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.

What: Shares of drug developer Human Genome Sciences (Nasdaq: HGSI) shed more than 10% in intraday trading as investors reacted to FDA comments about its drug Benlysta.

So what: Next week, a panel will meet to recommend to the Food and Drug Administration whether Benlysta -- developed by Human Genome along with partner GlaxoSmithKline (NYSE: GSK) -- should be approved. The drug is aimed at battling lupus, a potentially life-threatening auto-immune disease for which there hasn't been a new treatment approved in decades. Ahead of that panel meeting, the FDA presented a preliminary review of the drug, questioning both its effectiveness and safety. With the future of Human Genome riding squarely on the back of Benlysta, it's not surprising that the FDA comments made investors a little squeamish.

Now what: There's no doubt that the Benlysta case is high stakes for Human Genome -- not to mention Glaxo. Bloomberg recently estimated that the drug could bring in more than $2.1 billion in sales by 2014, and its approval could spark takeover offers for Human Genome from Glaxo, along with other giants like Amgen (Nasdaq: AMGN), Abbott Labs (NYSE: ABT), and Johnson & Johnson (NYSE: JNJ). The mixed comments from the FDA today may have some investors shifting in their seats, but from the sound of it, most experts seem to think the overall benefits trump the concerns and that the drug should still get the thumbs up. To be sure, the data have looked good. All eyes will now turn to the advisory panel next week and then the FDA's final decision.

Want to keep up to date on Human Genome Sciences? Add it to your watchlist by clicking here. Or are you following Benlysta from the Glaxo side? Go ahead and put Glaxo on your watchlist by clicking here.

GlaxoSmithKline is a Motley Fool Global Gains recommendation. Johnson & Johnson is a Motley Fool Income Investor selection. The Fool owns shares of and has written covered calls on GlaxoSmithKline. Motley Fool Options has recommended a diagonal call position on Johnson & Johnson. The Fool owns shares of Johnson & Johnson. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.                                                                      

Fool contributor Matt Koppenheffer owns shares of Johnson & Johnson and Abbott Labs, but does not own shares of any of the other companies mentioned. You can check out what Matt is keeping an eye on by visiting his Motley Fool CAPS portfolio, or you can follow Matt on Twitter @KoppTheFool or on his RSS feed. The Fool's disclosure policy assures you no Wookiees were harmed in the making of this article.