How does the drug Rituxan work?
What does Rituxan do to your body? What is Rituxan’s mechanism of action?
Rituxan (rituximab) is a monoclonal antibody that targets the CD20 protein found on the surface of B-cells, a type of white blood cell involved in immune responses. By binding to CD20, Rituxan helps eliminate these cells, which is beneficial in treating certain cancers and autoimmune disorders. Its mechanism of action involves multiple pathways to destroy these cells.
Rituxan in Lymphoma and Leukemia
Non-Hodgkin’s lymphoma (NHL) and chronic lymphocytic leukemia (CLL) are cancers that affect B-cells. CD20 is an antigen that is displayed on certain B-cells, providing a target for Rituxan to latch onto. Rituxan works by:
- Recruiting immune cells – It enlists the body’s immune system, including macrophages and natural killer cells, to attack B-cells. Rituxan activates immune cells to destroy B-cells, a process known as antibody-dependent cellular cytotoxicity.
- Triggering cell destruction – It may induce B-cell death through complement-dependent cytotoxicity and apoptosis (programmed cell death).
- Synergy with chemotherapy: Rituxan sensitizes cancer cells to chemotherapy, enhancing treatment effectiveness.
Complement-dependent cytotoxicity is also thought to be a mechanism via which Rituxan is able to destroy B-cells. The complement system, or complement cascade as it is also known, is a system made up of small proteins that circulate in the blood, which when activated lead to the B-cells being destroyed by phagocytosis. Rituxan is able to bind to proteins in the complement system and initiate the cascade of events that targets and destroys the B-cells that it attaches to.
Rituxan is also thought to work synergistically with the chemotherapy drugs that it is used with. It has been suggested Rituxan may induce apoptosis, or programmed cell death, in chemo-sensitized cells via direct signaling. It is thought that Rituxan may somehow sensitize cancer cells to the effects of other chemotherapy drugs.
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Rituxan in Autoimmune Disorders
In conditions like rheumatoid arthritis (RA), granulomatosis with polyangiitis (GPA), and microscopic polyangiitis (MPA), Rituxan helps by reducing the number of B-cells that produce harmful auto-antibodies. This decreases inflammation and joint damage.
Administration and Use
Rituxan is administered intravenously or subcutaneously and may be combined with other therapies depending on the condition. It is FDA approved for:
- Non-Hodgkin’s lymphoma
- Chronic lymphocytic leukemia
- Pediatric B-cell malignancies
- Rheumatoid arthritis
- Granulomatosis with polyangiitis
- Microscopic polyangiitis
- Pemphigus vulgaris
Summary
By targeting B-cells, Rituxan plays a critical role in treating both blood cancers and autoimmune diseases, often improving patient outcomes when used as part of a comprehensive treatment plan.
References
- Weiner GJ. Rituximab: mechanism of action. Semin Hematol. 2010 Apr; 47(2): 115–123. doi: 10.1053/j.seminhematol.2010.01.011.
- American Cancer Society. Types of B-cell Lymphoma. [Accessed May 6, 2020]. Available online at: https://www.cancer.org/cancer/non-hodgkin-lymphoma/about/b-cell-lymphoma.html.
- Randall KL. Rituximab in autoimmune diseases. Aust Prescr. 2016 Aug; 39(4): 131–134. doi: 10.18773/austprescr.2016.053.
- Cochrane. Rituximab for rheumatoid arthritis. January 20, 2015. [Accessed May 6, 2020]. Available online at: https://www.cochrane.org/CD007356/MUSKEL_rituximab-for-rheumatoid-arthritis.
- Rituxan for GPA MPA. How Rituxan is thought to work. [Accessed May 6, 2020]. Available online at: https://www.rituxanforgpampa.com/about-rituxan-gpa-mpa-treatment/how-rituxan-is-thought-to-work.html.
- Rituxan [package insert]. Updated January 2025. Genentech, Inc. Accessed March 26, 2025 at https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=b172773b-3905-4a1c-ad95-bab4b6126563
Read next
How long does it take for Rituxan to work?
Patients treated with Rituxan may notice an early response within 7-8 weeks of treatment. Most rheumatoid arthritis patients will notice some improvement in their symptoms, such as improvement in their levels of pain and inflammation, within 16 weeks of starting treatment with Rituxan. Continue reading
What are biosimilar drugs and how do they compare to biologics?
A biosimilar is a biological product that is similar to a reference biologic (usually the originally approved product) and for which there are no clinically meaningful differences in terms of safety, purity, and potency. One example is Amjevita (adalimumab-atto), the first biosimilar approved for Humira (adalimumab) in 2016.
Continue reading
Does Rituxan cause hair loss?
It’s possible for Rituxan (rituximab) to cause hair loss. This includes losing hair anywhere on your body, such as your head, legs, eyebrows, and eyelashes. Hair loss (alopecia) does not seem to be a common side effect of Rituxan. Continue reading
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Drug information
- Rituxan Information for Consumers
- Rituxan prescribing info & package insert (for Health Professionals)
- Side Effects of Rituxan (detailed)
- Rituxan user reviews (52)
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