DDEL-06. DRUG INTERACTION BETWEEN EVEROLIMUS AND CANNABIDIOL IN PEDIATRIC PATIENTS WITH SUBEPENDYMAL GIANT CELL ASTROCYTOMAS: A SINGLE INSTITUTION EXPERIENCE

Tuberous sclerosis complex (TSC) is an autosomal recessive genetic disorder associated with clinical manifestations including subependymal giant cell astrocytomas (SEGA) and seizures. The combination of everolimus and Epidiolex, a purified form of cannabidiol, has become an increasingly common treatment regimen in this population. Everolimus is primarily metabolized via CYP3A4, which may be inhibited by cannabidiol. We seek to describe our institution’s experience with this drug interaction. METHODS: Investigators conducted a retrospective review of neuro-oncology patients with TSC and SEGA who were treated concurrently with everolimus and cannabidiol. Data collected included demographics, body surface area, everolimus dose, everolimus troughs, date of cannabidiol initiation, documented symptoms, liver and renal function tests, and reason for discontinuing therapy. RESULTS: Three patients (ages 11–17 years) met inclusion criteria. All patients were stable on everolimus doses ranging from 6.5 to 9.5 mg/m(2)/day and achieving trough goals of 5–10 ng/mL. Two to four weeks after initiating cannabidiol, everolimus trough concentrations rose 200–860% above goal. One patient reported new-onset involuntary movements, but no other toxicities were noted. Cannabidiol was discontinued in all cases due to caregiver concerns regarding drug interactions. All patients were able to achieve goal trough concentrations on previously stable doses of everolimus after discontinuing cannabidiol. CONCLUSIONS: Cannabidiol appears to modulate everolimus metabolism leading to significantly elevated serum concentrations. Additional research is required to determine the need for empiric dose adjustments upon cannabidiol initiation. Patient counseling, frequent trough monitoring, and surveillance for adverse effects are crucial for optimizing outcomes in patients prescribed this regimen.