KEY Inclusion Criteria:

   - Diagnosis of primary HCC by tissue biopsy (histological/cytological diagnosis), or
   clinical diagnosis

   - Previously treated with sorafenib for ≥ 14 days and has discontinued sorafenib
   treatment at least 14 days prior to randomization due to either intolerance or
   radiographic progression NOTE: Sorafenib is NOT required to be the most recent
   treatment received for HCC

   - ECOG performance status 0, 1 or 2

   - Child-Pugh Class A; or Child-Pugh Class B7 without clinically significant ascites

   - Hematocrit ≥30% or Hemoglobin ≥10 g/dL

   - Tumor status: Measurable viable tumor in the liver and injectable under
   imaging-guidance; At least one tumor in the liver that has not received prior
   local-regional treatment OR that has exhibited >25% growth in viable tumor size since
   prior local-regional treatment.

KEY Exclusion Criteria:

   - Received sorafenib within 14 days prior to randomization

   - Received systemic anti-cancer therapy other than sorafenib within 28 days of
   randomization

   - Prior treatment with JX-594

   - Platelet count < 50,000 PLT/ mm3

   - Total white blood cell count < 2,000 cells/mm3

   - Prior or planned organ transplant

   - Known significant immunodeficiency due to underlying illness (e.g. HIV/AIDS) and/or
   medication

   - Severe or unstable cardiac disease

   - Viable CNS malignancy associated with clinical symptoms

   - Pregnant or nursing an infant

   - History of inflammatory skin condition (e.g., eczema requiring previous treatment,
   atopic dermatitis)