“Old” Monoclonal Antibody May Offer “New” Alternative

Newswise — Scientists from the Translational Lymphoma Research Laboratory of Myron S. Czuczman, MD, Departments of Medicine and Immunology at Roswell Park Cancer Institute (RPCI), will present laboratory and preclinical findings of the effects of blocking CD52 antigen by using alemtuzumab, a previously FDA-approved monoclonal antibody, in rituximab-resistant cells, at the 2007 centennial meeting of the American Association for Cancer Research (AACR), April 14-18, in Los Angeles, CA.

"CD52 Over-expression Affects Rituximab-associated Complement Mediated Cytotoxicity (CMC) but Not Antibody-dependent Cellular Cytotoxicity (ADCC): Preclinical Evidence Targeting CD52 with Alemtuzumab to Reverse Acquired Resistance to Rituximab in Non-Hodgkin's Lymphoma (NHL)" Embargoed until Tuesday, April 17, 12:10 pm PST Room 409 A-B, Los Angeles Convention Center

To identify the mechanisms of resistance to rituximab and improve the therapeutic efficacy of this immunotherapy in patients with non-hodgkin's lymphoma (NHL), researchers studied lymphoma cells that were made resistant to rituximab in the laboratory. They noted that these cells express significantly higher amounts of CD52 antigen, a protein molecule found on the surface of white blood cells and whose function is still largely unknown, as compared to the parental rituximab-sensitive cells. When these cells were exposed to a panel of available monoclonal antibodies, no biological activity was seen except for one that targets CD52 antigen, alemtuzumab.

The researchers have started to look at CD20 and CD52 expression in lymphoma specimens taken from a few patients treated at Roswell Park and have found variability in expression of these antigens. The study also found when the expression of CD52 was blocked with alemtuzumab, the cells regained at least partial sensitivity to rituximab.

This research project will continue and may be important in the future development of alternative approaches for the treatment of NHL (i.e. potential use of alemtuzumab for rituximab-refractory disease) cases that do not respond to conventional therapy.

Founded in 1907, the American Association for Cancer Research is the world's oldest and largest professional organization dedicated to advancing cancer research. Members include more than 24,000 basic, translational and clinical researchers, health care professionals and cancer survivors and advocates in the United States and more than 60 other countries.

Roswell Park Cancer Institute, founded in 1898, is the nation's first cancer research, treatment and education center and is the only National Cancer Institute-designated comprehensive cancer center in Upstate New York. RPCI is a member of the prestigious National Comprehensive Cancer Network, an alliance of the nation's leading cancer centers. Roswell Park has affiliate sites and collaborative programs in New York, Pennsylvania, and in China. For more information, visit RPCI's website at http://www.roswellpark.org, call 1-877-ASK-RPCI (1-877-275-7724) or e-mail [email protected].