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How long does it take for Rituxan to work?

How will I know if Rituxan is working?

Medically reviewed by Drugs.com. Last updated on May 8, 2020.

Official Answer

by Drugs.com

Rituxan (rituximab) is a monoclonal antibody therapy that targets a protein on the surface of B-cells called CD20. B-cells are a type of white blood cell and an important part of our immune system involved in fighting off foreign invaders. Rituxan is used in the treatment of non-Hodgkin’s lymphoma (NHL) and chronic lymphocytic leukemia (CLL), which are types of blood cancer that affect B-cells. It is also used to treat autoimmune disorders, such as rheumatoid arthritis, where B-cells attack a person’s cells by mistake causing the swelling and joint damage associated with the disease. Rituxan is administered via an intravenous infusion.

How quickly does Rituxan start working in patients with non-Hodgkin’s lymphoma and chronic lymphocytic leukemia?

Rituxan starts working rapidly in patients with NHL. An initial clinical trial showed CD20+ B-cells were rapidly depleted in the peripheral blood of patients 24-72 hours after they received Rituxan. Tumor biopsies taken 2 weeks after treatment with Rituxan revealed that the drug had attached itself to tumor cells and the number of B-cells had been decreased. Further investigation also confirmed that B-cells were depleted within the first 3 weeks.

In addition to these immediate effects of Rituxan on the body, researchers have investigated how long it takes for the drug to cause signs of cancer to decrease and disappear. In a key clinical trial conducted in 166 patients with NHL, the median time to onset of response was 50 days in the 48% of patients who responded to therapy.

Rituxan also works in the same way to cause a rapid depletion of B-cells in patients with CLL.

Your doctor will monitor you to see whether Rituxan is working for you and check for side effects.

How quickly does Rituxan start working in patients with rheumatoid arthritis?

Rituxan also rapidly depletes B-cells from the blood circulation in patients with rheumatoid arthritis. One dose of Rituxan is enough to deplete a patient’s B-cells. An important point to note however, is that Rituxan works more slower - has a slower onset of action - in people with rheumatoid arthritis compared with other biological DMARD (disease modifying anti-rheumatic drugs).

Patients treated with Rituxan may notice an early response within 8 weeks of treatment, but this is generally transient and due to the glucocorticoid pre-medication given alongside the Rituxan infusion. 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.

References
  • Maloney DG, Liles TM, Czerwinski DK, et al. Phase I clinical trial using escalating single-dose infusion of chimeric anti-CD20 monoclonal antibody (IDEC-C2B8) in patients with recurrent B-cell lymphoma. Blood. 1994 Oct 15;84(8):2457-66.
  • Maloney DG, Grillo-Lopez AJ, White CS, et al. IDEC-C2B8 (Rituximab) anti-CD20 monoclonal antibody therapy in patients with relapsed low-grade non-Hodgkin's lymphoma. Blood. 1997 Sep 15;90(6):2188-95.
  • Food and Drug Administration. Rituxan. Highlights of Prescribing Information. [Accessed May 8, 2020]. Available online at: https://www.accessdata.fda.gov/drugsatfda_docs/label/2020/103705Orig1s5458lbl.pdf.
  • Bryan J, Borthakur G. Role of rituximab in first-line treatment of chronic lymphocytic leukemia. Ther Clin Risk Manag. 2011; 7: 1–11. doi: 10.2147/TCRM.S5855.
  • Hainsworth JD. Safety of rituximab in the treatment of B cell malignancies: implications for rheumatoid arthritis. Arthritis Res Ther. 2003; 5(Suppl 4): S12–S16. doi: 10.1186/ar1008.
  • Randall KL. Rituximab in autoimmune diseases. Aust Prescr. 2016 Aug; 39(4): 131–134. doi: 10.18773/austprescr.2016.053.
  • Buch MH, Smolen JS, Betteridge N, et al. Updated consensus statement on the use of rituximab in patients with rheumatoid arthritis. Annals of the Rheumatic Diseases 2011;70:909-920.

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