In November 2019, Celltrion received approval in Europe for its subcutaneous (SC) form of infliximab. At that time, we speculated on the dramatic implications such an approval might have in the US. More than three years later, Celltrion’s US division announced that it had completed its 351(a) submission to the US Food and Drug Administration.
A potential approval in Q4 2023/Q1 2024 would provide a self-injectable form of infliximab that would easily be covered under the pharmacy benefit of health plans and insurers. As a result, payers generally favor self-injectables over infusibles. This would be stiff competition for the infusible biosimilars on the market. Janssen, manufacturer of the reference product Remicade®, introduced its low WAC-priced, unbranded infliximab infusion last year, perhaps sensing the looming implications of a Celltrion approval, along with the 2023 biosimilar launches of the competitor anti-TNF inhibitor adalimumab.
Currently available infusible infliximab biosimilars include Celltrion’s Inflectra® (marketed by Pfizer), Samsung Bioepis’ Renflexis® (marketed by Organon), and Amgen’s Avasola®. According to the 2022 Amgen Biosimilar Report, Remicade still represents 54% of the marketshare, followed by Inflectra at 29%, and the others with single-digit shares, as of Q2 2022.
Celltrion’s application for the approval of CT-P13 SC was based on phase 3 trials of patients with moderate to severe Crohn’s disease and ulcerative colitis, in both cases compared with placebo. The press release termed this move a “planned initial submission package,” implying others may follow. Whereas infusible Inflectra is currently approved for use in patients with inflammatory bowel disease, rheumatoid arthritis, and other autoimmune disorders, the FDA will likely require additional clinical studies to approve the SC formulation for the broader indication list. It is unclear, however, whether payers will limit the agent’s use to inflammatory bowel disease only if it gains FDA approval.
The reason for Celltrion’s filing a 351(a) biologic licensing application, and not a supplemental 351(k) biosimilar application, is that Remicade was not approved as an SC product. There was no reference product to compare with the SC formulation. In contrast, if Coherus Biosciences does apply for approval of an on-body injector form of Udenyca®, it could hypothetically be compared with Neulasta OnPro®, the reference pegfilgrastim product.