Merck’s ( MRK - Analyst Report ) vorapaxar was in the news recently with researchers presenting detailed results on the candidate from the TRA-2P (Thrombin-Receptor Antagonist in Secondary Prevention of Atherothrombotic Ischemic Events) TIMI 50 study.

Results showed that vorapaxar, when added to the standard of care, led to a significant reduction in the risk of the composite of cardiovascular (CV) death, heart attack, stroke or urgent coronary revascularization. Researchers noted that this is the first time that the addition of an anti-thrombotic medicine to the standard of care has resulted in additional and significant reduction in the secondary prevention setting.

However, higher bleeding risks continue to haunt vorapaxar. In this study too, a significant increase in bleeding, including intracranial hemorrhage (ICH) or bleeding within the brain, was observed in the vorapaxar arm. Merck noted that the risk of ICH was lower in patients who had not suffered a stroke previously.

TRA-2P was a prevention study conducted in patients who had experienced a heart attack or ischemic stoke or who had documented peripheral artery disease (PAD). The detailed results were presented at the American College of Cardiology Annual Scientific Session and were also published online in the New England Journal of Medicine.

Vorapaxar has already been in the news due to its higher bleeding risk. Merck had presented disappointing results on the candidate from another study at the American Heart Association in 2011. Results from the TRACER (Thrombin Receptor Antagonist for Clinical Event Reduction in Acute Coronary Syndrome) study showed that vorapaxar failed to meet its primary endpoint.

Besides failing to achieve its primary endpoint, a higher rate of bleeding was observed in the vorapaxar treatment arm compared to the standard of care. There was also a three-fold increase in intracranial hemorrhage.

Vorapaxar is being developed by Merck for the prevention of thrombosis and the reduction of cardiovascular events. Now that full results from the TRA-2P study are available, Merck intends to conduct discussions with investigators and other experts regarding vorapaxar’s role in secondary prevention.

We note that vorapaxar did not feature in Merck’s planned regulatory filings for 2012 and 2013 when the company announced fourth quarter results earlier this year. The five candidates that will be filed for regulatory approval include Bridion (a neuromuscular reversal agent), V503 (an investigational vaccine to help protect against certain HPV associated cancers), odanacatib (once-weekly oral treatment of osteoporosis), Tredaptive (atherosclerosis) and suvorexant (insomnia).

Neutral on Merck

We currently have a Neutral recommendation on Merck, which carries a Zacks #3 Rank (short-term ). With vorapaxar, Merck is looking to carve a position in a market which is dominated by players like Bristol-Myers Squibb Co.’s ( BMY - Analyst Report ) Plavix, Eli Lily & Co.’s ( LLY - Analyst Report ) Effient and AstraZeneca plc’s ( AZN - Analyst Report ) Brilinta among others. However, the increase in bleeding associated with vorapaxar could make it challenging for the candidate to take share once approved.