Celltrion and Teva's Truxima Becomes First Interchangeable Rituximab Biosimilar in the US

The FDA has granted interchangeability designation to Truxima (rituximab-abbs), Celltrion and Teva's biosimilar to Genentech's Rituxan, per the companies' July 1, 2026 announcement as reported by Goodwin. Truxima is the first rituximab biosimilar to receive interchangeable status in the United States, roughly seven years after its original November 2018 approval.

What does interchangeability actually change?

Interchangeability is a formal regulatory status under the Biologics Price and Competition and Innovation Act framework, recorded in FDA's Purple Book database, which lists licensed biological products alongside their reference products and interchangeability evaluations. A biosimilar that is not interchangeable may be dispensed only as prescribed; an interchangeable product may, subject to state pharmacy law, be substituted for the reference biologic without the prescriber's involvement. The designation therefore matters commercially mostly through pharmacy-level substitution volume.

Earning the status requires data beyond biosimilarity. Sponsors must show that the product can be switched to and from the reference biologic without diminished safety or efficacy, which typically means a switching study in patients. FDA's evaluations of both biosimilarity and interchangeability are published in the Purple Book, which covers all CDER-regulated licensed biologics, including biosimilar and interchangeable products.

Why does the rituximab market care now?

Rituximab is one of the highest-volume biologic targets of the past decade, and the US market has had three approved biosimilars. Per the Goodwin analysis on JD Supra, Amgen's Riabni (rituximab-arrx) and Pfizer's Ruxience (rituximab-pvvr) are the other two approved rituximab biosimilars, and neither has been approved as interchangeable. Truxima's new status is thus a category first rather than an incremental label update.

The history explains the timing. Truxima was approved by FDA in November 2018 for the same indications as Rituxan, including non-Hodgkin lymphoma, chronic lymphocytic leukemia, rheumatoid arthritis, granulomatosis with polyangiitis, and microscopic polyangiitis, per the same report. Following settlement of BPCIA litigation with Genentech, Celltrion and Teva launched the product in the United States on November 11, 2019. Interchangeability filings have followed after market entry, once switching-study data could be generated, which is the same sequence the adalimumab biosimilar market followed.

What comes next?

Watch two things. First, whether the designation converts into measurable share through substitution in states where pharmacy-level substitution is permitted, against a reference product and two non-interchangeable biosimilars. Second, whether Amgen or Pfizer respond with interchangeability supplements of their own; FDA's decisions on those filings would determine whether Truxima keeps its unique position. The Purple Book entries, updated as evaluations are completed, are the primary documents to track.

State law completes the picture. Substitution rules for interchangeable biologics vary by state, including whether pharmacy substitution is automatic or requires prescriber communication, so the commercial effect of the designation will differ market by market rather than uniformly. That patchwork is the same one the adalimumab biosimilar wave navigated after interchangeable status spread across that class.