PIK3CA and glioblastoma: Buparlisib can cross the blood–brain barrier; however, it has not demonstrated sufficient anti-tumor activity in combination with carboplatin and lomustine in a phase Ib/II trial in patients with recurrent glioblastoma previously treated with radiotherapy and temozolomide or as a single-agent in patients with PI3K-activated recurrent glioblastoma [112,113].