The present invention relates to novel polycyclic compounds of general Formula (I) wherein X represents N-R5, O, S, or S(O)2; Y represents optionally substituted
aryl or heteroaryl; and R1, R2, R3, R4 and R5 represent various groups. The compounds of the invention are useful as inhibitors of the MTHFD2
enzyme, in particular for use in the treatment of diseases associated with MTHFD2
enzyme such as, for example, auto-immune diseases, inflammatory diseases, and proliferative diseases.