Rituximab is a biologic medication widely used to treat various conditions, including certain types of cancer such as non-Hodgkin’s lymphoma and chronic lymphocytic leukemia, as well as autoimmune diseases like rheumatoid arthritis and certain vasculitides. These conditions often require long-term treatment, and the associated costs can be substantial. The availability of biosimilar versions of rituximab offers new possibilities for patient care.
Understanding Biologics and Biosimilars
Biologic drugs, like rituximab, are complex medications derived from living organisms, such as cells or microorganisms. Unlike traditional small-molecule drugs, which are made through chemical synthesis, biologics are large, intricate molecules. Their manufacturing involves elaborate biological processes that can result in minor variations between batches.
A biosimilar is a biologic medication approved based on demonstrating high similarity to an already approved original biologic, known as the reference product. This means there are no clinically meaningful differences between the biosimilar and the reference product in terms of safety, purity, and potency. Due to their complex biological origin and manufacturing, biosimilars are highly similar but not exact copies.
This distinguishes biosimilars from generic drugs. Generic drugs are exact chemical copies of small-molecule drugs, containing identical medicinal ingredients to their brand-name counterparts. In contrast, biosimilars are not considered exact replicas because of their biological origin and manufacturing processes.
Regulatory Approval and Safety
Regulatory bodies, such as the U.S. Food and Drug Administration (FDA), employ a rigorous approval pathway for biosimilar medications. This process ensures biosimilars are as safe and effective as their reference products. The FDA evaluates biosimilars using a “totality of the evidence” approach, which involves a comprehensive comparison to the reference product.
This approach includes extensive analytical studies to confirm structural and functional similarity between the biosimilar and the reference product. These analytical comparisons are the foundation of biosimilar development, highly sensitive in detecting potential differences. Animal studies may also be conducted to provide toxicology or pharmacology information.
Clinical pharmacology studies are performed in humans to demonstrate the biosimilar moves through the body and produces comparable effects as the reference product. A clinical study in a sensitive patient population may also confirm equivalent efficacy, safety, and immunogenicity. This thorough vetting process aims to reassure patients and healthcare providers about the quality and performance of approved biosimilars.
Available Rituximab Biosimilars
Several rituximab biosimilars have received approval from the FDA, providing additional treatment options. Truxima (rituximab-abbs) was the first rituximab biosimilar approved in the United States. It is indicated for adult patients with non-Hodgkin’s lymphoma (NHL), including follicular and diffuse large B-cell lymphoma, chronic lymphocytic leukemia (CLL), moderately-to-severely active rheumatoid arthritis (RA), granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) when used with glucocorticoids, and moderate to severe pemphigus vulgaris.
Ruxience (rituximab-pvvr) is another FDA-approved rituximab biosimilar, with indications largely mirroring those of the reference product. It is approved for adult patients with non-Hodgkin’s lymphoma, chronic lymphocytic leukemia, and rheumatoid arthritis. It is also indicated for adult patients with granulomatosis with polyangiitis and microscopic polyangiitis in combination with glucocorticoids, and moderate to severe pemphigus vulgaris.
Riabni (rituximab-arrx) is a third FDA-approved biosimilar option. Its approved uses include non-Hodgkin’s lymphoma, chronic lymphocytic leukemia, rheumatoid arthritis, granulomatosis with polyangiitis, microscopic polyangiitis when administered with glucocorticoids, and moderate to severe pemphigus vulgaris.
Patient Considerations
The introduction of biosimilars generally leads to increased competition and cost savings. Biosimilars are typically launched at a lower price point, potentially reducing out-of-pocket expenses for patients and lowering overall healthcare system costs. These savings can enhance access to important biologic therapies for a broader patient population.
Insurance coverage for biosimilars can vary among health plans, including commercial insurance and Medicare. While many plans cover biosimilars, the specific terms of coverage, such as whether a biosimilar is preferred, non-preferred, or covered on par with the reference product, differ. Patients should consult with their insurance provider to understand their specific formulary and coverage details.
A decision to switch from a reference biologic to a biosimilar should always involve a discussion with a healthcare provider. Studies evaluating the impact of switching from a reference biologic to a biosimilar have generally shown no differences in safety, efficacy, or immunogenicity outcomes. The FDA considers these studies when approving biosimilars, providing reassurance regarding the clinical performance of these medications.