What: Shares of The Medicines Company (MDCO), a drugmaker that specializes in developing medicines indicated for patients in acute and intensive care settings, saw its shares rise by more than 20% on exceptional volume today. This breakout was triggered by the news that an experimental cholesterol drug being co-developed by The Medicines Co. and Alnylam Pharmaceuticals (ALNY -0.11%) lowered LDL-C or "bad" cholesterol levels by around 83% in a small, early stage study. The drug, ALN-PCSsc, is an injected RNAi therapy designed to block the expression of the enzyme PCSK9, a protein that plays a critical role in regulating circulating levels of bad cholesterol in the blood. 

So what: Although these results should be viewed as preliminary given that the study wasn't large enough to truly assess efficacy, the two companies did note in their presentation that ALN-PCSsc's cholesterol lowering ability appears comparable to Amgen's and Sanofi/Regeneron's PCSK9 inhibitors that recently won FDA approval. The catch, though, is that ALN-PCSsc might be able to be dosed at intervals of up to six months, whereas these other two injected anti-cholesterol drugs are generally administered around every two weeks. 

Now what: The Medicines Co. and Alnylam plan on advancing the drug into a mid-stage study before year's end, with the goal of initiating a pivotal late-stage trial in 2017. That puts a potential regulatory filing on track for perhaps late 2018, or early 2019. By then, Pfizer may have already changed the game by introducing an oral PCSK9 inhibitor into the market, and perhaps an annual vaccine version as well. In short, this is a red hot area of pharma research, and there's no way to tell who's ultimately going to end up the winner. So, while this clinical update is unquestionably a step in the right direction, you may want to pause and consider the company's entire product and clinical portfolios before buying shares.