Selpercatinib-induced Acalculous Cholecystitis in an Elderly Patient with RET Fusion-positive Non-small Cell Lung Cancer.

The effectiveness of selpercatinib against RET-fusion-positive non-small cell lung cancer (NSCLC) in geriatric patients is underreported. We report the case of an 84-year-old woman in whom reduced-dose selpercatinib elicited a significant tumor response in KIF5B-RET fusion-positive NSCLC. However, she developed acalculous cholecystitis, which led to the discontinuation of the drug. This is the first reported case of selpercatinib-induced acalculous cholecystitis in a patient. The report highlighted the potential efficacy of selpercatinib in elderly patients while underscoring the risk of severe adverse events and emphasizing monitoring and personalized dose management.