When doctors use CAR T-cell therapy to fight cancer, they are essentially reprogramming your immune system. Sometimes, this powerful reset causes your body to react in unexpected ways, including attacking your own hormone glands. A recent look at safety reports from 2017 through the second quarter of 2025 found 14 specific signals pointing to these endocrine problems. The most common issue was high blood sugar, which often showed up when patients were already having a severe immune reaction. Other serious findings included adrenal insufficiency, where your body stops making enough stress hormones, and Hashimoto's thyroiditis, an autoimmune attack on the thyroid. The data also flagged a higher risk of death when these hormone issues occurred together with the severe immune reaction. These findings come from a database of safety reports, not a direct count of every patient, but the pattern is clear enough to suggest real danger.
CAR T-cell therapy linked to endocrine adverse events in FAERS analysisCAR T-cell therapy may trigger rare but serious hormone problems like adrenal failure
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This study was a retrospective disproportionality analysis and structured literature review using data from the FDA Adverse Event Reporting System (FAERS) database from 2017 to the second quarter of 2025. It focused on patients receiving CAR T-cell therapy, with 269 endocrine adverse event reports analyzed. The primary outcome was endocrine adverse events associated with CAR T-cell therapy, and no comparator was reported.
Main results showed 14 significant disproportionality signals for endocrine adverse events, including a reporting odds ratio of 14.93 for estrogen deficiency. Hyperglycemia was the most frequently reported event, with a 39% incidence, and it was associated with cytokine release syndrome (CRS). Mortality was frequently reported among cases with positive endocrine signals, indicating an increased risk when co-occurring with CRS, though exact numbers and statistical measures were not reported.
Safety data identified adverse events such as hyperglycemia, estrogen deficiency, adrenal insufficiency, hypothalamo-pituitary disorders, Hashimoto's thyroiditis, and central diabetes insipidus, with mortality as a serious adverse event; discontinuations and tolerability were not reported. Key limitations include that endocrine adverse events remain poorly characterized and FAERS data have inherent limitations of disproportionality analysis, such as potential reporting biases. The practice relevance is that proactive monitoring of endocrine function, especially in patients experiencing CRS, is warranted, but FAERS signals are disproportionality analyses, not direct incidence rates, and clinical evidence is based on case reports and retrospective studies.