Efficacy and Safety of Intrathecal Administration of Thiotepa in Combination With Trastuzumab in Breast Cancer With Leptomeningeal Metastasis

This was a II, single-arm, prospective, multicenter study designed to estimate the efficacy and safety of intrathecal administration of thiotepa in combination with Trastuzumab via the Ommaya Reservoir in HER2-positive breast cancer with leptomeningeal metastasis.

The primary end point was iORR [complete response (CR) + partial response (PR)] according to RANO-LM. Scoring based on radiographic assessment in leptomeningeal metastases . A composite score (total score) is calculated and compared with the baseline total score. A 25% worsening in the current score relative to baseline defines radiographic progressive disease. A 50% improvement in the current score defines a radiographic partial response. Resolution of all baseline radiographic abnormalities defines a complete response. All other situations define stable disease. The secondary end points were changes in iPFS,PFS, OS, and exploratory analysis of the relationship between molecular markers and therapeutic efficacy.

This study is planned to include 26 patients with leptomeningeal metastasis from breast cancer who meet the entry criteria.

Inclusion criteria

The subjects must meet all of the following criteria simultaneously:

• Histologically or cytologically confirmed HER-2 positive breast cancer (immunohistochemistry indicates HER-2 3+ and/or fluorescence in situ hybridization indicates HER-2 gene amplification)
• Diagnosed with breast cancer with leptomeningeal metastasis based on cerebrospinal fluid cytology combined with central nervous system function and brain imaging findings
• The patient has an Ommaya reservoir implanted or is eligible for implantation
• KPS ≥ 30
• Adequate bone marrow and liver and kidney function reserves: absolute neutrophil count (ANC) ≥ 1.5 x 109/L, platelets ≥ 100 x 109/L, hemoglobin ≥ 90 g/L. International normalized ratio (INR) or prothrombin time (PT) ≤ 1.5 x ULN. Activated partial thromboplastin time (aPTT) ≤ 1.5 x ULN. Total serum bilirubin ≤ 1.5 x ULN (patients with Gilbert's syndrome can be enrolled if total bilirubin < 3 x ULN). Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 2.5 x ULN; if the patient has liver metastasis, this criterion is AST and ALT ≤ 5 x ULN.
• Female, aged between 18 and 75 years old
• Left ventricular ejection fraction (LVEF) > 50%
• Voluntary signing of informed consent form

Exclusion criteria

Patients meeting any of the following criteria are not eligible to be included in this study:

• Subjects with other malignant tumors, excluding skin basal cell carcinoma and carcinoma in situ
• Presence of severe or uncontrollable systemic diseases, including uncontrollable hypertension or active bleeding tendency
• Patients judged by the investigator to be unsuitable for participation in the trial, or those with factors that may affect the patient's compliance with the protocol
• Toxicity caused by previous treatment has not recovered to normal state or is grade 1 according to NCI-CTCAE 5.0
• Allergic to or with metabolic disorders to the drugs in this protocol
• Pregnant or lactating women, or women with pregnancy plans during the study period and within 6 months after the last administration
• Patients participating in other clinical studies simultaneously