How to use nginx proxy_pass subroutes from node app?

I have a node app running on port 8002 with different subroutes like '/login' or '/facebook', i also have nginx (v1.6.0) and the following config:

  server {
      listen 80;
      server_name my-ghost-blog.com ;

      client_max_body_size 10M;

      location / {
              proxy_pass http://localhost:2368/;
              proxy_set_header Host $host;
              proxy_buffering off;
      }

      location ~ ^/(sitemap.xml) {
      	    root /var/www/ghost;
      }

      location ~ ^/(robots.txt) {
  	    root /var/www/ghost;
      }

      #proxy to a node app running on 8002 port
      location ^~ /auth/ {
          proxy_pass http://localhost:8002/;
      }
  }

when i go to '/auth/' it works, but when i try to go to a node app'subroute, 404 appears because nginx dont know how to handle it.

any ideas?

thanks