INNV-07. ADJUVANT POST-SURGERY TREATMENT OF RECURRENT IDH2 MUTANT ANAPLASTIC OLIGODENTROGLIOMA (AO) WITH IDH2 INHIBITOR, ENASIDENIB: A CASE REPORT

Abstract

Abstract INTRODUCTION Recent phase III trial presented by Mellinghoff at 2023 ASCO demonstrated successful treatment of Isocitrate dehydrogenase (IDH)–mutant grade 2 gliomas with Vorasidenib, an oral brain-penetrant inhibitor of mutant IDH1 and IDH2 enzymes. Ivosidenib and enasidenib are separate inhibitors of mutant IDH1 and IDH2, which have shown single-agent activity for the treatment of IDH1- or IDH2-mutant acute myeloid leukemia but the effect in the treatment of glioma is uncertain. Here we report a case of IDH2 mutant AO, who was treated with enasidenib for about two years with fair tolerance and was postponed the next intervention. CASE REPORT A 36 yo female was diagnosed anaplastic ogligodentroglioma in 2006, 17 yrs ago. The patient underwent surgery resection, radiation and Temozolomide (TMZ), and 4 cycles of adjuvant TMZ. In 2021, fifteen years later, she was found tumor recurrence. She had a second surgery with near gross total resection. Pathology confirmed anaplastic oligodentraglioma with negative IDH1 mutation but positive IDH2 R172K mutation. To avoid re-radiation nor re-challenge with TMZ, the patient opted IDH2 inhibitor therapy after surgery. The patient tolerated the treatment, and her brain MRI demonstrated no tumor recurrence until one year later when her brain MRI showed vague sub-centimeter nodular non-enhancing lesion at surgical area. Enasidenib was continued for additional 6 months until recent MRI showed small and slow growth. Total therapy is 20 months. Clinically, the patient has no symptoms from tumor. DISCUSSION Our case review found post-surgery therapy with IDH2 inhibitor Enasidenib for IDH2 mutant recurrent AO is tolerated and could postpone next intervention such as re-radiation or re-challenge with TMZ.