Clinical Scenario - Young Patient with IDH-Mutant Astrocytoma

Dr. Cloughesy presents a 38-year-old woman with first generalized tonic-clonic seizure and non-enhancing left frontal lesion. Following gross total resection, pathology revealed WHO grade 2 IDH-mutant astrocytoma without 1p19q co-deletion. She maintains good performance status, works part-time, and experiences breakthrough focal seizures on levetiracetam. Six-month MRI shows stable but measurable T2-FLAIR signal change at the resection margin.

Dr. Sener emphasizes that astrocytoma diagnosis driven by IDH mutation represents the key molecular change necessitating treatment consideration. Even with gross total resection, microscopic disease remains present and will continue growing. FDA-approved vorasidenib directly targets the tumor's underlying biology while potentially improving seizure control and delaying radiation/chemotherapy requirements.

The breakthrough seizure activity supports treatment initiation, as vorasidenib may reduce overall seizure burden and potentially allow anti-epileptic drug reduction, eliminating medication-related toxicities. The treatment approach aims to control disease course, reduce seizure frequency, and delay more toxic interventions.

For astrocytomas specifically, both panelists favor early treatment initiation given the tumor type's more aggressive behavior compared to oligodendrogliomas. The measurable residual disease provides additional rationale for immediate intervention rather than continued observation.

The case illustrates common clinical scenarios where patients have small amounts of residual disease post-surgery. Although INDIGO required measurable tumors for study endpoints, clinical practice doesn't necessitate waiting for tumor growth before treatment initiation, particularly for astrocytomas.