This is a Phase I, open-label, dose-escalation trial in patients with advanced/metastatic solid tumors refractory to standard therapy; tumors may include malignant melanoma, non-small cell lung cancer, renal cell carcinoma, and squamous cell carcinoma of the head and neck. These tumor types were selected because evidence of biological activity was observed in these tumor types in a Phase I study of JX-594 (Pexa-Vec) administered by intratumoral injection in patients with metastatic disease to the liver. Patients will receive treatment at one of five dose levels in a sequential dose-escalating design.

Inclusion Criteria:

• Histologically-confirmed, advanced/metastatic solid tumor refractory to standard therapy or the patient has refused or does not tolerate the standard therapy; tumors may include malignant melanoma, non-small cell lung cancer, renal cell carcinoma, and squamous cell carcinoma of the head and neck
• At least one measurable tumor mass by CT/MRI (i.e. lesion that can accurately be measured in at least one dimension with longest diameter > 1 cm)
• At least one tumor mass amenable to biopsy and/or FNA
• Expected survival for approximately 16 weeks or longer
• Karnofsky Performance Score (KPS) ≥ 70
• Age ≥18 years
• WBC ≥ 3,500 cells/mm3 and ≤ 50,000 cells/mm3
• ANC ≥ 1,500 cells/mm3
• Hemoglobin ≥ 10 g/dL
• Platelet count ≥ 100,000 plts/mm3
• Total bilirubin ≤ 1.5 x ULN
• AST, ALT ≤ 2.5 x ULN
• Serum chemistries within normal limits (WNL) or Grade 1 - If patients are diabetic or have a screening random glucose > 160 mg/dL, a fasting glucose must be done and patients must be WNL or Grade 1 in order to be eligible for the study.
• Acceptable coagulation status: INR ≤ (ULN + 10%)
• CD4 count ≥ 500/mm3

Exclusion Criteria:

• Significant immunodeficiency due to underlying illness (e.g. HIV/AIDS) and/or medication (e.g. systemic corticosteroids)
• Known myeloproliferative disorders requiring systemic therapy
• History of exfoliative skin condition (e.g. eczema or ectopic dermatitis) requiring systemic therapy
• Tumor(s) invading a major vascular structure (e.g. carotid artery)
• Tumor(s) in location that would potentially result in significant clinical adverse effects if post-treatment tumor swelling were to occur (e.g. tumors impinging on the upper airway or affecting biliary tract drainage, etc.)
• Clinically significant and/or rapidly accumulating ascites, peri-cardial and/or pleural effusions
• Severe or unstable cardiac disease
• Current, known CNS malignancy (history of completely resected or irradiated brain metastases allowed)
• Received anti-cancer therapy within 4 weeks prior to first treatment (6 weeks in case of mitomycin C or nitrosoureas)
• Use of anti-viral, anti-platelet, or anti-coagulation medication [Patients who discontinue such medications within 7 days prior to first treatment may be eligible for this study.]
• Pulse oximetry O2 saturation <90% at rest
• Experienced a severe systemic reaction or side-effect as a result of a previous smallpox vaccination

Household contact exclusions:

• Women who are pregnant or nursing an infant
• Children < 5 years old
• History of exfoliative skin condition (e.g. eczema) that at some stage has required systemic therapy
• Significant immunodeficiency due to underlying illness (e.g. HIV/AIDS) and/or medication (e.g. systemic corticosteroids)