The aims of this study were (i) to evaluate the effect of talazoparib (1 mg once daily) on cardiac repolarization in patients with advanced solid tumors by assessing corrected QT interval (QTc) and (ii) to examine the relationship between plasma talazoparib concentration and QTc. In this open-label phase 1 study, patients had continuous 12-lead ECG recordings at baseline followed by time-matched continuous ECG recordings and collection of talazoparib plasma pharmacokinetic samples predose and at 1, 2, 4, and 6 h postdose on treatment days 1 and 22 and before talazoparib administration on day 2. ECG recordings were submitted for independent central review where triplicate 10-s ECGs, extracted up to 15 min before pharmacokinetic samples, were assessed for RR, PR, QRS, and QT intervals and ECG morphology. QT interval was corrected for heart rate using Fridericia's (QTcF) and Bazett's (QTcB) formulae. Linear mixed-effects modeling was used to examine the relationship between QTc and RR interval change from baseline and plasma talazoparib concentration. Thirty-seven patients received talazoparib. Mean change in QTcF from time-matched baseline ranged from -3.5 to 6.9 ms, with the greatest change 1 h postdose on day 22. No clinically relevant changes in PR, QRS, QTcB, QTcF, or RR intervals, heart rate, or ECG morphology were observed. No concentration-dependent effect on heart rate or QTc was observed. No deaths, permanent treatment discontinuations due to adverse events were reported. Talazoparib (1 mg once daily) had no clinically relevant effects on cardiac repolarization.

Aim

This phase I study investigated talazoparib pharmacokinetics (PK) and safety in patients with advanced solid tumours and varying degrees of hepatic function.

Methods

Patients with advanced solid tumours and normal hepatic function or varying degrees of hepatic impairment (mild, moderate or severe, based on National Cancer Institute Organ Dysfunction Working Group classification) received talazoparib 0.5 mg once daily for 22 calendar days. Plasma and urine samples after single and multiple doses were collected and analysed for talazoparib using validated assays. Plasma PK data from all patients were analysed using the population PK method. Plasma and urine PK parameters in PK-evaluable patients were calculated using noncompartmental analysis (NCA). Safety was monitored in all enrolled patients.

Results

Thirty-eight patients were enrolled; 37 had ≥1 PK concentration, among which 17 were evaluable for NCA. Population PK analysis (n = 37) indicated no significant impact of hepatic function on apparent clearance (CL/F) of talazoparib. Baseline creatinine clearance was the only significant covariate on CL/F (α = 0.05). NCA of data (n = 17) showed no clear trend for increase in exposure on day 22 with worsening hepatic function. Talazoparib protein binding was comparable in patients with varying hepatic function. Talazoparib was generally well tolerated, and the safety profile observed in this study was consistent with the known safety profile of the drug.

Conclusions

Hepatic impairment (mild, moderate or severe) has no impact on the PK of talazoparib. No dose modification is recommended for patients with advanced solid tumours and various degrees of hepatic impairment, and this labelling language has been approved by the US Food and Drug Administration and the European Medicines Agency.

The aim of this study was to assess the potential effects of palbociclib in combination with letrozole on QTc. PALOMA-2, a phase 3, randomized, double-blind, placebo-controlled trial, compared palbociclib plus letrozole with placebo plus letrozole in postmenopausal women with estrogen receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer. The study included a QTc evaluation substudy carried out as a definitive QT interval prolongation assessment for palbociclib. Time-matched triplicate ECGs were performed at 0, 2, 4, 6, and 8 h at baseline (Day 0) and on Cycle 1 Day 14. Additional ECGs were collected from all patients for safety monitoring. The QT interval was corrected for heart rate using Fridericia's correction (QTcF), Bazett's correction (QTcB), and a study-specific correction factor (QTcS). In total, 666 patients were randomized 2 : 1 to palbociclib plus letrozole or placebo plus letrozole. Of these, 125 patients were enrolled in the QTc evaluation substudy. No patients in the palbociclib plus letrozole arm of the substudy (N=77) had a maximum postbaseline QTcS or QTcF value of ≥ 480 ms, or a maximum increase from clock time-matched baseline for QTcS or QTcF values of ≥ 60 ms. The upper bounds of the one-sided 95% confidence interval for the mean change from time-matched baseline for QTcS, QTcF, and QTcB at all time points and at steady-state Cmax following repeated administration of 125 mg palbociclib were less than 10 ms. Palbociclib, when administered with letrozole at the recommended therapeutic dosing regimen, did not prolong the QT interval to a clinically relevant extent.