A therapeutic agent comprising an RET kinase inhibitor substance intended for use in a method of treating a thyroid carcinoma, wherein the RET kinase inhibitor substance is at least one compound selected from the set that is composed from: 4- (3-Chloro-4- (cyclopropylaminocarbonyl) aminophenoxy) -7-methoxy-6-quinolinecarboxamide； 4- (3-Chloro-4- (ethylaminocarbonyl) aminophenoxy) -7-methoxy-6-quinolinecarboxamide； N6-methoxy-4- (3-chloro-4 - (((cyclopropylamino) carbonyl) amino) phenoxy) -7-methoxy-6-quinolinecarboxamide； 4- (3-Chloro-4- (methylaminocarbonyl) aminophenoxy) -7-methoxy-6-quinolinecarboxamide； N6-methoxy-4- (3-chloro-4 - (((ethylamino) carbonyl) amino) phenoxy) -7-methoxy-6-quinolinecarboxamide； and N- {2-chloro-4 - [(6,7-dimethoxy-4-quinolyl) oxy] phenyl} -N '- (5-methyl-3-isoxazolyl) urea； a pharmacologically acceptable salt from it or a solvate from it.Un agente terapéutico que comprende una sustancia inhibidora de una cinasa de RET destinada a su uso en un método para tratar un carcinoma de tiroides, en donde la sustancia inhibidora de una cinasa de RET es por lo menos un compuesto seleccionado entre el conjunto que se compone de: 4-(3-cloro-4-(ciclopropilaminocarbonil)aminofenoxi)-7-metoxi-6-quinolinacarboxamida； 4-(3-cloro-4-(etilaminocarbonil)aminofenoxi)-7-metoxi-6-quinolinacarboxamida； N6-metoxi-4-(3-cloro-4-(((ciclopropilamino)carbonil)amino)fenoxi)-7-metoxi-6-quinolinacarboxamida； 4-(3-cloro-4-(metilaminocarbonil)aminofenoxi)-7-metoxi-6-quinolinacarboxamida； N6-metoxi-4-(3-cloro-4-(((etilamino)carbonil)amino)fenoxi)-7-metoxi-6-quinolinacarboxamida； y N-{2-cloro-4-[(6,7-dimetoxi-4-quinolil)oxi]fenil}-N'-(5-metil-3-isoxazolil) urea； una sal farmacológicamente aceptable de ella o un solvato de ella.
