No QTc prolongation with CDK 4/6 inhibitor FCN-437c: results of a concentration-QTc analysis from a dedicated study in adult healthy subjects.

Unlabelled: Cardiotoxicity and QT interval prolongation have been a common cause of withdrawal of drugs from the market. FCN-437c is an oral, second-generation, potent, and selective CDK4/6 inhibitor for the treatment of patients with HR+/HER2- metastatic breast cancer. A single-center, double-blind, randomized, and placebo-controlled clinical study in healthy subjects was conducted to investigate the QTc prolongation potential of FCN-437c utilizing Concentration-QTc (C-QTc) modeling approach. FCN-437c was administered at doses of 300, and 400 mg with single oral administration, along with placebo, in 18 healthy subjects. Electrocardiograms (ECGs) through 24 h holter monitor and blood samples were collected. The C of 400 mg single dose in healthy subjects is similar to that from therapeutic dose 200 mg QD at steady state in patients with cancer. The 90% CI upper limit of ΔΔQTcF at the C geometric mean in both dose groups were <10 ms. It is concluded that FCN-437c has low risk of prolonging the QT interval at therapeutic dose.

Systematic Review Registration: https://clinicaltrials.gov/study/NCT06290466?term=NCT06290466&rank=1, identifier [NCT06290466].