To observe the toxic and side effects of TCM syndrome differentiation and treatment combined with abemaciclib and endocrine drugs in the treatment of hormone receptor ( HR ) positive and human epidermal growth factor receptor 2 ( HER2 ) negative advanced breast cancer and the dose of abemaciclib under the influence of toxic and side effects.

Patients with HR+/HER2- advanced breast cancer who received TCM combined with abemaciclib and endocrine therapy in Beijing Hospital of Traditional Chinese Medicine, Capital Medical University from March 2021 to February 2023 were selected, and the relevant data of East Asian population in MONARCH 2 and MONARCH 3 of abemaciclib random phase Ⅲ clinical study were extracted for retrospective cohort study. The TCM exposure cohort was divided into 20 cases of TCM + abemaciclib + fulvestrant group (EXP 1) and 22 cases of TCM + abemaciclib + aromatase inhibitor (AI) group (EXP 2). The East Asian populations in MONARCH 2 and 3 were non-exposed cohorts, which were divided into NEXP 1 group ( 146 cases ) and NEXP 2 group (102 cases). The safety analysis of the 2 cohorts was carried out, and the reduction and termination of abemaciclib taken by patients under the influence of toxic and side effects were counted.

①There were significant differences in CTCAE any grade, grade 2 (χ² values were 8.11, 4.59, respectively ) between EXP 1 group and NEXP 1 group, as well as in CTCAE any grade (χ²=18.57) between EXP 2 group and NEXP 2 group compare the incidence rate of diarrhoea (P<0.05 or P<0.01). There was significant differences in CTCAE ≥ grade 2 EXP 1 group compare the incidence rate of diarrhoea (χ²=5.56, P=0.02). The incidence of grade ≥ 3 neutropenia in EXP 1 was [ 5 cases (27.78%) ] and in EXP 2 was [ 2 cases (13.33%)]. There were 65 cases (44.52%) in NEXP 1 and 30 cases (29.41%) in NEXP 2, and the exposed cohort were lower than those in the non-exposed cohort. The increase of GPT, GOT and SCr in the exposed cohort were lower than those in the non-exposed cohort. ② Compared with the non-exposed cohort, the first occurrence time of diarrhea and neutropenia was prolonged and the duration was shortened in the exposed cohort. ③ The patients in the exposed cohort were less likely to take abemaciclib reduction and discontinuation due to diarrhea, neutropenia, impaired liver function, and elevated SCr than those in the non-exposed cohort.

TCM syndrome differentiation and treatment combined with abemaciclib and endocrine drugs is safe in the treatment of HR+/HER2- advanced breast cancer, which can effectively prevent and treat the toxic and side effects caused by abemaciclib, and reduce the drug reduction and discontinuation.

Breast neoplasms; Hormone receptor; Human epidermal growth factor receptor 2; Abemaciclib; CDK4/6 inhibitor; Traditional Chinese Medicine therapy; Safety