Rituximab: an insider's historical perspective.

Rituximab (Rituxan; Genentech, Inc, South San Francisco, CA and IDEC Pharmaceutical Corporation, San Diego, CA) is a unique monoclonal antibody for the treatment of non-Hodgkin's lymphoma. This chimeric mouse/human antibody was discovered in 1991 at IDEC Pharmaceuticals' laboratories, where the antibody was genetically engineered and produced utilizing high-yield expression systems. It is a human IgG1 kappa antibody with mouse variable regions isolated from a murine anti-CD20 antibody, IDEC-2B8, that binds with high affinity to cells expressing the CD20 antigen found on the surface of malignant and normal B cells, but not on other normal tissues. It mediates complement-dependent cell lysis in the presence of human complement, and antibody-dependent cellular cytotoxicity with human effector cells. Also, it has been shown to induce apoptosis and to sensitize chemoresistant human lymphoma cell lines in vitro. Clinical development was expedited (3 years) with the first patient entered in phase I trials in March 1993 and the last patient entered in the phase III study in March 1996. IDEC Pharmaceuticals began a collaboration with Genentech, Inc in March 1995 and with F. Hoffman-LaRoche (Nutley, NJ) shortly thereafter. Marketing approval was granted by the US Food and Drug Administration on November 26, 1997 (and by the European Union on June 2, 1998) for the indication of relapsed or refractory, CD20-positive, B-cell, low-grade or follicular non-Hodgkin's lymphoma. Rituximab is the first therapeutic monoclonal antibody approved for the treatment of cancer and the first single agent approved specifically for therapy for a lymphoma. Substantial research has been performed over the past 8 years to further the understanding of this novel therapeutic. Nevertheless, much remains to be accomplished in key areas such as mechanism of action and resistance, combinations with chemotherapy, biologics and radiotherapy/radioimmunotherapy, role within multimodality regimens, and nonmalignant applications. Research conducted in the coming years should be targeted toward resolving these important issues.