Phase I immunotherapy with a modified vaccinia virus (MVA) expressing human MUC1 as antigen-specific immunotherapy in patients with MUC1-positive advanced cancer

Background The MUC1 protein is a highly glycosylated mucin normally found at the apical surface of mucin-secreting epithelial cells in many types of tissues. MUC1 is expressed, but heavily underglycosylated, in different human tumors. TG4010 is a viral suspension of a recombinant vaccinia vector (MVA) containing DNA sequences coding for the human MUC1 antigen and interleukin-2 (IL-2). This product was developed for use as a vaccine in cancer patients whose tumors express the MUC1 antigen. The objective of the present study was to determine the safety of the product and to define the dose of TG4010 to be used in further clinical trials. Materials and methods Thirteen patients with different solid tumors were treated by repeated intramuscular injection with increasing doses of TG4010 in two separate phase I studies, one in Europe (Basel - CR) and one in the United States (UCLA - RF): a total of 6 patients were treated at a dose of 5 x 10(6) pfu, 3 patients at 5 x 10(7) pfu, and 4 patients at 10(8) pfu. Safety, efficacy, and different immunological tests were the endpoints of the study. Results Tolerance of TG4010 was excellent, and side effects mainly consisted of injection site pain and influenza-like symptoms. There was no apparent detrimental effect of repeated injections of the vaccinia virus. Four of thirteen evaluable patients showed stabilization of their disease for 6 to 9 months. One lung cancer patient who was initially progressing after the first injections later showed a marked decrease in the size of his metastases that lasted for 14 months. Some T cell proliferative immune responses were seen in five patients. Conclusions The administration of TG4010 was generally well tolerated in patients with metastatic tumors, and transient disease stabilization was observed in several patients, warranting further clinical studies with the product. Copyright (C) 2003 John Wiley Sons, Ltd.