I'm not familiar with a Cassandra database.
It also appears that there is no library for the cassandra db built into PHP or through pecl, so you'll either need to construct your own drivers for use with the PDO, or use standard socket communication.
Remote doesn't matter. So long as its exposed, you can give it the ip/name and port combinations to communicate with it when you establish a socket connection.
header('HTTP/1.1 420 Enhance Your Calm');