Abstract PO3-18-03: Preoperative single-dose camrelizumab and/or microwave ablation in women with early-stage breast cancer: A randomized window-of-opportunity trial

Abstract Immune checkpoint blockade (ICB) has shown low response rates for advanced breast cancer, and combinatorial strategies are needed to improve the effect of ICB. As an effective local therapy, microwave ablation (MWA) may be a trigger of antitumor immunity. This window-of-opportunity trial was conducted to determine the safety and feasibility of camrelizumab (anti-PD-1 antibody) combined with MWA in the treatment of early-stage breast cancer preoperatively. The peripheral immune response was also investigated. 60 participants were randomized to receive single-dose camrelizumab alone (n=20), microwave ablation (n=20), or both camrelizumab and microwave ablation (n=20), preoperatively. Camrelizumab and MWA were well tolerated alone and in combination. Different from that in single-dose camrelizumab or MWA group, participants showed stable quantity of blood cells after the combination therapy. After the combination therapy, peripheral CD8+T cells showed enhanced cytotoxic and effect-memory functions. Clonal expansional CD8+T cells showed different functions from emergent clones after the combination therapy, suggesting that the expansional clones may play a vital role in the enhanced biological functions of CD8+T cells. Enhanced interactions between clonal expansional CD8+T cells and monocytes was observed, suggesting monocytes contributed to enhanced functions of clonal expansional CD8+T cells. MHC I related pathways and interferon signaling pathways were activated in monocytes by the combination therapy. In conclusion, camrelizumab combined with MWA was feasible for the treatment of early-stage breast cancer. The peripheral CD8+T cells were activated after the combination therapy, dependent on monocytes with activated MHC I pathways. Citation Format: Wenbin Zhou, Hui Xie, Qiang Ding, Shui Wang. Preoperative single-dose camrelizumab and/or microwave ablation in women with early-stage breast cancer: A randomized window-of-opportunity trial [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-18-03.