Попробуйте
preg_replace('/^([^(]+(?:\([^)]+\))?).*/','$1', $item);
Несколько объяснений
^ - start of the string
[^(]+ - match characters before first bracket
\([^)]+\) - match first bracket
(?: ... )? - optional
.* - eat the rest
$1 - replace with match string
Или просто удалить последнюю часть
preg_replace('/(?<=\))\s*\(.*$/','', $item);
(?<=\)) - if there is ) before pattern
(\s*\(.*$ - remove everything after `(` and also zero or more whitespaces before last bracket.