Abstract P2-12-06: Pathological response-guided postoperative treatment strategy for positive HR/negative HER2 and positive lymphnodes breast cancer patients with non-responsive pathological results to neoadjuvant chemotherapy

Abstract

Abstract Objective: No consensus up to date suggesting whether patients with positive HR/negative HER-2 and positive lymph nodes breast cancer should receive additional adjuvant chemotherapy following a poor response to neoadjuvant chemotherapy to acquire a better DDFS. The main aim of this trial is to compare the 5-year DDFS between additional adjuvant chemotherapy plus endocrine therapy group and endocrine alone group following 4 cycles neoadjuvant chemotherapy. Method: A multicenter, open-label, randomized, controlled, phase 3 trial was conducted. All patients enrolled in the study were HR+ HER2- LN+ breast cancer patients completing four cycles neoadjuvant chemotherapy, with a non-responsive pathological result to neoadjuvant chemotherapy. The non-responsive criterion was defined as Miller and Payne staging grade1 to grade 3, or any grade of Miller and Payne staging but residual positive lymph nodes were found in surgical specimen. All enrolled patients were randomly assigned to receive four cycles non-cross resistant regimen plus endocrine therapy, or endocrine therapy alone. The primary endpoint was DDFS, and the secondary endpoint was iDFS and OS. Result: From October 2010 to September 2018, a total of 391 patients were enrolled for eligibility. The final ITT analysis compromised 379 patients (187 in adjuvant chemotherapy plus endocrine therapy group, and 192 in endocrine therapy alone group). After a median follow-up of 72.4 months, the 5-year distant disease free survival estimate was 92% (95% CI 88-96) in the adjuvant chemotherapy group and 90% (86-94) in the endocrine therapy alone group (HR 0.79, 95% CI 0.45-1.37) (P=0.401). In the prespecified CEF subgroup, the 5-year DDFS was 94% (95% CI 90-98) in adjuvant chemotherapy group, and 91% (95% CI 87-94) in endocrine group (HR 0.68, 95% CI 0.36-1.30) (P=0.249). In the exploratory analysis, we found a better 5-year DDFS trend in adjuvant chemotherapy group in ypN+ patients in CEF subgroup (P=0.196). Conclusion: A better 5-year DDFS trend in additional adjuvant chemotherapy plus endocrine therapy can be found for patients with positive HR/negative HER-2 and positive lymph nodes following a poor response to neoadjuvant chemotherapy. Citation Format: Yang Yang, Xue Chen, Zhaoqing Fan, Yingjian He, Yuntao Xie, Jinfeng Li, Tianfeng Wang, Tao Ouyang. Pathological response-guided postoperative treatment strategy for positive HR/negative HER2 and positive lymphnodes breast cancer patients with non-responsive pathological results to neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-12-06.