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 Regado Biosciences (UNKNOWN:RGDO.DL), a clinical-stage biopharmaceutical company focused on developing drugs used to thwart thrombotic events in acute and non-acute cardiovascular indications, imploded and fell as much as 58% after it announced the initiation of an unplanned data safety monitoring board review of REG1 (also known as Revolixys Kit), its lead investigational antithrombotic drug system.

So what: According yesterday's late-night press release, patient enrollment in Regado's REGULATE-PCI trial has been halted until the Data Safety Monitoring Board completes a review which is expected within the next eight weeks. As noted, the DSMB plans to conduct "a full analysis of safety and treatment benefit-risk ratio of all patients enrolled to date (3,234) with a focus on serious adverse events related to allergic reactions."

Now what: There's obviously a lot of promise behind REG1 as it targets a wide audience of acute coronary syndrome patients and could give physicians the ability to up- and down-regulate anticoagulation properties to avoid potential bleeding incidents in patients while also protecting them from potentially deadly blood clots.

However, beyond REG1 Regado's pipeline is fairly thin. It has REG2, a venous thrombosis-fighting therapy that just began phase 1 studies and REG3, a preclinical anti-platelet candidate. Therefore, if there are concerns about REG1's safety this early on in its extensive phase 3 study then Regado's valuation, should REG1 not succeed or be proven too dangerous relative to its benefits profile, may likely take a major hit – perhaps even bigger than today's drop. With no partner on this project, and now plenty of questions raised regarding REG1's safety, I believe you have all the makings of a stock you should keep your distance from.