SAT453 Endocrine Related Adverse Events Of Immune Checkpoint Inhibitors In Cancer Patients Visiting Tertiary Care Center In Saudi Arabia

Disclosure: A.M. Alqahtani: None. A.S. Alghassab: None. L.A. Alghamdi: None. M. Almalki: None. Introduction: Immune checkpoint inhibitors (ICIs) have been approved for the treatment of a different types of cancers. Those agents may result in exaggerated immune response leading to numerous toxicities referred to as immune-related adverse events particularly endocrinopathies affecting most commonly the thyroid and pituitary glands. Methods: We carried out a retrospective analysis of endocrine dysfunction in cancer patients receiving immune checkpoint inhibitors therapy namely pembrolizumab, nivolumab and ipilimumab between July 2018 and July 2022. A total of 123 patients were included in this analysis. We reviewed pituitary-, thyroid-, and adrenal-related hormone test results, as well as the clinical perspective of patients, to identify and characterize cases of hypophysitis, hypothyroidism, thyroiditis, and adrenal dysfunction. Results: A total of 123 patients were included in our study. Among them, Female participants were 67 (54.5%) and males were 56 (45.5%) with mean age of 53.7 years. Majority of the included patients (91.1%) received single agent and only 8.9% received combination therapy. The most used ICI in our cohort was pembrolizumab 73.9% followed by nivolumab 17.8% and the combination of either one of them (beside ipilimumab) was used in 8.9% of the time. The most frequent indication for ICIs was breast cancer (27.6%) followed by lung cancer (19.5%) and metastatic renal cell carcinoma (8.9%). The average number of cycles was 12 cycles, and the average duration of treatment was 12 months. The total incidence of all endocrinopathies was 22.7%. Out of 123 patients, 24 patients developed thyroid dysfunction in term of thyroiditis (1), subclinical hypothyroidism (7) or overt hypothyroidism (16). Hypophysitis occurred in one patient only. There was no occurrence of new onset diabetes mellitus in all groups. Pembrolizumab is thought to be the culprit in 18 patients of thyroid dysfunction and the patient who developed hypophysitis. Nivolumab was responsible about 4 cases of thyroid dysfunction. The rest of the cases were attributed to the combination therapy. The mean TSH level at the time of hypothyroidism diagnosis (overt hypothyroidism and subclinical hypothyroidism) was 95.8 mIU/L. And the mean free thyroxine level in overt hypothyroidism group was 6.3 pmol/L. Conclusion: Our cohort demonstrated an increased risk of thyroid dysfunction among cancer patients who receive immune checkpoint inhibitors. Pituitary dysfunction is infrequent adverse effect of these agents. Endocrine assessment is recommended prior to initiation of therapy and periodically afterward. Special attention should be given to pituitary dysfunction as it might be overlooked due to non-specific symptoms. Presentation: Saturday, June 17, 2023