Pimo Study: Extracellular Vesicle-based Liquid Biopsy to Detect Hypoxia in Tumours

Aim: To analyse tiny cancer cell fragments called extracellular vesicles isolated from blood samples for their ability to identify patients with tumours that are relatively oxygen-starved and expected to be resistant to ionising radiation and many chemotherapy drugs.

Participants: 16 patients with proven cancer plus 4 healthy volunteers who give written informed consent to participate will be included in the study.

Recruitment: Eligible patients will be identified in the Outpatient Department at The Royal Marsden in Sutton or London and given a copy of the Information Sheet describing the study in detail. Dr Somaiah's team will call these potential volunteers at least 24 hours after they have received written information about the study to answer any questions. The same consent process will be followed for staff members who agree to participate as healthy volunteers. Research subjects who offer verbal agreement to participate will be asked for written consent and will be allocated a study ID. This will be used on all trial documentation and blood samples together with their initials and date of data/sample collection.

Pimonidazole administration: This well-established drug has the valuable property of binding exclusively to oxygen- starved tissues in a form that can be detected as a colour change in cell fragments released into the blood stream. A single oral dose of pimonidazole 500 mg/m2 will be prescribed and administered in a Royal Marsden outpatient clinic after confirmation of eligibility and completion of written informed consent. A member of the research team will monitor subjects to ensure that the prescribed drug is successfully taken (swallowed with water) before leaving the hospital (or going back to work/home in the case of healthy volunteers).

Blood sample: A peripheral venous blood sample of 20 ml will be collected from each participant the day after administration of pimonidazole, since it takes several hours for the drug to be absorbed and to bind to proteins and other molecules in oxygen-starved cells. A second sample will be collected 14 ±5 days later in order to confirm that all coloured cell fragments have disappeared from the circulation.