VectorWorks is the only program that can reliably export .vwx files and it also supports saving to Autocad format (.dwg), so is obvious choice for vwx to dwg conversion.
As far as we know, AutoCAD does not support Nemetschek VectorWorks graphics (.vwx) and same goes to other similar CAD /3D modeling alternatives. Unfortunately, we haven't found any type of vwx to dwg converter or similar utility, so using VectoWorks to convert vwx to dwg seems to be the only option.