Are app-related trademarks allowed as keyword for an app in the App Store?
You shouldn't use trademarked words as keywords for your app:


  When choosing a keyword, don’t use competing app names, company or product names, or trademarked names. Avoid inappropriate or objectionable terms or irrelevant words such as celebrity names; all keyword submissions are reviewed by Apple.


Source: iTunes Connect Developer Guide: First Steps: Identifying Your App in iTunes Connect: Set Up Searching and Browsing: Keywords: Get the Best Results; emphasis mine.