Celltrion files IND for high-dose Zymfentra phase 4 trial in US

Celltrion has begun clinical procedures to establish a high-dose prescribing basis for Zymfentra (infliximab), its subcutaneous autoimmune disease treatment that has gained a foothold in the US market.

Celltrion announced Tuesday that it had submitted an investigational new drug application to the US Food and Drug Administration for a phase 4 clinical trial to support 240 mg high-dose administration of Zymfentra.

The phase 4 trial will enroll 447 patients with Crohn's disease and ulcerative colitis across 55 sites in the United States. The study aims to directly demonstrate the non-inferiority of Zymfentra 240 mg against high-dose intravenous infliximab, generating objective clinical data for high-dose use ahead of any regulatory requirement.

Celltrion plans to bring to the US market the tailored dose-escalation strategy it has already validated in Europe. Remsima SC, which contains the same active ingredient, holds about a 32% market share across the five major EU countries as of the first quarter of this year, with high-dose prescribing calibrated to disease severity credited for driving that share higher.

By securing the new data, Celltrion intends to complete a "two-track" lineup in the US pairing the existing 120 mg dose with 240 mg, giving local physicians greater prescribing flexibility and improving patient convenience at the same time.

Alongside the dosing expansion, the company is pursuing additional indications to broaden the drug's potential market. Celltrion is running a global clinical program in parallel to add a rheumatoid arthritis indication — a condition with a large patient population in the US — to the existing inflammatory bowel disease label, widening the pool of eligible patients.

Zymfentra has already secured reimbursement coverage of more than 90 percent through contracts with major US pharmacy benefit managers. Supported by synergies with its direct-sales distribution network, the product posted first-half sales of 99.5 billion won ($73.9 million), a jump of 176.4 percent from the same period last year.

The phase 4 launch is a strategic move to draw into the subcutaneous segment those intravenous patients who previously required dose increases due to diminishing efficacy, cementing Zymfentra's dominance as the only subcutaneous infliximab formulation available in the United States.

"This trial will be an opportunity to diversify tailored treatment options based on patient condition and elevate the clinical value of Zymfentra to a new level," a Celltrion official said. "We will combine clinical data with our direct-sales capabilities to lead the autoimmune disease treatment market in the United States."