IDEC-C2B8 (Rituximab) Shows Promise for Treatment of Low-Grade NHL

Treating cancer always involves trade-offs. Although many are treated using the shotgun approach with chemotherapy, the side effects resulting from such treatments can be just as awful as the disease itself. Furthermore, since chemotherapy doesn't discriminate between cancerous and noncancerous cells, a patient's immune system is compromised, leaving this person vulnerable to deadly infections. Fortunately new, more targeted treatments that avoid some of these pitfalls are being developed.

Non-Hodgkin's Lymphoma (NHL), a cancer affecting B lymphocytes, has been particularly difficult to treat since most patients undergo a series of treatments with chemotherapy, each with increasing toxicity and decreasing bone marrow reserves, until they eventually die either from the disease or from an opportunistic infection. The Levy Lab at Stanford has been conducting studies with a monoclonal antibody called IDEC-C2B8 (Rituximab) that targets CD20, an antigen specific to the B cells, and, thus far, it seems to show great promise. IDEC-C2B8 is a chimera of murine (mouse) variable regions with human IgG1 and κ constant regions. This hybrid allows researchers to use a NHL mouse model while preventing rejection by patients.

In a somewhat recent (2007) study, patients were given 4 infusions peripherally with IDEC-C2B8 MoAbs and complete or partial clinical responses were observed in 37% of these patients. Since CD20 is not expressed on differentiated ab secreting plasma cells, IgG, IgA, and IgM antibody levels experienced only transient decreases, if at all. Though some side-effects were reported, most were mild. The median time to progression for the clinical responders was 10.2 months, with 5patients exceeding 20 months and 2 patients exceeding 30 months. Future research hopes to test extended and repeated dosing times and combination with or after standard chemotherapy. Already CD20 antibodies armed with small radioactive particles that deliver radiation directly to non-Hodgkin’s lymphoma cells have been used as well. Obviously there are huge upsides to this type of treatment and the future certainly looks bright.