Three cases of immune-related hypopituitarism after atezolizumab–bevacizumab treatment for hepatocellular carcinoma

We herein report three cases of immune-related hypopituitarism after atezolizumab–bevacizumab treatment for hepatocellular carcinoma (HCC). Case 1 was a man in his 60s with hepatitis C-related liver cirrhosis. He had been diagnosed with HCC and undergone surgical resection. However, HCC recurred 17 months after surgery. After 13 cycles of atezolizumab–bevacizumab therapy, general fatigue, appetite loss, and muscle weakness appeared. The plasma levels of adrenocorticotropic hormone (ACTH) and cortisol were decreased. He was diagnosed with central adrenal insufficiency associated with hypopituitarism. Glucocorticoid therapy rapidly improved his symptoms. Case 2 was a man in his 70s with HCC associated with non-alcoholic steatohepatitis (NASH). After eight cycles of atezolizumab–bevacizumab therapy, general fatigue, appetite loss, and muscle weakness appeared. Hyponatremia and eosinophilia were observed. He was also diagnosed with hypopituitarism, and glucocorticoid therapy rapidly improved his symptoms. Case 3 was a man in his 60s with HCC associated with alcoholic liver cirrhosis. After 10 cycles of atezolizumab–bevacizumab therapy, hypopituitarism developed. In these cases, the presence of hyponatremia and/or eosinophilia was useful for making a diagnosis. Cytotoxic T lymphocyte-associated protein 4 (CTLA-4) antibody is reported to be likely to induce hypophysitis two to three months after its administration. In contrast, anti-programmed cell death 1 (PD-1) antibody is likely to induce hypopituitarism six to seven months after its administration. These three patients treated with anti-programmed death ligand 1 (PD-L1) antibody developed hypopituitarism six to nine months later, close to the condition with anti-PD-1 antibody administration. Although immune-related hypopituitarism after atezolizumab–bevacizumab treatment is rare, we should be alert for hypopituitarism developing during atezolizumab–bevacizumab treatment.