Eli Lilly in the Drug Discovery & Development Pharma 50Last year, Lilly’s (NYSE:LLY) Alzheimer’s monoclonal antibody donanemab appeared to be a superior therapy to aducanumab from Biogen (Nasdaq:BIIB) and Eisai (OTCMKTS:ESALY), the first such antibody to win FDA approval. But facing criticism over its decision to grant accelerated approval to aducanumab, FDA has sent Lilly a complete response letter for the accelerated approval submission of donanemab to treat early symptomatic Alzheimer’s disease.

Specifically, the FDA noted that a limited number of patients with at least 12 months of drug exposure data were included in the submission.

LLY shares fell 2.23% to $343.26 in afternoon trading.

The Alzheimer’s Association supports the move

The Alzheimer’s Association released a statement praising FDA’s decision, saying that it appreciated its “methodical process in reviewing treatments for Alzheimer’s disease.”

The association noted that the FDA’s demand for additional data to decide whether to grant accelerated approval of donanemab “demonstrates the rigorous approach the agency takes in reviewing individual treatments.”

Phase 3 donanemab data coming later in 2023

Lilly anticipates that data would be ready for a definitive Phase 3 readout from the TRAILBLAZER-ALZ 2 study and submission for traditional approval by the middle of 2023.

FDA asked Lilly to provide data from at least 100 patients who had at least 12 months of continuous donanemab therapy.

Lilly has experienced strong growth following the FDA approval of its antidiabetic medication Mounjaro (tirzepatide) to treat type 2 diabetes in May 2022. In addition, Tirzepatide received FDA fast-track designation to treat obese and overweight adults with weight-related comorbidities.

UBS projects that tirzepatide could have peak sales of $25 billion. In September 2022, UBS Managing Director, Biotechnology Colin Bristow noted that it views donanemab as a “risk” and “not critical for the buy thesis” for Lilly but added that the antibody is “the highest potential late-stage Alzheimer’s asset.”

Since that report was authored, FDA approved Eisai’s, Leqembi (lecanemab), an amyloid beta-directed antibody for Alzheimer’s.

UBS projected in September 2022 that donanemab would generate peak risk-adjusted sales of $4.8 billion with a 60% probability of success.