Transferring nginx settings to F5

Hi, I've faced with a problem during transferring my nginx settings to F5 using irules:

Example: https://domain.com/instance_id/

location ~* ^(/[^/]+)(/(.+)?) {
    set $prefix $1;
    set $request_url $2;
    proxy_set_header X-URI-Prefix $prefix;
    proxy_pass http://fe-nodes$request_url$is_args$args;
    break;

The question is how we can emulate "proxy_pass $request_url$is_args$args" using irule? Thanks