Requisite for transfer (generally speaking) is a parallel curriculum. One of the reasons that transfers have become so uncommon (even between US MD schools) is that curricula vary so much now. There was a time (decades ago) when someone with a compelling reason for transfer who had successfully completed two years with a strong USMLE score and a letter of support from their dean had a fighting chance at transfer. Even then, it was rare and almost always between LCME accredited schools.