Normally, like LP just said, in post you would use the Alpha/ID of the occluding object(s) to "cut-away" the alpha of your target object.
However, you seem to want to make a single pass with this operation already done.
So, below is the fastest and easiest way this can be achieved directly in Maya rather than the normal way of using matte or ID passes:
-Select the shader that you have applied to the box, and open its' attribute editor and under Matte Opacity, change the drop-down box to BLACK HOLE.
This will do exactly what you require to both the color and the alpha of the result.
There are also other ways to achieve this directly in Maya, but like I said normally in production one would do this operation in post and simply use the alpha or ID pass of the "occluding" object to remove/occlude the contents of your box
Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS