The following ivosidenib pharmacokinetic parameters were observed following administration of ivosidenib 500 mg as a single dose or daily dose (for steady-state), unless otherwise specified. The steady-state pharmacokinetics of ivosidenib 500 mg were comparable between patients with newly diagnosed AML and patients with relapsed or refractory AML.
The mean peak plasma concentration (Cmax) is 4,503 ng/mL [% coefficient of variation (%CV: 38)] after a single dose, and 6,551 ng/mL (%CV: 44) at steady-state. The steady-state area under the concentration time curve (AUC) is 117,348 ng∙hr/mL (%CV: 50).
The AUC and Cmax of ivosidenib increase in a less than dose-proportional manner from 200 mg to 1,200 mg daily (0.4 to 2.4 times the approved recommended dosage). Accumulation ratios were approximately 1.9 for AUC and 1.5 for Cmax over one month. Steady-state plasma levels are reached within 14 days.
Absorption
The median time to Cmax is approximately 3 hours.
Effect of Food
Following administration of a single dose in healthy subjects, a high-fat meal (approximately 900 to 1,000 calories, 500 to 600 fat calories, 250 carbohydrate calories and 150 protein calories) increased ivosidenib Cmax by 98% (90% CI: 79%, 119%) and AUCinf by approximately 25%.
Distribution
The mean apparent volume of distribution of ivosidenib at steady-state is 234 L (%CV: 47). Protein binding of ivosidenib ranges from 92 to 96% in vitro.
Elimination
Ivosidenib has a terminal half-life of 93 hours (%CV: 67) and an apparent clearance (CL/F) of 4.3 L/hour (%CV: 50).
Metabolism
Ivosidenib is the predominant component (>92%) of total radioactivity in plasma. Ivosidenib is primarily metabolized by CYP3A4 with minor contributions by N-dealkylation and hydrolytic pathways.
Excretion
After a single oral administration of radiolabeled ivosidenib to healthy subjects, 77% of ivosidenib was eliminated in the feces (67% as unchanged) and 17% in the urine (10% as unchanged).
Specific Populations
No clinically meaningful effects on the pharmacokinetics of ivosidenib were observed based on age (18 years to 89 years), sex, race (White, Asian, Black or African American), body weight (38 to 150 kg), ECOG performance status, or mild or moderate renal impairment (eGFR ≥30 mL/min/1.73m2, MDRD). The pharmacokinetics of ivosidenib in patients with severe renal impairment (eGFR <30 mL/min/1.73m2, MDRD) or renal impairment requiring dialysis is unknown.
Patients with Hepatic Impairment
Following a single dose of TIBSOVO 500 mg, the geometric mean ratio (90% confidence interval) of ivosidenib systemic exposure (AUC0-INF) in subjects with mild hepatic impairment (Child-Pugh A) was 0.85 (0.62, 1.15) and moderate hepatic impairment (Child-Pugh B) was 0.71 (0.48, 1.05) as compared to that in subjects with normal hepatic function. The pharmacokinetics of ivosidenib in patients with severe hepatic impairment (Child-Pugh C) is unknown.
Drug Interaction Studies
Clinical Studies and Model-Based Approaches
Effect of Strong or Moderate CYP3A4 Inhibitors on Ivosidenib
Itraconazole was used as a strong CYP3A4 index inhibitor to evaluate the effect of CYP3A4 inhibition on the pharmacokinetics of ivosidenib single-dose in a drug-drug interaction study in healthy subjects. Co-administration of 250 mg ivosidenib with itraconazole (200 mg itraconazole once daily for 18 days) increased ivosidenib single-dose AUC to 269% of control (90% CI: 245%, 295%) with no change in Cmax. In regards to multiple-dosing, note that because ivosidenib induces the metabolism of CYP3A4 substrates following ivosidenib multiple dosing, itraconazole (a CYP3A4 substrate) is not recommended to be used concomitantly with TIBSOVO in patients (see Effect of Ivosidenib on CYP3A4 Substrates).
Based on physiologically-based pharmacokinetic modeling, co-administration of 500 mg ivosidenib with the moderate CYP3A4 inhibitor fluconazole (dosed to steady-state) is predicted to increase ivosidenib single-dose AUC to 173% of control with no change in Cmax. In regards to multiple-dosing, co-administration with ivosidenib and fluconazole is predicted to increase ivosidenib steady-state Cmax to 152% of control and AUC to 190% of control [see Drug Interactions (7.1)].
Effect of Strong CYP3A4 Inducers on Ivosidenib
Co-administration of ivosidenib with a strong CYP3A4 inducer (600 mg rifampin once daily for 15 days) is predicted to decrease ivosidenib steady-state AUC by 33% [see Drug Interactions (7.1)].
Effect of Ivosidenib on CYP3A4 Substrates
Ivosidenib induces CYP3A4, including its own metabolism. Co-administration of ivosidenib with CYP3A4 substrates such as itraconazole is expected to decrease itraconazole steady-state AUC to a clinically relevant extent [see Drug Interactions (7.2)].
Effect of Gastric Acid Reducing Agents on Ivosidenib
Gastric acid reducing agents (e.g., proton pump inhibitors, H2-receptor antagonists, antacids) do not affect ivosidenib concentrations.
In vitro Studies
Metabolic Pathways
Ivosidenib may induce CYP2B6, CYP2C8, and CYP2C9 and therefore may affect the pharmacokinetics of sensitive substrates of these enzymes [see Drug Interactions (7.2)].
Drug Transporter Systems
Ivosidenib is a substrate for P-glycoprotein (P-gp). Ivosidenib is not a substrate for BCRP or hepatic transporters OATP1B1 and OATP1B3.
Ivosidenib does not inhibit BCRP, OATP1B1, OATP1B3, OAT1, and OCT2 at clinically relevant concentrations. Ivosidenib is an inhibitor of OAT3 and P-gp.