The present invention provides compounds of formula I-IV and pharmaceutically acceptable salts thereof that exhibit rearranged kinase inhibition (RET) during transfection. In particular, this document provides new crystalline forms of 4- (6- (4 - ((6-methoxypyridin-3-yl) methyl) piperazin-1-yl) pyridin-3-yl) -6- (1-methyl- 1H-pyrazol-4-yl) pyrazolo [1,5-a] pyridine-3-carbonitrile (Formula I)； 6- (2-hydroxy-2-methylpropoxy) -4- (6- (6 - ((6-methoxypyridin-3-yl) methyl) -3,6-diazabicyclo [3.1.1] heptan-3-yl) pyridine -3-yl) pyrazolo [1,5-a] pyridine-3-carbonitrile (formula II)； 6- (2-hydroxy-2-methylpropoxy) -4- (6- (6- (6-methoxynicotinoyl) -3,6-diazabicyclo [3.1.1] heptan-3-yl) pyridin-3-yl) pyrazolo [ 1,5-a] pyridine-3-carbonitrile (formula III)； 6- (2-hydroxy-2-methylpropoxy) -4- (6- (4-hydroxy-4- (pyridin-2-ylmethyl) piperidin-1-yl) pyridin-3-yl) pyrazolo [1,5-a ] pyridine-3-carbonitrile (formula IV) and pharmaceutically acceptable salts thereof, pharmaceutical compositions containing said compounds, methods for preparing said compounds and the use of said compounds in therapy. More specifically, this application relates to new crystalline forms of formulas I-IV and their pharmaceutically acceptable salts, which are useful for the treatment and prevention of diseases that can be treated with an inhibitor of RET kinase, including RET-associated diseases and disorders.В данном изобретении предложены соединения формулы I-IV и их фармацевтически приемлемые соли, которые демонстрируют реаранжированное во время трансфекции ингибирование киназы (RET). В частности, в данном документе предложены новые кристаллические формы 4-(6-(4-((6-метоксипиридин-3-ил)метил)пиперазин-1-ил)пиридин-3-ил)-6-(1-метил-1H-пиразол-4-ил)пиразоло[1,5-a]пиридин-3-карбонитрила (формула I)； 6-(2-гидрокси-2-метилпропокси)-4-(6-(6-((6-метоксипиридин-3-ил)метил)-3,6-диазабицикло[3.1.1]гептан-3-ил)пиридин-3-ил)пиразоло[1,5-а]пиридин-3-карбонитрила (формула II)； 6-(2-гидрокси-2-метилпропокси)-4-(6-(6-(
