Evaluation of the effect of dabrafenib and metabolites on QTc interval in patients with BRAF V600–mutant tumours Academic Article uri icon

abstract

  • AIMS:The effect of repeat oral supratherapeutic dosing of the BRAF inhibitor dabrafenib on QTc interval was assessed in patients with BRAF V600-mutant tumours. METHODS:Part 1 of this phase 1, multicentre, 2-part study (BRF113773/NCT01738451) assessed safety/tolerability of dabrafenib 225 or 300 mg twice daily (BID) to inform part 2 dosing. Patients in part 2 received dabrafenib-matched placebo on day -1, single-dose dabrafenib 300 mg on day 1, 300 mg BID on days 2 to 7, and 300 mg on day 8 (morning), followed by 24-h Holter electrocardiographic monitoring and pharmacokinetics sample collection each dose day. Pharmacokinetics/pharmacodynamics analysis assessed combined dabrafenib and metabolite effects on QTc interval. RESULTS:Part 1 (n = 12) determined supratherapeutic dosing, 300 mg BID, for part 2. Thirty-one patients completed part 2. Mean maximum ΔΔQTcF occurred on day 8, 10 h postdose (2.86 msec; 90% CI, -1.36 to 7.07). Categorical analysis showed no placebo and dabrafenib outliers (increase >60 msec; QTcF >500 msec). Day 1 dabrafenib 300 mg Cmax and AUC(0-∞) were ≈ 2-fold higher than with single-dose 150 mg. Day 8 AUC(0-τ) with 300 mg BID was ≈ 2.7-fold higher than with 150 mg BID. Dabrafenib metabolites showed similar trends. Pharmacokinetics/pharmacodynamics modelling/simulation showed that median QTc increase was <5 msec (upper 90% CI, <10 msec). No unexpected toxicities occurred with supratherapeutic dosing. CONCLUSION:Repeat oral supratherapeutic dabrafenib 300 mg BID dosing had no clinically relevant effect on QTc interval, with no new safety signals seen.

authors

  • Nebot, Noelia
  • Arkenau, Hendrik-Tobias
  • Infante, Jeffrey R
  • Chandler, Jason C
  • Weickhardt, Andrew
  • Lickliter, Jason D
  • Sarantopoulos, John
  • Gordon, Michael S
  • Mak, Gabriel
  • St-Pierre, Annie
  • Tang, Lihua
  • Mookerjee, Bijoyesh
  • Carson, Stanley W
  • Hayes, Siobhan
  • Grossmann, Kenneth F

publication date

  • 2018

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