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

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

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


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 C max 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.

Original languageEnglish (US)
Pages (from-to)764-775
Number of pages12
JournalBritish Journal of Clinical Pharmacology
Issue number4
StatePublished - Apr 2018


  • QT prolongation
  • drug safety
  • oncology
  • pharmacodynamics
  • pharmacokinetics

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)


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