Alternative Targets for Immunotherapy: Targeting CD22 With Monoclonal Antibodies for the Treatment of Non-Hodgkin?s Lymphoma
Presenter: John P. Leonard, MD
Affiliation: Cornell University
While mortality rates for patients with prostate cancer or breast cancer are decreasing, death rates for patients with non-Hodgkin?s lymphoma continue to rise. Accordingly, the search for more efficacious agents continues.
Indolent lymphomas are generally incurable with current therapies and have a median survival of 8-10 years. Aggressive lymphomas such as diffuse large cell subtype are treated with chemotherapy and/or radiation therapy. Ninety percent of all lymphomas are of B cell origin. These cells have certain characteristic structures on their surface. One such structure is CD22, a protein and sugar molecule that is found on the surface of mature B cells. While CD22 normally is involved with cell communication and regulation, it can also be targeted by cancer drugs.
Epratuzumab is one such agent that is being used to attack CD22 positive cancer cells. It is a humanized monoclonal antibody that has activity against a number of different types of lymphoma. The main side effects of this drug include chills, rigors and fatigue.
In one phase I study, 6 of 25 patients (34%) with indolent lymphoma and 23% of patients with diffuse large cell lymphoma had a complete response to this medication. This drug is currently in phase III trials and not yet approved by the FDA. Yttrium Y 90 epratuzumab is a radioactive form of this agent that also shows anti-tumor activity against several forms of lymphoma.
Antibodies against tumor cells such as the ones discussed here appear to have activity against various forms of lymphoma while also having a tolerable side-effect profile. Such agents may one day become the drugs of choice for those patients not cured by current standard treatments.