This should fulfill your requirements.
ABC:\s*(\(\D+\)\s*.*?)\\n
Here it is with some tests http://www.regexplanet.com/cookbook/ahJzfnJlZ2V4cGxhbmV0LWhyZHNyDgsSBlJlY2lwZRiEjiUM/index.html
Futher reading on regular expressions: http://www.regular-expressions.info/characters.html