The whole biotech sector has been battered. It seems like 90% of biotech stocks have had a really bad 2-3 weeks now. Many are approaching their 52- week lows. With this in mind, Zlcs is doing OK. I see no evidence yet whatsoever that anyone has inside info that the trials have failed. What actually could happen is that the bad environment we're in for biotechs could temper the pop after positive trial results. That could mean that some longs might sell too low, which, in fact, could create another buying opportunity post-results.
So...Z might be a sleeper sort of stock. This sort of stable behavior not meeting flash expectations would be a clever way to deceive the get-rich-qwik crowd. The market will usually do whatever it takes to fool the majority.