Durvalumab as Maintenance Following Chemoradiation for Unresectable Esophageal Squamous Cell Carcinoma

Inclusion Criteria:

1. Body weight \>30kg and body mass index ≥ 16 kg / m2;
2. Patients aphagic or able to ingest only liquids should also receive enteral nutritional sup-port before being included in the study;
3. Patients must have histologically confirmed esophageal or esophagogastric junction (Siewert I or II) squamous cell carcinoma, irrespective of PD-1/PD-L1 or other biomarkers expression;
4. Patients must have had a persistent disease 6-8 weeks after completing chemoradiotherapy with at least 50 Gy and platinum-based chemo and without complete response or progressive disease, based on upper endoscopy and/or CT scans;
5. Patients must have realized CT scans within 6-8 weeks after completion of chemoradiotherapy, revealing persistent disease;
6. Patients must be included \<12 weeks after completing chemoradiotherapy;
7. Patients must be unsuitable to salvage esophagectomy, according multidisciplinary local board;
8. All the tumor volume should have been treated with CRT (included in the radiation field);
9. Eastern Cooperative Oncology Group (ECOG)\>\>\<\<World Health Organisation (WHO) performance status of 0 or 1;
10. Male or female aged 18 years or older at time of study entry;
11. Life expectancy of \> 12 weeks;
12. Adequate normal organ and marrow function as defined below:

    * Haemoglobin ≥9.0 g/dL
    * Absolute neutrophil count (ANC) 1.5 x (\> 1500 per mm3)
    * Platelet count ≥100 x 109/L
    * Serum bilirubin ≤1.5 x institutional upper limit of normal (ULN). \<\<This will not apply to patients with confirmed Gilbert's syndrome (persistent or recurrent hyperbilirubinemia that is predominantly unconjugated in the absence of hemolysis or hepatic pathology), who will be allowed only in consultation with their physician.
    * AST (SGOT)/ALT (SGPT) ≤2.5 x institutional upper limit of normal unless liver metastases are present, in which case it must be ≤5x ULN
    * Measured creatinine clearance (CL) \>40 mL/min or Calculated creatinine CL\>40 mL/min by the Cockcroft-Gault formula (Cockcroft and Gault 1976) or by 24-hour urine collection for determination of creatinine clearance: CrCl, mL/min = (140 - age) × (weight, kg) × (0.85 if female) / (72 × Cr)
13. All toxicities attributed to prior chemoradiotherapy other than alopecia, fatigue, or peripheral neuropathy must have resolved to grade 2 or less;

Exclusion Criteria:

1. Patients with metastases including lymph node not included in the radiation field;
2. Patients currently receiving or have had prior use of immunosuppressive medication within 28 days before the first dose of study drug (10 milligrams/day of prednisone or an equivalent corticosteroid is allowed);
3. Received any immunotherapy for esophageal cancer;
4. Patients with active hepatitis B, hepatitis C or human immunodeficiency virus (HIV1/2 antibodies);
5. Has known active or prior autoimmune disease, except for:

   * skin diseases (vitiligo, psoriasis, alopecia)
   * diabetes mellitus type 1, with hormone replacement
   * hypothyroidism, with hormone replacement
6. Receipt of live attenuated vaccine within 30 days prior to the first dose of IP.
7. Grade 3 or higher pulmonary toxicity of dyspnea, hypoxia, or pneumonitis experienced during chemoradiation;
8. Presence of fistula between esophagus and trachea unless treated with endoscopic prosthesis.