I know you asked for one Regex, and @rray posted the solution that does exactly what you asked (and already took my +1). Anyway I think it’s important to comment that PHP already has a solution made as a glove for your specific case, and that does not need to Regex.
Just that, clean and short to write:
'ALL'.strstr( '99-01[10-10-2010]', '-' );
An example code:
$s = '99-01[10-10-2010]';
echo 'ALL'.strstr( $s, '-' );
Iterating on a array:
$strings = array(
'99-01[10-10-2010]',
'29-02[10-11-2011]',
'95-03[10-12-2013]',
'88-04[10-10-2015]',
'59-06[11-12-2016]'
);
foreach( $strings as $s ) echo 'ALL'.strstr( $s, '-' );
See working on IDEONE.