The present disclosure relates to a piston pump assembly comprising a piston with a variable stroke and to a hydraulic braking system comprising the same. The piston pump assembly comprises at least: a rotatable drive shaft defining an axis of rotation of the rotatable drive shaft; a cam disposed on the drive shaft; and the piston biased toward the cam and configured to reciprocate along a piston axis for displacing a hydraulic fluid. The cam is movable relative to the piston axis and is selectively placed in one of a first position at a first distance from the piston axis and a second position at a second distance from the piston axis; and wherein the cam comprises at least two portions each of which has, at a given position of the cam relative to the piston axis, a different non-circular cross section in a plane perpendicular to the axis of rotation and/or a different eccentricity with respect to the axis of rotation, the at least two portions of the cam comprising at least a first cam portion having a first non-circular cross section and/or a first eccentricity, and a second cam portion having a second non-circular cross section and/or a second eccentricity.