Sanofi's hopes for rare blood disease candidate sutimlimab on hold after FDA blasts 3rd-party manufacturer

FDA Building 2
The FDA has been particularly tough on drug applications this year with the pandemic preventing inspections. (FDA)

When a new drug goes in front of the FDA for consideration, a lot of moving pieces must be in place for a successful review—manufacturing standards included. That didn't happen for Sanofi, which is pressing pause on a rare disease candidate after the FDA found issues at a contract manufacturer's plant.

The FDA blasted a third-party manufacturer of Sanofi's rare blood disease drug sutimlimab in a complete response letter, citing "certain deficiencies" at the contractor's site, the French drugmaker said Friday. 

A Sanofi spokeswoman declined to specify who the manufacturer cited in the FDA's letter was or what the nature of the deficiencies were.  

With its application on hold, Sanofi said it would work with its manufacturer and the FDA to resolve the issues in a "timely manner." The drugmaker didn't say how quickly it expected to turn around a new application. 

The untimely feedback from the FDA dims C1 inhibitor sutimlimab's chances in cold agglutinin disease (CAD), a rare blood disease characterized by anemia, fatigue and other symptoms. 

RELATED: Sanofi nabs speedy review of sutimlimab, aiming for a November approval

In May, the FDA accepted Sanofi's sutimlimab application under priority review based on the strength of the drug's pivotal phase 3 data, Sanofi believed. Those results, unveiled in late 2019, showed 13 of the 24 patients treated with sutimlimab after 26 weeks met the study's primary endpoint, a composite assessment that looked at hemoglobin and freedom from transfusions.

Close to two-thirds of participants met the hemoglobin part of the endpoint, indicating they either experienced a 2 g/dL increase from baseline or ended the study with 12 g/dL or higher, a level that is at the bottom of the normal range for women and just below it for men. More than two-thirds of the subjects were free from transfusions from week five onward.

The FDA's letter did not target sutimlimab's clinical findings or safety, Sanofi noted in a release.

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