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 (NASDAQ:RGDO), 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.

Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

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