The present invention is related to 6-6 Fused Bicyclic Heteroaryl Compounds of the Formula A2 or A1 and their Use as LATS Inhibitors, or a salt, stereoisomer or pharmaceutical composition thereof; wherein the variables are as defined herein (A1 & A2). The present invention further relates to a method of LATS inhibition in a cell population using a compound of Formula A1, or a salt, stereoisomer or pharmaceutical composition thereof. The present invention further provides a method for manufacturing compounds of the invention, and its therapeutic uses. The invention further provides methods to their preparation, to their medical use, their use in the treatment and management of diseases or disorders.