Is there a way to cancel or compete with an unconfirmed transaction to make the original one invalid?

https://blockchain.info/tx/22284fac41ed4e78cb531f020d8f21dd0285694809f1d048a02aae4915161ccd

That's a hacker transferring out 52 BTC fresh from DGEX exchange's payout account.

We are not expecting to get it back but it would be nice to know. Thank you for any advice.