Ofatumumab, a human anti-CD20 monoclonal antibody.
BACKGROUND
Since relapse of chronic lymphocytic leukemia (CLL), and refractoriness to treatment following relapse, is inevitable after initial treatment, development of novel treatment strategies is necessary.


METHODS
CD20 as a therapeutic target for CLL, successes and limitations of current anti-CD20 monoclonal antibody (mAb) therapy, and implications of preclinical and clinical developments of novel alternatives, including ofatumumab, that may enhance anti-CD20 mAb therapy are reviewed. The literature reviewed encompasses papers and congress abstracts from the past 13 years.


RESULTS
While rituximab combined with chemotherapy has considerably improved outcomes for some but not all CLL patients, single-agent use is limited in relapsed/refractory CLL. Novel anti-CD20 mAbs in development, such as ofatumumab, may bypass some limitations by virtue of alternative epitope binding and modified effector functions. Ofatumumab induces significant complement-dependent cell lysis in vitro, particularly in cells with low CD20 expression. The FDA recently approved ofatumumab for treatment of CLL refractory to fludarabine and alemtuzumab.


CONCLUSIONS
CD20-targetting chemoimmunotherapeutic options have advanced treatment of CLL. Results for single-agent ofatumumab and other new CD20 mAbs, in different lines of therapy and in combination with chemotherapy, will guide optimal use of these alternative therapies for B-cell malignancies.
Osterborg
Anders
A
Department of Hematology, Karolinska University Hospital Solna, Stockholm, Sweden. anders.osterborg@karolinska.se
D000818:Animals; D000911:Antibodies, Monoclonal / Q000009:adverse effects / Q000276:immunology / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D018951:Antigens, CD20 / Q000276:immunology*; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000188:drug therapy*
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D018951:Antigens, CD20; C527517:ofatumumab