SCREENING: Patient eligibility will be determined by protocol inclusion/exclusion criteria including HLA (human leukocyte antigen) screening and a biopsy (or collection of archival tumor tissue) for biomarker screening. If the patient is eligible, white blood cells will be taken during leukapheresis for the manufacture of the an IMA203 or an IMA203CD8 product.

MANUFACTURING: IMA203 product and IMA203CD8 products will be made from the patient patients&apos ;s ; white blood cells.

TREATMENT: Lymphodepletion with cyclophosphamide and fludarabine will occur in the days before the IMA 203 203/IMA203CD8 product infusion to improve the duration of time that IMA 203 203/IMA203CD8 product stays in the body. The patient will be admitted to the hospital during the treatment T-cell infusion.

After the IMA 203 203/IMA203CD8 product infusion, a low dose of IL-2 will be given subcutaneously twice daily for 14 10 days.

Since this study involves gene therapy, patients will be monitored throughout the study and for up to a total of 15 years. In Extension Cohort B (IMA203) nivolumab will be administered intravenously.

Patients will be monitored closely throughout the study. The follow-up phase ends 5 years post infusion.

Inclusion Criteria:

• Pathologically confirmed advanced and/or metastatic solid tumor
• Patients may enter screening procedure before, during, or after the last available indicated standard of care treatment. There is no limitation for prior anti cancer treatments.
• Acceptable organ and bone marrow function per protocol
• Acceptable coagulation status per protocol
• Adequate hepatic function per protocol
• Serum creatinine within normal range for age OR creatinine clearance with a recommended estimated glomerular filtration rate ≥ 60 mL/min/1.73 m2
• Confirmed availability of production capacities for IMA203 product
• 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 phenotype positive HLA phenotype positive for the study
• Measurable disease Measurable disease according to RECIST 1.1
• Adequate pulmonary selected organ function per protocol
• Patient's tumor must express tumor antigen by qPCR using a tumor biopsy specimen OR be a tumor type with at least 95% known prevalence of protocol-specific antigen expression Patient's tumor must express tumor antigen by "IMADetect® RT-qPCR
• Life expectancy more than 3 months
• For hepatocellular carcinoma (HCC) patients only, Child-Pugh score of ≤ 6 and model for end-stage liver disease (MELD) score ≤ 15
• IMA203 product must have passed all of the release tests
• Female patient of childbearing potential must use adequate contraception prior to study entry until 6 12 months after the infusion of IMA203/IMA203CD8
• Male patient must agree to use effective contraception or be abstinent while on study and for 90 days 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
• Solid tumors with low likelihood of tumor biomarker expression per protocol
• 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 hypersensitivity to cyclophosphamide (CY), fludarabine (FLU), or IL-2
• 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 2.5-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.).
• HIV infection, active hepatitis B or C infection. History of treated hepatitis B or C is permitted if the viral load is undetectable per qPCR and or nucleic acid testing.

Other protocol defined inclusion/exclusion criteria could apply

Note: HCC patients with controlled hepatitis B virus (HBV) infection as defined by subjects with resolved (anti-surface antigen [HBs-Ag] antibody negative, anti-core antigen [HBc Ag] antibody positive) or chronic stable (anti HBs-Ag antibody positive HBV) HBV infection will be eligible for screening. HCC patients with HBV infections who are not on anti-HBV treatment will be excluded from the study. HCC subjects with hepatitis C virus (HCV) infections will be allowed for screening; however, subjects with both HBV and HCV infections will be excluded for screening.

• Any condition contraindicating leukapheresis
• Patients with active brain metastases

NOTE: Patients with a history of brain metastases may be eligible, if an imaging scan with contrast enhancement not older than 4 weeks is able to exclude the existence of currently active brain metastasis.

• Treatment with protocol-defined excluded treatments, medical devices, and/or procedures per protocol
• The patient has not recovered from any grade 2 or greater side effect of prior therapy to grade 2 or lower (except for non-clinically significant toxicities, e.g., alopecia, vitiligo) prior to lymphodepletion.