The objective of this Phase II trial is to compare the efficacy and safety of 6 months of treatment with thymalfasin plus trans arterial chemoembolization (TACE) with TACE alone in adult patients with non-surgical hepatocellular carcinoma (HCC).

Inclusion Criteria:

• Signed written informed consent.

• Diagnosis of HCC by:

  1. Presence of HCC on biopsy (core biopsy), or, if biopsy is strongly contra-indicated due to safety or patient-related concerns, then the diagnosis of HCC can be determined by:

  2. A new hepatic defect on imaging with an AFP > 1000 ng/ml, or

  3. A new hepatic defect on ultrasound or CT with an AFP < 1000 ng/ml when one of the following is present:

     1. At least two additional imaging techniques show signs characteristic of HCC, or
     2. The new hepatic defect has doubled in diameter over time, or
     3. The AFP has progressively risen to > 200 ng/ml and triples the mean baseline.

• HCC must be unresectable and non-transplantable.

• Hematocrit > 30%, platelet count >= 50,000 per microliter, WBC > 2.0 x 109/L, and polymorphonuclear white cell count >= 1.0 x 109/L.

• Adequate renal function as demonstrated by serum creatinine level < 1.5 mg/dl.

• If the patient is a woman, she is using a definitive method of birth control in consultation with her physician, or is surgically sterile or post-menopausal.

Exclusion Criteria:

• Concomitant chronic use of any drug known to be hepatotoxic, or of any immunosuppressive drug (Use of oral contraceptives will not exclude an otherwise eligible patient).
• Presence of main portal vein thrombosis or hepatic artery malformation.
• HCC amenable to treatment by surgical resection or hepatic transplantation.
• HIV infection diagnosed by HIV seropositivity and confirmed by Western blot.
• Concomitant or prior history of malignancy other than HCC within the last 10 years, except for curatively treated skin cancer or surgically cured in situ carcinoma of the cervix.
• Active infectious process that is not of a self-limiting nature. TB and AIDS are examples of infectious processes that are not of a self-limiting nature.
• Pregnancy as documented by a urine pregnancy test. Women with reproductive potential must agree to practice an adequate method of birth control for the duration of the study.
• Alcohol or intravenous drug abuse within the previous 1 year.
• Previous treatment with thymalfasin.
• Patients with known hypersensitivity to iodine.
• Simultaneous participation in another investigational drug study, or participation in any clinical trial involving investigational drugs within 30 days of study entry.