Eli Lilly’s classification battle with the Food and Drug Administration over its obesity drug retatrutide is intensifying as the company prepares to file for approval, according to an Aug. 5 report. The outcome of this dispute could determine how long Lilly has market exclusivity for the potential blockbuster therapy.
Since September 2024, Lilly has been engaged in litigation with the FDA regarding whether retatrutide qualifies as a biologic. The FDA concluded that retatrutide is neither a protein nor a biological product, making it ineligible for a biologics license application (BLA). Instead, Lilly would need to pursue approval through a new drug application (NDA), which offers five years of exclusivity compared to twelve years under a BLA.
On an earnings call, Chief Executive Officer Dave Ricks addressed the ongoing litigation and said, “We’ve been pursuing this for a little while because we believe retatrutide is a biologic application, both in terms of [the] amino acid count rule as well as analogous to a protein, so that’s our position.”
The legal disagreement centers on definitions: the FDA defines proteins as alpha amino acid polymers with at least 40 amino acids. While Lilly argues that retatrutide’s 41 amino acids meet this threshold, the agency contends that not all are alpha amino acids and classifies it as a drug. During oral arguments in September 2025, lawyers representing the FDA maintained that historical precedent supports their interpretation.
The courts have issued mixed rulings so far—vacating one FDA decision but sending back questions about whether retatrutide is “analogous to” a protein. Lilly has appealed and hopes for resolution soon. Ricks said, “Obviously, it’s active litigation, but we would hope to come to a conclusion with the FDA to support a BLA application.”
Ricks also confirmed preparations are underway for global regulatory submissions targeting obesity and other conditions such as obstructive sleep apnea and knee osteoarthritis pain. He added that additional manufacturing data collection continues ahead of their planned first quarter 2027 submission: “While that’s going on, you could bet we’re in communication with the agency, and we’ll give an update to investors as there’s any progress on the filing status for retatrutide.”
