Were Katherine Hepburn and Audrey Hepburn related to eachother?

-I was wondering if the two women were related given that they share the same last name.While both actresses share a surname, they are only very distantly related. I am uncertain as to the relation, if it is by blood or by marriage, however I do know that Audrey formally changed her name to Hepburn only after Katherine had rose to prominence in Hollywood. I truly hope this helps.Audrey's birth name was Audrey Kathleen Ruston, and she was born in Belgium. Katherine's parents were Thomas Hepburn and Katherine Houghton. The original spelling for Katherine's grandfather was Hepbron. Her father's family came from Virginia.

I am not aware of any actual relationship of any kind.

edit

Samantha is correct on the spelling for the first name. The surname and relationship is the issue.
It is Katharine Hepburn, not Katherine