25 - Autoimmune Pancreatitis Secondary to Immune Checkpoint Inhibitor Therapy (Type 3 AIP): Insights into a New Disease from Clinical Review and Serial Pancreatic Imaging

Award: ACG Governors Award for Excellence in Clinical Research

Anusha S. Thomas, MD, Michael Abreo, BS, Ahmed Sayed Ahmed, , Yinghong Wang, MD, PhD, Sireesha Yedururi, MD, Suresh Chari, MD
MD Anderson Cancer Center, Houston, TX

Introduction: Background: Autoimmune pancreatitis (AIP), types 1 and 2, are well described. While type 1 AIP is a pancreatic manifestation of immunoglobulin G4-related disease (IgG4-RD) and type 2 AIP is a duct-centric pancreatic injury sometimes associated with inflammatory bowel disease. A third form of AIP (type 3) is caused by increased immune activity by immune checkpoint inhibitor therapy (ICI-℞) for advanced malignancies. We describe the clinico-radiological spectrum and short-term natural history of type 3 AIP.

Methods: We performed a detailed clinical record review of the 248/11,165 (2.2%) adult patients receiving ICI-℞ who developed type 3 AIP ( >3-fold serum lipase elevation + pain, absent other etiologies). A radiologist reviewed 379 abdominal computerized tomography scans (CT) and measured pancreas volume in a subset of CTs done before, during and after pancreatitis.

Results: At onset, type 3 AIP was painful in 96 (38%) and asymptomatic in 154 (62%); none had jaundice or local/systemic complications. CT showed normal pancreas (43%), peri-pancreatic edema (27%), loss of feathery pattern (21%) or diffuse/focal pancreatic enlargement (10%). A minority achieved complete and persistent biochemical resolution, more often when ICI-℞ was held (32/89) vs no intervention (13/84, p.003) or vs steroid treatment alone (2/23, p=.01). Early or late relapses occurred equally frequently regardless of intervention. Compared to pancreas volume before ICI-℞, >20% volume loss occurred in 55% 1 year post-pancreatitis, more so with dual ICI-Rx, regardless of pain or steroid therapy at presentation. 18% had new diabetes within 2 years of pancreatitis. No patient developed calcifications or duct dilation.

Discussion: Type 3 AIP is a novel drug-induced chronic inflammatory disease of the pancreas. Predominantly asymptomatic and mild in severity, it causes rapid pancreatic atrophy and functional endocrine failure despite steroid therapy or ICI-℞ withdrawal.




Disclosures:


Anusha S. Thomas, MD, Michael Abreo, BS, Ahmed Sayed Ahmed, , Yinghong Wang, MD, PhD, Sireesha Yedururi, MD, Suresh Chari, MD, 25, Autoimmune Pancreatitis Secondary to Immune Checkpoint Inhibitor Therapy (Type 3 AIP): Insights into a New Disease from Clinical Review and Serial Pancreatic Imaging, ACG 2022 Annual Scientific Meeting Abstracts. Charlotte, NC: American College of Gastroenterology.