[Monoclonal antibody therapy and laboratory medicine]

Monoclonal antibodies (mAbs) therapies have been introduced to the many kinds of malignancies. Rituximab (Rituxan), a chimeric anti-CD20 monoclonal antibody, has improved clinical outcome in the patients with B cell non-Hodgkin's lymphoma (NHL) as a single agent as well as combination with chemotherapies including CHOP and stem cell transplantation. The efficacy has been reported in the patients with follicular lymphoma as well as aggressive NHL. The expression of CD20 should be confirmed by immunopathological staining or flow cytometry before the treatment. Gemtuzumab ozogamicin (Mylotarg), calicheamicin conjugates of anti-CD33 mAb, has been introduced in the treatment of AML. CD33 is not expressed by immature pluripotent stem cells even though expressed on myeloid progenitor cells. Mylotarg is internalized via CD33, however, detouched calicheamicin might be pumped out by multi-drug resistant related p glycoprotains (p-gp). The expression of CD33 and p-gp should be analyzed by flow cytometry before the treatment. We should give another caution to tumor-lysis syndrome and veno-occlusive disease.