The present disclosure relates to ultra-pure forms, polymorphs, amorphous forms, and formulations of N-[(1r,4r)-4-(3-chloro-4-cyanophenoxy)cyclohexyl]-6-[4-({4-[2-(2,6-dioxopiperidin-3-yl)-6-fluoro-1,3-dioxo-2,3-dihydro-1H-isoindol-5-yl]piperazin-1-yl}methyl)piperidin-1-yl]pyridazine-3-carboxamide, referred to herein as Compound A: The present disclosure also relates methods of manufacturing and purifying the same, as well as intermediates useful in the synthesis of Compound A. The ultra-pure forms, polymorphs, amorphous forms, and formulations of Compound A can be used as therapeutic agents for the treatment of various diseases and conditions such as cancer.