Modulation of HMGB1, PRF1, TRAIL, and M-CSF after TARGIT-IORT in breast-conserving surgery: defining a unique acute immune landscape

Background: Targeted intraoperative radiotherapy (TARGIT-IORT) delivers a single high-dose boost to the tumor bed during breast-conserving surgery (BCS) and is now recommended only within clinical trials or registries. Its acute systemic immunogenic effects relative to BCS-only are not well characterized. Methods: Women with histologically confirmed breast carcinoma were allocated in an alternating 1:1 sequence to BCS + TARGIT-IORT or BCS-only groups. Peripheral blood was sampled pre-operatively and 24 h post-surgery. ICD and cytokine/DAMP mediators, including HMGB1, PRF1, TRAIL, FASL-NFSF6, CASP-8, GZMB, CRT, TLR4, RAGE, GDF15, and M-CSF, were quantified using ELISA. Perioperative changes were analyzed using the Wilcoxon signed-rank test; between-group Δ differences were assessed using the Mann–Whitney U test. Results: Forty-two patients were enrolled (26 BCS + TARGIT-IORT; 16 BCS-only). TARGIT-IORT induced a distinct early immune shift across ICD markers. HMGB1 showed the most pronounced change (3410.5 → 359.8 pg/ml; p < 0.001), significantly greater than that after BCS-only (1040.7 → 263.6 pg/ml; Δp < 0.001). TRAIL (246.1 → 155.5 pg/ml; p = 0.001) and FASL-NFSF6 (1087.1 → 839.3 pg/ml; p = 0.003) also declined significantly after TARGIT-IORT, whereas changes following BCS alone were modest. TARGIT-IORT increased M-CSF (266.7 → 386.7 pg/ml; p = 0.037) and reduced TLR4 (1456.3 → 1331.3 ng/ml; p = 0.007), with no significant perioperative changes in RAGE, GDF15, CRT, GZMB, or CASP-8. Discussion: Within 24 h, TARGIT-IORT generates a coordinated ICD-related and cytokine/DAMP signature, marked HMGB1 depletion, death ligand modulation, TLR4 engagement, and M-CSF upregulation, consistent with rapid immune priming. These findings are exploratory and should be interpreted within a translational framework. Larger, randomized multicentre studies with extended longitudinal and tissue-level immune profiling are needed to confirm these signals. © The Author(s) 2026.