Patient description: A 53-year-old man presents with chronic HCV infection for the past 2 years. His past medical history is only significant for inguinal hernia surgery when he was 20 years old. He is on IFN (100 mg/week) plus RBV (400 mg/day) combination therapy for the past 9 months. Direct antiviral drugs were added to his treatment 6 months ago. His medical record shows previous positive HCV RNA tests as well as positive enzyme immunoassay for anti-HCV-antibodies. The recent biopsy was negative for hepatocellular carcinoma and was only remarkable for chronic inflammation compatible with a chronic viral hepatitis. There is no evidence of alcoholic liver disease, bleeding from esophageal varices, hemochromatosis, autoimmune hepatitis or metabolic liver disease. He is an alert male with no acute distress. His BP: 130/75, HR: 90/min and BMI: 27. His abdomen is soft with no ascites or tenderness. The lower extremities are normal with no edema.

Clinical trial eligibility criteria: eligible ages (years): 18.0-65.0,  Chronic Delta Hepatitis Willing and able to comply with study procedures and provide written consent 2. 18 years old 3. Body mass index (BMI) of ≥ 18 kg/m2 and weighs ≥ 45 kg 4. CHD infection of at least 6 months' duration documented by a positive HDV antibody (Ab) test and HDV RNA ≥ 3 log10/mL by qPCR at study entry 5. Serum ALT > upper limit of the normal range (ULN) and < 10 × ULN 6. Liver biopsy within 12 months of Day 1 demonstrating evidence of chronic hepatitis. If no liver biopsy is available, the patient must be willing to consent to and have no contraindication to liver biopsy 7. ECGs demonstrating no acute ischemia or clinically significant abnormality and a QT interval corrected for heart rate (QTcF) < 450 ms for male patients and < 460 ms for female patients 8. Dilated retinal examination ≤ 1 year before screening: For patients with diabetes, hypertension, or other risk factors for retinal disease, performed by a licensed ocular specialist; for all other patients, a normal retinal examination as assessed by the investigator or a licensed ocular specialist 9. Female patients of childbearing potential and male patients with partners of childbearing potential must agree to use adequate methods of contraception during the study and for 90 days after the last dose of study drug. Female patients of childbearing potential are all those except patients who are surgically sterile, who have medically documented ovarian failure, or who are at least 1 year postmenopausal. For females: 2 of the following contraceptive methods, with at least 1 being a barrier method Hormonal contraceptives for ≥ 3 months before screening Intrauterine device (IUD) in place ≥ 3 months before screening Double-barrier methods (use of condom [male partner] with either diaphragm with spermicide or cervical cap with spermicide) from screening Surgical sterilization of the partner (vasectomy ≥ 1 month before screening) For males Surgical sterilization (vasectomy ≥ 1 month before screening) or Both of the following contraceptive methods from screening Consistently and correctly use a condom Partner must agree to use a hormonal contraceptive or a nonhormonal barrier method (IUD or diaphragm with spermicide or cervical cap with spermicide)  General Exclusions 1. Participation in a clinical trial with, or use of, any investigational agent within 30 days before screening 2. Previous use of LNF. 3. Female patients who are pregnant or breastfeeding. Male patients must confirm that their female sexual partners are not pregnant. Female patients must have a negative serum or urine pregnancy test (minimum sensitivity 25 IU/L or equivalent units of human chorionic gonadotropin [hCG]) within 24 hours prior to the start of any investigational agent). Exclusions Based on Disease 4. Current or previous history of decompensated liver disease (Child-Pugh Class B or C) 5. Co-infected with human immunodeficiency virus (HIV) or hepatitis C virus (HCV). 6. Positive results for HIV or HCV Ab at screening. Patients with a positive HCV Ab at screening are allowed if they have completed a curative antiviral regimen and have documented undetectable HCV RNA for at least 3 months before screening and at screening. 7. Past history or current evidence of decompensated liver disease, defined as any of the following at screening Bilirubin level ≥ 2.5 mg/dL unless due to Gilbert's disease Serum albumin level < 3.0 g/dL International normalized ratio (INR) ≥ 1.5 8. Evidence of significant portal hypertension such as hepatic venous pressure gradient (HVPG) ≥ 10 mmHg; current presence or history of esophageal or abdominal varices, variceal bleeding, or splenomegaly > 12 cm length on imaging 9. Current evidence or history of ascites requiring diuretics or paracentesis, or hepatic encephalopathy 10. Current evidence or history of hepatic encephalopathy 11. Any of the following abnormal laboratory test results at screening Platelet count < 90,000 cells/mm3 White blood cell (WBC) count < 3,000 cells/mm3 Absolute neutrophil count (ANC) < 1,500 cells/mm3 Hemoglobin < 11 g/dL for women < 12 g/dL for men