Inclusion Criteria:

- Histologically confirmed metastatic, or recurrent esophageal squamous cell carcinoma

- Age > 18 years

- ECOG performance status 0 - 2

- At least one measurable lesion(s) by RECIST 1.1 criteria

- Life expectancy ≥ 3 months

- At least one cytotoxic chemotherapy regimen (adjuvant chemotherapy will be considered
as one regimen if administered within 6 months from the date of study entry) (upto
three prior regimens will be allowed)

- Prior radiotherapy must be completed 2 weeks before study entry.

- Adequate bone marrow function (≥ ANC 1,500/ul, ≥ platelet 100,000/ul, ≥ Hemoglobin
9.0 g/dl)

- Adequate renal function (≤ serum creatinine 1.5 mg/dl or CCr ≥ 50 ml/min)

- Adequate liver function (≤ serum bilirubin 1.5 mg/dl, ≤ AST/ALT x 3 upper normal
limit)

- Written informed consent

Exclusion Criteria:

- Evidence of serious gastrointestinal bleeding

- Serious pulmonary conditions/illness (e.g. chronic lung disease with hypoxemia)

- Serious metabolic disease such as severe non-compensated diabetes mellitus

- History of significant neurologic or psychiatric disorders

- Serious uncontrolled intercurrent infections, or other serious uncontrolled
concomitant disease

- Pregnant or lactating woman