ESTRO 2024 - Abstract Book

S5312

Radiobiology - Tumour biology

ESTRO 2024

29

Digital Poster

Plasma proteomic profiling of bladder cancer patients with hypoxic tumours undergoing radiotherapy.

Conrado Guerrero Quiles 1 , Hanan Abumanhal-Masarweh 2 , Marilena Hadjidemetriou 3 , Peter Hoskin 1 , Catharine West 1 , Ananya Choudhury 1 1 University of Manchester, Cancer Sciences, Manchester, United Kingdom. 2 University of ManchesterU, Cell Matrix Biology & Regenerative Medicine, Manchester, United Kingdom. 3 University of Manchester, Cell Matrix Biology & Regenerative Medicine, Manchester, United Kingdom

Purpose/Objective:

Hypoxia is a feature present in most solid tumours, which affects patient prognosis and radiotherapy efficacy. In bladder cancer, hypoxia is especially prevalent, with up to 70% of tumours expressing hypoxia markers (e.g. CA9, GLUT1)1. Hypoxia modifying drugs are clinically available to improve radiotherapy outcomes in bladder cancer, but no biomarkers have been implemented in the clinic to aid patient selection. We previously developed and validated a 24-gene hypoxia-associated signature for bladder cancer, which predicts benefit from hypoxia modifying treatment2. However, gene signatures require the use of tumour biopsies, an invasive approach not suitable for patient monitoring. Characterisation of hypoxia effects in plasma can identify novel biomarkers, but it has been impaired due to highly abundant proteins (e.g. albumin), which ‘mask’ the plasma composition, a problem that can be overcome using nano-proteomics3. In this project, we aimed to: (1) characterise the plasma proteome of bladder cancer patients with intra-tumoral hypoxia before and during radiotherapy; and (2) identify a novel plasma proteomics hypoxia signature amenable to serial measurements.

Material/Methods:

A cohort of 23 bladder cancer patients (stages T2 to T3b) undergoing radiotherapy (55Gy, 4 weeks) was recruited prospectively. Blood samples were collected weekly before and during radiotherapy (five collection time-points). Formalin-fixed paraffin-embedded (FFPE) diagnostic biopsies were retrieved, RNA extracted, and expression measured of the clinically validated 24-gene hypoxia signature2. Patients were then stratified into high or low hypoxia groups based on the median signature score2. Lipid nanoparticles were used to concentrate plasma protein levels by inducing the formation of a protein corona3. Concentrated samples were analysed using liquid chromatography coupled to a tandem mass spectrometry. Resulting proteomics data was analysed in silico using Progenesis QI and RStudio software.

Results:

Comparison of patients with low vs high tumour hypoxia identified a total of 77 plasma proteins (fold change≥2 or ≤- 2, p. adj.<0.05) were identified across all collection time-points. Gene Ontology (GO) enrichment analyses highlighted hypoxia affects extracellular matrix (ECM) signalling, humoral immune response, and coagulation cascades. Differences before and during radiotherapy time-points were observed; ECM signalling was only hypoxia-associated before radiotherapy, while coagulation cascades were affected only during the first two weeks of radiotherapy.

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