13 patients were in cohort 1 (dose level 1) and 4 in cohort 2 (dose level 6). After receiving MBV, 11 of them experienced fever (cohort 1). The serum IL-6 levels increased consistently in 10 out of 12 patients, with the maximum levels occurring at the same time as the highest body temperatures. A subgroup of patients displayed rising TNF-, IFN-, and IL1- levels. The partial tumour response in a patient with metastatic bladder cancer was closely linked with MBV-induced fever and raised levels of numerous cytokines. This evidence concerns the gene IL1B and neoplasm.