Can a modified cold virus injected into tumors help immunotherapy fight advanced breast cancer?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Age 18 to 75 years, both genders; * Pathologically confirmed breast cancer (Stage IV)； * Disease progression after at least one line of standard systemic therapy； * ECOG performance status 0-2； * Intolerant to or refusal of standard chemotherapy； * At least one radiologically measurable lesion per RECIST 1.1 criteria； * At least one lesion amenable to puncture/injection (i.e., accessible for intratumoral injection)； * Estimated life expectancy ≥3 months； * Adequate major organ function as defined by the following laboratory values:Absolute neutrophil count (ANC) ≥1.5×10⁹/L,Platelet count (PLT) ≥100×10⁹/L,Hemoglobin (Hb) ≥90 g/L,Alanine aminotransferase (ALT) and Aspartate aminotransferase (AST) ≤2.5× upper limit of normal (ULN),Serum creatinine (Cr) ≤1.5× ULN； * Signed informed consent form； * Agreement to provide tumor tissue samples and peripheral blood samples before and after treatment for research purposes.。 Exclusion Criteria: * Known allergy to H101 formulation, PD-1 inhibitors, or any of their excipients ; * Lymphocyte count \<0.5×10⁹/L; * Severe infection, active infection (particularly HBV, HCV, HIV), or severely immunocompromised status; * Presence of lesions that cannot be safely punctured/injected; * Prior treatment with PD-1/PD-L1 inhibitors with grade ≥3 immune-related adverse events that have not resolved; * Concurrent active malignancy other than breast cancer (except for those cured for \>5 years with no evidence of recurrence); * Uncontrolled brain metastases; * Pregnant or breastfeeding wome; * Psychiatric disorders, cognitive impairment, or poor compliance that may interfere with study participation and completion; * Severe cardiac, hepatic, or renal failure; * Long-term immunosuppressive therapy; * Uncontrolled active autoimmune disease.