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FDA rejects Vertex’s application for expanded use of drug

The Vertex building at 50 Northern Ave in Boston. Craig F. Walker/Globe Staff

US regulators dealt a blow to Vertex Pharmaceuticals Inc. on Friday, rebuffing the company’s application to sell its first cystic fibrosis drug to a new subset of patients.

In what is known as a complete response letter, the Food and Drug Administration said it could not approve the Boston biotech company’s application in its current form, according to Vertex. The news sent Vertex shares down 5.5 percent to close at $86.61 on the Nasdaq.

Vertex’s application sought to extend the use of Kalydeco, which now is approved to treat about 2,000 cystic fibrosis patients in the United States with 10 different mutations, to about 1,500 others age 2 and older who have one of 23 types of genetic mutations.

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The company said in a statement that it “plans to meet with the FDA to determine an appropriate path forward.” The FDA’s action does not preclude Vertex from submitting another application based on new clinical data.

FDA officials declined to comment, citing an agency policy not to discuss or even acknowledge unapproved drug applications.

While the company did not spell out the FDA’s objections, Vertex spokeswoman Dawn Kalmar said its application “was made with limited data” because of the difficulty of including patients with so many different genetic mutations in a single clinical study.

In addition to a small clinical study, Vertex sought to win approval based on the experience of the patients who have taken Kalydeco since it was approved four years ago.

It also submitted preclinical data showing the drug was effective in synthetically created cells harboring different mutations, some of which affect only small numbers of people in the United States. While this is a well-validated research approach, companies typically don’t ask the FDA to accept the effectiveness of a drug based on such preclinical data.

“They were venturing into new territory with this application,” said Geoffrey Porges, biotech analyst at Boston health care investment bank Leerink Partners. “It was audacious of them to file it in the first place.” By not accepting the application, he said, the FDA was saying, in effect, “no shortcuts.”

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Porges, however, said he doesn’t think the rejection will hurt Vertex’s strategy to expand the reach of its cystic fibrosis medicines, Kalydeco and Orkambi, along with other drug candidates and combinations, to new groups of patients with the obstructive lung disease.

“Our intention with this submission was to rapidly bring Kalydeco to additional people with CF who we believe may benefit,” Vertex chief medical officer Jeffrey Chodakewitz said in the company’s statement. “We chose to pursue this approach given our strong belief in the science of CF and in the well-established safety of Kalydeco across many different groups of people with CF.”

Porges said the FDA’s move “reflects a minor setback for Vertex” because the number of patients represents only a small slice of the 30,000 people in the United States and 75,000 people worldwide with CF that the company hopes to treat.

In a note to investors, Porges said the company could still win Kalydeco approval for the same patient population by including them in late-stage trials that will report results by the middle of next year. That would delay approval — and incremental Vertex revenue of about $300 million in the United States — for 18 to 24 months, he wrote.

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The Vertex clinical trial enrolled two dozen patients representing eight of the 23 gene mutations that it sought to treat with Kalydeco. “We’re dealing with such small numbers of patients that it’s challenging to get the data that we need for such an application,” Kalmar said.


Robert Weisman can be reached at robert.weisman@globe.com. Follow him on Twitter @GlobeRobW.