Patients
Lymphocytes isolated from five pairs of endoscopically obtained
“pinch” colon biopsies were studied from 12 patients with melanoma
treated with combination ipilimumab and nivolumab therapy in Oxford,
United Kingdom (Cohort 1). These included six patients with active
IN-COL and six IN-NAE patients that were recruited as part of a larger
longitudinal study collecting colonic biopsy from patients on ICIs at
Week 7-10 regardless of colitis status (Predicting Immunotherapy Adverse
Events “PRISE” Study). Six patients with endoscopically and
histologically-confirmed active UC and six healthy volunteers undergoing
benign polyp surveillance (with no pathology apparent on endoscopy) were
studied as comparators. All patients provided written informed consent
in line with local procedure (Oxford Centre for Histopathology Research
16/A019).
Viably cryopreserved PBMC from 20 treatment-naïve patients with
metastatic melanoma obtained from drug licencing trials, were studied
(Cohort 2; from Melanoma Institute Australia). These included patients
who received combination ipilimumab and nivolumab therapy and developed
colitis (IN-COL; N=9) and those who received combination ipilimumab and
nivolumab who did not develop colitis nor (in order to prevent
confounding) any autoimmune adverse events to-date according to clinical
record review (IN-NAE; N=11). IN-COL PBMC were studied at baseline (i.e.
prior to IN treatment) and at the time of colitis. We included blood
samples taken up to seven days preceding diagnostic endoscopy. IN-NAE
were studied at baseline and week 7-10 of treatment (“TX”; a
comparable time-point to time of colitis onset in the IN-COL group).
These samples were compared with PBMC from patients with active UC (N=6)
at a single time-point, where disease activity was determined by
clinical assessment in those with an established diagnosis and by
endoscopy and histopathological assessment for new cases. Healthy
laboratory-staff volunteers (N=17) were studied at a single time-point
as controls. Written informed consent was obtained from each subject
according to local institutional policy (Human Research Ethics Committee
protocols from Royal Prince Alfred Hospital Protocol X15-0454 and
HREC/11/RPAH/444, St Vincent’s Hospital Sydney HREC/13/SVH/145, Westmead
Hospital HREC/14/WMEAD/324(4081)).
PBMCs from 26 additional patients with melanoma receiving combination
ipilimumab and nivolumab therapy were studied at therapeutic baseline in
Oxford and Liverpool, United Kingdom (Cohort 3). These patients also
provided written informed consent in line with local procedure (Oxford
Centre for Histopathology Research 16/A019 and18/A064, Liverpool
Hospital 12/NW/0525). The baseline MAIT cell count was compared to that
found in 35 community blood donors.