Apache RewriteRule 502 Error on dev server, works on live

I'm on Apache 2.2.15. My vhost.conf contains a RewriteRule to handle article URLs;

# handling for neat article titles
RewriteRule ^/news/[0-9]{4}/[A-za-z]{3}/([0-9a-zA-Z-]*)/([0-9]{4})([0-9]{6})/?$ "/news/article.cfm?clk=$2&article_id=$3&urltitle=$1" [P,L]

This is working correctly on our live server however on my local development server I'm getting a 502 Error in the browser when I try to load an article:

Proxy Error

The proxy server received an invalid response from an upstream server.
The proxy server could not handle the request GET /news/2015/news-article/0123012345.

Reason: DNS lookup failure for: localhost.example.com

Apache/2.2.15 (CentOS) Server at localhost.example.com Port 80

This is what I've got in the error log;

[Wed Oct 28 10:00:25 2015] [error] [client 192.168.1.66] proxy: DNS lookup failure for: localhost.example.com returned by /news/2015/news-article/0123012345, referer: http://localhost.example.com/

This leads me to believe that there must be something different in the config of the local server which is causing it problems.

These are the Apache modules I have enabled;

$ apachectl -M | grep proxy
 proxy_module (shared)
 proxy_balancer_module (shared)
 proxy_ftp_module (shared)
 proxy_http_module (shared)
 proxy_ajp_module (shared)
 proxy_connect_module (shared)
Syntax OK
$ apachectl -M | grep rewrite
 rewrite_module (shared)
Syntax OK

Sorry if I've left out any pertinent information, grateful for any advice.