Intestinal Microbiota in Prostate Cancer Patients as a Biomarker for Radiation-INduced Toxicity (IMPRINT)

Intestinal Microbiota in Prostate Cancer Patients as a Biomarker for Radiation-INduced Toxicity (IMPRINT): A Prospective Biomarker Study

Radiotherapy (RT) of the abdomen and/or pelvis is known to cause acute and late gastrointestinal (GI) toxicities. While radiation dose and volume are known risk factors for developing such side effects, recent evidence suggests patterns of disturbance in the composition of the GI microbiota - so called "dysbiosis" - may also promote the host's susceptibility to GI toxicities through impaired intestinal barrier function and inflammation. The IMPRINT-study aims to expand the current knowledge on the role of intestinal bacteria and their metabolites involved in the pathophysiology of radiation-induced GI toxicities by longitudinally examining the microbiota composition (feces), the associated metabolome (blood, feces and urine) and bacterial extracellular vesicles (BEVs) (blood and feces).

The IMPRINT-study is a prospective biomarker study assessing the impact of different treatment field sizes and associated radiation doses on the patient's microbiome and metabolome, whereby the link with radiation-induced GI toxicities will be emphasized. Blood, urine and fecal samples will be longitudinally collected at 4 different time points: (1) shortly before, (2) during and (3) shortly after RT treatment, as well as (4) one-month post-RT. To our knowledge, this is the first clinical research project relating the impact of multiple radiation parameters on fecal-, urine- and blood-based biomarkers to risk of GI toxicities in a homogeneously defined study population.

Inclusion Criteria:

• Histologically proven (initial) adenocarcinoma of the prostate
• Localized (confined to primary site) and/or regional (spread to regional pelvic lymph nodes) disease stage at diagnosis
• Age ≥ 18 years
• RT is an integral part of the treatment - primary, adjuvant or salvage
• WHO performance status 0-2
• Administration of androgen deprivation therapy (ADT) before RT
• Absence of any psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule
• Signed informed consent form (ICF) according to ICH/GCP and national/regional regulations

Exclusion Criteria:

• Other primary tumor (except for non-melanoma skin cancer) diagnosed < 5 years before enrollment
• Diagnosis of inflammatory bowel disease (e.g. Crohn's disease or ulcerative colitis)
• Administration of systemic therapy during RT other that ADT
• Subjected to antibiotic treatment or medically imposed dietary restrictions < 1 month prior to enrollment
• Body mass index (BMI) > 35
• Administration of pelvic RT < 1 year