Makes perfect sense, both longs and shorts (especially biotech traders) are out to make a killing on the upcoming results. Good results won't send it up percentage wise as much as bad results will send it down. The key is the likelihood of either good or bad results obtaining; it's not even impossible to conceive of somewhat neutral results.
I would look for short interest to remain high and possibly grow right up to the results coming out. Some biotech traders only show up for such "binary" events. If they perceive the range to be from $2 to $12, they may well play a straddle, eg., buy $5 puts and buy $9 calls, haven't stopped to figure how that might work, but I do know both sides are expensive to trade.
