use warnings;
use strict;

while ( my $line = <DATA> ) {
    my ( $first, $fourth ) = (split(/:/, $line))[0,3];
    $fourth =~ s/,.+$//;
    print "$first, $fourth\n";
}

__DATA__
First column:Second:Third:Fourth Column, with some extra crap:Fifth
First column:Second:Third:Fourth Column, with some extra crap, and even more:Fifth