Endocrine Abstracts

Immunotherapy, a cancer treatment leveraging the individual’s immune system, has demonstrated its efficacy by eliciting responses from immune cells in and around tumors, notably tumor-infiltrating lymphocytes (TILs). The presence of TILs often correlates with more favorable outcomes in cancer cases. Immune-mediated adverse events (imAEs) accompany immunotherapy in 13.7-54% of patients, with the involvement of the endocrine system detected in nearly 10% of cases, representing a common form of imAEs. Despite the potential involvement of any secreting endocrine glands, immune-mediated thyroid dysfunction stands out as the most prevalent variant. A distinctive aspect of endocrine imAEs lies in the ability to safely continue immune therapy concurrently with replacement hormonal treatment. On the other hand, if these issues are discovered later, they may worsen and necessitate resuscitation or urgent care. Immune-mediated diabetes is a rare complication, with an incidence rate reported at only 0.1%. This report aims to describe a clinical case involving the primary development of diabetes during ongoing immunotherapy with pembrolizumab, coupled with the secondary development of thyroid gland pathology. The case involves a 51-year-old female diagnosed with Central cancer of the right intermediate bronchus (squamous cell carcinoma), stage IIB (pT2bN1(1/30) cM0). Since June 13, 2023, the patient has been undergoing adjuvant immunotherapy with pembrolizumab. Her medical history includes prior observation by an endocrinologist due to nodal formations in the thyroid gland without thyroid disfunction. After completing 4 th cycles of immunotherapy, she noticed a sudden and significant change in her health condition, characterized by a strong thirst and a dry mouth. Immediate medical check revealed elevated blood glucose levels up to 17 mmol/l, glucosuria, acetone in urine (+++), glycated hemoglobin at 8.3%, C-peptide (fasting) at 1.16 µIU/ml, Insulin (fasting) at 1.16 µIU/ml, and TSH at 3.2 µIU/ml. The presence of absolute insulin deficiency did not raise any doubts, and the diagnosis of type 1 immune-mediated diabetes was established. Insulin therapy in a basal-bolus regimen was immediately initiated, complemented by continuous glucose monitoring. Subsequent blood monitoring indicated a decrease in TSH levels and an increase in free T3, signaling the initiation of thyroid tissue destruction amidst ongoing treatment. This case underscores the importance of timely identification and management of immune-related complications on such therapy, shedding light on the unique challenges presented by the interplay between immunotherapy, endocrine function, and resultant adverse events.