Provided are crystalline forms of 2-acetyl-4H, 9H-naphtho[2,3-b]furan-4,9-dione, specifically a crystalline form characterised by having two or more peaks from the group consisting of peaks at least at about 10.2, 11.9, 14.1, 14.5, 17.3, 22.2, and 28.1 degrees 2&thetas. Also disclosed are purified compositions comprising said crystalline forms, pharmaceutical compositions comprising said crystalline forms following micronisation, methods for their preparation and uses thereof. The compound and compositions thereof are useful in the treatment of cancer, particularly colorectal adenocarcinoma, breast cancer, ovarian cancer, head and neck cancer, melanoma, angiosarcoma and gastric adenocarcinoma.
