Since you sent it from an exchange to another exchange, then I believe that only the exchange could save you currently, but you need to check their policies about sending coins to a wrong address because some exchanges stated that they can do nothing about it if this kind of mistake occurs, once it is stated then I think you have no choice anymore than to let go of the coin, but if it is not stated, then you need to send a message to the support team of poloniex so that they can use the private key of the wallet to retrieve coin.