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.

Gilead Sciences (NASDAQ:GILD)Isis Pharmaceuticals (NASDAQ:IONS), and Opka Health (NASDAQ:OPK) could loom large in health care headlines this morning. Let's take a quick look over the major news for these stocks.

Europe grants compassionate use of new hep C drug combo
Shares of Gilead Sciences (NASDAQ:GILD) should be in for a good day after the European Medicines Agency's, or EMA, Committee for Medicinal Products for Human Use, or CHMP, gave a positive opinion on the compassionate use of the fixed-dose combination of ledipasvir and sofosbuvir for the treatment of hepatitis C virus for patients in urgent need of therapy. The compassionate use designation is specifically for patients suffering from genotype 1 and that have failed other therapies.

Gilead (NASDAQ:GILD) has already filed a New Drug Application for this all-oral combo pill in the U.S. and is expected to file for Marketing Authorization in the EU later this quarter. In short, the EMA's willingness to allow this combo to be used for compassionate use now should bode well during the formal review of the drug's broader marketing authorization.

Given the top-notch nature of the late-stage clinical trial data for the ledipasvir and sofosbuvir combo, however, most experts believe the regulatory filings are essentially a matter of formality at this point. This breakthrough, all-oral hepatitis treatment could thus be approved for wider use in both the U.S. and EU before year's end, putting further pressure on AbbVie and Enanta Pharmaceutical's competing drug. 

Isis reports positive interim data – details to follow
Isis Pharmaceuticals
(NASDAQ:IONS) might be another winner in the sector today following their premarket release of positive interim data for an early stage study of ISIS-SMN Rx, an experimental treatment for spinal muscular atrophy in children. The company has scheduled a conference call at 8:30am this morning to discuss the results in more detail.

Per the initial release, however, Isis (NASDAQ:IONS) gave investors a couple of key points to whet their appetites. Specifically, children in the trial exhibited an average increase of 3.7 points in muscle function score when treated with 9 mg of the drug, which was coupled to a subsequent increase in SMN protein. Should you keep tabs on this story? In my opinion, that's a big yes! Isis (NASDAQ:IONS) has a licensing deal with Biogen that gives the company milestone payments throughout the course of the drug's development. So, stay tuned!

Insiders keep buying Opka
Despite a potentially massive valuation gap, insiders continue to gobble up shares of Opka Health (NASDAQ:OPK). The latest buy by Dr. Philip Frost hit the Street this morning, coming it at a notable $236,000 worth of shares, right after Tuesday's purchase of $182,000 in shares. Wednesday's buy marks Dr. Frost's ninth buy since the start of the year, even though Opka (NASDAQ:OPK) shares have fallen almost 9% over the last three months.

Why is Dr. Frost buying? My view is that he is optimistic about Opka's (NASDAQ:OPK) point-of-care system and 4K Test, which has been a point of contention among analysts of late. Unfortunately, there isn't enough data publicly available for outsiders to make a call one way or another. So, while massive insider buying always peaks my interest, I think it might be best to wait until Opka (NASDAQ:OPK) releases earnings next month before wading into these waters. 

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.