Provided are crystalline forms of 2-acetyl-4H, 9H-naphtho[2,3-b]furan-4,9-dione, purified compositions comprising said crystalline forms, pharmaceutical compositions comprising said crystalline forms following micronisation, methods for their preparation and uses thereof. Said compound is useful in the treatment of cancer, particularly colorectal adenocarcinoma, breast cancer, ovarian cancer, head and neck cancer, melanoma, angiosarcoma, gastric adenocarinoma, and adrenocorticoid.
