Inhibition of lung metastases in mice bearing a malignant fibrosarcoma by treatment with liposomes containing human C-reactive protein.

Recent studies suggest an immune modulator role for C-reactive protein (CRP). We have tested the effect of CRP in a tumor system designed for study of metastases. Fibrosarcoma T241 was implanted on one hind foot of syngeneic C57BL/6 mice. After 17 days, the tumor-bearing feet were amputated, and i.v. therapy of liposomes containing CRP or control reagents was started. Examination of the lungs on Day 35 showed that CRP:liposome-treated animals had significantly fewer and smaller metastases as compared with those in the control groups. Moreover, 38% of the animals in the former groups were completely free of metastases as compared with 0 to 2% of the controls. Significantly, enhanced survival was also noted in the CRP liposome-treated group. CRP may have biological response modifier" function of value in cancer therapy.