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.