Leone (biceps) threw a bullpen session earlier in the week, Jenifer Langosch of MLB.com reports.
It's the first confirmed report of Leone having returned to throwing off a mound, certainly a welcome development in what has been a prolonged recovery period. The right-hander spent several weeks waiting on nerve regeneration in his throwing arm before beginning a strengthening program in mid-June. He's apparently made steady progress since then, and a minor-league rehab assignment may not be far off as a result.