As we know, GPL is intended especially for software products, but it may be used for any work if the creator thinks it is OK.
If the original work and a modified work are both software, I see no problem as far as my question is concerned.
If the original work is a software, but the derivative work is not a software, there arises a problem in some cases, especially if the derivative work does not have a source code.
I will try to explain this by an example: - A video game is licensed under GPL v3. - Someone prepares a derivative work of this video game by using the story of the game, and makes a feature film, or writes a novel.
How will the GPL apply to the derivative work in this case? Of course, contacting the original creator and obtaining permission to do such a derivative work is the reasonable method, but this may not be possible at all situations.