A Novel Therapeutic Vaccine (EO2401) in Metastatic Adrenocortical Carcinoma, or Malignant Pheochromocytoma/Paraganglioma

Main Inclusion Criteria: 1. For inclusion in Cohort 1 patients should have adrenocortical carcinoma(ACC), or malignant pheochromocytoma/paraganglioma (MPP), as defined below for Cohorts 2A and 3A. 2. For inclusion in Cohorts 2A and 2B patients should have histologically confirmed (at primary diagnosis) unresectable locally advanced or metastatic adrenocortical carcinoma. 3. For inclusion in Cohorts 3A and 3B patients should have histologically confirmed (at primary diagnosis) unresectable malignant (defined as metastatic disease, i.e. presence of chromaffin tissue in non-chromaffin organs) pheochromocytoma/paraganglioma, and RECIST defined progression should have been documented during a maximum of an 18-months period. 4. Patients with an age ≥ 18 years old. 5. Patients who are human leukocyte antigen (HLA)-A2 positive. 6. Patients with an Eastern Cooperative Oncology Group (ECOG) performance status ≤ 1. 7. Patients with a life expectancy \> 4 months as judged by their treating physician. 8. Patients with at least one measurable lesion according to RECIST 1.1. 9. Males or non-pregnant, non-lactating, females. 10. Patients willing and able to comply with the scheduled visits, treatment plan, laboratory tests, and other study procedures indicated in the protocol. 11. Patients having received the information sheet and who have provided written informed consent prior to any study-related procedures. Main Exclusion Criteria: 1. Patients treated with dexamethasone \> 2 mg/day or equivalent (i.e. 13 mg/day of prednisone, or 53 mg/day of hydrocortisone) within 14 days before the first EO2401 administration, unless required to treat an adverse event. 2. Patients with prior treatment with immune check-point inhibitors 3. Patients with prior exposure to EO2401. 4. Patients treated with immunotherapy (meaning immunostimulatory or immunosuppressive therapy; beside excluded, or allowed, compounds per other inclusion/exclusion criteria specifications), radionuclide therapy, radiotherapy, cytoreductive therapy, or received treatment with any other investigational agent within 28 days before the first EO2401 administration. 5. Patients with an initial diagnosis of ACC less than 9 months from start of screening part 2. 6. Patients with ACC and any individual lesion according to RECIST 1.1 having a maximum diameter of more than 125 mm; irrespective if the lesion is proposed as a target lesion, or not, according to RECIST 1.1. 7. Patients with ACC with more than three organs involved by disease, combined with unresectable primary tumor. 8. Patients with ACC and uncontrolled hormonal secretion (according to the judgement of the treating physician). 9. Patients with MPP and uncontrolled blood pressure (according to the judgement of the treating physician). 10. Patients with abnormal laboratory values. 11. Patients with persistent Grade 3 or 4 toxicities. 12. Uncontrolled central nervous system (CNS) metastasis. 13. Other malignancy or prior malignancy with a disease-free interval of less than 3 years 14. Patients with clinically significant disease. 15. Patients with suspected autoimmune or active autoimmune disorder or known history of an autoimmune neurologic condition (e.g. Guillain-Barré syndrome). 16. Patients with history of solid organ transplantation or hematopoietic stem cell transplantation. 17. Patients with history or known presence of tuberculosis. 18. Pregnant and breastfeeding patients. 19. Patients with history or presence of human immunodeficiency virus and/or potentially active hepatitis B virus/hepatitis C virus infection. 20. Patients who have received live or attenuated vaccine therapy used for prevention of infectious diseases including seasonal (influenza) vaccinations within 4 weeks of the first dose of study drug. 21. Patients with a history of hypersensitivity to any excipient present in the pharmaceutical forms of the study treatments. 22. Patients treated with herbal remedies with immunostimulating properties or known to potentially interfere with major organ function. 23. Patients with known ongoing drug and alcohol abuse. 24. Patients with known or underlying medical or psychiatric condition that, in the Investigator's opinion, would make the administration of study drug hazardous to the patient or obscure the interpretation of toxicity determination or AEs. 25. Patients deprived of their liberty, under protective custody, or guardship.