OBJECTIVES: To evaluate the effects of recombinant human interleukin (rhIL)-11 on liver histology in patients with chronic hepatitis C virus (HCV) infection and advanced liver disease who had failed antiviral therapy. METHODS: This was an open-label study of rhIL-11 (Neumega), Wyeth Laboratories, Collegeville, PA) at a dose of 5 microg/kg administered by subcutaneous injection daily for 12 wk. The primary efficacy endpoint was the change in the Knodell Histology Activity Index (HAI) between pre- and posttreatment liver biopsies. Secondary efficacy endpoints included changes in plasma alanine transaminase (ALT) concentrations and in the number of platelets. RESULTS: The Knodell HAI improved in 11 (55%) of the 20 subjects enrolled, with the mean score improving from 7.3 to 5.9 (p= 0.006). Eight subjects (40%) experienced significant improvement as defined by a decrease of at least two points in the HAI. IL-11 treatment was also associated with a decrease in ALT levels from a mean level of 113 IU/L at baseline to 65 IU/L at week 12 (p < 0.001). Platelet levels increased from a mean of 143 x 10(3)/microl at baseline to 198 x 10(3)/mul at week 12 of treatment (p < 0.001). Overall, rhIL-11 was well tolerated and no serious adverse events (AEs) were reported. The most common AE was edema of the lower extremities, which occurred in all subjects. CONCLUSIONS: The findings from this pilot study suggest that rhIL-11 may be beneficial for patients with hepatic inflammation and advanced liver disease associated with chronic HCV infection. Larger clinical trials are warranted to further evaluate the long-term antiinflammatory and antifibrotic effects of rhIL-11.