a partner “important.” The analysts discussed what the delay means for partnering talks.

“Management is pleased with the progress on this front to date,” the analysts said. “The extension of the PDUFA date gives the company additional time to secure a partnership, but receiving approval would also be an important milestone in partnership discussions.”

The delay also defers what could become the first treatment for NRG1-positive cancers. NRG1 fusions are rare oncogenic drivers found in a variety of solid tumors. Multiple companies have targeted the fusions but the pack has thinned in recent years.

Elevation Oncology picked up seribantumab from Merrimack Pharmaceuticals and set out to establish the anti-HER3 antibody in NRG1-fusion tumors, regardless of where in the body they are found. Later, Elevation paused investment in the program pending a partnership that is yet to arrive. Rain Oncology terminated its NRG1 fusion study in 2021.