MON-300 - Real-World Spectrum of Endocrine Immune-Related Adverse Events from Immune Checkpoint and Tyrosine Kinase Inhibitors: A Philippine Case Series

Background: Immune checkpoint inhibitors (ICIs) and tyrosine kinase inhibitors (TKIs) are targeted cancer therapies that improve outcomes by enhancing immune responses or blocking tumor growth pathways. As their use expands, endocrine complications are increasingly encountered. In low- and middle-income settings, delayed recognition and limited access to endocrine monitoring further complicate care, highlighting the need for local real-world case series to guide timely recognition and management.

Objective: To describe the real-world spectrum, presentation, and management of endocrine immune-related adverse events associated with ICIs and TKIs in a Philippine tertiary hospital.

Methods: We conducted a retrospective case series of adult patients who developed endocrine immune-related adverse events during ICI and/or TKI therapy. Clinical records were reviewed for treatment exposure, time to onset, type of endocrinopathy, diagnostic evaluation, management, and short-term outcomes.

Results: Three patients developed heterogeneous endocrine immune-related adverse events. A 71-year-old female with endometrial carcinoma developed primary hypothyroidism six months after pembrolizumab–lenvatinib initiation, with a TSH level of 37.8 µIU/mL, requiring long-term levothyroxine without interruption of cancer therapy. A 68-year-old male receiving durvalumab for squamous cell lung carcinoma presented after four months with severe euvolemic hyponatremia, an indeterminate morning serum cortisol level of 8.80 µg/dL, and inappropriately normal plasma ACTH (18.8 ng/L, N 8–25), consistent with immune-mediated central adrenal insufficiency, initially requiring intravenous glucocorticoids and later tapered to stress-dose steroid coverage. A third patient, a 28-year-old female on pembrolizumab–lenvatinib for renal cell carcinoma, developed hypothyroidism followed by amenorrhea with elevated FSH (104 mIU/mL, N < 25) and LH (116 mIU/mL, N < 25) and low–normal estradiol (69 pg/mL), which improved after temporary drug interruption with lower FSH (26.9), LH (36.0), and preserved estradiol (78.6 pg/mL), suggesting partially reversible ovarian dysfunction. Time to onset and severity varied across agents and endocrine axes.

Conclusion: This Philippine case series highlights the broad spectrum and variable presentation of endocrine immune-related adverse events associated with ICIs and TKIs, underscoring the need for early surveillance, timely hormone replacement, and multidisciplinary collaboration in resource-limited settings.

*Unless otherwise noted, all abstracts presented at ENDO must not be released to the press or the public until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.*