Why are these options passed to \LoadClass ignored?

I found a solution in one of the related posts: I need to pass the options to the package typearea explicitly.

% === this is myclass.cls ===
\NeedsTeXFormat{LaTeX2e}
\ProvidesClass{myclass}[2014/07/01 1.0 current]
\PassOptionsToPackage{paper=a5,pagesize}{typearea}
\LoadClass[paper=a5,pagesize]{scrbook}