Celltrion has submitted an Investigational New Drug (IND) application to the U.S. Food and Drug Administration (FDA) for a Phase 4 clinical trial of Zymfentra (subcutaneous infliximab, sold as Remsima SC in Europe). The study aims to generate clinical evidence supporting a high-dose 240 mg maintenance regimen alongside the currently approved 120 mg dose.
In the United States, Zymfentra is currently approved as a 120 mg biweekly maintenance therapy for adult patients with Crohn’s disease and ulcerative colitis—the two primary forms of inflammatory bowel disease (IBD), characterized by chronic intestinal inflammation caused by immune system dysregulation. By securing regulatory data for a 240 mg option, Celltrion seeks to provide clinicians with flexible, personalized dosing tailored to disease severity.
Replicating European Success in the U.S. Market
The strategic move extends Celltrion’s European model to the American healthcare market. Across the top five European markets (Germany, France, Italy, Spain, and the UK), Remsima SC achieved approximately a 32 percent market share in the first quarter of 2026, driven largely by high-dose prescribing tailored to individual patient conditions.
The U.S. Phase 4 post-marketing trial will enroll 447 patients with Crohn's disease and ulcerative colitis across 55 clinical sites. The trial design will evaluate non-inferiority between a high-dose intravenous (IV) infliximab control group and patients receiving 240 mg of subcutaneous Zymfentra.
Expanding Indications Beyond Inflammatory Bowel Disease
"This trial represents a crucial opportunity to elevate Zymfentra's clinical utility by expanding personalized treatment regimens based on patient needs," a Celltrion official said on Sept. 15.
Concurrently, Celltrion is conducting global clinical trials to expand Zymfentra's label to include rheumatoid arthritis (RA). Because rheumatoid arthritis represents a substantial segment of the U.S. autoimmune therapeutic market, adding the indication would significantly expand Zymfentra's addressable patient population beyond gastrointestinal disorders.
