Cap and not Cap uri

Yes you can use string to lower,

when HTTP_REQUEST {
if { [HTTP::host] equals "www.abc.com" } {
  switch -glob [string tolower [HTTP::path]] {
    "/app/events/calendar.aspx" {
      HTTP::respond 301 Location "https://www.def/redirect/Calendar.aspx"
    }
    default {
      pool default_pool
    }
  }
}
}