• Patient (female or male) has signed informed consent according to ICH/GCP and national/local regulations prior to any trial-specific procedure.

• Patient is 18 years or older at the time of signing the informed consent form.

• Patient must live in an area where a hospital for care can be reached within a maximum of 50 km.

• Patient has histological or cytological confirmation of:

‣ colorectal cancer, which is stage IV (any T / any N / M1), not amenable to curative surgery, OR

⁃ prostate cancer, which is stage III locally advanced, not amenable to curative surgery (T3-4 / N0 / M0 or any T / N1 / M0), or stage IV metastatic (any T / any N / M1)

• Patient has received all lines of therapy that

‣ are considered SOC for the patient's indication according to applicable European/national professional society medical guidelines and local medical practice at time of enrollment

⁃ are available via the national health insurance system and the patient is considered eligible for but led to insufficient response or were medically not justified or refused by the patient.

• Patient has confirmed disease progression by radiologic imaging from the previous line of therapy.

• Patient has sufficient amount of previously not irradiated tumor tissue in adequate quality for TIL harvest and expansion, i.e., either:

‣ Primary or metastatic lesion has been selected for surgery (e.g., to reduce tumor burden, pain relief), Or

⁃ Patient has consented to surgery for the purpose of tissue harvesting for TIL expansion and is considered suitable to undergo surgery for this purpose. Note: Patients with a non-justifiable anesthesiologic and/or surgical risk, as determined by the investigator, should be excluded

• Patient has a least one measurable or assessable lesion according to RECIST 1.1 remaining after tumor resection for CC-38 manufacturing has been performed.

• Patient has ECOG performance status of 0 or 1.

• Patient has a minimum life expectancy of 6 months in the opinion of the investigator from the time of consent date.

• Patient has adequate bone marrow, hepatic and renal function in the opinion of the investigator:

∙ Hemoglobin ≥ 9.0 g/dL,

‣ Absolute neutrophil count (ANC) ≥ 1.0 x 109 /L,

‣ Platelets ≥ 80 x 109 /L,

‣ Calculated creatinine clearance ≥ 50 mL/min (Cockcroft-Gault formula),

‣ Serum bilirubin ≤ 1.5 x ULN (or ≤ 2.5 x ULN in the presence of documented Gilbert's Syndrome \[unconjugated hyperbilirubinemia\] or liver metastases),

‣ AST/ ALT and alkaline phosphatase ≤ 2.5 x ULN (or ≤5 times ULN in the presence of bone and/or liver metastases), ALP ≤ 2.5 x ULN,

‣ International normalized ration (INR) ≤ 1.5 or prothrombin time (PT) ≤ ULN + 4 seconds.

• Female patients must be post-menopausal or use contraceptive methods with a failure rate of \< 1% 6 months after last administration of CC-38, whatever is later, to prevent pregnancy. Male patients with fertile female partners must be willing to use condoms with spermicide, and the fertile partner must use contraceptive methods with a failure rate of \< 1% for the same time period. Male patients must also refrain from donating sperm for the same time period.

• Successful tumor tissue sampling by surgery, including presence of TILs in the tumor tissue in the pathological evaluation.

• Successful TIL expansion defined as obtaining the final CC-38 drug product