Let's take a look at today's top stories in biotech and health care. Keep an eye out for Johnson & Johnson (NYSE:JNJ) and Sarepta Therapeutics (NASDAQ:SRPT)

Analysts are optimistic about Johnson & Johnson's second quarter earnings 
With J&J set to reveal second quarter earnings next Tuesday, July 15, Wall Street analysts are predicting that the company will beat consensus earnings per share of $1.54, fueled by better than expected pharma sales. In the first-quarter, J&J surprised the Street with stellar sales of its hepatitis C drug, Olysio, which helped propel pharmaceutical growth by 10.8% year over year and compensate for weakness in its other business segments.  

While I think the analysts are on target with their optimistic expectations for the second quarter, J&J does have major competition to worry about for some of its key drugs like Zytiga and Olysio. AbbVie's hepatitis C drug, for instance, should gain approval later this year and poses a major threat to Olysio's commercial performance going forward.

In short, I think J&J's bull run is close to coming to an end, despite what looks to be a strong second quarter. And thus far, the market also doesn't appear to be impressed with these positive comments, given that J&J's shares remain unchanged in premarket trading this morning.   

Will Sarepta rebound today?
Sarepta saw a strong sell-off yesterday following a 144-week clinical update for its open-label extension study of its exon-skipping Duchenne muscular dystrophy, or DMD, drug eteplirsen. Specifically, patients participating in the open-label portion of the study declined by about 8.5% on average from baseline in walking ability, which was the biggest decrease in walking performance observed thus far. 

Although shares rebounded late in the session, they still ended the day down nearly 13%. Shares are presently down over 1% in premarket trading on moderate volume. 

In a note to investors, Needham suggested that the sell off was unwarranted and caused primarily by misleading article that appeared in The Wall Street Journal. By the same token, we saw a number of downgrades by other firms for Sarepta yesterday based on this latest clinical update.

Looking ahead, the main concern is that eteplirsen will turn out to be ineffective at improving walking ability over the long term in DMD patients, perhaps even lowering its chances of gaining a regulatory approval. While the jury is still out on eteplirsen's regulatory risk following this latest clinical update, Sarepta should certainly be interesting to watch today as the bulls and bears battle it out.