A first aspect of the invention relates to a compound of formula (I), or a pharmaceutically acceptable salt thereof, for use in treating a proliferative disorder, wherein: X is NR7 R1 and R2 are each independently H, alkyl or cycloalkyl R3 is a 6-membered heterocycloalkyi group selected from piperidinyl, piperazinyl, morpholinyl and tetrahydropyranyl, wherein said heterocycloalkyi group is optionally further substituted by one or more (CH2)nR19 groups R4 and R4 are each independently H or alkyl or R4 and R4 together form a spiro cycloalkyl group Q is CH or N R6 is OR8 or halogen n is 1, 2 or 3 R19 is H, alkyl, aryl or a cycloalkyl group R7 and R8 are each independently H or alkyl and wherein said compound is administered in accordance with a dosing regimen which: (i) maintains a plasma concentration of from about 50 to about 500 nM for a period of up to about 16 hours or (ii) maintains a plasma concentration of from about 0.5 μΜ to about 1 μΜ for a period of up to about 6 hours or (iii) achieves a maximum plasma concentration (Cmax) of no more than about 500 nM within a period of about 6 hours or (iv) achieves a maximum plasma concentration (Cmax) of no more than about 200 nM within a period of about 16 hours or (v) achieves a maximum plasma concentration (Cmax) of about 0.5 μΜ to about 1 μΜ within about 6 hours. Further claims relate to a method of treatment based on this dosing regimen, and kits relating to the same.Un premier aspect de la présente invention concerne un composé de formule (I), ou un sel pharmaceutiquement acceptable de celui-ci, pour une utilisation dans le traitement dun trouble prolifératif, dans lequel: X est NR7 R1 et R2 sont chacun indépendamment H, alkyle ou cycloalkyle R3 est un groupe hétérocycloalkyle à 6 chaînons choisi parmi pipéridinyle, pipérazinyle, morpholinyle et tétrahydropyranyle, dans lequel ledit groupe hétérocycloalkyle est en outre facultativement substitué par un ou plusieurs groupes (CH2) nR19 R4 et R4sont chacun indépendam
