Evaluation of extended-interval thyroid function monitoring during pembrolizumab treatment
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Publication Date
2025
Keywords
oregon, oaa 2025
Disciplines
Medical Education | Pharmacy and Pharmaceutical Sciences
Abstract
Abstract: Thyroid dysfunction is a common immune-related toxicity in patients treated with immune checkpoint inhibitors, with hypothyroidism being more common than hyperthyroidism. The National Comprehensive Cancer Network (NCCN) Guidelines conditionally recommend extending thyroid function monitoring from every 4 to 6 weeks to every 12 to 18 weeks in patients without baseline thyroid abnormalities. Currently, the Providence Cancer Institute Franz Clinic checks thyroid function every treatment cycle. A treatment cycle for a common immune checkpoint inhibitor called pembrolizumab is 3 weeks for fixed-dose 200 mg. This study aims to evaluate whether reducing the frequency of thyroid-stimulating hormone (TSH) and free thyroxine (T4) lab monitoring impacts patient management in terms of safety and provides potential cost savings. This single-institute retrospective observational study includes patients aged 18 years or older who received pembrolizumab 200 mg between September 1, 2023, and August 31, 2024. Patients were excluded if they received pembrolizumab for research purposes, had fewer than four doses, had baseline thyroid function abnormalities, or were taking thyroid hormone replacement prior to pembrolizumab treatment. The primary endpoint for determining patient safety was assessed using a Kaplan-Meier survival analysis, comparing 3-week monitoring with extended intervals by evaluating the number of missed or delayed detections of thyroid abnormalities. Compared with 3-week monitoring, 6-week monitoring identified 9 additional cases (p = 0.14), 11 cases with 12-week monitoring (p = 0.08), 12 cases with 18-week monitoring (p = 0.05), and 17 cases with 21-week monitoring (p < 0.05). Among the 98 patients, 42% (n=41) developed thyroid abnormalities after receiving pembrolizumab treatment. Fourteen had subclinical hyperthyroidism, eleven had subclinical hypothyroidism, and sixteen had clinical hypothyroidism. None of the patients with subclinical hypo- or hyperthyroidism were found to have received drug therapy. No cases of clinical thyroid level abnormalities occurred within the first 42 days of treatment. Three patients developed clinical hypothyroidism between 42 and 84 days, while thirteen patients developed clinical hypothyroidism after 84 days. The median time from the first dose to the onset of any type of abnormal thyroid function was 86 days. The secondary endpoint estimated yearly cost savings if extended lab monitoring was utilized in the treatment group. Cost savings of $75,590.67 was found with 6-week monitoring, $113,386.00 with 12-week monitoring, and $125,984.44 with 18-week monitoring. In conclusion, extending thyroid function monitoring to every 12 weeks for patients receiving pembrolizumab without baseline thyroid abnormalities was found to be safe and to provide significant cost savings for patients. (IRB exempt) Learning objectives: Determine whether extending the thyroid function monitoring interval is safe for patients treated with pembrolizumab who do not have baseline thyroid abnormalities. Assess the potential cost savings for patients when using extended-interval thyroid function monitoring. Presentation category: Oncology/Hematology
Specialty/Research Institute
Graduate Medical Education
Specialty/Research Institute
Pharmacy
