Brain tumour-initiating cells (BTICs) are stem cell-like transformed cells that promote the formation and recurrence of gliomas. Sarkar et al. studied the growth of BTICs isolated from patients with malignant gliomas. They found that microglia or medium conditioned by microglia, monocytes or macrophages from non-glioma patients could inhibit BTIC growth in vitro. By contrast, microglia from patients with glioma did not restrict BTIC growth. The authors screened more than 1,000 compounds and found that treatment of microglia with the anti-fungal drug amphotericin B increased their ability to inhibit BTIC growth. Notably, microglia from patients with glioma could inhibit BTIC growth if they were treated with amphotericin B, and the drug also inhibited brain tumour growth in mice. This study suggests that amphotericin B could be used to promote antitumour immune responses in patients with glioma.