use Regexp::Assemble;

my $r = Regexp::Assemble->new;
while( <DATA> ) {
    chomp;
    $r->add( $_ );
}
print $r->as_string;
# produces ^(?:K[LM]|P[AM]|S[LZ]|CP|ME|WX|YZ)XX1

__DATA_
^CPXX1
^KLXX1
^KMXX1
^MEXX1
^PAXX1
^PMXX1
^SLXX1
^SZXX1
^WXXX1
^YZXX1

##</code><code>##

print Regexp::Assemble
    ->new( chomp=> 1 )
    ->add( <DATA> )
    ->as_string;