use strict;
my $str = '{
"url": "RETURNED URL",
"repository_url": "RETURNED URL",
"labels_url": "RETURNED URL",
"comments_url": "RETURNED URL",
"events_url": "RETURNED URL",
"html_url": "RETURNED URL",
"id": "RETURNED_ID",
"node_id": "RETURNED id",
"number": 10,
...
"author_association": "xxxx",
"active_lock_reason": null,
"body": "text \\"text\\" text, text text, text \\\\\\"text text\\", text, text text",
"performed_via_github_app": null
}';
my $regex = qr/(\G(?!^)|\"body\"\s*:\s*\")([^\",\\]*(?:\\.[^\",\\]*)*),/mp;
my $subst = '$1$2';
my $result = $str =~ s/$regex/$subst/rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html