Haproxy Scan Response Body

Hi ,
I am trying to scan the response body which we get from the server and match with a regex before forwarding it to the client.
Is there any way we could grab the response body with res.payload().?
Im having a hard time forming an acl to match the response body with a regex.

Idea is to match the response body with regex ,if match occurs then need to set response status code and send an error message.

Any ideas and thoughts on this ?
Thank you.