Change from Kaftrio/Kalydeco to Alyftrek

Question

Hello, my daughter takes Kaftrio and Kalydeco for some years and is going to take Alyftrek instead soon.
Do the blood values have to be controlled in short intervals even if there is a change from one modulator to the other and if yes, which values have to be controlled and how often?
Best regards

Answer

Hello,
for Alyftrek the same frequencies of controlling blood values pertain as for Kaftrio/Kalydeco; the European Medical Agency recommends to test the liver values (ASAT, ALAT and Gamma-GT) every 3 months in the first year of intake, than once a year. The US-Agency even recommends to do a check-up of liver values every 4 weeks in the first 6 months of intake. All those recommendations are irrespective of Kaftrio/Kalydeco has been taken before or of someone starts the first time on modulators. This is because there have been cases reported, that showed an increase in liver enzymes after taking Alyftrek even if Kaftrio/Kalydeco was tolerated well before and the other way round.
In our CF center, we take blood to control liver enzymes 4 weeks after starting on Alfyftrek, especially in children. If the liver values are normal, we continue to control them every 3 months in the first year.
Furthermore children starting on Kaftrio/Kalydeco or changing to Alyftrek should have an appointment at an ophtalmologist to check for a cataract; if this is ok, an eye-control should be done every year.
Best regards,
Daniela d'Alquen

20.01.2026