Forbes reports that a new cystic fibrosis drug made by Vertex is being hailed by the company as a game-changer but others see it as a small addition to the arsenal of drugs available to these patients. 

“This one may be a tiny bit better,” says Brian O’Sullivan, a pediatric pulmonologist at Dartmouth-Hitchcock in Manchester, New Hampshire. “It’s not dramatically better. I do think there are fewer drug-drug interactions, which I think is a real plus. And there may be fewer discontinuations. It’s a little hard to tell from this study.”

Look at the numbers: compared to Orkambi, Vertex’s existing cystic fibrosis combo pill, the new pill containing tezacaftor is only slightly better. In patients who have two copies of a genetic variant called F508del–the people for whom Orkambi is approved–the Vertex studies released last night show an increase in FEV1, a measure of lung capacity, of more than 4%. For Orkambi, the number was less than 3%. The new drug may be better, but it’s hard to say for certain comparing across studies. (Both tevacaftor and Orkambi are given as single-pill combinations that also contain Vertex’s original CF drug, Kalydeco.)