Clinical Outcome of Breast and Ovarian Cancer Patients Treated after High-Dose Chemotherapy and Autologous Stem Cell Rescue with Theratope (STn-KLH) Cancer Vaccine

Abstract

The success of autologous peripheral blood stem cell transplantation (ASCT) as treatment for breast and ovarian cancer is limited by high relapse rates. Following ASCT, patients have lower tumor burden, may have decreased number of regulatory cells that can suppress ability to mount immune response and have lower amounts of circulating immunosuppressive tumor-associated molecules like MUC1 that cause anergy. As a consequence, after ASCT patients are more likely to respond immunlogically to a cancer vaccine. ASCT thus provides a platform for delivering effective immunotherapy. We speculated that the successful delivery of immunotherapy after ASCT might decrease relapse rates and prolong survival. Theratope (Sialyl TN-keyhole limpet hemocyanin (STn-KLH)) vaccine incorporates a synthetic STn antigen that mimics the unique tumor-associated STn carbohydrate on MUC1 found on breast and ovarian cancer cells. From 1995 through 2000, 70 patients (16 with stage II/III breast cancer, 17 with stage III/IV ovarian cancer and 37 with stage IV breast cancer) were treated after ASCT with two different formulations of Theratope given with Detox B. Theratope was generally well tolerated with minimal toxicity. Both humoral and cellular responses were able to be measured in the laboratory in the vaccinated patients. In this chapter, we report on the long term outcome of the Theratope vaccinated ASCT patients in correlation with measurable immune responses.