BOSTON (TheStreet) -- A group of outside experts convened by the U.S. Food and Drug Administration is meeting Tuesday to review a new combination therapy for cystic fibrosis developed by Vertex Pharmaceuticals(VRTX) - Get Report.

Vertex is counting on the new therapy, known as Orkambi, to deliver billions of dollars in sales and sustainable profits for the first time. Orkambi combines Vertex's already-approved drug Kalydeco with a new medicine known as lumacaftor. The combination therapy, if approved, would be used to treat approximately 8,500 patients with the most common genetic mutation that causes cystic fibrosis. This represents about 30% of the overall cystic fibrosis patient population.

The FDA advisory panel meeting Tuesday is charged with reviewing the clinical efficacy and safety data of Orkambi and voting on a recommendation to approve, or not. The FDA is not required to follow the recommendation of its advisory panels but usually does. Most investors expect Tuesday's FDA panel to recommend the approval of Orkambi.

The bigger test for the company will come when the therapy is approved. Insurance companies and pharmacy benefit managers are already raising pre-emptive concerns about the expected high cost of Orkambi, akin to what to happened to Gilead Sciences when it launched its hepatitis C pill Sovaldi.

Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback; click here to send him an email.