Arzerra™ Effective For CLL

Arzerra™ (ofatumumab), a human anti-CD20 monoclonal antibody, is effective for the treatment of patients with refractory chronic lymphocytic leukemia (CLL), according to the results of a study presented at the annual meeting of the American Society of Hematology on December 8, 2008 in San Francisco, California.[1]

CLL is the most common form of adult leukemia and is characterized by the production of atypical lymphocytes. Lymphocytes are specialized immune cells that exist in two forms: B- and T-cells. These cells are produced in the bone marrow and each serves a specific function in fighting infection. The large majority of CLL cases involve mature B-lymphocytes that tend to live much longer than normal, accumulating in the blood, bone marrow, lymph nodes, and spleen. This results in overcrowding of these areas and suppression of the formation and function of blood and immune cells. Additionally, the cancerous lymphocytes themselves do not function normally, leading to a further decrease in the body’s ability to fight infection.

Refractory CLL refers to disease that does not respond to a certain treatment. Patients with CLL who have failed treatment with Fludara and Campath are considered double refractory (DR), and patients with bulky disease who have failed Fludara are considered bulky Fludara-refractory (BFR). These patients have a poor prognosis, with an overall response rate to salvage therapy of about 20% and a median survival of nine months.

Arzerra is a human monoclonal antibody that targets the CD20 antigen, which is expressed on most B cells. It is an investigational drug that is under development for the treatment of B-cell lymphoid malignancies and rheumatoid arthritis.

The study presented at ASH involved 138 patients who were either double-refractory (59) or bulky Fludara-refractory (79). Patients received eight weekly infusions of Arzerra followed by four monthly infusions. The primary endpoint of the study was to determine the overall response rate, which was 51% for the double-refractory group and 44% for the bulky Fludara-refractory group. The complete results of the study are presented in the table below. (See Table 1.)

Table 1: Response to Arzerra in Patients with Refractory CLL

Double Refractory

Bulky Fludara-refractory

Number of Patients



Overall Response Rate



Complete Response


1 patient

Partial Response



Stable Disease



Progressive Disease



Time to Retreatment

9 months

8 months

Median Survival

13.7 months

15.4 months

The researchers found that Arzerra was well-tolerated with no unexpected toxicities. They concluded that Arzerra was an effective treatment option for patients with refractory CLL and warrants further investigation.


[1] Osterborg A, Kipps TJ, Mayer J, et al. Ofatumumab (HuMax-CD20), a novel CD20 monoclonal antibody, is an active treatment for patients with CLL refractory to both fludarabine and alemtuzumab or bulky fludarabine-refractory disease: Results from the planned interim analysis of an international pivotal trial. Blood. 2008; 112 (126): Abstract 328.

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