ACTengine® IMA203/IMA203CD8 as Monotherapy or in Combination With Nivolumab in Recurrent and/or Refractory Solid Tumors

Inclusion Criteria: * Patients must have recurrent/progressing and/or refractory solid tumors and must have received or not be eligible for all available indicated standard of care treatment. * Eastern Cooperative Oncology Group (ECOG) performance status 0-1 * HLA-A\*02:01 positive * For patients with ovarian/fallopian tube cancer only: Patients must have confirmed diagnosis of high-grade serous or endometrioid epithelial ovarian cancer (EOC), primary peritoneal cancer, or fallopian tube cancer. * For patients with endometrial carcinoma only: Patients must have a histologically confirmed diagnosis of recurrent or persistent endometrial carcinoma. * Measurable disease according to RECIST 1.1 * Adequate selected organ function per protocol * Patient's tumor must express tumor antigen by "IMADetect® RT-qPCR. Retrospective testing will be required for patients that qualify. * Life expectancy more than 5 months * Female patient of childbearing potential must use adequate contraception prior to study entry until 12 months after the infusion of IMA203/IMA203CD8 * Male patient must agree to use effective contraception or be abstinent while on study and for 6 months after the infusion of IMA203/IMA203CD8 * The patient must have recovered from any side effects of prior therapy to Grade 1 or lower prior to lymphodepletion. Exclusion Criteria: * History of other malignancies (except for adequately treated basal or squamous cell carcinoma or carcinoma in situ) within the last 3 years * Pregnant or breastfeeding * Serious autoimmune disease Note: At the discretion of the investigator, these patients may be included if their disease is well controlled without the use of immunosuppressive agents. * History of cardiac conditions as per protocol * Prior stem cell transplantation or solid organ transplantation * Concurrent severe and/or uncontrolled medical disease that could compromise participation in the study * History of or current immunodeficiency disease or prior treatment compromising immune function at the discretion of the treating physician * Positive for HIV infection or with active hepatitis B virus (HBV) or active hepatitis C virus (HCV) infection. * Patients with LDH greater than 2.0-fold ULN. * Any condition contraindicating leukapheresis, lymphodepletion, low-dose IL-2, and/or IMA203/IMA203CD8 treatment * Patients with active brain metastases * Concurrent treatment in another clinical trial. * For nivolumab treatment, patients must not have a history of severe immune-related toxicities, defined as any Grade 3 or 4 toxicities related to prior PD1/PD-L1 inhibitor therapy (e.g., atezolizumab, pembrolizumab or nivolumab etc.). Other protocol defined inclusion/exclusion criteria could apply