High dose proton FLASH irradiation under hypoxic conditions results in reduced DNA damage in normal pancreatic cells

Eva Bogaerts; Ellina Macaeva; Anne-Catherine Heuskin; Stéphane Lucas; Edmond Sterpin; Karin Haustermans

doi:10.1093/bjr/tqaf295

High dose proton FLASH irradiation under hypoxic conditions results in reduced DNA damage in normal pancreatic cells

Eva Bogaerts
, Ellina Macaeva
, Anne-Catherine Heuskin
, Stéphane Lucas
, Edmond Sterpin
, Karin Haustermans

Research output: Contribution to journal › Article › peer-review

Abstract

OBJECTIVES: Ultra-high dose rate (UHDR) irradiation spares normal tissues while achieving similar tumor control compared to conventional dose rate (CONV) irradiation in preclinical setting. However, the underlying biological mechanisms remain unclear. In this study, we examined the relationship between DNA damage and UHDR proton irradiation in both normal and cancerous pancreatic cells.

METHODS: Normal human pancreatic cells (H6c7) and human pancreatic adenocarcinoma cells (PANC-1) were exposed to 3 and 15 Gy of 4 MeV protons (LET = 10 keV/µm) at 0.025 Gy/s (CONV) or 375 Gy/s (UHDR) under normoxic (21% O2) or hypoxic (1% O2) conditions. DNA damage was assessed by yH2AX immunofluorescence and by the alkaline comet assay.

RESULTS: Following 3 Gy irradiation no significant differences in DNA damage were found between UHDR- and CONV-irradiated cells. In contrast, 15 Gy of UHDR irradiation significantly reduced DNA damage in H6c7 cells compared to CONV irradiation under hypoxia but not normoxia. No statistically significant FLASH sparing was found in PANC-1 cells irradiated with 15 Gy under either normoxic or hypoxic conditions.

CONCLUSIONS: UHDR proton irradiation shows potential in reducing radiation-induced DNA damage in normal but not cancer cells compared to CONV proton irradiation at relatively high doses and low oxygen levels.

ADVANCES IN KNOWLEDGE: This is the first study that compared the responses of normal and cancerous cells-from the same background-to UHDR and CONV proton irradiation. In addition, our data confirm the importance of dose and oxygen concentration for observing the FLASH effect in normal cells.

Original language	English
Journal	British Journal of Radiology
DOIs	https://doi.org/10.1093/bjr/tqaf295
Publication status	E-pub ahead of print - 5 Mar 2026

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 3 Good Health and Well-being

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10.1093/bjr/tqaf295

5 Article
1 Review article

The FLASH Effect in 3D and 2D Models: Preserving Tumor Control while Reducing Apoptosis in Normal Cells
Scarmelotto, A., Lambert, E., Delprat, V., Koumeir, C., Michiels, C., Lucas, S. & Heuskin, A.-C., 27 Mar 2026, In: Radiation Research. p. 32-42 206:1.
Research output: Contribution to journal › Article › peer-review
Decoding the chemistry of the FLASH effect: a physicochemical model of dose-rate, pH and oxygen-dependent H₂O₂ production
Tonneau, R., Rudi, L., Lucas, S. & Heuskin, A.-C., 27 Nov 2025, In: Physics in Medicine and Biology. 70, 23
Research output: Contribution to journal › Article › peer-review

Open Access
File
10 Downloads (Pure)
Senescence Under the Lens: X-ray vs. Proton Irradiation at Conventional and Ultra-High Dose Rate
De Meester, M.-E., Paulus, H., Michiels, C., Heuskin, A.-C. & Debacq-Chainiaux, F., 1 Nov 2025, In: Radiation Research. 204, 5, p. 467-476 10 p.
Research output: Contribution to journal › Article › peer-review

Open Access

1 Finished

EPT: Emerging Proton Therapies
Lucas, S. (PI), Heuskin, A.-C. (Support role), Scarmelotto, A. (Researcher), Delprat, V. (Researcher) & Tonneau, R. (Researcher)
1/10/20 → 30/09/24
Project: Research

Synthesis, Irradiation and Analysis of Materials (SIAM)
Louette, P. (Manager), Colaux, J. (Manager), Felten, A. (Manager), Tabarrant, T. (Operator), COME, F. (Operator) & Debarsy, P.-L. (Manager)
Technological Platform Synthesis, Irradiation and Analysis of Materials
Facility/equipment: Technological Platform

Cite this

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title = "High dose proton FLASH irradiation under hypoxic conditions results in reduced DNA damage in normal pancreatic cells",

abstract = "OBJECTIVES: Ultra-high dose rate (UHDR) irradiation spares normal tissues while achieving similar tumor control compared to conventional dose rate (CONV) irradiation in preclinical setting. However, the underlying biological mechanisms remain unclear. In this study, we examined the relationship between DNA damage and UHDR proton irradiation in both normal and cancerous pancreatic cells.METHODS: Normal human pancreatic cells (H6c7) and human pancreatic adenocarcinoma cells (PANC-1) were exposed to 3 and 15 Gy of 4 MeV protons (LET = 10 keV/µm) at 0.025 Gy/s (CONV) or 375 Gy/s (UHDR) under normoxic (21\% O2) or hypoxic (1\% O2) conditions. DNA damage was assessed by yH2AX immunofluorescence and by the alkaline comet assay.RESULTS: Following 3 Gy irradiation no significant differences in DNA damage were found between UHDR- and CONV-irradiated cells. In contrast, 15 Gy of UHDR irradiation significantly reduced DNA damage in H6c7 cells compared to CONV irradiation under hypoxia but not normoxia. No statistically significant FLASH sparing was found in PANC-1 cells irradiated with 15 Gy under either normoxic or hypoxic conditions.CONCLUSIONS: UHDR proton irradiation shows potential in reducing radiation-induced DNA damage in normal but not cancer cells compared to CONV proton irradiation at relatively high doses and low oxygen levels.ADVANCES IN KNOWLEDGE: This is the first study that compared the responses of normal and cancerous cells-from the same background-to UHDR and CONV proton irradiation. In addition, our data confirm the importance of dose and oxygen concentration for observing the FLASH effect in normal cells.",

author = "Eva Bogaerts and Ellina Macaeva and Anne-Catherine Heuskin and St{\'e}phane Lucas and Edmond Sterpin and Karin Haustermans",

note = "Publisher Copyright: {\textcopyright} The Author(s) 2026. Published by Oxford University Press on behalf of the British Institute of Radiology. All rights reserved. For commercial re-use, please contact [email protected] for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact [email protected].",

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doi = "10.1093/bjr/tqaf295",

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journal = "British Journal of Radiology",

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T1 - High dose proton FLASH irradiation under hypoxic conditions results in reduced DNA damage in normal pancreatic cells

AU - Bogaerts, Eva

AU - Macaeva, Ellina

AU - Heuskin, Anne-Catherine

AU - Lucas, Stéphane

AU - Sterpin, Edmond

AU - Haustermans, Karin

N1 - Publisher Copyright: © The Author(s) 2026. Published by Oxford University Press on behalf of the British Institute of Radiology. All rights reserved. For commercial re-use, please contact [email protected] for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact [email protected].

PY - 2026/3/5

Y1 - 2026/3/5

N2 - OBJECTIVES: Ultra-high dose rate (UHDR) irradiation spares normal tissues while achieving similar tumor control compared to conventional dose rate (CONV) irradiation in preclinical setting. However, the underlying biological mechanisms remain unclear. In this study, we examined the relationship between DNA damage and UHDR proton irradiation in both normal and cancerous pancreatic cells.METHODS: Normal human pancreatic cells (H6c7) and human pancreatic adenocarcinoma cells (PANC-1) were exposed to 3 and 15 Gy of 4 MeV protons (LET = 10 keV/µm) at 0.025 Gy/s (CONV) or 375 Gy/s (UHDR) under normoxic (21% O2) or hypoxic (1% O2) conditions. DNA damage was assessed by yH2AX immunofluorescence and by the alkaline comet assay.RESULTS: Following 3 Gy irradiation no significant differences in DNA damage were found between UHDR- and CONV-irradiated cells. In contrast, 15 Gy of UHDR irradiation significantly reduced DNA damage in H6c7 cells compared to CONV irradiation under hypoxia but not normoxia. No statistically significant FLASH sparing was found in PANC-1 cells irradiated with 15 Gy under either normoxic or hypoxic conditions.CONCLUSIONS: UHDR proton irradiation shows potential in reducing radiation-induced DNA damage in normal but not cancer cells compared to CONV proton irradiation at relatively high doses and low oxygen levels.ADVANCES IN KNOWLEDGE: This is the first study that compared the responses of normal and cancerous cells-from the same background-to UHDR and CONV proton irradiation. In addition, our data confirm the importance of dose and oxygen concentration for observing the FLASH effect in normal cells.

AB - OBJECTIVES: Ultra-high dose rate (UHDR) irradiation spares normal tissues while achieving similar tumor control compared to conventional dose rate (CONV) irradiation in preclinical setting. However, the underlying biological mechanisms remain unclear. In this study, we examined the relationship between DNA damage and UHDR proton irradiation in both normal and cancerous pancreatic cells.METHODS: Normal human pancreatic cells (H6c7) and human pancreatic adenocarcinoma cells (PANC-1) were exposed to 3 and 15 Gy of 4 MeV protons (LET = 10 keV/µm) at 0.025 Gy/s (CONV) or 375 Gy/s (UHDR) under normoxic (21% O2) or hypoxic (1% O2) conditions. DNA damage was assessed by yH2AX immunofluorescence and by the alkaline comet assay.RESULTS: Following 3 Gy irradiation no significant differences in DNA damage were found between UHDR- and CONV-irradiated cells. In contrast, 15 Gy of UHDR irradiation significantly reduced DNA damage in H6c7 cells compared to CONV irradiation under hypoxia but not normoxia. No statistically significant FLASH sparing was found in PANC-1 cells irradiated with 15 Gy under either normoxic or hypoxic conditions.CONCLUSIONS: UHDR proton irradiation shows potential in reducing radiation-induced DNA damage in normal but not cancer cells compared to CONV proton irradiation at relatively high doses and low oxygen levels.ADVANCES IN KNOWLEDGE: This is the first study that compared the responses of normal and cancerous cells-from the same background-to UHDR and CONV proton irradiation. In addition, our data confirm the importance of dose and oxygen concentration for observing the FLASH effect in normal cells.

U2 - 10.1093/bjr/tqaf295

DO - 10.1093/bjr/tqaf295

M3 - Article

C2 - 41787979

SN - 0007-1285

JO - British Journal of Radiology

JF - British Journal of Radiology

ER -

High dose proton FLASH irradiation under hypoxic conditions results in reduced DNA damage in normal pancreatic cells

Abstract

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Research output

The FLASH Effect in 3D and 2D Models: Preserving Tumor Control while Reducing Apoptosis in Normal Cells

Decoding the chemistry of the FLASH effect: a physicochemical model of dose-rate, pH and oxygen-dependent H₂O₂ production

Senescence Under the Lens: X-ray vs. Proton Irradiation at Conventional and Ultra-High Dose Rate

Projects

EPT: Emerging Proton Therapies

Equipment

Synthesis, Irradiation and Analysis of Materials (SIAM)

Cite this