Phase 1 summary of plasma concentration-QTc analysis for idasanutlin, an MDM2 antagonist, in patients with advanced solid tumors and AML.

Purpose: Idasanutlin, a selective small-molecule MDM2 antagonist in phase 3 testing for refractory/relapsed AML, is a non-genotoxic oral p53 activator. The aim of this analysis is to examine the potential of idasanutlin to prolong the corrected QT (QTc) interval by evaluating the relationship between plasma idasanutlin concentration and QTc interval.
Method: Intensive plasma concentration QTc interval data were collected at the same timepoints, from three idasanutlin (RO5503781) phase 1 studies in patients with solid tumors and AML. QTc data in absolute values and changes from baseline (Δ) were analyzed for a potential association with plasma idasanutlin concentrations with a linear mixed effect model. Categorical analysis was also performed.
Results: A total of 282 patients were exposed to idasanutlin and had at least one observation of QTc and idasanutlin plasma concentration. There was no apparent increase of QTcF or ΔQTcF in a wide idasanutlin plasma concentration range, even at concentrations exceeding the exposure matching the dose adopted in the ongoing phase 3 study (300-mg BID). Categorical analysis did not detect a potential signal of QT prolongation.
Conclusion: The concentration-QTc analysis indicates that idasanutlin does not prolong the QT interval within the targeted concentration range currently in consideration for clinical development.