The present invention provides a compound of formula (I) or a pharmaceutically acceptable salt thereof;Wherein R1, R3-R6, X2and X3are as defined herein, a method for manufacturing the compounds of the invention, and its therapeutic uses. The present invention further provides a combination of pharmacologically active agents and a pharmaceutical composition.本發明提供一種式(I)化合物或其醫藥學上可接受之鹽;其中R1、R3-R6、X2及X3如本文所定義;提供一種用於製造本發明化合物之方法及其治療性用途。本發明進一步提供一種藥理學活性劑與醫藥組合物的組合。