Antibody therapy with Rituximab for patients with low-grade non-Hodgkin's lymphoma

Rituximab (Mabthera(R) Rituxan(R)) is a genetically engineered chimeric mur ine/human monoclonal antibody directed against the CD20 antigen found on th e surface of normal and malignant B lymphocytes; it has recently been licen sed in the United States and Europe as a novel antibody therapy for patient s with relapsed or refractory low-grade or follicular, CD20 positive, B-cel l non-Hodgkin's lymphoma (NHL). Preclinical studies have shown that rituxim ab specifically recognizes the CD20 antigen, can induce human effector mech anisms in vitro, and effectively depletes B cells in cynomolgus monkeys wit h limited toxicity. Previous clinical studies have demonstrated that 4 infu sions of 375 mg/m(2) rituximab given over a 22-day period in patients with low-grade NHL is effective, with an overall response rate of 50%. Adverse e vents associated with treatment are primarily mild and are most frequent wi th the first infusion, decreasing with subsequent infusions. B cells are ef fectively depleted during treatment: Levels return to normal ranges between 9 and 12 months post-treatment. Immunoglobulin levels of IgM, IgG, and IgA remain within the normal range. A human anti-chimeric antibody response ha s been detected in only less than 1% of patients treated and has not interf ered with treatment. Rituximab offers a novel, effective, well-tolerated al ternative treatment for NHL compared with existing therapies. The clinic al success of rituximab reinforces the promising potential of a nti body ther apy.