PWE-085 Immune checkpoint inhibitor induced acute liver injury – a national cohort study

Background Immune checkpoint inhibitors (CPI) against lymphocyte antigen-4 (CTLA-4) and programmed cell death-1 (PD-1) are a novel therapeutic breakthrough in an increasing number of malignancies. CPI induced acute liver injury (ALI) is the second most frequently encountered organ toxicity occurring in up to 30% patients. There are no reported data on ALI disease pathogenesis, clinical evolution and outcome of patients treated with CPI therapy. Our multicentre cohort study evaluated clinico-pathological aspects of CPI-induced ALI. Method A retrospective analysis was performed of patients with CPI induced ALI presenting to 6 UK oncology centres between 2013 and 2017. Indices of acute liver injury, treatment related complications and outcome were recorded. Severity scoring of liver injury was based on Common Terminology Criteria for Adverse Events (ALI grade 1–4). Results 65% (36/57) patients received ipilimumab +pembrolizumab or nivolumab (combo group) and 35% (21/57) pembrolizumab or nivolumab alone (mono group). Median treatment duration to development of ALI was 96 days in the mono and 22 days in the combo group. All patients presented with acute elevations in transaminases (ALT 325 [155–543], ALP 111 [72–250]). Immungolulins and autoantibodies were normal. One patient developed acute synthetic dysfunction with no encephalopathy (Bilirubin 64, INR 1.5). 79% received steriods (mean dose:1.3 mg/kg); 34% MMF. Steroid refractory ALI was treated with anti-thymocyte globulin (ATG) in 4 patients. Pathological findings (n=6 liver biopsies) revealed lobular hepatitis and myelo-lymphoid cell infiltrate/aggregates (CD3+,CD8+,CD68+). Patients with severe, refractory (grade 4) ALI had signifcant reductions in circulating lymphocytes/monocytes. 63% (n=35) had a temporal association between recent infection and ALI. 15% (n=8) had colitis prior to onset of ALI. Anti-TNF-a administration for colitis was not associated with more severe ALI. 21% (n=11) developed bacterial infections. Fungal sepsis (aspergillus) occurred in all ATG (n=4) treated patients. Overall 14 patients died with 93% (n=13) due to disease progression and 7% (n=1) due to immunotherapy related neuropathy. All deaths due to progressive disease were in patients with grade 3–4 ALI. Acturial median survival was significantly lower in grade 3–4 (14.5 months) vs grade 1–2 (25 months) liver injury. Conclusion Our data report on the largest cohort of CPI induced ALI identifying disease evolution, markers of disease severity and strong correlation with increased morbidity and mortality. Further research is required to delineate triggers and pathogenesis of CPI induced ALI in order to develop calibrated therapies to ameliorate liver injury.