Evaluation of the effect of the EGFR antibody-drug conjugate ABT-414 on QT interval prolongation in patients with advanced solid tumors likely to over-express EGFR.

Purpose: ABT-414 is an antibody-drug conjugate (ADC) being developed for the treatment of tumors harboring amplification of the epidermal growth factor receptor (EGFR). This study evaluated the potential of ABT-414 to prolong the QT interval as part of the initial phase 1 study (NCT01741727).

Methods: Data from patients who received ABT-414 monotherapy at a dose of 1-4 mg/kg once every 3 weeks or 1 or 1.5 mg/kg weekly for 2 out of every 3 weeks (alternate schedule) by intravenous infusion were included in the analysis of triplicate 12-lead ECGs obtained before dosing and through 168 h after dosing. Data from time-matched pharmacokinetic samples and QT interval assessments were evaluated using linear mixed-effects modeling to determine the effects of ABT-414, total ABT-806, and cysteine-maleimidocaproyl monomethyl auristatin F (Cys-mcMMAF) on the QT interval corrected using Fridericia's formula (QTcF).

Results: Fifty-one patients were included in the analyses. ABT-414 had no clinically meaningful effect on QTcF. Using pooled data from doses ≥2 mg/kg, the estimated mean ∆QTcF reached a maximum of 4.30 ms after dosing, with a one-sided 95% upper confidence bound of 8.32 ms. The exposure-response analysis showed no statistically significant relationship between ΔQTcF and the concentration of any analyte (P > 0.05). No patient had a QTcF value >480 ms or a ∆QTcF value >30 ms.

Conclusions: ABT-414 had no clinically meaningful effect on the QTcF interval at doses being evaluated for treatment of patients with solid tumors.