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Supplementary Figure from Model-Based Characterization of the Bidirectional Interaction Between Pharmacokinetics and Tumor Growth Dynamics in Patients with Metastatic Merkel Cell Carcinoma Treated with Avelumab

Supplementary Table from Model-Based Characterization of the Bidirectional Interaction Between Pharmacokinetics and Tumor Growth Dynamics in Patients with Metastatic Merkel Cell Carcinoma Treated with Avelumab

Purpose:Empirical time-varying clearance models have been reported for several immune checkpoint inhibitors, including avelumab (anti–programmed death ligand 1). To investigate the exposure-response relationship for avelumab, we explored semimechanistic pharmacokinetic (PK)–tumor growth dynamics (TGD) models.Patients and Methods:Plasma PK data were pooled from three phase I and II trials (JAVELIN Merkel 200, JAVELIN Solid Tumor, and JAVELIN Solid Tumor JPN); tumor size (TS) data were collected from patients with metastatic Merkel cell carcinoma (mMCC) enrolled in JAVELIN Merkel 200. A PK model was developed first, followed by TGD modeling to investigate interactions between avelumab exposure and TGD. A PK-TGD feedback loop was evaluated with simultaneous fitting of the PK and TGD models.Results:In total, 1,835 PK observations and 338 TS observations were collected from 147 patients. In the final PK-TGD model, which included the bidirectional relationship between PK and TGD, avelumab PK was described by a two-compartment model with a positive association between clearance and longitudinal TS, with no additional empirical time-varying clearance identified. TGD was described by first-order tumor growth/shrinkage rates, with the tumor shrinkage rate decreasing exponentially over time; the exponential time-decay constant decreased with increasing drug concentration, representing the treatment effect through tumor shrinkage inhibition.Conclusions:We developed a TGD model that mechanistically captures the prevention of loss of antitumor immunity (i.e., T-cell suppression in the tumor microenvironment) by avelumab, and a bidirectional interaction between PK and TGD in patients with mMCC treated with avelumab, thus mechanistically describing previously reported time variance of avelumab elimination.

A phase I/II trial evaluated the safety, antitumor activity, and pharmacokinetics of avelumab (anti-PD-L1 antibody) in pediatric patients with refractory/relapsed solid tumors (NCT03451825). This study aimed to inform avelumab dose selection in pediatric populations using population pharmacokinetic modeling and simulations.Patients aged 18 years with refractory/relapsed solid tumors enrolled in phase I received avelumab 10 or 20 mg/kg intravenously every 2 weeks. A pediatric population pharmacokinetic model was developed via the frequentist prior approach.Pharmacokinetic parameters from 21 patients who received avelumab 10 mg/kg (n = 6) or 20 mg/kg (n = 15) were analyzed. Patients had a wide range of weights and ages (medians, 37.3 kg and 12 years). Exposures with 10-mg/kg dosing were lower vs adult dosing, particularly in patients weighing 40 kg, whereas 20-mg/kg dosing achieved or exceeded adult exposures, irrespective of body weight. A two-compartment linear model with time-varying clearance using body weight as a covariate, with the frequentist prior approach, best described pediatric data. In this model, optimal overlap in exposure with adult data was achieved with 800 mg every 2 weeks for patients aged ≥ 12 years and weighing ≥ 40 kg, and 15 mg/kg every 2 weeks for patients aged 12 years or weighing 40 kg.Based on exposure matching, the recommended doses for further avelumab studies, including combination studies, are 15 mg/kg every 2 weeks for pediatric patients aged 12 years or weighing 40 kg and the adult flat dose of 800 mg every 2 weeks for pediatric patients aged ≥ 12 years and weighing ≥ 40 kg.ClinicalTrials.gov NCT03451825.

Purpose: Empirical time-varying clearance models have been reported for several immune checkpoint inhibitors, including avelumab (anti–programmed death ligand 1). To investigate the exposure-response relationship for avelumab, we explored semimechanistic pharmacokinetic (PK)–tumor growth dynamics (TGD) models. Patients and Methods: Plasma PK data were pooled from three phase I and II trials (JAVELIN Merkel 200, JAVELIN Solid Tumor, and JAVELIN Solid Tumor JPN); tumor size (TS) data were collected from patients with metastatic Merkel cell carcinoma (mMCC) enrolled in JAVELIN Merkel 200. A PK model was developed first, followed by TGD modeling to investigate interactions between avelumab exposure and TGD. A PK-TGD feedback loop was evaluated with simultaneous fitting of the PK and TGD models. Results: In total, 1,835 PK observations and 338 TS observations were collected from 147 patients. In the final PK-TGD model, which included the bidirectional relationship between PK and TGD, avelumab PK was described by a two-compartment model with a positive association between clearance and longitudinal TS, with no additional empirical time-varying clearance identified. TGD was described by first-order tumor growth/shrinkage rates, with the tumor shrinkage rate decreasing exponentially over time; the exponential time-decay constant decreased with increasing drug concentration, representing the treatment effect through tumor shrinkage inhibition. Conclusions: We developed a TGD model that mechanistically captures the prevention of loss of antitumor immunity (i.e., T-cell suppression in the tumor microenvironment) by avelumab, and a bidirectional interaction between PK and TGD in patients with mMCC treated with avelumab, thus mechanistically describing previously reported time variance of avelumab elimination.

Avelumab (anti-PD-L1) is an approved anticancer treatment for several indications. The JAVELIN Gastric 100 phase III trial did not meet its primary objective of demonstrating superior overall survival (OS) with avelumab maintenance versus continued chemotherapy in patients with advanced gastric cancer/gastroesophageal junction cancer; however, the OS rate was numerically higher with avelumab at timepoints after 12 months. Machine learning (random forests, SIDEScreen, and variable-importance assessments) was used to build models to identify prognostic/predictive factors associated with long-term OS and tumor growth dynamics (TGDs). Baseline, re-baseline, and longitudinal variables were evaluated as covariates in a parametric time-to-event model for OS and Gompertzian population model for TGD. The final OS model incorporated a treatment effect on the log-logistic shape parameter but did not identify a treatment effect on OS or TGD. Variables identified as prognostic for longer OS included older age; higher gamma-glutamyl transferase (GGT) or albumin; absence of peritoneal carcinomatosis; lower neutrophil-lymphocyte ratio, lactate dehydrogenase, or C-reactive protein (CRP); response to induction chemotherapy; and Eastern Cooperative Oncology Group performance status of 0. Among baseline and time-varying covariates, the largest effects were found for GGT and CRP, respectively. Liver metastasis at re-baseline predicted higher tumor growth. Tumor size after induction chemotherapy was associated with number of metastatic sites and stable disease (vs. response). Asian region did not impact OS or TGD. Overall, an innovative workflow supporting pharmacometric modeling of OS and TGD was established. Consistent with the primary trial analysis, no treatment effect was identified. However, potential prognostic factors were identified.

Purpose To report integrated electrocardiogram (ECG) summary and exposure–QTc analyses for avelumab, a human immunoglobulin G1 monoclonal antibody that binds programmed cell death 1 ligand 1, to assess potential effects on cardiac repolarization. Methods Data were pooled from three-phase 1/2 studies of patients with advanced solid tumors who received avelumab monotherapy (22,000 ECGs from 1818 patients). All analyses used 12-lead singlet ECGs taken using local ECG machines before and approximately 2 h after avelumab infusion on prespecified days. The exposure–QTc and outlier analyses used locally read ECGs; since larger variability is known to be associated with local reading, outlier ECGs were subsequently reevaluated by central read. QTc derived from Fridericia’s formula (QTcF) and a project-specific formula (QTcP) were analyzed. Multivariable linear mixed-effects models were used to describe the relationship between serum concentration of avelumab and QTc absolute value or change from baseline (ΔQTc). Results Exposure–QTc models showed that the effect of avelumab on QTc or ΔQTc was minimal and not statistically significant for both QTcP and QTcF. In addition, models including avelumab concentration and diphenhydramine premedication use did not show a clinically meaningful effect on the QT interval. The frequency of QTc outliers in both short and long ranges was overestimated by local reads. Six patients (0.3%) were QTc outliers; all had either received concomitant medication known to cause QT prolongation or had a preexisting cardiac condition. Conclusion Avelumab does not have any clinically relevant effect on cardiac repolarization.

Avelumab, an anti–programmed death‐ligand 1 monoclonal antibody approved for the treatment of metastatic Merkel cell carcinoma and platinum‐treated urothelial carcinoma, was initially approved with a 10 mg/kg weight‐based dose. We report pharmacokinetic (PK)/pharmacodynamic analyses for avelumab comparing weight‐based dosing and a flat 800 mg dose, developed using data from 1,827 patients enrolled in 3 clinical trials ({"type":"clinical-trial","attrs":{"text":"NCT01772004","term_id":"NCT01772004"}}NCT01772004, {"type":"clinical-trial","attrs":{"text":"NCT01943461","term_id":"NCT01943461"}}NCT01943461, and {"type":"clinical-trial","attrs":{"text":"NCT02155647","term_id":"NCT02155647"}}NCT02155647). PK metrics were simulated for weight‐based and flat‐dosing regimens and summarized by quartiles of weight. Derived exposure metrics were used in simulations of exposure‐safety (various tumors) and exposure‐efficacy (objective responses; Merkel cell or urothelial carcinoma). Flat dosing was predicted to provide similar exposure to weight‐based dosing, with slightly lower variability. Exposure‐safety and exposure‐efficacy simulations suggested similar benefit:risk profiles for the two dosing regimens. These pharmacometric analyses provided the basis for the US Food and Drug Administration approval of a flat dose of avelumab 800 mg every 2 weeks in approved indications.

The disposition of 3,3-difluoropyrrolidin-1-yl{(2S,4S)-4-[4-(pyrimidin-2-yl)piperazin-1-yl]pyrrolidin-2-yl}methanone (PF-00734200), a dipeptidyl peptidase IV inhibitor that progressed to phase 3 for the treatment of type 2 diabetes, was examined in rats, dogs, and humans after oral administration of a single dose of [(14)C]PF-00734200. Mean recoveries of administered radioactivity were 97.1, 92.2, and 87.2% in rats, dogs, and humans, respectively. The majority of radioactive dose was detected in the urine of dogs and humans and in the feces of rats. Absorption of PF-00734200 was rapid in all species, with maximal plasma concentrations of radioactivity achieved within 1 h after the dose. Circulating radioactivity was primarily composed of the parent drug (79.9, 80.2, and 94.4% in rat, dog, and human, respectively). The major route of metabolism was due to hydroxylation at the 5' position of the pyrimidine ring (M5) in all species. In vitro experiments with recombinant cytochrome P450 isoforms suggested that the formation of M5 was catalyzed both by CYP2D6 and CYP3A4. Molecular docking simulations showed that the 5' position of the pyrimidine moiety of PF-00734200 can access the heme iron-oxo of both CYP3A4 and CYP2D6 in an energetically favored orientation. Other metabolic pathways included amide hydrolysis (M2), N-dealkylation at the piperazine nitrogen (M3) and an unusual metabolite resulting from scission of the pyrimidine ring (M1). Phase II metabolic pathways included the following: carbamoyl glucuronidation (M9), glucosidation (M15) on the pyrrolidine nitrogen, and conjugation with creatinine to form an unusual metabolite/metabonate (M16). The data from these studies suggest that PF-00734200 is eliminated by both metabolism and renal clearance.

OBJECTIVE To evaluate the pharmacokinetics, pharmacodynamics, safety, and tolerability of PF-00734200, a potent dipeptidyl peptidase-IV (DPP-IV) inhibitor, in Japanese subjects, and compare the results with those in Western subjects. MATERIALS AND METHODS Eight healthy Japanese subjects received a single dose of PF-00734200 10 mg, 100 mg, or placebo. Another 8 subjects received PF-00734200 20 mg or placebo single dose once daily for 6 days. Serum and urine PK, plasma DPP-IV activity, and plasma glucagon-like peptide 1 (GLP-1) levels were measured. RESULTS Linear pharmacokinetics was observed over the single dose range 10 - 100 mg. Following multiple-dose administration, 37.3 ± 4.33% of the unchanged PF-00734200 was excreted in the urine and renal clearance was calculated as 33.9 ± 6.56 ml/min. After the standardized meals, GLP- 1 levels increased ~ 2-fold compared with placebo, and no further increase in GLP-1 levels was observed at doses above 10 mg. The steady state DPP-IV inhibition at 24 h was ~ 75%. CONCLUSION Pharmacokinetics of PF-00734200, inhibition of DPP-IV, and non-linear increases in GLP-1 were similar between healthy Japanese and Western subjects.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • Data demonstrating the pharmacokinetics (PK), efficacy and tolerability of PF-734200, a potent DPP-IV inhibitor in subjects with normal renal function, have been published or presented. WHAT THIS STUDY ADDS • This study provides better data on the PK of PF-734200 in subjects with varying degrees of renal insufficiency and in subjects with end-stage renal disease undergoing haemodialysis. In assessing the effects of renal impairment on the PK of PF-734200, this study provides evidence for potential dose adjustment of PF-734200 in patients with certain categories of renal impairment. AIMS PF-734200 is a potent, selective inhibitor of DPP-IV. This two-part study evaluated the pharmacokinetics (PK) of oral 20 mg PF-734200 in subjects with varying degrees of renal insufficiency or with end-stage renal disease (ESRD) requiring chronic haemodialysis (HD). The study also assessed the HD clearance of PF-734200 in ESRD. METHODS Part 1 included subjects with normal renal function or renal insufficiency but not on HD. Subjects received a single dose of 20 mg PF-734200 while fasting and serum and urine samples were collected. In part 2, period 1, 1 h after HD, a single 20-mg dose was given to subjects with ESRD and serum samples were collected. After a 7-day washout, subjects received another dose followed by collection of serum samples (period 2), during which HD was initiated 4 h after dosing. Dialysate samples were collected to quantify amount of drug removed, from which HD clearance was calculated. The fraction of drug dialysed was calculated using an AUC-based method. RESULTS Systemic exposures of PF-734200 increased approximately 1.5-, 2.2-, 2.1- and 2.8-fold in subjects with mild, moderate, or severe renal insufficiency or ESRD, respectively, compared with subjects with normal renal function. The terminal half-life increased from 16.2 h in subjects with normal renal function to 36.6 h in subjects with ESRD. Approximately, 29% of PF-734200 in the body after a single-dose administration was dialysed by 4 h HD. CONCLUSIONS Systemic exposure of PF-734200 increases with decreasing renal function. The effect of HD on drug removal is modest.

Diabet. Med. 28, 464–469 (2011) Abstract Aims PF-734200 is a potent and selective oral dipeptidyl peptidase-4 (DPP-4) inhibitor. This study assessed the efficacy and safety of PF-734200 at dose rates of 20 and 30 mg/day in subjects with Type 2 diabetes mellitus inadequately controlled on metformin monotherapy. Methods This was a placebo-controlled, double-blind, randomized, multicentre, 12 week study. Subjects with Type 2 diabetes mellitus were eligible if screening glycosylated haemoglobin (HbA1c) was 7–11% (53.0–96.7 mmol/mol) and they had been receiving metformin monotherapy for ≥2 months. Subjects receiving metformin and an insulin secretagogue or metformin and thiazolidinedione needed to have a screening HbA1c of 6.5–9.5% (47.5–80.3 mmol/mol), measured prior to discontinuing the insulin secretagogue or thiazolidinedione. The primary end-point of the study was a change from baseline to week 12 in HbA1c levels. Results Baseline characteristics for 289 subjects randomized to PF-734200 or placebo groups were similar (mean age 56.5 years, mean body mass index 32.2 kg/m2 and mean HbA1c 8.2%, 66.1 mmol/mol). In the predefined per protocol data set, least-squares mean HbA1c at week 12 was reduced by 0.79 (8.6 mmol/mol 95% confidence interval –1.10 to –0.49, −12.0 to −5.4 mmol/mol) and 0.92% (10.1 mmol/mol; –1.23 to –0.61, −13.4 to −6.7 mmol/mol) in the 20 and 30 mg groups, respectively, compared with placebo. Differences from placebo were statistically significant (P

The purpose of this study was to examine the feasibility of the microdialysis sampling technique as a method to precisely and conveniently measure drug release from microcarrier systems such as liposomes and microspheres. Release of 5-fluorouracil (5-FU) from liposomes and microspheres was evaluated in vitro using microdialysis. Retrodialysis calibration using 5-chlorouracil (5-CU) was performed in conjunction with on-line HPLC analysis. At a microdialysis perfusate flow rate of 0.5 muL/min, concurrent 5-FU gain and 5-CU loss ranged from 72% to 75%, while concurrent 5-FU loss and 5-CU ranged from 69% to 71%. After calibration, simultaneous 5-FU release profiles were obtained by continuous microdialysis and discrete equilibrium dialysis sampling using a side-by-side diffusion apparatus. Release rates were characterized by a first-order release model. The release rate constants for a representative liposomal formulation were 0.30 and 1.85/h by microdialysis in the acceptor and donor compartments, respectively, and 0.39/h by equilibrium dialysis in the acceptor compartment. The calculated release rate constant determined by equilibrium dialysis in the donor compartment (1.98/h) agrees with that determined by microdialysis (1.85/h) when the resistance of the equilibrium dialysis membrane with associated first-order rate constant of transfer of 0.42/h is taken into account. Release profiles of 5-FU from a number of different liposome and microsphere formulations were determined. The results indicate that a convenient and reproducible characterization of drug release from various liposome and microsphere formulations is readily obtainable by microdialysis.

Pemetrexed disodium is a novel antifolate that exhibits potent inhibitory effects on multiple enzymes in folate metabolism. Phase II/III clinical trials have shown that pemetrexed is effective against various solid tumors. Like methotrexate, pemetrexed may be useful in treatment of primary and secondary brain tumors. In this study, we examined the central nervous system (CNS) distribution of pemetrexed and the interaction with an organic anion transport inhibitor indomethacin. Male Wistar rats were administered pemetrexed by either single intravenous bolus or constant intravenous infusion. Unbound pemetrexed in blood and brain was measured by simultaneous arterial blood and frontal cortex microdialysis sampling. In the i.v. bolus experiments, indomethacin was administered by i.v. bolus (10 mg/kg) followed by i.v. infusion (0.1 mg/kg/h) in a crossover manner. In the infusion experiments, the same dose of indomethacin was administered after a steady state was reached for pemetrexed. CNS distributional kinetics was analyzed by compartmental and noncompartmental methods. Both bolus and infusion studies showed that pemetrexed has a limited CNS distribution. The mean area under concentration-time curve (AUC)(brain)/AUC(plasma) ratio of unbound pemetrexed was 0.078 +/- 0.038 in the i.v. bolus study. The pemetrexed steady-state brain-to-plasma unbound concentration ratio after i.v. infusion was 0.106 +/- 0.054. The distributional clearance into the brain was approximately 10% of the clearance out of the brain in both the compartmental and noncompartmental analyses. Indomethacin had no effect on either the brain-to-plasma AUC ratio or the steady-state brain-to-plasma concentration ratio. The distribution of pemetrexed into the brain is limited, and an efflux clearance process, such as an efflux transporter, may be involved.

The central nervous system (CNS) contains important cellular barriers that maintain homeostasis by protecting the brain from circulating toxins and through the elimination of toxic metabolites generated in the brain. The barriers that limit the concentration of toxins and xenobiotics in the interstitial fluids of the CNS are the capillary endothelial cells of the blood-brain barrier (BBB) and the epithelial cells of the blood-cerebrospinal fluid barrier (BCSFB). Both of these barriers have cellular tight junctions and express transport systems which serve to actively transport nutrients into the brain, and actively efflux toxic metabolites and xenobiotics out of the brain. This review will focus on the expression and function of selected drug efflux transporters in these two barriers, specifically the multidrug resistance transporter, p-glycoprotein, and various organic anion transporters, such as multidrug resistance-associated proteins, organic anion transporter polypeptides, and organic anion transporters. These transport systems are increasingly recognized as important determinants of drug distribution to, and elimination from, different compartments of the CNS. Consequences of drug efflux transporters in barriers of the CNS include limiting the distribution of substrates that are beneficial to treat CNS diseases, and increasing the possibility of drug-drug interactions that may lead to untoward toxicities. Therefore, the study of these transporters is important in examining the various determinants of drug delivery to the CNS.

The effects of elevated glucose and aldose reductase inhibitor (ARI:ONO-2235) on nitric oxide (NO) production in cultured human umbilical endothelial cells (HUVEC) were evaluated. Aldose reductase and nitric oxide synthase(NOS) share NADPH as an obligate cofactor, therefore it is suggested that the enhanced of glucose flux (27.5 mM) by aldose reductase inhibited NO production by blunting NOS activity. However, the addition of ONO-2235 (100 μM) prevented the inhibition of [NO 2 − ] production. Since ARI decreases glucose-mediated inhibition of NO production in HUVEC, this agent might ameliorate endothelial function associated with diabetes.

The purpose of this phase 2, multicentre, randomized, double-blind, placebo-controlled, 12-week dose-ranging study was to assess the efficacy, safety, and tolerability of the dipeptidyl peptidase-IV (DPP-IV) inhibitor PF-734200 in adult subjects with type 2 diabetes who were on a stable dose of metformin. Men and women with inadequate glycaemic control with metformin as their sole diabetes medication were randomized to placebo or PF-734200 2 mg, 5 mg, 10 mg, or 20 mg every day. A population subset underwent mixed meal tolerance tests (MMTT) at baseline and week 12. A total of 301 subjects were treated. At week 12, PF-734200 doses of ≥5 mg produced a statistically significant reduction in haemoglobin A (1C) (HbA (1c)) compared with placebo. The mean (95% confidence interval) placebo-adjusted changes in HbA (1c) were -0.31% (-0.70 to 0.08), -0.74% (-1.12 to -0.36), -0.70% (-1.02 to -0.38), and -0.75% (-1.07 to -0.43) for the 2 mg, 5 mg, 10 mg, and 20 mg doses, respectively. PF-734200 20 mg significantly reduced glucose area under the curve following MMTT (-12.8% [-22.9 to -2.7]; p=0.003) compared with placebo. The reductions observed with other doses were not statistically significant. PF-734200 was safe and well tolerated at all doses tested when added to metformin. PF-734200 safely and effectively lowered HbA (1c) in subjects receiving metformin. The 20 mg dose provided the greatest improvements in post-prandial glucose.

A randomized, placebo-controlled study evaluated the effects multiple-doses (28 days) dipeptidyl peptidase-IV (DPP-IV) inhibitor PF-734200 on DPP-IV activity, glucose, glucagon-like peptide-1 (GLP-1), glucagon and insulin levels in 72 subjects with type 2 diabetes. The relationship between changes in active GLP-1 and glucose during a meal test appeared non-linear.

Increased glucose flux through the polyol pathway and the resultant oxidative stress is thought to be a major mechanistic contributor to microvascular diabetic complications. Inhibition of flux through this pathway can be blocked through inhibition of either of 2 enzymes, aldose reductase (AR) or sorbitol dehydrogenase (SDH). This report describes the pharmacokinetics, biomarker pharmacodynamics, and safety of CP-642,931, a potent and specific sorbitol dehydrogenase inhibitor (SDI). CP-642,931 was administered for 7 days to 57 healthy volunteers in doses ranging from 1 to 35 mg daily. After the 35-mg dose, CP-642,931 showed a t((1/2)) of 20.1 hours and t(max) at 0.5 to 1.25 hours. After a 35-mg dose, maximum inhibition of SDH was 91% (on days 1 and 7), and maximum serum sorbitol increase was 152-fold on day 7 compared to control. Five participants discontinued the study due to adverse events, including myalgia, muscle spasm, and muscle fatigue. All symptoms resolved in all but 1 participant, who continued to report intermittent muscle fasciculations upon follow-up. In conclusion, CP-642,931 is a potent and specific SDI that is rapidly absorbed through the oral route and effectively inhibits SDH. However, the drug is not well tolerated due to adverse neuromuscular effects.