It has some relationship to X-pack for Executable.
This aPACK is not related to
apack, a component of the atool archive management utility.
Based on information from the file command, compressed EXE files have bytes
8e c0 b9 08 00 f3 a5 4a 75 eb 8e c3 8e d8 33 ff be 30 00 05 at offset 53.
For compressed COM files, the byte sequence
50 a4 ff d5 73 appears somewhere early in the file.