CATIA CAD software from Dassault Systemes supports many CAD and 3D modeling formats for export purposes, and thus should help you with export of 3DXML CAD files to some exchange alternatives, for example the ISO STEP product data (.stp, .step) format.
Some viable alternative would be to use some dedicated 3D model conversion tool with support of Dassault Systemes formats which should allow 3dxml to stp conversion.