What happened

Bristol Myers Squibb (BMY -0.30%) stock was down by a noteworthy 5.4% as of 1:32 p.m. ET Monday afternoon. Bristol's share price is in retreat mode today after the company announced over the weekend that its mid-stage blood thinner candidate, milvexian, missed the mark on a composite endpoint consisting of new symptomatic ischemic stroke and new covert brain infarction at day 90.

Bristol is co-developing milvexian with Johnson & Johnson's (JNJ -1.52%) biopharma-oriented subsidary, Janssen. Despite these disappointing phase 2 results for a potential blockbuster medication, J&J's stock was only down by 0.56% at the time of this writing. 

A person sits in front of a laptop and covers their eyes with their hands.

Image source: Getty Images.

So what

Bristol's shares are slumping on this news today because milvexian is a key component of the company's strategy to power through a slew of upcoming patent expirations. In particular, the drugmaker had designs on milvexian being the eventual successor to its mega-blockbuster blood thinner, Eliquis. J&J, for its part, doesn't have nearly as much at stake as Bristol in regard to milvexian's clinical fate. This simple fact is probably why the healthcare giant's shareholders don't appear to be reacting to this clinical setback today. 

Bristol and J&J aren't throwing in the towel, however. The pharma titans noted in their joint press release that milvexian did exhibit a 30% relative risk reduction in recurrent symptomatic ischemic strokes, along with a favorable safety profile. Based on this positive outcome, Bristol and J&J said they plan to push the drug into late-stage testing.

Now what

Is Bristol's stock a buy in the wake of this clinical setback? While milvexian may not be Eliquis' heir apparent, Bristol still has a wide array of other high-value drugs under development. In other words, the drugmaker's shares will probably shake off this news in fairly short order. As a result, savvy investors may want to take advantage of this weakness in the big pharma's stock price.