hola.
first off, it usually helps if we can see a more complete chunk of your code. in your pasted example, $response will always be 0. i know that people have a tendency to paste 'demo' code, but the more representative that your example is, the more accurate our response can be.
so let's presume that you're manipulating $response somehow. while perl doesn't have a built-in switch statement, you can always use a simple if-elsif-else structure. e.g.

if ($response == 200) {
  #
}
elsif ($response == 500) {
  next; # or last, or whatever.
}
else {
  # default
}
[download]

or, if you just want to skip to the next line if a specific condition is met, try

next if ($response == 500);
[download]

just as in english, it's generally more clear to ask in the affirmative: "is it raining?" vs. "it is not raining, is it"? that's often applicable for your code as well with if vs. unless.

also fyi, goto needs a label (or expression that returns a label), not another keyword. if you'd use strict and -w, you'd probably catch these things...
cheers..