‘Rare’ type 3 autoimmune pancreatitis results in rapid pancreatic atrophy
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CHARLOTTE, N.C. — Type 3 autoimmune pancreatitis led to rapid pancreatic atrophy and functional endocrine failure despite steroid therapy or immune checkpoint inhibitor withdrawal, a researcher reported at ACG Annual Scientific Meeting.
“Immune checkpoint inhibitors have revolutionized cancer care. ... By blocking [regulators of the immune system], they evoke an unmitigated immune response that is highly efficacious in anti-tumor activity,” Anusha S. Thomas, MD, assistant professor of gastroenterology, hepatology and nutrition at the University of Texas MD Anderson Cancer Center, said. “However, in the process, [they] predispose to inflammatory toxicities that we refer to as immune-related adverse events.”
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Thomas described two established forms of autoimmune pancreatitis (AIP): type 1, a pancreatic manifestation of immunoglobin G4-related disease, and type 2, a duct-centric pancreatic injury often associated with inflammatory bowel disease.
A third form, type 3, is “rare with an estimated incidence of about 0.6% to 4% and is characterized by pancreatic injury induced by checkpoint inhibitors,” she said.
Seeking to detail the clinico-radiological spectrum and short-term natural history of type 3 AIP, Thomas and colleagues analyzed 248 patients who received immune checkpoint inhibitor therapy (ICI) and developed type 3 AIP, defined as a greater than threefold serum lipase elevation with or without pain and no other etiologies up to 1 year after ICI.
CT imaging was performed before ICI, 3 months before elevated lipase, at elevated lipase and at 1 and 2 years after lipase elevation.
At onset, researchers reported type 3 AIP was painful in 38% of patients and asymptomatic in 62% of patients; no patients had jaundice or local/systemic complications. CT evaluation revealed normal pancreas in 43% of patients, peri-pancreatic edema in 27%, loss of feathery pattern in 21% and diffuse or focal pancreatic enlargement in 10%.
Complete and persistent biochemical resolution was more often achieved in patients with ICI held compared with no intervention (32/89 vs. 13/84; P = .003) or compared with steroid treatment along (2/23; P = .01).
Compared with pancreas volume before ICI use, more than 20% of volume loss occurred 1-year post-pancreatitis among 55% of patients. Further, a new diabetes diagnosis occurred within 2 years of pancreatitis among 18% of patients. According to Thomas, none of the patients developed calcifications or duct dilation.
“Type 3 AIP is a novel, drug-induced chronic inflammatory disease of the pancreas that is predominantly asymptomatic and mild in severity but causes a rapid pancreatic atrophy,” Thomas concluded. “It is more pronounced in those receiving combination immunotherapy and occurs despite steroid therapy or holding immunotherapy.”
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Thomas AS, et al. Abstract S4: Autoimmune pancreatitis secondary to immune checkpoint inhibitor therapy (type 3 AIP): Insights into a new disease from clinical review and serial pancreatic imaging. Presented at: ACG Annual Scientific Meeting; Oct. 21-26, 2022; Charlotte, N.C. (hybrid meeting).
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