Active specific
immunotherapy (ASI) is a promising approach to treating
cancer. Numerous studies in the laboratory have demonstrated that various
cancer vaccines can stimulate antibody and cell mediated immune responses against tumour-associated
antigens [1-9]. Yet few studies have demonstrated convincing clinical responses. Sialyl-Tn (STn) is a
carbohydrate associated with the
MUC1 mucin on a number of human
cancer cells and is associated with more aggressive disease. Consequently, STn is an ideal candidate for ASI
therapy.
Theratope vaccine is a
cancer vaccine that was designed by Biomira, Inc. (Edmonton, Alberta, Canada) by incorporating a synthetic STn
antigen that emulates the
carbohydrate seen on human tumours. The clinical trials conducted to date with
Theratope vaccine are outlined in this report. Overall,
Theratope vaccine has been well-tolerated with minimal toxicity. The most common side effects have been in duration and
erythema at the site of
injections. Both in a non-transplant setting following low dose iv.
cyclophosphamide and high dose autologous transplant setting, there has been a trend toward
Theratope vaccine decreasing the risk for relapse, prolonging the time to relapse and thus impacting on overall survival. The definitive Phase III trial comparing the outcome of patients with metastatic
breast cancer receiving vaccinations with
Theratope vaccine versus vaccination with the nonspecific immune stimulants
Keyhole Limpet Hemocyanin (KLH) and Detox -B stable
emulsion (Detox-B) (now called Enhanzyn
Immunostimulant) was closed to enrolment on March 30, 2001. Over 1000 women with distant metastatic
breast cancer were enrolled into the program.