Abstract: Objective To observe and evaluate the efficacy of Xinmailong injection in reducing cardiovascular toxicity associated with adjuvant chemotherapy following breast cancer surgery. Methods Female breast cancer patients who underwent radical mastectomy and subsequently received 8 cycles of adjuvant chemotherapy with a regimen of epirubicin hydrochloride and cyclophosphamide followed by paclitaxel, at the Cancer Hospital of the Chinese Academy of Medical Sciences, between March 2019 and December 2019 were enrolled. Patients were randomized into the Xinmailong injection group or the Dexrazoxane group to receive Xinmailong injection or dexrazoxane for cardiac toxicity prevention, respectively. Changes of myocardial injury markers including cardiac troponin T (cTnT), B⁃type natriuretic peptide (BNP), creatine kinase MB isoenzyme (CK⁃MB) were compared between the two serum groups before and after treatment. Echocardiography was used to assess the ratio of early⁃to⁃late diastolic filling velocities (E/A), left ventricular ejection fraction (LVEF), left ventricular end⁃systolic diameter (LVESD), and left ventricular end⁃diastolic diameter (LVEDD). Electrocardiographic changes and adverse events were also monitored. Results A total of 60 patients were enrolled, with 30 in each group. After treatment, the cTnT level increased by 0.006 ng/mL in the Xinmailong injection group, while decreased by 0.020 ng/mL in the Dexrazoxane group, indicating that Xinmailong injection was less effective than Dexrazoxane in reducing cTnT levels (P<0.001). BNP levels decreased by 3.130 pg/mL in the Xinmailong injection group and by 0.204 pg/mL in the Dexrazoxane group, indicating a better prevention of BNP elevation with Xinmailong injection (P=0.167). No significant differences were observed between groups in the changes of CK⁃MB, E/A ratio, LVESD, LVEF and LVEDD; the total number of new cardiac events, new ST⁃T segment changes, new QT interval prolongation, new AV block, and new ventricular premature contractions after treatment; as well as in the incidence of adverse events such as nausea and vomiting, dizziness, headache, or bone marrow suppression (leukopenia)  (all P>0.05). All related adverse reactions improved after symptomatic treatment. Conclusions Xinmailong injection demonstrated favorable safety and potential efficacy in preventing anthracycline⁃induced cardiac toxicity. It may show superiority over Dexrazoxane in preventing BNP elevation, but its ability to reduce cTnT levels was inferior to Dexrazoxane. 

Key words: Breast cancer, Xinmailong injection, Dexrazoxane, Chemotherapy, Cardiovascular toxicity