Lilly working to resolve mirikizumab manufacturing issues following CRL

Eli Lilly expects mirikizumab to become the first IL-23p19 to treat UC once manufacturing issues highlighted by the US FDA are resolved.

Dan Stanton, Managing editor

May 17, 2023

2 Min Read
Lilly working to resolve mirikizumab manufacturing issues following CRL
Image: DepositPhotos/ tashatuvango

Eli Lilly expects mirikizumab to become the first interleukin-23 subunit alpha (IL-23p19) to treat ulcerative colitis once manufacturing issues highlighted by the US FDA are resolved.

Last month, the US Food and Drug Administration (FDA) issued a complete response letter (CRL) to Eli Lilly for mirikizumab, its monoclonal antibody candidate for the treatment of ulcerative colitis (UC).

Patrik Jonsson, president of Lilly Immunology, discussed his company’s approach to resolving the issue at the Bank of America Securities 2023 Healthcare Conference last week.


Image: DepositPhotos/

When asked whether the CRL was a surprise, Jonsson acknowledged that such letters are never expected. However, he emphasized that there were no concerns related to the medical or safety profile of mirikizumab, nor with its label.

“The FDA raised objections in terms of the proposed manufacturing process for mirikizumab, and we believe that we are on top of that,” he said.

“We’re working very closely with the FDA to resolve this as quickly as possible, and we are still expecting to be the first IL-23p19 for treating ulcerative colitis in the US.”

IL-23p19, a protein subunit that forms part of the interleukin-23 cytokine, is involved in regulating the immune system and plays a role in chronic inflammation and autoimmune diseases. By targeting IL-23p19, therapies can be developed to modulate the immune response and potentially treat conditions such as psoriasis, psoriatic arthritis, and inflammatory bowel diseases.

While focusing on resolving the manufacturing issue, Eli Lilly also highlighted their ongoing efforts to launch mirikizumab in other regions. In Japan, the drug recently received approval from the Pharmaceuticals and Medical Devices Agency (PMDA), while the EU’s Committee for Medicinal Products for Human Use (CHMP) has also provided a positive opinion.

The CRL will not impact any other Lilly asset, Jonsson confirmed. “We are very confident with the quality of the medicines we are producing and having in the marketplace today. This is a mirikizumab-specific objection only, and only related to the proposed manufacturing process of miri and nothing else. And we don’t foresee that it will have an impact on the upcoming launches in Japan or in Europe either.”

About the Author(s)

Dan Stanton

Managing editor

Journalist covering the international biopharmaceutical manufacturing and processing industries.

Founder and editor of Bioprocess Insider, a daily news offshoot of publication Bioprocess International, with expertise in the pharmaceutical and healthcare sectors, in particular, the following niches: CROs, CDMOs, M&A, IPOs, biotech, bioprocessing methods and equipment, drug delivery, regulatory affairs and business development.

From London, UK originally but currently based in Montpellier, France through a round-a-bout adventure that has seen me live and work in Leeds (UK), London, New Zealand, and China.

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