Legal recourse after VC disclosure without NDA?

If a potential investor asks for materials on an undeveloped app ("blueprints") without an NDA, is there any legal recourse left if he then commercializes the product himself (paying coders, hiring a manager)? Or is this perhaps something that never happens?

I am talking to a VC who really likes the vision, but does not seem to be interested very much in me or the fact that there is no team yet.