In vitro-in vivo extrapolation of bexarotene metabolism in the presence of chronic kidney disease and acute kidney injury in rat using physiologically based pharmacokinetic modeling and extrapolation to human.

Renal impairment can affect the elimination of hepatically metabolized drugs. Bexarotene (BXT) used for cutaneous T-cell lymphoma is highly bound in plasma and metabolized by CYP3A4. The BXT European Medicine Agency and Food and Drug Administration packages recommended the evaluation of renal impairment on BXT metabolism. The plasma protein binding of BXT can be changed in patients with renal dysfunction due to hypoalbuminemia and accumulation of uremic toxins. In vitro, microsomal stability and plasma protein binding studies were pursued. A preclinical pharmacokinetic study was pursued in control, chronic kidney disease (CKD), and acute kidney injury (AKI) rats. A BXT physiologically based pharmacokinetic (PBPK) model that utilized in vitro-in vivo extrapolation of metabolism was established and verified in healthy rats, customized to CKD and AKI rats, and extrapolated to healthy human subjects and those with CKD stages 3, 4, and 5. In vitro studies showed that AKI and CKD significantly increased the BXT fraction unbound in plasma (from 0.011 to 0.018 and 0.022, respectively) and decreased intrinsic clearance (from 4.1 to 2.5, and 2.2 mL/min/g liver, respectively). This could explain the reduced in vivo clearance observed in CKD rats (from 0.4 to 0.28 L/h/kg) and the 1.3-fold increase in BXT exposure. Changes in BXT disposition in AKI rats were not straightforward due to simultaneous changes in BXT distribution. The human PBPK model predicted an increased BXT exposure by 2-fold in CKD patients, suggesting the need for dose reduction and drug monitoring. The reduced BXT metabolism due to renal impairment is especially relevant in cancer patients with CKD.

Physiologically-based pharmacokinetic model for alectinib, ruxolitinib, and panobinostat in the presence of cancer, renal impairment, and hepatic impairment.

Renal (RIP) and hepatic (HIP) impairments are prevalent conditions in cancer patients. They can cause changes in gastric emptying time, albumin levels, hematocrit, glomerular filtration rate, hepatic functional volume, blood flow rates, and metabolic activity that can modify drug pharmacokinetics. Performing clinical studies in such populations has ethical and practical issues. Using predictive physiologically-based pharmacokinetic (PBPK) models in the evaluation of the PK of alectinib, ruxolitinib, and panobinostat exposures in the presence of cancer, RIP, and HIP can help in using optimal doses with lower toxicity in these populations. Verified PBPK models were customized under scrutiny to account for the pathophysiological changes induced in these diseases. The PBPK model-predicted plasma exposures in patients with different health conditions within average 2-fold error. The PBPK model predicted an area under the curve ratio (AUCR) of 1, and 1.8, for ruxolitinib and panobinostat, respectively, in the presence of severe RIP. On the other hand, the severe HIP was associated with AUCR of 1.4, 2.9, and 1.8 for alectinib, ruxolitinib, and panobinostat, respectively, in agreement with the observed AUCR. Moreover, the PBPK model predicted that alectinib therapeutic cerebrospinal fluid levels are achieved in patients with non-small cell lung cancer, moderate HIP, and severe HIP at 1-, 1.5-, and 1.8-fold that of healthy subjects. The customized PBPK models showed promising ethical alternatives for simulating clinical studies in patients with cancer, RIP, and HIP. More work is needed to quantify other pathophysiological changes induced by simultaneous affliction by cancer and RIP or HIP.