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How does the drug Rituxan work?

Medically reviewed by Kristianne Hannemann, PharmD. Last updated on March 26, 2025.

What does Rituxan do to your body? What is Rituxan’s mechanism of action?

Official answer

by Drugs.com

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.

Related questions

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

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.

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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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