Help with SED in Ubuntu

[sudburr]

I want to SED a file. That file contains many lines. There is a two-possibilities string I want to replace:

scenario 1:
///

scenario 2:
//anything/

In both cases I want to replace what occurs between // and /.

What I’m trying:

VAR=<something>
sed -i "s;//([^/]+)/;//$VAR/; " /path/file

This only works for scenario 2. I already have a second sed line in place to brute force replace /// whenever it occurs, but I would love to have it in a single command if possible.