Neoadjuvant Chemotherapy With or Without GnRH Agonist for Premenopausal Triple-negative Early Breast Cancer Patients

Breast cancer (BC), especially premenopausal, is emerging rapidly in East Asia in recent 20 years. Half of the breast cancer patients in Asia are younger than 50 years of age. In general, younger or premenopausal patients are associated with poorer prognosis. Premenopausal patients have higher estrogen levels than those in older (postmenopausal) patients. Estrogen is known to suppress anti-tumor T cell response and leading to tumor progression in different animal models (Clin Cancer Res 2016 22:6204), including lung cancer, melanoma, ovarian cancer. One of the mechanisms that contributes to estrogen's suppression of T cell function is via the mobilization of myeloid-derived suppressor cells (MDSC). Targeting ER signaling with hormonal therapy can abolish MDSC mobilization, and sensitize tumor cells to antigen specific T cell or NK cell killing (Cancer Discovery 2018 7:72 2017). These study results further support the hypothesis that, E2 is associated with immunosuppressive effect, and may contribute to the suppression of immune surveillance in young female breast cancer patients. These results suggest that E2 may suppress anti-tumor immunity, and E2 reduction improve the anti-tumor immunity. In our preliminary works, the investigators found higher dose (equivalent to premenopausal women serum level) of E2 suppressed T cell activities, while lower dose E2 (postmenopausal serum level) activated T cell activity. The investigators have investigated the combination of anti-PD1 antibody and GnRH agonist plus exemestane (an aromatase inhibitor which will block the production of E2 from adipose tissue) in ER positive premenopausal breast cancer patient refractory to prior endocrine therapy in metastatic setting. The response rate was 38.4%, and median progression-free survival (PFS) was 10.2 months. This outstanding result were presented in AACR 2021 oral session (Cancer Res 2021 81:13\_Supplement, CT028). On the other hand, progesterone is also well known for its anti-inflammation and immune tolerance activity. This possibly makes estrogen reduction treatments, such as gonadotropin-releasing hormone agonist (GnRH agonist), an important partner in augmenting neoadjuvant therapy for patients with premenopausal breast cancer. For triple negative breast cancer (TNBC), endocrine therapy has no anti-tumor effect. On the other hand, the use of GnRH agonist has been tested for the protection of ovary function of young female while receiving adjuvant chemotherapy. Surprisingly, the concomitant use of goserelin and adjuvant chemotherapy improved disease-free survival (HR 0.47, P=0.04) and overall survival (HR 0.45, P=0.05) versus chemotherapy alone in ER negative premenopausal early BC patients in POEMS study, which was initially aimed to improve the success pregnant rate (N Engl J Med 2015 372;923). Endocrine therapy is theoretically antagonist to chemotherapy therapy when concomitantly use. In another report analyzed the outcome of both pre- and postmenopausal women who entered two randomized trials (Gruppo Oncologico Nord-Ovest-Mammella Intergruppo studies) on adjuvant chemotherapy and received either concomitant or sequential hormonal therapy. The result showed a decreasing trend (P = 0.015) in hazard ratio of death with increasing age was observed, indicating that concomitant therapy is more effective than sequential therapy in young patients (Annals of Oncology 2008;19(2):299-307). These results support the hypothesis that, E2 suppression/ER inhibition therapy may modulate immune microenvironment, thereby enhancing the chemotherapy induced immunogenic death effect. The investigators hypothesized that, estrogen level reduction by ovarian function suppression can modulate immune microenvironment, thereby augmenting adjuvant chemotherapy efficacy, regardless of the estrogen receptor (ER) status of cancer cell. Therefore, the investigators plan to test this hypothesis in real clinical model, with standard clinical recommended treatment doses. The study is designed to evaluate whether the GnRH agonist can provide the therapeutic benefit for premenopausal TNBC patients via modulating immune microenvironment. Premenopausal TNBC patients will receive GnRH agonist and neoadjuvant chemotherapy, and the efficacy and immune microenvironment change of co-administration arm will be measured and compared with chemotherapy alone control arm.