ESTRO meets Asia 2024 - Abstract Book

S254

Interdisciplinary – Radiobiology

ESTRO meets Asia 2024

typically immunologically ‘cold’ MOC2 tumours: infiltration of leukocytes, T cells, and CD8 + cytotoxic T cells increased, while immunosuppressive cell populations, such as T regulatory cells, remained unchanged compared with 8 Gy treated tumours, Figure 2. Alongside acute alterations to the TME, changes in tumour cell and blood vessel morphology were observed in MOC2 tumours. Whilst H&E staining revealed tumour morphology was heterogenous, we observed a larger proportions of cells resembling normal squamous mucosa in the combined USMB and 8 Gy cohort. Within these regions CD31 staining revealed blood vessels that were more similar in morphology to vessels within non cancerous tissues. Together, this indicates a more well-differentiated phenotype. Our results demonstrate that USMB can be used as a localised adjunct treatment to enhance response of HNC to radiotherapy. A single dose of USMB with radiation enhanced tumour perfusion, increased infiltration of immunostimulatory cells and promoted a tumour cell phenotype which is associated with better treatment response and survival. Future work will aim to further explore the molecular mechanisms responsible for observed TME changes and radiosensitising effects. Additionally, alternative regimens using USMB with radiotherapy will be assessed, such as treatment fractionation and combinations with immune or chemotherapies. Conclusion:

Keywords: Vasculature, Immunology, Ultrasound

References:

[1] El Kaffas A, Gangeh MJ, Farhat G, Tran WT, Hashim A, Giles A, et al. Tumour Vascular Shutdown and Cell Death Following Ultrasound-Microbubble Enhanced Radiation Therapy. Theranostics. 2018;8(2):314-27.

[2] Lai P, Tarapacki C, Tran WT, El Kaffas A, Lee J, Hupple C, et al. Breast tumor response to ultrasound mediated excitation of microbubbles and radiation therapy in vivo. Oncoscience. 2016;3(3-4):98-108.

[3] McNabb E, Al-Mahrouki A, Law N, McKay S, Tarapacki C, Hussein F, et al. Ultrasound-stimulated microbubble radiation enhancement of tumors: Single-dose and fractionated treatment evaluation. PLoS One. 2020;15(9):e0239456.

[4] Kooiman K, Roovers S, Langeveld SAG, Kleven RT, Dewitte H, O'Reilly MA, et al. Ultrasound-Responsive Cavitation Nuclei for Therapy and Drug Delivery. Ultrasound Med Biol. 2020;46(6):1296-325.

293

Proffered Paper

Biological role of tRFs mediated ferroptosis regulating radioresistance of cervical carcinoma

Wu Ning

Department of Radiation Oncology, China-Japan Union Hospital of Jilin University, Changchun, China

Purpose/Objective: