A brief tutorial on how to exclude URLs from Apache's ProxyPass was published by Tecadmin.
Excluding URLs from ProxyPass in Apache – TecAdmin
Apache’s mod_proxy module allows you to forward requests to another server using the ProxyPass and ProxyPassReverse directives. However, in some cases, you may want to exclude certain URLs from being proxied. In this tutorial, I will show you how to exclude an URL from ProxyPass in Apache.