Background and importance Immunotherapy stimulates the body’s natural defences to fight tumour cells. In the literature, it is considered a safe drug. However, one of the adverse reactions described in the data sheet as uncommon is autoimmune pancreatitis.

Aim and objectives To describe two cases of pancreatitis related to immunotherapy.

Material and methods This was a descriptive retrospective clinical study. Data were obtained from the clinical records. A literature search was conducted on the adverse effects of immunotherapy. The causality of the adverse reaction was established using the algorithm of Karch–Lasagna modified by Naranjo.

Results A 67-year-old man was diagnosed with non-small cell lung cancer and received palliative treatment with nivolumab, 37 cycles. After 18 months of treatment, the patient complained of abdominal pain the days following the infusion. Analytical tests were performed showing an increase in amylase and lipase. Gastroscopy was performed, confirming the diagnosis of pancreatitis. The patient remained asymptomatic, so no specific treatment was initiated, but nivolumab was discontinued. A few weeks later, the patient arrived at the hospital complaining of abdominal pain, nausea and vomiting. The analysis showed a higher increase in both enzymes. The diagnosis of immunomediated pancreatitis was confirmed by gastroscopy. Enolic and lithiasic origin were ruled out, due to the absence of previous episodes. Corticotherapy was initiated, obtaining clinical and analytical improvement.

A 58-year-old woman was diagnosed with poorly differentiated carcinoma of probable pulmonary origin and received palliative treatment with pembrolizumab, 25 cycles. She went to the emergency room for abdominal pain and vomiting. A CAT scan was performed where radiological findings compatible with pancreatitis were found. High dose steroid therapy and antibiotherapy treatment was initiated. She was left with fluid therapy and days after she began a pancreatic diet. The patient progressed favourably. After applying the Karch–Lasagne–Naranjo algorithm, we established a probable causal relationship between immunotherapy and pancreatitis.

Conclusion and relevance Immunotherapy has demonstrated efficacy and a good safety profile in clinical trials but possible adverse effects due to its use can be observed, with little evidence described in the literature. In the event of any suspicion, it is important to notify the official organisations and to establish a possible causal relationship by means of an approved test.

References and/or acknowledgements No conflict of interest.