A tandem modular endograft includes a main elongate tubular graft body having at least one circumferential inflatable channel disposed towards a proximal portion of the graft body wall and a plurality of circumferential inflatable channels disposed towards a distal portion of the graft body wall. A proximal expansion anchor is disposed at or secured to a proximal neck portion of the graft body wall. First and second elongate tubular stent-graft extensions may be percutaneously disposed into a distal end of the tubular graft body. In combination, proximal portions of the first and second stent-graft extensions are conformable to a shape of the open lumen of the main graft body.