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 pulmonology and hepatology drug developer InterMune (Nasdaq: ITMN) caught a second wind today, rising as much as 12.3% on extremely heavy volume.

So what: The former Rule Breaker just published new results from long-term safety tests of Esbriet, a medicine for patients with mild to moderate idiopathic pulmonary fibrosis. As it turns out, the drug appears safe for extended treatment and perhaps ready for approval in the U.S. market.

Now what: IPF is an oftentimes fatal lung disease with a lower five-year survival rate than many cancers and more than 30,000 new cases discovered in just Europe every year. Esbriet was recently launched in Germany at an annual cost of $51,000 to the patient, and should enter a 100,000-patient test in America soon. Do the math and you'll see a potential multibillion-dollar blockbuster that could be to InterMune what Tysabri is to Elan (NYSE: ELN) or what Lipitor has been to Pfizer (NYSE: PFE). Any good news on the road to widespread approval will have this rocket-booster effect on InterMune's shares.

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