Solid forms of the compound, [5-(5-chloro-1H-pyrrolo[2,3-b]pyridin-3-ylmethyl)-pyridin-2-yl]- (6-trifluoromethyl-pyridin-3-ylmethyl)-amine HCl salt (Compound I) and its free base, active on the receptor protein kinases c-Kit and/or c-Fms and/or Flt3, were prepared and characterized: Also provided are methods of using the solid forms.本發明製備並表徵對受體蛋白質激酶c-Kit及/或c-Fms及/或Flt3有活性之化合物[5-(5-氯-1H-吡咯并[2,3-b]吡啶-3-基甲基)-吡啶-2-基]-(6-三氟甲基-吡啶-3-基甲基)-胺HCl鹽(化合物I)及其游離鹼之固態形式:亦提供使用該等固態形式之方法。