Effect of thermoimmunotherapy with OK-432 on the development of spontaneous lung metastases in mice

The effect of combined hyperthermia and intratumoral administration of OK-432 (Picibanil) on the development of spontaneous lung metastases was studied. The spontaneous non-immunogenic fibrosarcoma, FSa-II, transplanted into the right foot of C3Hf/Sed mice, was used throughout. Hyperthermia was given locally by immersing the animal foot in a water bath set at 44.0 degrees C for 30 min. OK-432 in the dose of 2.5 KE was injected into the tumour 3 h before hyperthermia. This treatment has been shown to strongly inhibit local tumour growth. Sham hyperthermia, i.e. restraining the mice in holders, as well as local injection of saline solution, increased metastases incidence. The high incidence of metastases following combined sham hyperthermia and saline injection was substantially reduced by intratumoral administration of OK-432 given alone or combined with hyperthermia.