Substituted pyrazole derivatives as selective CDK12/13 inhibitors

A compound of formula (I):

• or a pharmaceutically acceptable salt, a N-oxide or a stereoisomer thereof;
• wherein,
• ------ is an optional bond;
• each X1, X2 and X3 are independently CR3 or N;
• each Y1 and Y2 are independently C, CH or N;
• R1 is hydrogen or alkyl;
• R2 is
• or —C≡N;
• each R3 is independently selected from hydrogen, halogen, cyano and alkyl;
• R4 is hydrogen, alkyl or —(CH2)n—NRaRb;
• R4′ & R4″ are each independently hydrogen or alkyl;
• R5 is hydrogen or alkyl;
• Ra and Rb are each independently hydrogen or alkyl;
• alternatively, Ra and Rb together with the nitrogen atom to which they are attached form an optionally substituted heterocyclic ring containing 0-2 additional heteroatoms independently selected from N, O and S;
• n is 1 to 3;
• and
• p and q are each independently selected from 0 to 2.