The present invention relates to solid dispersions of amorphous 1, 1, 1, 3, 3, 3-hexafluoro-2-(((5-fluoro-2-(1-(2-fluorobenzyl)-5-(isoxazol-3-yl)-1H-pyrazol-3-yl)pyrimidin-4-yl)amino)methyl)propan-2-ol (Compound I) or a pharmaceutically acceptable salt thereof. It also relates to pharmaceutical compositions and pharmaceutical oral dosage unit forms comprising them, and their uses thereof.