Sony Computer Entertainment America (SCEA) filed in the US two new trademarks: “Entwined” and “Kill Strain”. The company entered the Trademark Reporting and Monitoring System (TRAM) on April 17/18.
You can check both trademarks in the USPTO (United States Patent and Trademark Office) website.
All Sony first party studios are working on new games for PlayStation 4, but currently we only know three of them: The Order 1886, DriveClub and Uncharted 4. Maybe these trademarks are related with new games for PS4 that could be unveiled in the next E3.