A Real-World Observational Study of Intratumoral H101 Oncolytic Adenovirus Combined With Immune Checkpoint Inhibitors for Advanced Metastatic Breast Cancer

This prospective, single-center, open-label, real-world observational study plans to enroll 10-15 patients with advanced (Stage IV) breast cancer who have failed multiple prior therapies \[aged 18-75, Eastern Cooperative Oncology Group Performance Status Clinical Classification（ECOG） 0-2, with measurable and injectable lesions\]. It aims to preliminarily evaluate the antitumor activity, safety, and immune-microenvironment modulation of intratumoral H101（Recombinant Human Adenovirus Type 5 Injection） oncolytic virus combined with immune checkpoint inhibitors (ICIs) in real-world practice. The regimen is determined by physicians based on clinical status and multidisciplinary input, but follows a standardized framework: 2- to 3-week cycles; H101 injected on day 1 (dose stratified by lesion size), with ICI infusion started 7±2 days later, for 4 planned cycles. Paired tumor biopsies (when feasible) and peripheral blood are collected at baseline and after 4 cycles for single-cell RNA sequencing and immune profiling, focusing on changes in T lymphocyte (T), Natural Killer cell (NK), dendritic, and macrophage subsets and correlating with clinical outcomes. Primary endpoints include adverse events (Common Terminology Criteria for Adverse Events (CTCAE) Version 5.0（CTCAE v5.0）), objective response and local control rates (Response Evaluation Criteria in Solid Tumors Version 1.1（RECIST 1.1）), 4-cycle completion, and toxicity-related discontinuation. Secondary endpoints include disease control rate, progression-free survival (Kaplan-Meier), and dynamic immune changes. First radiological assessment occurs at 6-8 weeks post-treatment, then every 3 months until progression, loss to follow-up, or 1 year. If re-biopsy is unsafe, only peripheral blood may be collected without protocol violation. Comprehensive follow-up, data confidentiality, and missing-data handling are in place to ensure scientific validity and participant protection.

Sex

All

Minimum age

18 Years

Maximum age

75 Years

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.

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