Nirogacestat is a 1H-imidazole substituted with a 1-[(2,2-dimethylpropyl)amino]-2-methylpropan-2-yl group at position 1 and a {N-[(2S)-6,8-difluoro-1,2,3,4-tetrahydronaphthalen-2-yl]-L-norvalyl}amino group at position 4. It is a gamma-secretase inhibitor and antineoplastic agent, indicated as a hydrobromide salt for adult patients with progressing desmoid tumours requiring systemic treatment. It belongs to the classes of imidazoles, tetralins, organofluorine compounds, secondary carboxamides, and secondary amino compounds, and is a conjugate base of nirogacestat(2+).