A Study of SI-B003, BL-B01D1+SI-B003 and BL-B01D1+PD-1 Monoclonal Antibody in Patients With Locally Advanced or Metastatic Esophageal Cancer, Gastric Cancer, Colorectal Cancer and Other Gastrointestinal Tumors

Inclusion criteria

• Sign the informed consent form voluntarily and follow the protocol requirements;
• Gender is not limited;
• Age: ≥18 years old and ≤75 years old;
• Expected survival time ≥3 months;
• Patients with locally advanced or metastatic esophageal cancer, gastric cancer, colorectal cancer and other gastrointestinal tumors;
• Agreed to provide primary tumors or metastases 2 years archive of tumor tissue samples or fresh tissue samples;
• At least one measurable lesion meeting the RECIST v1.1 definition was required;
• ECOG 0 or 1;
• The toxicity of previous antineoplastic therapy has returned to ≤ grade 1 as defined by NCI-CTCAE v5.0;
• No severe cardiac dysfunction, left ventricular ejection fraction ≥50%;
• No blood transfusion, no use of cell growth factors and/or platelet-raising drugs within 14 days before screening, and organ function levels must meet the criteria;
• Blood coagulation function: international standardization ratio of 1.5 or less, and the part activated clotting time live enzymes ULN 1.5 or less;
• Urinary protein ≤2+ or ≤1000mg/24h;
• For premenopausal women with childbearing potential, a pregnancy test must be performed within 7 days before starting treatment, serum or urine must be negative for pregnancy, and must be non-lactating; All enrolled patients (male or female) were advised to use adequate barrier contraception throughout the treatment cycle and for 6 months after the end of treatment.

Exclusion criteria

• Antitumor therapy such as chemotherapy or biological therapy was used within 4 weeks or 5 half-lives before the first dose in this study; Mitomycin and nitrosoureas were administered within 6 weeks before the first dose; Oral drugs such as fluorouracil;
• Cohort using BL-B01D1, previously treated with an ADC drug with topoisomerase I inhibitor as toxin; Immunomodulatory drugs were administered within 2 weeks before the first dose in this study;
• Systemic corticosteroids were required within 2 weeks before the first dose of the study;
• Had received immunotherapy and developed grade ≥3 irAE or grade ≥2 immune-related myocarditis according to the CSCO guidelines;
• History of severe heart disease;
• QT prolongation, complete left bundle branch block, III degree atrioventricular block;
• Active autoimmune and inflammatory diseases;
• Other malignant tumors were diagnosed within 5 years before the first dose in this study;
• Presence of: a) poorly controlled diabetes mellitus before starting study treatment; b) poorly controlled hypertension; c) history of hypertensive crisis or hypertensive encephalopathy;
• Pulmonary disease defined as grade ≥3 according to CTCAE v5.0; The patient was diagnosed with grade ≥1 radiation pneumonitis according to the RTOG/EORTC definition. Patients with existing or a history of interstitial lung disease;
• Unstable thrombotic events requiring therapeutic intervention within 6 months before screening; Infusion-related thrombosis was excluded;
• Patients with unstable pericardial effusion, pleural effusion, ascites and other serous cavity effusion;
• Patients with active central nervous system metastasis;
• Patients with a history of allergy to recombinant humanized antibody or human-mouse chimeric antibody or to any ingredient of BL-B01D1 or SI-B003;
• Prior organ transplantation or allogeneic hematopoietic stem cell transplantation (Allo-HSCT);
• Human immunodeficiency virus antibody positive, active tuberculosis, active hepatitis B virus infection or hepatitis C virus infection;
• Active infections requiring systemic therapy, such as severe pneumonia, bacteremia, sepsis, etc;
• Enrolled in another clinical trial within 4 weeks before the first dose of this study;
• Patients who received live vaccine within 4 weeks before the first dose;
• Patients with a history of mental illness or drug abuse who are unable to cooperate with clinical trial requirements;
• The investigator did not consider it appropriate to apply other criteria for participation in the trial.