The Alliance A071401 study tested the efficacy of abemaciclib, an oral CDK4/6 inhibitor, in patients with grade 2 or 3 meningiomas that had progressed after surgery and/or radiotherapy.[1][2] The study enrolled 36 patients with NF2 mutations or CDK pathway alterations who received abemaciclib at a dose of 200 mg twice daily.[1][2] The primary endpoint was progression-free survival at 6 months (PFS6) and objective response to treatment.[1][2] Results showed that 55% of patients had PFS6 (95% CI 40–75%), with a median overall survival of 29 months.[2][3] Median progression-free survival was 7.6 months.[2] Patients with NF2 mutations had better PFS6 outcomes (58%) compared to patients with only CDK pathway alterations (25%).[2] Treatment was well tolerated, with diarrhea, fatigue, headache, and nausea being the most common adverse events, and only a quarter of patients experiencing grade 3 or 4 serious adverse events.[3] The study met its primary endpoint and abemaciclib appears to be a promising candidate for further clinical investigation in patients with progressive meningiomas.[1][2]