Diagnosis: Cancer
Treatment: Pharmacy/Prescription Drug.
The insurer denied Tibsovo.
The denial is upheld in whole.

The patient is a male with a low grade oligoastrocytoma. The patient has undergone resection but has progressed despite adjuvant radiation and temozolomide. The tumor is isocitrate dehydrogenase (IDH1) mutated. Ivosidenib (Tibsovo) has been recommended and is under review for medical necessity.

The health plan's determination is upheld in whole.

The treatment with Tibsovo is not medically necessary. Ivosidenib, a mutant-IDH1 inhibitor approved in the United States for advanced acute myeloid leukemia, was well tolerated with no dose-limiting toxicities in a phase I trial in 66 patients with advanced IDH1-mutant astrocytoma, oligodendroglioma, or glioblastoma (Mellinghoff IK, et al). Among 35 patients with progressive non-enhancing gliomas, a partial response or stable disease was observed in 3 and 86 percent of patients, respectively, with a median progression-free survival of 13.5 months. There were no objective responses in enhancing tumors, although a decrease in volumetric growth rate was observed in some patients.
Lacking more definitive data, neither the authors of UpToDate nor the National Comprehensive Cancer Network (NCCN) recommends the use of these agents in this clinical scenario; the former labels the use of ivosidenib an investigational approach. The agent remains the subject of ongoing investigation in this clinical scenario. For these reasons medical necessity cannot be established for this service.