This mini-symposium presents recent developments in advanced spline methods for Isogeometric Analysis (IGA). It brings together theoretical and computational perspectives on the construction and analysis of spline spaces, with a focus on approximation, adaptivity, efficiency, and flexibility. Particular attention is given to modern spline technologies that enable refined and adaptive discretizations, improved computational performance, and the treatment of complex geometries and challenging problems. The mini-symposium aims to provide an overview of current trends in spline-based IGA and to foster discussion on new developments, challenges, and future directions in the field.