Study to Evaluate the Efficacy, Safety and Pharmacokinetics of CT041 Autologous CAR T-cell Injection

Inclusion Criteria: 1. Be willing to participate in a clinical trial, be informed and sign inform consent; and be willing to follow and be able to complete all trial procedures; 2. Aged 18 to 75 years; 3. Phase Ib：Patients with pathologically diagnosed advanced gastric/ gastroesophageal junction adenocarcinoma who have failed at least 2 prior lines treatment; or patients with pathologically diagnosed advanced pancreatic cancer who have failed at least 1 prior line treatment ; Phase II：Patients with pathologically diagnosed advanced gastric/ gastroesophageal junction adenocarcinoma who have failed at least 2 prior lines treatment; 4. Phase Ib：Tumor tissue samples were positive for CLDN18.2 IHC staining； Phase II：Tumor tissue samples were positive for CLDN18.2 IHC staining and HER2 expression was negative; 5. Estimated life expectancy \>12 weeks; 6. According to the RECIST 1.1, there is measurable tumor lesions; 7. ECOG physical status score 0 \~ 1 at screening, within 24 hours prior to apheresis, and at baseline; 8. Sufficient venous access for mononuclear cell collection; 9. Unless otherwise specified, patients should meet the certain conditions prior to screening and pre-treatment and be allowed one week to retest if an abnormal laboratory test does not meet the criteria, and if the criteria are still not met, the screening is considered to have failed; 10. Female patients of childbearing age must undergo a serum pregnancy test at screening and prior to pretreatment and the results must be negative, and are willing to use a very effective and reliable method of contraception within 1 year after the last study treatment; 11. Men who have actively sexual intercourse with women with child-bearing potential, must agree to use barrier-based contraception if they have no vasectomy. Exclusion Criteria: 1. Pregnant or lactating women; 2. HIV, Treponema pallidum, HCV serologically positive, EBV-DNA, CMV-DNA or 2019-ncov nucleic acid positive; 3. Any uncontrollable active infection, including but not limited to active tuberculosis, HBV infection; 4. The side effects caused by the previous treatment of the subjects did not return to CTCAE ≤1; except hair loss and other tolerable events determined by investigator; 5. Patients known to have active autoimmune diseases, including but not limited to psoriasis or rheumatoid arthritis, or other diseases requiring long-term immunosuppressive therapy; 6. Previously allergic to immunotherapy and related drugs,history of severe allergies, or allergic to components of CT041. 7. Previously received any gene-modified cell therapies(including CAR-T, TCR-T); 8. Patients have brain metastasis or symptoms of brain metastasis; 9. Patients at high risk of hemorrhage or perforation; 10. Patients requiring anticoagulant therapy; 11. Patients requiring continuous anti-platelet therapy; 12. Patients with a history of organ transplantation or awaiting organ transplantation; 13. Patients who have undergone major surgery or significant trauma within 4 weeks prior to apheresis, or who are expected to undergo major surgery during the study; 14. Presence of other serious pre-existing medical conditions that may limit patient participation in the study; 15. The investigator assessed that the patient was unable or unwilling to comply with the requirements of the study protocol; 16. The patient has a central nervous system disease sign or an abnormal neurological test result with clinical significance; 17. The patient is currently suffered from or have suffered from other incurable malignant tumors within previous 3 years, except in situ cervical cancer or skin basal cell cancer.