Autoimmune hypophysitis induced by Anti-PDL1 therapy

Yesmine Elloumi; Wissal Abbes; Salah Dhoha Ben; Omaima Dimassi; Kouloud Boujelben; Hadjkacem Faten; Nadia Charfi; Mouna Mnif; Mohamed Abid; Mouna Elleuch; Majdoub Nabila Rekik

doi:10.1530/endoabs.110.EP1144

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Endocrine Abstracts (2025) 110 EP1144 | DOI: 10.1530/endoabs.110.EP1144

ECEESPE2025 ePoster Presentations Pituitary, Neuroendocrinology and Puberty (220 abstracts)

Autoimmune hypophysitis induced by Anti-PDL1 therapy

Yesmine Elloumi ¹ , Wissal Abbes ¹ , Dhoha Ben Salah ¹ , Omaima Dimassi ¹ , Kouloud Boujelben ¹ , Hadjkacem Faten ¹ , Nadia Charfi ¹ , Mouna Mnif ¹ , Mohamed Abid ¹ , Mouna Elleuch ¹ & Nabila Rekik Majdoub ¹

Author affiliations

¹Hedi Chaker University Hospital, Endocrinology Department, Sfax, Tunisia

JOINT1469

Background: New Cancer Immunotherapies such as Immune checkpoint inhibitors enhance the immune system’s ability to combat tumors. However, they can trigger various autoimmune manifestations, particularly endocrine disorders, including hypophysitis. While the incidence of hypophysitis is higher with anti-CTLA-4 agents, we report a case of autoimmune hypophysitis induced by anti-PDL1 therapy.

Case Report: A 52-year-old female patient, with no family history of autoimmune diseases, was diagnosed with infiltrating triple-negative breast carcinoma. Immunohistochemical analysis for the anti-PDL1 antibody revealed that more than 75% of tumor cells were positive for this marker. The patient underwent neoadjuvant chemotherapy (paclitaxel and carboplatin) and neoadjuvant immunotherapy (pembrolizumab) before surgery. After six months, she presented with asthenia and pallor, without nausea or abdominal pain. Laboratory tests revealed normal electrolyte levels, but morning cortisol was low at 1.87 ng/ml, with ACTH <1.5 pg/ml. Thyroid function tests showed FT4 at 10.2 pmol/l(normal range: 12–22) and TSH at 2.46 mIU/l, with normal prolactin levels. Autoimmune markers, including ANA, anti-smooth muscle antibodies, and anti-TPO antibodies, were negative. Hypothalamic-pituitary MRI showed no abnormalities in the pituitary stalk or gland. The patient was started on hormone replacement therapy for corticotropic and thyrotropic deficiencies.

Conclusion: Understanding the endocrine side effects of immunotherapies is crucial and must be promptly diagnosed, as they can significantly impact the patient’s prognosis and, in some cases, may be life-threatening.