Abstract PS5-08-29: Trend-02 study - a phase ii exploratory de-escalation trial of neoadjuvant sacituzumab govitecan plus tislelizumab (sg/i) in early triple-negative breast cancer

Abstract Background: Neoadjuvant immune checkpoint inhibitor (ICI) combined with chemotherapy has improved pathological complete response (pCR) in triple-negative breast cancer (TNBC). Sacituzumab govitecan (SG), a TROP-2-targeted antibody-drug conjugate, demonstrates efficacy in metastatic TNBC, while tislelizumab (I), a high-affinity PD-1 inhibitor with 14 approved indications in China, shows survival benefits solid tumors. The TREND trial previously reported that eight cycles of tislelizumab plus low-dose chemotherapy achieved a 68.18% pCR, while NeoSTAR showed four cycles of SG plus pembrolizumab yielded 32% pCR with reduced toxicity versus standard care. These findings highlight the need to explore de-escalated, biomarker-driven regimens to optimize efficacy and safety in TNBC neoadjuvant therapy. Objectives: This phase II trial aims to evaluate the pathological complete response (pCR) rate of neoadjuvant SG/I in early TNBC, stratified by TROP-2 expression and combined positive score (CPS). Secondary objectives include assessing imaging response rate (RECIST v1.1), safety profile (CTCAE v5.0), requirement for additional neoadjuvant chemotherapy (NACT), and 2-year event-free survival (EFS). Exploratory analyses will characterize tumor microenvironment dynamics and identify biomarkers associated with treatment response, aiming to establish a precision de-escalation strategy for TNBC. Methods: This single-center, open-label trial enrolls 30 patients with stage II-III TNBC (ER/PR