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CFTR Modulators for Cystic Fibrosis

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By Editorial Team

3 min read

Reviewed by: HU Medical Review Board | Last reviewed: June 2025 | Last updated: June 2025

The symptoms of cystic fibrosis (CF) are caused by mutations in a gene called the cystic fibrosis transmembrane conductor regulator (CFTR). People with CF inherited 2 copies of the defective gene – 1 copy from each parent.

Mutations in the CFTR gene mean that CFTR proteins are not made correctly. The faulty protein does not provide a channel for chloride, an element of salt, to move through the cell walls. This creates a thick, sticky mucus that clogs the lungs, pancreas, sinuses, and more.

What are CFTR modulators?

A class of drugs called CFTR modulators targets specific defects in the CFTR protein so that the protein can work properly. CFTR modulators do not fully restore chloride flow, but they do improve the flow enough to help lessen CF symptoms.

There are currently 3 types of CFTR modulators:1,2

  1. Potentiators (ivacaftor)
  2. Correctors (vanzacaftor/tezacaftor/deutivacaftor, lumacaftor, tezacaftor, and elexacaftor)
  3. Amplifiers

CFTR potentiators

The 3 different types of CFTR modulators work on distinct parts of the CFTR protein to help it work better. The CFTR protein is shaped like a tunnel with gates that open and close, offering access out of the cell. Potentiators help chloride move through the CFTR protein, providing a channel to the cell surface. Potentiators hold the gate open. Potentiators work on gating, conduction, residual function, and splice mutations. Ivacaftor (brand name Kalydeco) has been approved for use in the US.3,4

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CFTR correctors

Correctors help the CFTR protein form the right shape so that it is able to move to the cell surface and stay there longer. The following CFTR correctors have been approved for use in the US:1,3,4

  • Lumacaftor (Orkambi) – approved for use in people aged 1 and older
  • Tezacaftor (Symdeko)
  • Vanzacaftor/tezacaftor/deutivacaftor (Alyftrek)

These correctors are used in combination with the potentiator ivacaftor to increase their effectiveness. Both lumacaftor and tezacaftor are first-generation modulators. This means they were the first modulators used to treat CF.1,3,4

Elexacaftor is a “next-generation” modulator. This means it may be more effective than previous modulators. Elexacafor is combined with tezacaftor and the potentiator ivacaftor to form the brand name Trikafta. This triple combination drug allows more people with CF a variety of treatment options.1,2

CFTR amplifiers

One amplifier, PTI-428, is currently being tested, so this drug is not yet available. Amplifiers increase the amount of CFTR protein that a cell makes, which should help those people with CF who do not produce enough CFTR protein. The theory is that if the cells make more CFTR protein, the potentiators and correctors could allow more chloride to flow through the cell membrane. Research continues on many other next-generation CFTR modulators.5

Which CFTR modulator is the best for treating cystic fibrosis?

Not all CFTR modulators work for all CF patients. That is because different genetic mutations cause different types of CFTR protein defects. Each CFTR modulator is designed to correct specific problems caused by the mutated CFTR protein.1

What are the risks or common side effects of CFTR modulators?

Side effects of CFTR modulators vary according to the drug taken, but nausea and sinus congestion are common to all 3 types of therapies. The long-term risks of taking this new class of drugs are unknown, but since the medications cause such dramatic improvements in symptoms, including lung function and body mass index (BMI), CFTR modulators are considered game-changers for the future of people with CF.

Help paying for CFTR modulators

CFTR modulators are expensive, even with insurance coverage. If you are having trouble paying for your CFTR modulator, the manufacturer, Vertex, offers patient assistance services at 1-877-752-5933 (press 2). The CF Foundation offers the Compass service, which offers personalized, one-on-one support for insurance, financial, and legal issues related to cystic fibrosis.6

You can also contact CF Foundation Compass, a service that provides strategies and information for people living with CF and their families. You can contact them at 1-844-COMPASS (1-844-266-7277) or compass@cff.org.7

Treatment results and side effects can vary from person to person. This treatment information is not meant to replace professional medical advice. Talk to your doctor about what to expect before starting and while taking any treatment.