Spotlight On: Rituxan® (Rituximab) / Truxima® (Rituximab-Abbs) / Ruxience® (Rituximab-Pvvr) / Riabni™ (Rituximab-Arrx) - May 2026

Why It Matters

Understanding the counting methodology clarifies the true scope of patent risk for biosimilar entrants, influencing launch timing and licensing strategies in the lucrative oncology market.

Key Takeaways

• Rituximab patents face challenges in both IPRs and court lawsuits
• Claims are counted per proceeding, causing multiple tallies for same patent
• Within a single litigation, each claim appears only once
• IPRs count each claim once, regardless of §102 or §103 basis
• Overlapping counts can inflate perceived patent pressure on biosimilars

Pulse Analysis

Rituximab remains a cornerstone therapy for non‑Hodgkin lymphoma and rheumatoid arthritis, making its patent estate a high‑value target for generic and biosimilar manufacturers. The four branded versions—Rituxan, Truxima, Ruxience and Riabni—share a common set of foundational patents that protect the molecule, formulation, and delivery methods. When challengers file inter partes reviews at the Patent Trial and Appeal Board, they can contest the same claim under multiple statutory grounds, yet the IPR process records each claim only once. In parallel, federal courts hear infringement lawsuits where each alleged infringing claim is listed in the complaint, again counted singularly per case. This dual‑track approach creates a layered landscape where the same patent can be listed repeatedly across distinct forums, inflating the headline number of challenged claims.

The counting conventions matter because they shape how companies assess the intensity of patent opposition. Analysts who simply sum the reported claim counts may overestimate the actual breadth of the patent barrier, potentially leading to overly cautious market entry strategies. Conversely, a nuanced view that de‑duplicates overlapping claims reveals a more precise picture of the remaining enforceable scope. For biosimilar developers, this insight informs decisions on whether to pursue a design‑around, negotiate a settlement, or wait for patent expirations, each path carrying distinct cost and timeline implications.

From a broader industry perspective, the rituximab case illustrates how complex patent portfolios can be leveraged to extend market exclusivity beyond the nominal expiration dates. The practice of filing multiple IPRs and lawsuits, while legally permissible, raises policy questions about the balance between rewarding innovation and preventing undue delay of affordable therapies. Stakeholders—including regulators, payers, and patient advocacy groups—must monitor these tactics to ensure that the patent system continues to serve its dual purpose of incentivizing drug development while facilitating timely access to life‑saving treatments.