Camrelizumab, Pirfenidone, and Chemotherapy in the Treatment of Advanced Triple-Negative Breast Cancer

Inclusion Criteria: * Female, aged 18-70 years. * Histologically confirmed recurrent/metastatic TNBC (ER-negative: IHC ER \<1%; PR-negative: IHC PR \<1%; HER2-negative: IHC -/+, or IHC ++ but FISH/CISH negative), with at least one measurable lesion per RECIST v1.1. * ECOG performance status 0-2. * Estimated life expectancy ≥3 months. * Received first-line chemotherapy + PD-1/PD-L1 inhibitor for metastatic or locally advanced unresectable TNBC, with response of CR/PR or stable disease lasting ≥3 months. For neoadjuvant/adjuvant therapy, disease progression during treatment or within 6 months after completion will be considered as first-line failure. * Adequate organ function (no transfusion, growth factor, or thrombopoietic agents within 2 weeks before screening): * Hematology: ANC ≥1.5×10⁹/L; PLT ≥90×10⁹/L; Hb ≥90 g/L. * Serum chemistry: TBIL ≤1.5×ULN; ALT and AST ≤1.5×ULN; ALP ≤2.5×ULN; BUN and Cr ≤1.5×ULN with creatinine clearance ≥50 mL/min (Cockcroft-Gault). * TSH ≤ULN (if abnormal, T3 and T4 must be assessed; enrollment allowed if T3/T4 normal). * Cardiac: LVEF ≥50% by echocardiography; 18-lead ECG with QTcF \<480 ms (female). * Women of childbearing potential must have negative pregnancy test (serum or urine) within 7 days prior to enrollment and agree to use adequate contraception during treatment and for 4 months after last dose. * Voluntarily signed informed consent and good compliance. Exclusion Criteria: * Concurrent participation in another interventional cancer trial. * Received other antitumor therapy within 14 days before first dose. * Prior treatment with pirfenidone. * Untreated active brain metastases or leptomeningeal disease. * Major non-breast cancer surgery within 4 weeks prior to enrollment or incomplete recovery from such surgery. * Active or history of autoimmune disease (except vitiligo, resolved childhood asthma without treatment in adulthood). * Severe cardiac disease (e.g., heart failure with LVEF \<50%, uncontrolled arrhythmias, angina requiring medication, significant valvular disease, recent myocardial infarction, poorly controlled hypertension \>180/100 mmHg). * Congenital or acquired immunodeficiency (e.g., HIV infection). * Live vaccination within 4 weeks before or during study. * Known allergy to study drugs or excipients. * Severe concomitant disease or condition that may interfere with study participation per investigator judgment