8812 Incidence And Clinical Experience Of Immune Checkpoint Inhibitors-Induced Endocrine Side Effects Among Filipino Cancer Patients: A Single-Center Retrospective Study

Abstract Disclosure: N.B. Luna: None. E. Mendoza: None. S.A. Kho: None. Incidence And Clinical Experience Of Immune Checkpoint Inhibitors-Induced Endocrine Side Effects Among Filipino Cancer Patients: A Single-Center, Retrospective Study Immune checkpoint inhibitors (ICIs) serve as immunomodulatory antibodies, which enhance the immune system and substantially improve the prognosis for patients with advanced malignancies [1]. Referral to endocrinology have been increasing because ICIs were associated with endocrine-related adverse effects including hypothyroidism, hyperthyroidism, diabetes, hypophysitis and adrenalitis. Hence, the study aimed to retrospectively determine the local prevalence and profile of Filipino patients who developed endocrinopathies during ICI therapy at the University of Santo Tomas Hospital (USTH), Manila, Philippines from 2013-2019. A single-center retrospective study of ICI-treated cancer patients with serial biochemical and/or radiologic monitoring of endocrine adverse effects was done upon approval by the Research Ethics Committee. A total of 27 subjects were included with a median age of 60 years and male predominance. Pembrolizumab consisted 93% of the ICIs given. The incidence of thyroid dysfunction was 36% (18% overt hypothyroidism, 9% subclinical hypothyroidism, and 9% subclinical hyperthyroidism). The median time at risk for development of overt hypothyroidism is 4 weeks with median TSH level of 9.05 uIU/mL from baseline level of 3.77 uIU/mL. All patients who had baseline hypothyroidism worsened with increase from baseline levothyroxine dose by 50 to 230% in order to achieve euthyroidism (p 0.037). Serial monitoring was done every 2 weeks until euthyroidism. ICIs were temporarily put on hold in 75%. Diabetes (p 0.05), renal carcinoma (p 0.001) and dose of 200mg (p 0.42) were associated to developing overt hypothyroidism. Checking of glycemic levels was not routine among non-diabetic patients. Fifteen percent of diabetic patients had worsening of control (median HbA1c 8.5% [8-9] and 23% were newly diagnosed pre-diabetes (median fasting glucose 114mg/dL [104-120]). With the available imaging results, there were no abnormal adrenal metabolic uptake on PET scan and no evidence of hypophysitis in pituitary MRI. In conclusion, overt hypothyroidism is a common occurrence during ICI therapy (18%). Worsening occurred among all patients with hypothyroidism at baseline. New-onset pre-diabetes and worsening of glycemic control were seen in 15 and 23%, respectively. Serial clinical and biochemical monitoring is important and referral to endocrinology should be made if deemed necessary. [1] L Agrawal, A Bacal, S Jain, V Singh, N Emanuele, Ma Emanuele & F Meah (2020) Immune checkpoint inhibitors and endocrine side effects, a narrative review, Postgraduate Medicine, 132:2, 206-214, DOI: 10.1080/00325481. 2019. 1709344 Presentation: 6/1/2024