Every Sunday I make it a point to examine a combination of earnings stories or Food and Drug Administration panel reviews or PDUFA decisions in the upcoming week that you can't afford to miss. This week, it's much simpler than that.

The buzz in the health-care sector this week has nothing to do with earnings reports and everything to do with an expected PDUFA decision by the FDA on GlaxoSmithKline (NYSE:GSK) and Theravance's (NASDAQ: THRX) chronic obstructive pulmonary disease, or COPD, inhaled drug, Breo Ellipta.

COPD is the fourth-leading cause of the death in the U.S., so any new therapies that reduce COPD flare-ups or reduce the severity of exacerbations are most welcome. Currently there is no shortage of FDA-approved COPD treatments on the market.

Glaxo's Advair, which came off patent last year, is still going strong because generic competitors have had a hard time creating a biosimilar compound. There's also Novartis' (NYSE:NVS) once-daily inhaled powder, Arcapta, for the long-term maintenance of COPD, which was approved in July 2011 and is a beta-2-andrenergic agonist that helps muscles around the airways of the lungs stay relaxed. Forest Laboratories (NYSE: FRX) also has a pair of FDA-approved COPD treatments in Daliresp, which was approved in March 2011 as a once-daily pill to decrease the worsening of symptoms from COPD, and Tudorza Pressair, a twice-daily inhaler aimed at long-term maintenance of bronchospasms associated with COPD that was approved last year. And who can forget AstraZeneca's blockbuster Symbicort or Pfizer and Boehringer Ingelheim's Spiriva?

What COPD sufferers gain in choices, they lose in potentially serious side effects from these drugs. Tudorza, for example, can cause paradoxical bronchospasm and new or worsened acute narrow-angle glaucoma. An even more striking example is Merck's (NYSE:MRK) Foradil inhaler, which the FDA approved in 2005, but which also comes with a black box warning that some patients had a severe exacerbation of their asthma symptoms while on the inhaler.

However, GlaxoSmithKline and Theravance's Breo Ellipta inhaler may be the next big thing in COPD care. Combining Glaxo's long-acting muscarinic antagonists with Theravance's long-acting beta-2 agonists, Breo was shown to be effective at reducing COPD exacerbations and in treating airflow obstruction -- at least according to the FDA panel that voted 9-4 in favor of recommending approval of the inhaled drug last month. Furthermore, the FDA panel voted 10-3 that Breo Ellipta adequately demonstrated the safety needed to be approved for its proposed indications. The big sticking point with prior COPD indications had been safety -- and Breo Ellipta appears to come with far fewer serious side effects than many of its peers.

All told, this could be a drug that brings in $1.5 billion to as high as $4 billion annually. That will somewhat depend on whether it gains EU approval (under the trade name Relvar), but it all starts with the PDUFA decision expected toward the end of this week. Keep your eyes and ears peeled, as this will be a big bottom-line boost to both companies if approved.