The purpose of this study is to evaluate the safety, tolerability, and virologic activity of escalating single and multiple doses of XTL6865, a mixture (1:1) of two human monoclonal antibodies (HCV-AbXTL68 and HCV-AbXTL65), in patients with chronic hepatitis C virus infection.~An additional purpose of this study is to assess the pharmacokinetics of XTL6865 in the presence and absence of viral infection.~This study is a randomized, double blind, placebo-controlled, multi-center design of ascending single doses in patients with chronic hepatitis C virus (HCV) infection. In addition to Placebo, the following XTL6865 doses will be administered: 5 mg, 20 mg, 75 mg, 250 mg, 600 mg, 1200 mg, and 2400 mg. No patient will be enrolled in more than one dose level. At each dose level, 3 patients will receive XTL6865 and 1 patient will receive the Placebo. After the single dose infusion, the patients will be followed for 6 weeks.~If certain criteria are met and the safety review of the 1200 mg dose cohort data determines that XTL6865 was safely administered and tolerated at that dose level, the patients in the 600 mg and 1200 mg dose levels are eligible for the multiple dosing phase. Infusions of 600 mgs will be given to 4 eligible patients, one infusion per day, for 5 days. One patient will receive Placebo and 3 patients will receive XTL6865 600 mg. The patients will be followed for 6 additional weeks.~If certain criteria are not met, the 2400 mg dose cohort will be infused. After the safety review has determined that XTL6865 was safely administered and tolerated, the patients in the 1200 mg and 2400 mg dose levels are eligible for the multiple dosing phase. Infusions of 1200 mgs will be given to 4 eligible patients, one infusion per day, for 5 days. One patients will receive Placebo and 3 patients will receive XTL6865 1200 mg. The patients will be followed for 6 additional weeks.
Evaluate the safety, tolerability, and virologic activity of escalating single (and multiple) doses of XTL6865, a mixture (1:1) of two human monoclonal antibodies (HCV-AbXTL68 and HCV-AbXTL65), in patients with chronic hepatitis C virus infection.~Assess the pharmacokinetics of XTL6865 in the presence and absence of viral infection.