FLASH treatment with Neon ions: The HI-FLASH project at GSI
By Jeannete Jansen
Neon ions are attracting renewed interest in radiotherapy because they offer an intermediate position between carbon and even heavier ions, combining very high LET in the tumour with potentially exploitable physical and biological advantages. Historically, 20Ne beams were already used in early heavy-ion trials at LBNL, including a small glioblastoma series that hinted at durable local control in a subset of patients, but clinical development was discontinued.
From a physics and radiobiology perspective, neon can achieve dose-averaged LET values well above those typical of current carbon ion treatments, which translates into higher RBE and a stronger reduction in oxygen enhancement ratio in the Bragg peak region, making it particularly attractive for hypoxic and intrinsically radioresistant tumours.
The new ERC-funded HI-FLASH programme (PI: Prof. Marco Durante) leverages this effect to investigate 20Ne-ion even at ultra-high (FLASH) dose rates in a preclinical glioblastoma (GBM) rat model. GBM is typically radioresistant due to its highly hypoxic microenvironment. While clinically used carbon ions often fail to reach the required LET to overcome this hypoxia, heavier ions like 20Ne-ion provide significant advantage. Adding FLASH to the picture, healthy tissue can potentially be spared. Together, the project will compare Neon at FLASH dose rates against the same ions at conventional dose rates and against UHDR protons as a reference, with endpoints including survival, toxicity and tumour control.
If successful, HI-FLASH will provide the first robust in vivo evidence that very heavy ions at UHDR can be both safe and exceptionally effective for radioresistant brain tumours, providing a strong physical and biological rationale for future clinical translation. For the particle therapy community, it charts a path toward integrating FLASH with high‑LET beams, positioning next-generation heavy-ion facilities—and FAIR / GSI in particular—as key drivers of innovation in the treatment of aggressive, otherwise incurable cancers.
https://www.gsi.de/work/forschung/biophysik/erc-grants/hi-flash
