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 antibody-drug conjugate research firm Seattle Genetics (NASDAQ:SGEN) tumbled as much as 14% today after the company reported disappointing third-quarter results and receiving an analyst downgrade.

So what: For the quarter, Seattle Genetics reported robust revenue growth of 141% to $49.8 million and a loss of $0.12 per share. Relative to Wall Street's expectations, it came in $0.02 ahead of EPS estimates, but fell shy of the $52.8 million consensus. Of specific interest were sales of Adcetris -- Seattle Genetics' only FDA-approved drug for the treatment of Hodgkin's lymphoma and systemic anaplastic large cell lymphoma -- which came in below many Wall Street analysts forecasts at $33.7 million. Although Seattle Genetics forecast full-year revenue of $132 million-$137 million for Adcetris, it nonetheless prompted Cantor Fitzgerald to lower its rating on the company to "sell" from "hold" and to reduce its price target to $20 from $30.

Now what: As for me, I'm incredibly optimistic about the potential for Adcetris and the 12 other clinical-stage drugs currently in Seattle Genetics' pipeline. Earlier this week, ImmunoGen (NASDAQ:IMGN) and collaborative partner Roche (NASDAQOTH:RHHBY) announced that their HER2-positive breast cancer treatment, T-DM1, has received priority review status by the Food and Drug Administration which should set up Seattle Genetics' studies for priority review assuming they meet their endpoint. The FDA has expressed a willingness to expedite review status on ADC treatments which leads me to believe it could be the future of cancer treatments. Clearly, Seattle Genetics has a ways to go before it's regularly profitable, but for those of you with a passion for biotech investing, I'd consider doing your research and using today's drop as a possible entry point.

Craving more input? Start by adding Seattle Genetics to your free and personalized watchlist so you can keep up on the latest news with the company.

Fool contributor Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

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