*The use of fecal calprotectin in detecting immunotherapy induced colitis and feasibility for the use of immunohistochemical markers in patients receiving checkpoint inhibitors*- a pilot study

Checkpoint inhibitors can effectively induce an anti-tumour immune response.
However, they may also cause immune related phenomena like colitis.
Clinical presentation alone cannot distinguish colitis from diarrhoea with
other causes based on clinical presentation. Also, in some cases patients may
not experience symptoms until life threatening ulcerations and perforation
occurs. Therefore, stool biomarkers may be useful in patients treated with
checkpoint inhibitors. Fecal calprotectin is successfully used as a marker in
inflammatory bowel disease, but has not been validated in immunotherapy induced
colitis. The pathogenesis of immunotherapy induced colitis is not clear.
Depletion or function inhibition of mucosal regulatory Foxp3+ T cells may play
an important role.

Primary: To determine fecal calprotectin in patients treated with checkpoint
inhibitors.
Secondary: To describe endoscopic and histologic findings in patients with
symptoms that may indicate colitis.
To study cytokine production profiles of the mucosal immune system by
immunohistochemistry of colonic biopsies (by means of staining of Foxp3, TGF-B,
IL-17, IL-10, TNF-a, IFN -y) to gain more insight into the pathogenesis of
immunotherapy induced colitis.
To detect risk factors for developing colitis.

pilot study

Participants are asked to collect feces every two or three weeks (depending on
the interval of the administration of the immunotherapy) starting prior to the
first cycle of immunotherapy until 2-3 weeks after the last cycle. They will be
questioned every 2-3 weeks (either during regular visits or by means of a
telephone call) about gastro-intestinal symptoms.
If patients experience gastrointestinal symptoms which may indicate colitis a
colonoscopy with at least 10 biopsies will be performed.