PERM approved but changed employer recently

Hello, I understand my PERM is approved but I recently changed my employer. Can my new employer file I-140 with this approved PERM? How to make use of the priority date.

Thanks

Anybody got L1A Approved after submitting RFE response. I have responsed to RFE on March 3 2014, but still no response. Status still shows the same thing for almost 56 days over (“RFE Response Review”)

Thanks