However, final intent-to-treat analyses showed no significant difference between groups at 24 weeks in the primary end point, defined as achievement of a serum ALT level of 45 IU/L or lower (approximately the upper limit of normal) or a drop in serum ALT level of at least 50% to less than 65 IU/L (approximately 1.5 times the upper limit of normal).
Just 3.8% of patients in the placebo group met this end point, as did 4% in the silymarin 420-mg group and 3.8% in the silymarin 700-mg group.
"We really looked at many different subpopulations, and we could not find any signal at all," Dr. Fried said; additionally, the findings were much the same in per-protocol analyses.
The treatment groups were also statistically indistinguishable with respect to the changes from baseline in ALT levels and in HCV RNA levels, and with respect to changes from baseline in scores on questionnaires assessing depression, physical and mental health, and quality of life specific to chronic liver disease.
"Silymarin was well tolerated with an adverse event profile similar to placebo," Dr. Fried said. The three treatment groups did not differ significantly with respect to rates of adverse events (most of which were mild or moderate) or serious adverse events.
Dr. Fried reported that he is a consultant to Genentech, Tibotec, Vertex, Merck, Abbott, and Pharmasset; receives grant or research support from Genentech, Tibotec, Vertex, Merck, Anadys, Abbott, and Bristol-Myers Squibb; is an adviser or reviewer for GlaxoSmithKline; and has stock in Pharmasset. Dr. Liang reported that he had no relevant conflicts of interest.