Rituxan

Bradley Somer, MD
Last Modified: November 1, 2001

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Question
Hello,  
My wife was diagnosed with Chronic Lymphocytic Leukemia (CLL) in October and has just recently completed 6 cycles of chemotherapy. She has one more of four treatments with an experimental drug, Rituxan left.

Can I get some assistance with information on this treatment?  
Thank You.


Answer
Bradley Somer, MD, Editorial Assistant for OncoLink, responds:

Dear K,
Rituximab (Rixutan) is one of the newest drugs of a progressive form of cancer therapy. It is a novel "monoclonal antibody" — a class of drugs that aim to specifically target the malignant cells. This class of drugs is referred to in lay literature as the "smartbombs" of cancer therapy. Rituxan is an antibody that was engineered to target the CD20 antigen which "B lymphocytes" of lymphoma or lymphocytic leukemia commonly express. Once targeted, this complex sends a signal to induce the body's inherent immune system to destroy these cells.

Rituximab is FDA approved for the use in relapsed or refractory low-grade or follicular, CD-20 positive, B-cell Non-Hodgkin's lymphoma. Trials using Rituximab show that half of the patients treated experience substantial shrinking of their lymph nodes. This was seen at 1-2 months. The duration of response was 10-12 months, thus patients eventually relapse. The therapy is usually done as an outpatient. It is generally given as a weekly infusion for 4 weeks,.

Other than its current indication, Rituxan is being used in a number of novel ways. These treatments are especially appealing given the relative paucity of major systemic toxicity (side effects). New Rituxan applications include treatment of any B-lymphocytic malignancy including: more advanced grades of lymphoma; concurrent therapy with standard chemotherapy; concurrent with standard therapy for CLL; primary therapy in the elderly; and "maintenance" therapy for all types of B-lymphocyte malignancy (to prevent relapse). One recent trial evaluating standard CHOP (cyclophosphamide + doxorubicin + vincristine + prednisone) with Rituxan, displayed a 95% response rate with a duration of response currently at >29 months (has not reached the median duration of response in this period of time). There are multiple clinical trials aimed at answering the questions of efficacy for each of these uses. Patients are encouraged to ask their physicians about whether they are eligible for any of these studies.

In CLL, it has been found that Rituxan does a very good job of normalizing the peripheral white blood cell count, however, it takes longer to shrink the lymph nodes. There is no data on the response rate or on its effect on survival.

Because it is so specific, this drug tends to have less systemic side effects than standard chemotherapy. The most common immediate side effects are fever and chills/rigors. These occur only during the infusion (mostly the first infusion) and are usually mild to moderate and reversible. Other rare side effects include low white count and low platelets, low blood pressure, angioedema & wheezing. Angina recurrence and arrhythmias have been reported in patients with underlying heart disease.

Based on this theme, there are some new drugs that are currently experimental but look promising. One such combination is the monclonal antibody with a radioisotope added to more effectively kill the malignant cells.

You are encouraged to ask your wife's oncologist about the use of Rituxan in her case.