Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of the clinical-stage biopharma Heron Therapetics (NASDAQ:HRTX) climbed by 15% on heavy volume today. The apparent catalyst behind this double-digit move is the news that hedge fund manager Kevin C. Tang, who is the Chairman of the Heron's Board Directors, bought a decently sized chunk of shares. Over the prior three trading sessions, Tang reportedly purchased 150,000 shares at prices ranging from $19.30 to $23.84.  

So what: This largish insider buy comes on the heels of the company's positive top-line data release for its drug Sustol's pivotal late-stage trial called "MAGIC", where the drug was shown to be an effective treatment for chemotherapy-induced nausea and vomiting after administration of highly emetogenic chemotherapy agents.

As the drug is now barreling toward a regulatory filing by mid-year and a possible approval in the first-quarter of 2016, the Street seems to think that this insider activity is a good indication that the drug should live up to its lofty commercial expectations. 

Now what: Heron is expected to file for approval with the Food and Drug Administration this month, meaning that a commercial launch could take place early next year. The key issue to understand is that industry experts believe Sustol has the potential to reach blockbuster status within the next decade, especially as it appears to be more effective than the current market leader Aloxi.

That said, Heron has proven itself to be lacking in how it handles regulatory applications, given that Sustol was rejected twice before for "manufacturing issues and data analysis problems". In short, investors shouldn't count their chickens before they're hatched in terms of a regulatory approval. After all, this drug appeared to be "de-risked" before on two occasions, only to later leave investors wondering what happened. 

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.