Efficacy and Safety of Extended-Dose Interval Immunotherapy Versus Standard-Dose Interval Immunotherapy for Advanced Triple-Negative Breast Cancer

Inclusion criteria

• Voluntary consent to participate in this study and signing of the informed consent form.
• The age of the signatory of the informed consent form should be ≥18 years old and ≤70 years old.
• Advanced (locally recurrent inoperable or metastatic) TNBC confirmed by histology or cytology, defined as ER-negative, PR-negative, and HER2-negative.
• PD-L1 IHC detection in tumor tissue with a CPS score ≥1.
• Have received first-line standard immunotherapy combined with chemotherapy or immunotherapy combined with ADC and completed 6 cycles, with the last dose administered no more than 28 days before randomization.
• The therapeutic efficacy was confirmed as CR, PR or SD after 6-cycle standard treatment according to the RECIST v1.1 criteria.
• Plan to continue receiving immunotherapy.
• An Eastern Cooperative Oncology Group performance-status score of 0 or 1.
• The expected survival period exceeds 12 weeks.
• Adequate organ function:.
• No mental or intellectual abnormalities.
• Willing and able to comply with the trial protocol during the trial period.
• Female subjects of childbearing potential must agree to use highly effective contraceptive measures starting at least 7 days before the first dose and continuing until 24 weeks after the last dose. The serum pregnancy test result must be negative within 7 days prior to the first dose.

Exclusion criteria

• Untreated active brain metastases or meningeal metastases.
• Concomitant other malignant tumors with progression within the recent 5 years or requiring active treatment (excluding adequately treated and controlled carcinoma in situ and non-melanoma skin cancer).
• Concomitant severe non-malignant diseases that would affect the patient's compliance or put the patient at risk.
• Concomitant active infection.
• Receiving other anti-tumor therapies or participating in other interventional clinical trials.
• Inflammatory breast cancer.
• Dementia, intellectual disability, or any mental disorders that hinder the understanding of the informed consent form.
• History of allergic reactions to any components of the study drugs or existing contraindications to their use.
• Presence of any active autoimmune diseases or history of autoimmune diseases.
• Presence of poorly controlled clinical cardiac symptoms or diseases, such as:1) Heart failure of NYHA class II or above;2) Unstable angina pectoris;3) Myocardial infarction occurring within 1 year;4) Clinically significant supraventricular or ventricular arrhythmias requiring treatment or intervention.
• Presence of grade ≥3 toxicities related to prior treatments that restrict the continuation of maintenance therapy.
• History of immunodeficiency, including HIV positivity, active HBV/HCV infection, other acquired or congenital immunodeficiency diseases, and history of organ or allogeneic stem cell transplantation.
• Vaccination with live vaccines within 4 weeks prior to the administration of study drugs or planned vaccination during the study period.
• Prior administration of irinotecan, topotecan, or any other topoisomerase I inhibitors (including investigational topoisomerase I inhibitors), or known history of allergies to the above-mentioned drugs.
• Use of systemic glucocorticoids at a dose exceeding 10 mg/day of prednisone equivalent within 14 days prior to the administration of study drugs, or planned long-term use of the above dose during the study period (topical, inhaled, or short-term (≤7 days) pulse doses ≤10 mg/day of prednisone equivalent, or physiological dose replacement therapy are allowed for inclusion).
• Need for use of any immunosuppressants within 14 days prior to the administration of study drugs or planned use during the study period.
• Pregnant or lactating women, or women of childbearing potential who refuse to accept contraceptive measures.
• Patients who are difficult or impossible to follow up.
• Subjects judged by the investigator to have conditions that may affect compliance or other circumstances making them unsuitable for inclusion.