Although reports of endocrine side effects caused by cancer immune therapy are abundant, their exact prevalence and mechanism are unclear. Well-designed correlative studies oriented to finding and validating predictive factors of autoimmune toxicity are urgently needed.
mAbs are established targeted therapies for several diseases, including hematological and solid malignancies. These agents have shown a favorable toxicity profile, but, despite their high selectivity, new typical side-effects have emerged. In cancer patients, pituitary dysfunction may be mainly due to brain metastases or primary tumors and to related surgery and radiotherapy. Anticancer agents may induce hypopituitarism in patients cured for childhood cancers. These agents infrequently affect pituitary function in adult cancer patients. Notably, hypophysitis, a previously very rare disease, has emerged as a distinctive side-effect of ipilimumab and tremelimumab, two mAbs inhibiting the cytotoxic T-lymphocyte antigen-4 receptor, being occasionally seen with nivolumab, another immune checkpoint inhibitor. Enhanced antitumor immunity is the suggested mechanism of action of these drugs and autoimmunity the presumptive mechanism of their toxicity. Recently, ipilimumab has been licensed for the treatment of patients affected by metastatic melanoma. With the expanding use of these drugs, hypophysitis will be progressively encountered by oncologists and endocrinologists in clinical practice. The optimal management of this potentially life-threatening adverse event needs a rapid and timely diagnostic and therapeutic intervention. Hypopituitarism caused by these agents is rarely reversible, requiring prolonged or lifelong substitutive hormonal treatment. Further studies are needed to clarify several clinical and pathogenic aspects of this new form of secondary pituitary dysfunction.European Journal of Endocrinology 169 R153-R164
Learning Objectives:
After completing this course, the reader will be able to:
Identify symptoms of hypophysitis as an infrequent immune related side effect of ipilimumab and other anti‐CTLA‐4 monoclonal antibodies.
Select the appropriate diagnostic and therapeutic work‐up for patients suspected of having anti‐CTLA‐4 monoclonal‐induced hypophysitis.
This article is available for continuing medical education credit at http://CME.TheOncologist.com
Specific human monoclonal antibodies antagonize cytotoxic T‐lymphocyte antigen 4 (anti–CTLA‐4 mAbs), a negative regulator of the immune system, inducing unrestrained T‐cell activation. In patients with advanced or metastatic melanoma, one of these agents, ipilimumab, produced considerable disease control rates and, for the first time, a clear improvement in overall survival outcomes. However, accumulating clinical experience with anti–CTLA‐4 mAbs identified a novel syndrome of autoimmune and autoinflammatory side effects, designated as “immune‐related adverse events,” including mainly rash, colitis, and hepatitis. Autoimmune hypophysitis has emerged as a distinctive side effect induced by anti–CTLA‐4 mAbs. This condition may be life threatening because of adrenal insufficiency if not promptly recognized, but it may easily be diagnosed and treated if clinically suspected. Hypopituitarism caused by these agents is rarely reversible and prolonged or life‐long substitutive hormonal treatment is often required. The precise mechanism of injury to the pituitary triggered by anti–CTLA‐4 mAbs is yet to be fully elucidated.
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