Phase I/II Evaluation of a Cancer Lysate Vaccine and Montanide(R) ISA-51 VG With Entinostat and Nivolumab as Adjuvant Therapy Following Chemoradiation Therapy With or Without Surgery for Locally Advanced Esophageal Cancer

* INCLUSION CRITERIA: * Participants with clinical Stage II (T2/N0-N1; T3/N0) or Stage III (T1-T2/N2, T3/N1-N2) EsC per 8th edition TNM Staging System who have histologically documented or suspected residual disease in the esophagus or regional nodes following nCRT. Diagnosis must be confirmed by the NIH Laboratory of Pathology. * No prior anti-PD1/anti-PD-L1 therapy for their EsC. * Participant must be enrolled within 16 weeks following completion of nCRT or nCRT/surgery * ECOG performance status of 0-1. * 18 years of age or older * Participant must be willing to co-enroll on 06C0014 (Prospective Analysis of Genetic and Epigenetic Alterations in Patients with Thoracic Malignancies) allowing for the use of tumor or normal tissues for correlative experiments pertaining to this protocol and related translational research efforts in the Thoracic Surgery Branch (TSB). * Adequate bone marrow reserve, hepatic and renal function as evidenced by the following laboratory parameters (all eligibility assessment/enrollment bloodwork must be done at NIH no more than 2 weeks prior to initiation of study therapy): * Absolute neutrophil count greater than 1500/mm\^3 * Platelet count greater than 100,000/mm\^3 * Hemoglobin greater than 8 g/dL (participants may receive transfusions to meet this parameter) * INR \<= 1.5 x ULN * Total bilirubin \<1.5 x upper limits of normal (except those with Gilberts disease) * Serum creatinine less than or equal to 1.6 mg/mL or the eGFR (calculat…