Prenatal therapy of everolimus for large fetal cardiac rhabdomyoma in tuberous sclerosis

Fetal cardiac rhabdomyoma is the most common prenatal cardiac tumor and is frequently associated with tuberous sclerosis complex (TSC). Everolimus, a mammalian target of rapamycin inhibitor, is an established postnatal therapy for TSC-related tumors, but its prenatal use remains rare. A 27-year-old primigravida was referred at 21 weeks’ gestation for evaluation of a left ventricular mass. Given the rapid, severe progression of tumor size, maternal oral everolimus therapy was initiated at 28 weeks, with dose titration to achieve drug levels of 3–8 ng/ml. At 32 weeks, the tumor size regressed significantly. Neonatal serum everolimus on day 1 was 5.2 ng/mL, confirming transplacental transfer. Therapy was resumed postnatally, and at 5 months, the tumor had completely resolved, with normal neurodevelopment and no seizures. While short-term safety and efficacy of prenatal everolimus therapy are promising, further studies are needed to establish standardized dosing, safety profiles, and long-term developmental outcomes.