Devanand, P. | Search bioRxiv

bioRxiv2025

Decrease in dose per fraction impairs the FLASH sparing effect in murine intestine model

PurposeFLASH radiotherapy (FLASH) can ease radiation-induced normal tissue toxicities; however, its benefit in clinically relevant fractionation protocols remains insufficiently explored. This study investigated the FLASH sparing effect under two fractionated regimens using a murine model of acute gastrointestinal toxicity. Methods and MaterialsTumor-free C57BL/6 mice received abdominal irradiation with either conventional radiotherapy (CONV) or FLASH using a 9 MeV electron beam. Three dose delivery protocols were assessed: single-fraction delivery, two equal fractions over two consecutive days, and ten equal daily fractions over two weeks. Dose escalation was performed within each protocol, while overall survival was used to monitor normal tissue sparing. The FLASH dose modifying factor (FDMF) was derived from normal tissue toxicity probability (NTCP) curves to quantify the relative protective effect of FLASH. ResultsThe single-fraction irradiation demonstrated a significant FLASH sparing effect, with an FDMF of 1.14. In contrast, this protective effect was diminished in the fractionated protocols, with the two-fraction regimen yielding an FDMF of 1.03, while the ten-fraction regimen showed no measurable sparing (FDMF = 1.00). ConclusionsIn an acute responding model of radiation-induced abdominal toxicity, the FLASH sparing effect was substantially reduced with a two-fraction regimen and completely absent with a ten-fraction regimen. These findings suggest that the benefit of FLASH may be limited at lower doses per fraction and highlight the need for further studies in other clinically relevant models to better define the boundaries of its therapeutic applicability. HighlightsO_LIFLASH-RT spares mice intestine from acute toxicity for single-dose delivery. C_LIO_LIFLASH effect declines in mice intestine with more fractions and less dose/fraction. C_LIO_LIFLASH sparing in mice intestine is lost with ten equal fractions over two weeks. C_LI

cancer biology↗

bioRxiv2025

Multi-modal image analysis for large scale cancer tissue studies within IMMUcan

MotivationMultiplexed imaging is increasingly used to study tissue architecture in health and disease. To investigate the cancer tumor microenvironment, typically either tissue micro-arrays or small patient cohorts are used to collect and process data. However, studies performed over the course of years, collecting data from thousands of samples are rare and require specialized workflows to ensure sample throughput and reproducibility for data production and processing. Here, we present two such workflows for multiplexed immunofluorescence and imaging mass cytometry of cancer tissues which are applied to a total of roughly 10000 samples from 2500 patients over six years. SummaryIn cancer research, multiplexed imaging allows detailed characterization of the tumor microenvironment (TME) and its link to patient prognosis. The IMMUcan consortium collects multi-modal imaging data from thousands of cancer patients to perform broad molecular and cellular spatial profiling across five cancer indications. Here, we describe two workflows for multiplexed immunofluorescence (mIF) and imaging mass cytometry (IMC) developed within IMMUcan to enable analysis of thousands of cancer tissues. IFQuant supports web-based, user-friendly, and reproducible analysis of mIF data. High sample throughput for IMC is achieved by optimizing experimental protocols and developing a robotic arm for automated slide loading. We provide a resource of 350000 manually labelled cells across 180 cancer samples to accurately annotate cell phenotypes in IMC. All major cell phenotypes and tissue structures correlate well between mIF and IMC. These pipelines form the basis for multiplexed image analysis within IMMUcan and provide computational tools for the larger community.

cancer biology↗