Abstract
Keytruda (pembrolizumab) is an immunomodulator that prevents the interaction between programmed cell death protein (PD-1) and programmed death ligand (PD-L1/2) on immune cells and tumour cells, thereby preventing T cell dysfunction. At times, mounting a strong immune response against tumour cells may not spare normal cells, leading to a variety of multisystemic adverse effects. With this, we present a case of a 64-year-old male who developed acute pancreatitis after completing eight cycles of Keytruda for castrate-resistant metastatic prostate cancer for six months, after all other causes of pancreatitis were excluded.