Phase I safety and pharmacokinetic study of cipatinib, an original dual tyrosine kinase inhibitor.

BACKGROUND

Cipatinib is a novel tyrosine kinase inhibitor against both EGFR and HER2/neu. This phase I trial was conducted to assess the safety, dose-limiting toxicities (DLTs), and maximum-tolerated dose of cipatinib in HER2-positive patients with advanced breast cancer.

METHODS

Eligible adults with advanced breast cancer were administered cipatinib 200 mg/day (n = 3) as an initial dose, with escalating dosages of 400 mg (n = 4), 800 mg (n = 2), 1200 mg (n = 3), 1400 mg (n = 3), 1600 mg (n = 3), and 1800 mg (n = 2) in 21 day cycles. DLTs were monitored until the end of cycle 2. Physical examinations, vital signs, blood sampling for hematology, clinical chemistry, and pharmacokinetics were performed throughout the trial.

RESULTS

Of the 26 subjects enrolled, 23 completed the trial. A total of 143 adverse events (AEs) were reported, of which 87 were associated with cipatinib treatment and comprised: neutropenia (38%), hypertriglyceridemia (15%), fatigue (15%), nausea (12%), fever (19%), and myocardial ischemia (19%). Six AEs were graded 3-4 (neutropenia, increases in aspartate aminotransferase, and total bilirubin, fatigue, dizziness and nodal tachycardia), but none of the AEs observed were considered to be DLTs.

CONCLUSIONS

This tolerability study revealed that despite a mild toxicity profile, cipatinib was well tolerated up to the anticipated maximum dosage of 1800 mg/m2 . Further clinical trials are warranted.