On April 15, 2024, Dr. Simon Pimstone, chair of the board of directors (the ?Board?) of Xenon Pharmaceuticals Inc. (the ?Company?), and Dr. Mohammad Azab, a member of the Board, each informed the Company of their respective decisions not to stand for re-election to the Board at the Company?s 2024 annual meeting of shareholders (the ?AGM?). Each director will continue to serve on the Board until the AGM. The decisions of Dr. Pimstone and Dr. Azab not to stand for re-election were not due to any disagreement between either director and the Company regarding its operations, policies or practices.