Chinese Hero Zhao Zi Long was a Chinese drama with two Korean leads, Im Yoona and Kang Junghoon. It has 60 episodes though that are all 40 minutes each..
The Lover, a Korean drama, had one of its (many) leads as Japanese member Terada Takuya of Cross Gene.
I think that's all I've seen foreign lead wise... I know there was a couple Chinese movies with Korean idol members as leads I think but I can't remember the titles.