Optimal neoadjuvant treatment and prognostic factors in patients with HR-positive/HER2-positive early or locally advanced breast cancer: A national real-world study in China.

e12514 Background: Few data have been reported regarding breast cancer (BC) population characterized by HR+/HER2+ especially in a real-world setting in China. This analysis aimed at identifying differences in short-term treatment outcomes of different neoadjuvant therapy (NAT) regimens, effects of the demographics and clinical features on short-term outcomes of NAT, and further understanding the prognostic factors related to those outcomes in HR+/HER2+ early (EBC) or locally advanced BC (LABC) pts by using dataset from National Cancer Information Database (NCID) in China. Methods: This retrospective, multicenter, real-world study used electronic medical record data from NCID. We analyzed HR+/HER2+ EBC or LABC Chinese pts who were initially diagnosed between Jan 1, 2019 and May 31, 2022 and received NAT followed by surgery during study period. Primary endpoints included total pathological complete response (tpCR) and breast pCR (bpCR). Secondary endpoints included disease-free survival (DFS) and event-free survival (EFS). Results: 3792 pts from NCID covering 51 hospitals, 26 provinces met inclusion criteria and were included. After controlling for age and post-surgery N staging, 1-, 2- and 3-yr DFS was similar between trastuzumab (T) and T+pertuzumab (P) NAT subgroup (92.79%, 87.20% and 83.32% vs 94.83%, 88.82% and 87.88%; p=0.1120). 1-, 2- and 3-yr EFS was higher in T+P subgroup (T vs T+P: 85.24%, 82.35%, 77.01% vs 90.86%, 89.65%, 82.78%; p = 0.0003). Logistic regression multivariate analysis showed improved tpCR and bpCR was independently positively associated with receiving T+P NAT (vs T: both p 40 yrs, < 64 yrs: p = 0.0116 and 0.0290, resp.), or post-surgery ER positive (vs negative: both p < 0.0001). Conclusions: HR+/HER2+ EBC or LABC gained short- and long-term benefit from HER2 dual-blockade therapy in clinical practice. Prognostic factors for improved tpCR and bpCR included T+P and platinum NAT, whereas ≥ 65 yrs and post-surgery ER+ were predictive of decreased tpCR and bpCR. Table: see text