Trojan.Agent refers to a generic Trojan malware detection. It is used for detections that are either associated with no specific malware families or not enough information is available to pinpoint the malware family.
LuminosityLink is offered for download on the publishers site as a remote administration tool. Although the application itself is a legitimate one, it is often abused (as in these Trojans).
Malwarebytes can remove Backdoor.LuminosityLink without further user interaction. You may find other malware if this Trojan has been active. Users of infected system should be aware that important credentials may have been stolen.