INNV-32. Successful treatment of metastatic grade III meningioma and comorbid invasive ductal carcinoma of breast with abemaciclib: A case report

Abstract Metastatic meningioma is a rare clinical entity with no currently established consensus on management. Systemic therapy approaches remain largely investigational with robust responses reported in a small subset of patients. No prior reports have described successful treatment of metastatic meningioma and co-primary breast cancer with systemic therapy. We present a unique case of a 63-year-old woman with a remote history of WHO grade I parasagittal meningioma who, during staging for newly diagnosed breast cancer, was found to have recurrent intracranial meningioma and new intrapulmonary metastasis. Tissue analysis of the lung lesion confirmed WHO grade III meningioma positive for ESR1 mutation and homozygous CDKN2A/B deletion. The patient was treated with 12 cycles of abemaciclib with marked radiographic response of both malignancies on serial PET/CT imaging. This case illustrates the potential role of targeted systemic therapy in metastatic malignant meningioma, particularly in patients with co-primary malignancies harboring shared molecular features.