Not many effective treatments are available for cystic fibrosis, considered to be a serious inherited disease. Therefore, there are chances that this point can get approval of Vertex Pharmaceuticals Inc.'s experimental combination drug.

Analysts said that the drug can get the go-ahead signal despite the fact that regulators have raised questions over the drug's efficacy.

Alan Carr, an analyst for local investment bank Needham & Co, affirmed that the regulators want to have the evidence of the efficacy level. But then, in this situation the drug will be approved as no other disease-modifying treatments are available for the patient population.

The debated drug is Orkambi, which is the combination of the company's already approved drug Kalydeco and a new drug, lumacaftor. The first drug has been approved for the treatment of a type of a cystic fibrosis, which affects around 5 to 10% of patients suffering from it.

The new drug is meant to treat those affected by mutations from which 50% of patients suffer. In a briefing yesterday, the Food and Drug Administration stated that still there are questions with regard to drug as whether the second drug, lumacaftor, would provide any added benefit.

Michael Yee, a San Francisco-based analyst at RBC Capital Markets, said the questions raised by the FDA are about the statistical significance of Orkambi's effectiveness. As per him, the questions are irrelevant.

"The combination is absolutely better than the monotherapy. Whether it is statistically significant has not been proven, but it's not going to block approval", affirmed Yee.

Vertex spokesman Zach Barber affirmed that they are quite confident over the data for this medicine. It can be used to treat 8,500 patients in America. On Tuesday, an FDA advisory panel will meet in Gaithersburg, Md., to discuss further issues.