certain information has been excluded from this exhibit because it is both not material and would likely cause competitive harm to the registrant if publicly disclosed. omissions are designated as [ * * * ]. certain information has been excluded from this exhibit because it is both not material and would likely cause competitive harm to the registrant if publicly disclosed. omissions are designated as [ * * * ]. april 12, 2022 alpine immune sciences inc. 188 e blaine st suite 200 seattle, wa 98102 united states attention : paul rickey, cfo re : the option and license agreement between alpine immune sciences inc. ( “ alpine ” ) and abbvie global enterprises ltd. ( as assignee of abbvie ireland unlimited company ) ( “ abbvie ” ), made and entered into as of june 17, 2017 ( the “ agreement ” ) to whom it may concern : this letter serves to memorialize the agreement between abbvie and alpine to replace schedule 1. 157 of the agreement with the schedule 1. 157 attached to this letter as exhibit a. please countersign this letter below and return a copy to abbvie. this letter will be effective upon execution by each of the parties. if you have any questions regarding this letter, please contact john larson, senior director, alliance management, at [ * * * ]. sincerely, / s / arthur c. price abbvie global enterprises ltd. name : arthur c. price title : director agreed : / s / paul rickey alpine immune sciences inc. name : paul rickey title : cfo exhibit a schedule 1. 157 [ * * * ] success completion criteria [ * * * ]