Landscape of peripheral immune response induced by multimodal thermal therapy combined with chemoimmunotherapy in patients with early-stage HER2-negative breast cancer.

e12654 Background: Multimodal thermal therapy (MTT), consisting of alternated liquid nitrogen cooling and radiofrequency heating, was proven to effectively trigger systemic antitumor immunity. However, their immune response induced by this emerging therapy has not been fully reported in breast cancer. This pilot study (ClinicalTrials.gov: NCT06636591) was conducted to determine the effect of MTT combined with preoperative chemoimmunotherapy in the treatment of early-stage HER2-negative breast cancer. Methods: Twelve HER2-negative breast cancer patients were recruited to preoperatively receive MTT followed by chemoimmunotherapy [6 cycles of Paclitaxel, Carboplatin and Camrelizumab (an anti-PD-1 antibody)]. Single-cell RNA sequencing was performed on peripheral blood mononuclear cells (PBMCs) from all patients at three timepoints [baseline (Day 0); prior to chemoimmunotherapy (Day 7); mid-on-treatment (Cycle 3)]. The primary goal was to explore the changes of PBMCs induced by the combination of MTT and chemoimmunotherapy. Results: MTT and chemoimmunotherapy were well tolerated in combination without any delay in prescheduled surgery. No treatment-related grade III/IV adverse events were observed. Single-cell RNA sequencing analysis of PBMCs revealed early systemic immune priming on Day 7 post-MTT but prior to chemoimmunotherapy. Specifically, increased plasma-cell frequency, elevated KLRK1 expression in NK cells, upregulated HLA molecules in antigen-presenting cells (APCs), and higher CCR2 expression in circulating monocytes were observed in patients achieving favorable axillary/breast responses and total pathological complete response (tpCR). These findings suggest that early peripheral signatures may serve as predictors of clinical benefit from subsequent therapy. By Cycle 3 of chemoimmunotherapy, peripheral plasma cells and APCs increased across the cohort, with expansion being most pronounced in patients with tpCR. This was accompanied by heightened expression of effector molecules and Fcγ receptor–related gene in NK cells and APCs. Furthermore, HLA molecules and CD40 expression on APCs were significantly upregulated than those on Day 7 after MTT, followed by increased CX3CR1 and PDCD1 expression on CD4⁺/CD8⁺ T cells. Additionally, enhanced interactions between monocytes/B cells and effector T/NK cells, coupled with the upregulation of tumor-homing chemokine receptors, indicating reinforced lymphocyte trafficking to tumor sites in patients with favorable response. Conclusions: The study reported global characteristics of the MTT-induced systemic immune response, providing an opportunity for the identification of potential targets to improve the efficacy of combined chemoimmunotherapy. Clinical trial information: NCT06636591 .