Correlation analysis between camrelizumab trough concentration levels and efficacy or safety in East Asian patients with advanced lung cancer

BACKGROUND

Camrelizumab combined with chemotherapy is approved across tumor types. However, only a fraction of patients benefits from immunotherapy, and biomarkers such as the expression of PD-L1, tumor mutational burden, and CXCL11 are expensive and suboptimal specificity for cancer patients. An exposure-response (E-R) relationship has been reported in many immune checkpoint inhibitors (ICIs), and the trough concentrations and other drug exposure metrics are broadly used to guide dosing decisions, assess exposure-outcomes relationships, and ultimately predict outcomes based on those relationships. However, the potential use of trough concentration levels for camrelizumab is still not clear.

METHODS

Blood samples were obtained at trough levels after doses 3 and 4 from 77 patients with advanced lung cancer who received camrelizumab (200 mg Q3 W) monotherapy or combined with chemotherapy. We optimized a competitive ELISA method to measure the trough concentration.

RESULTS

We found that the trough concentration was steady after 3 dose cycles, and the trough concentration level of camrelizumab was higher in patients who developed immune-related adverse effects (irAEs) than in those who did not (P < 0.05) but was not observed in disease progression and PFS (P > 0.05). Age (< 65 years old), no smoking history, and efficacy evaluation after 4-dose treatment were associated with PFS (P < 0.05), but no significance was observed in other clinical characteristics. Total bilirubin and albumin had an influence on trough concentration, and monocytes and albumin were independent risk factors for PFS (P < 0.05).

CONCLUSIONS

Our results suggest that the trough concentration level of camrelizumab might be a risk factor for the occurrence of irAEs in advanced lung cancer, and using the immunotherapy as early as possible may bring better clinical outcomes.

Population pharmacokinetic and pharmacokinetic-pharmacodynamic modeling of bempedoic acid and low-density lipoprotein cholesterol in healthy subjects and patients with dyslipidemia

Population pharmacokinetics (popPK) of bempedoic acid and the popPK/pharmacodynamic (popPK/PD) relationship between bempedoic acid concentrations and serum low-density lipoprotein cholesterol (LDL-C) from baseline were characterized. A two-compartment disposition model with a transit absorption compartment and linear elimination best described bempedoic acid oral pharmacokinetics (PK). Multiple covariates, including renal function, sex, and weight, had statistically significant effects on the predicted steady-state area under the curve. Mild (estimated glomerular filtration rate (eGFR) 60 to < 90 mL/min vs. ≥ 90 mL/min) and moderate (eGFR 30 to < 60 mL/min vs. ≥ 90 mL/min) renal impairment, female sex, low (< 70 kg vs. 70-100 kg) and high (> 100 kg vs. 70-100 kg) body weight were predicted to have a 1.36-fold (90% confidence interval (CI) 1.32, 1.41), 1.85-fold (90% CI 1.74, 2.00), 1.39-fold (90% CI 1.34, 1.47), 1.35-fold (90% CI 1.30, 1.41), and 0.75-fold (90% CI 0.72, 0.79) exposure difference relative to their reference populations, respectively. An indirect response model described changes in serum LDL-C with a model-predicted 35% maximal reduction and bempedoic acid IC50 of 3.17 µg/mL. A 28% reduction from LDL-C baseline was predicted for a steady-state average concentration of 12.5 µg/mL after bempedoic acid (180 mg/day) dosing, accounting for approximately 80% of the predicted maximal LDL-C reduction. Concurrent statin therapy, regardless of intensity, reduced the maximal effect of bempedoic acid but resulted in similar steady-state LDL-C levels. While multiple covariates had statistically significant effects on PK and LDL-C lowering, none were predicted to warrant bempedoic acid dose adjustment.

Nonlinear low dose hematotoxicity of benzene; a pooled analyses of two studies among Chinese exposed workers

BACKGROUND

Impairment of the hematopoietic system is one of the primary adverse health effects from exposure to benzene. We previously have shown that exposure to benzene at low levels (<1 ppm) affects the blood forming system and that these effects were proportionally stronger at lower versus higher levels of benzene exposure. This observation is potentially explained by saturation of enzymatic systems.

METHODS

Here we extend these analyses by detailed modeling of the exposure response association of benzene and its major metabolites (i.e. catechol, muconic acid, phenol, and hydroquinone) on peripheral white blood cell (WBC) counts and its major cell-subtypes (i.e. granulocytes, lymphocytes, and monocytes) using two previously published cross-sectional studies among occupationally exposed Chinese workers.

RESULTS

Supra-linear exposure response associations were observed between air benzene concentrations (range ∼ 0.1 - 100 ppm) and WBC counts and its cell-subtypes, with a larger than proportional decrease in cell counts at lower than at higher levels of benzene exposure. The hematotoxicity associations were largely similar in shape when the analyses were repeated with benzene urinary metabolites suggesting that enzymatic saturation is not a full explanation of the observed non-linearity with WBC endpoints.

DISCUSSION

We hypothesize that the flattening of the exposure response curve especially at higher benzene exposure levels may reflect a response by the bone marrow to maintain hematopoietic homeostasis. Toxicity to the bone marrow and an induced hyper-proliferative response could both contribute to risk of subsequently developing a hematopoietic malignancy. Additional work is needed to explore this hypothesis.

Exposure-response analyses of BRAF- and MEK-inhibitors dabrafenib plus trametinib in melanoma patients

INTRODUCTION

Dabrafenib and trametinib are currently administered at fixed doses, at which interpatient variability in exposure is high. The aim of this study was to investigate whether drug exposure is related to efficacy and toxicity in a real-life cohort of melanoma patients treated with dabrafenib plus trametinib.

PATIENTS AND METHODS

An observational study was performed in which pharmacokinetic samples were collected as routine care. Using estimated dabrafenib Area Under the concentration-time Curve and trametinib trough concentrations (C_min), univariable and multivariable exposure-response analyses were performed.

RESULTS

In total, 140 patients were included. Dabrafenib exposure was not related to either progression-free survival (PFS) or overall survival (OS). Trametinib exposure was related to survival, with C_min ≥ 15.6 ng/mL being identified as the optimal threshold. Median OS was significantly longer in patients with trametinib C_min ≥ 15.6 ng/mL (22.8 vs. 12.6 months, P = 0.003), with a multivariable hazard ratio of 0.55 (95% CI 0.36-0.85, P = 0.007). Median PFS in patients with trametinib C_min levels ≥ 15.6 ng/mL (37%) was 10.9 months, compared with 6.0 months for those with C_min below this threshold (P = 0.06). Multivariable analysis resulted in a hazard ratio of 0.70 (95% CI 0.47-1.05, P = 0.082). Exposure to dabrafenib and trametinib was not related to clinically relevant toxicities.

CONCLUSIONS

Overall survival of metastasized melanoma patients with trametinib C_min levels ≥ 15.6 ng/mL is ten months longer compared to patients with C_min below this threshold. This would theoretically provide a rationale for therapeutic drug monitoring of trametinib. Although a high proportion of patients are underexposed, there is very little scope for dose increments due to the risk of serious toxicity.

A comprehensive regulatory and industry review of modeling and simulation practices in oncology clinical drug development

Exposure-response (E-R) analyses are an integral component in the development of oncology products. Characterizing the relationship between drug exposure metrics and response allows the sponsor to use modeling and simulation to address both internal and external drug development questions (e.g., optimal dose, frequency of administration, dose adjustments for special populations). This white paper is the output of an industry-government collaboration among scientists with broad experience in E-R modeling as part of regulatory submissions. The goal of this white paper is to provide guidance on what the preferred methods for E-R analysis in oncology clinical drug development are and what metrics of exposure should be considered.

Characterization of exposure-Clinical Dementia Rating-Sum of Boxes relationship in subjects with early Alzheimer's disease from the aducanumab Phase 3 trials

Clinical Dementia Rating-Sum of Boxes (CDR-SB) assessments from two Phase 3 studies (ENGAGE and EMERGE) of aducanumab in subjects with early Alzheimer's disease (AD) were pooled to develop an exposure-response (ER) model. A linear model in the logit-transformed scaled CDR-SB best characterized the time profile for placebo- and aducanumab-treated subjects, with concentration as the exposure metric. The model allowed delineation of slow (4%), typical (86%), and fast (10%) progressing subpopulations in the data. The estimated drug effect on the disease progression rate was significant, 2.05 L/(g·year), with a 95% confidence interval (1.60, 2.50) that did not include zero. Following an evaluation of a series of ER model forms including differential drug and null effects either between the studies or among the three progression classes, the final ER model with a common (pooled) estimate of the drug effect between the studies and among the three progression classes was considered parsimonious. The final model provides supportive evidence that the two studies demonstrate a common intrinsic pharmacology. None of the identified covariates (Mini-Mental State Examination-BL score and Asian race) were clinically meaningful. Finally, simulations demonstrated that the intrinsic pharmacology remained consistent between the two Phase 3 studies.

Randomized, open-label, phase 2a study to evaluate the contribution of artefenomel to the clinical and parasiticidal activity of artefenomel plus ferroquine in African patients with uncomplicated Plasmodium falciparum malaria

BACKGROUND

The contribution of artefenomel to the clinical and parasiticidal activity of ferroquine and artefenomel in combination in uncomplicated Plasmodium falciparum malaria was investigated.

METHODS

This Phase 2a, randomized, open-label, parallel-group study was conducted from 11th September 2018 to 6th November 2019 across seven centres in Benin, Burkina Faso, Gabon, Kenya, and Uganda. Patients aged ≥ 14-69 years with microscopically confirmed infection (≥ 3000 to ≤ 50,000 parasites/µL blood) were randomized 1:1:1:1 to 400 mg ferroquine, or 400 mg ferroquine plus artefenomel 300, 600, or 1000 mg, administered as a single oral dose. The primary efficacy analysis was a logistic regression evaluating the contribution of artefenomel exposure to Day 28 PCR-adjusted adequate clinical and parasitological response (ACPR). Safety was also evaluated.

RESULTS

The randomized population included 140 patients. For the primary analysis in the pharmacokinetic/pharmacodynamic efficacy population (N = 121), the contribution of artefenomel AUC_0-∞ to Day 28 PCR-adjusted ACPR was not demonstrated when accounting for ferroquine AUC_0-d28, baseline parasitaemia, and other model covariates: odds ratio 1.1 (95% CI 0.98, 1.2; P = 0.245). In the per-protocol population, Day 28 PCR-adjusted ACPR was 80.8% (21/26; 95% CI 60.6, 93.4) with ferroquine alone and 90.3% (28/31; 95% CI 74.2, 98.0), 90.9% (30/33; 95% CI 75.7, 98.1) and 87.1% (27/31; 95% CI 70.2, 96.4) with 300, 600, and 1000 mg artefenomel, respectively. Median time to parasite clearance (Kaplan-Meier) was 56.1 h with ferroquine, more rapid with artefenomel, but similar for all doses (30.0 h). There were no deaths. Adverse events (AEs) of any cause occurred in 51.4% (18/35) of patients with ferroquine 400 mg alone, and 58.3% (21/36), 66.7% (24/36), and 72.7% (24/33) with 300, 600, and 1000 mg artefenomel, respectively. All AEs were of mild-to-moderate severity, and consistent with the known profiles of the compounds. Vomiting was the most reported AE. There were no cases of QTcF prolongation ≥ 500 ms or > 60 ms from baseline.

CONCLUSION

The contribution of artefenomel exposure to the clinical and parasitological activity of ferroquine/artefenomel could not be demonstrated in this study. Parasite clearance was faster with ferroquine/artefenomel versus ferroquine alone. All treatments were well tolerated.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03660839 (7 September, 2018).

Population Pharmacokinetics and Exposure-Response Analyses of Ustekinumab in Patients With Moderately to Severely Active Crohn's Disease

PURPOSE

Ustekinumab, a fully human immunoglobulin G1κ monoclonal antibody that antagonizes human interleukin-12/23p40, is an effective therapy for several immune-mediated inflammatory diseases, including Crohn's disease (CD). This work characterizes the population pharmacokinetic (PK) and exposure-response (E-R) relationships of ustekinumab in patients with CD using data from four Phase IIb/III clinical studies.

METHODS

Serum ustekinumab concentration-time data from 1673 patients after IV and/or SC administration of ustekinumab were fitted simultaneously using nonlinear mixed effects modeling to develop a population PK model, which was subsequently used to evaluate simulation scenarios. Logistic regression E-R models were used to assess relationships between serum ustekinumab concentrations and clinical remission after induction (n = 1910) and maintenance (n = 387) treatment.

FINDINGS

Ustekinumab PK properties are well described by a two-compartment model with first-order absorption and elimination. Typical values of PK parameters for a 70-kg patient were: clearance, 0.192 L/d; volume of distribution at steady state, 4.62 L; and intercompartmental clearance, 0.287 L/d. Ustekinumab terminal elimination t_1/2 was 19 days, and bioavailability after SC administration was 78.3%. Ustekinumab clearance was not affected by coadministration of immunosuppressive agents or corticosteroids. Body weight, serum albumin, and C-reactive protein (CRP) concentrations, tumor necrosis factor (TNF) antagonist failure status, sex, race (Asian vs non-Asian), and anti-ustekinumab antibody status significantly affected ustekinumab disposition; however, the effects of these covariates on ustekinumab exposure were not clinically relevant. The population PK model predicts that a milligram/kilogram dosing approach will result in lower ustekinumab exposure in patients with lower body weight. A positive E-R relationship was established between ustekinumab concentration and efficacy outcomes. The treatment effect of ustekinumab after induction therapy was more pronounced among patients with higher baseline CRP concentrations relative to those with lower values.

IMPLICATIONS

In patients with CD, ustekinumab disposition after IV and SC administration was biexponential and consistent with those in patients with ulcerative colitis. Prior treatment with TNF antagonists or the concomitant use of immunosuppressive agents or corticosteroids had no effect on ustekinumab disposition. None of the covariates that affected ustekinumab clearance had a clinically meaningful impact on ustekinumab exposure. E-R models support recommended posology of ustekinumab in adults with CD; however, an ∼6 mg/kg IV induction dose in pediatric patients with lower body weights may not provide exposure that matches that in adult patients.

CLINICALTRIALS

gov identifiers: NCT00771667, NCT01369329, NCT01369342, and NCT01369355. (Clin Ther. 2022;44:XXX-XXX) © 2022 Elsevier HS Journals, Inc.

RELAY, ramucirumab plus erlotinib versus placebo plus erlotinib in untreated EGFR-mutated metastatic non-small cell lung cancer: exposure-response relationship

PURPOSE

In RELAY, ramucirumab plus erlotinib (RAM + ERL) improved progression-free survival (PFS) in patients with untreated, metastatic, EGFR-mutated, non-small cell lung cancer (NSCLC). Here, we present the exposure-response relationship of RAM from RELAY.

METHODS

Patients received ERL (150 mg/day) with either RAM (10 mg/kg) or placebo (PBO + ERL) every 2 weeks (Q2W). A population pharmacokinetic model predicted RAM minimum concentration after first dose (Cmin,1), and at steady state (Cmin,ss), which were used to evaluate correlation between RAM exposure and efficacy and safety. The Kaplan-Meier method and Cox regression analyses were utilized to evaluate exposure-efficacy by Cmin,1 quartile. Exposure-safety was evaluated by assessing incidence rates for safety parameters by Cmin,ss quartile, with ordered categorical analysis used for ALT/AST only.

RESULTS

Analyses included 216 patients treated with RAM + ERL and 225 patients treated with PBO + ERL. Adjusting for significant baseline covariates, no exposure-efficacy relationship was identified in RELAY: PFS hazard ratio (mean, 95% confidence intervals) for the Cmin,1 quartiles were 0.67 (0.45-0.99), 0.77 (0.53-1.12), 0.57 (0.38-0.84), and 0.50 (0.33-0.76). No apparent exposure-safety relationship was observed for selected safety endpoints, including Grade ≥ 3 hypertension, diarrhea, and dermatitis acneiform, and any grade hypertension, any grade and Grade ≥ 3 proteinuria, and any grade ALT/AST increased within liver failure/liver injury.

CONCLUSIONS

No association was observed between RAM exposure and response, suggesting that the RELAY regimen of RAM 10 mg/kg Q2W with ERL is an optimized, efficacious, and safe first-line treatment for patients with untreated, metastatic, EGFR-mutated NSCLC.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02411448.

Efficacy and safety exposure-response relationships of apalutamide in patients with metastatic castration-sensitive prostate cancer: results from the phase 3 TITAN study

PURPOSE

Apalutamide plus androgen-deprivation therapy (ADT) has been approved for treatment of patients with metastatic castration-sensitive prostate cancer (mCSPC) based on data from phase 3 TITAN study. This analysis was conducted to describe pharmacokinetics of apalutamide and N-desmethyl-apalutamide and explore relationships between apalutamide exposure and selected clinical efficacy and safety observations.

METHODS

1052 patients were randomized to apalutamide + ADT (n = 525) or placebo + ADT (n = 527). A previously developed population pharmacokinetic model was applied. Cox regression analysis investigated the relationships between apalutamide exposure and overall survival (OS; n = 1004) and radiographic progression-free survival (rPFS; n = 1003). Logistic regression analysis assessed the relationships between apalutamide exposure and selected clinically relevant adverse events (n = 1051).

RESULTS

Apalutamide + ADT treatment was efficacious in extending rPFS and OS versus placebo + ADT. Within a relatively narrow apalutamide exposure range (coefficient of variation: 22%), no statistical association was detected between rPFS, OS and apalutamide exposure quartiles. Incidence of skin rash and pruritus increased significantly with increasing apalutamide exposure.

CONCLUSIONS

Differences in apalutamide exposure were not associated with clinically relevant differences in rPFS or OS in patients with mCSPC. Patients with increased apalutamide exposure are more likely to develop skin rash and pruritus. Dose reductions may improve these adverse events, based on an individual risk-benefit approach.

Lurbinectedin-induced thrombocytopenia: the role of body surface area

Lurbinectedin is an alkylating agent approved for the second-line treatment of small cell lung cancer. Although initial studies showed no association between body surface area (BSA) and drug clearance, the recommended dose is 3.2 mg/m² every 3 weeks. This recommendation was based on an exposure-response study, which demonstrated that patients with lower BSA had a higher incidence of thrombocytopenia. Herein we present the factors associated with BSA and thrombopoiesis, which may have contributed to the observed relationship.

Efficacy and safety exposure-response analyses of entrectinib in patients with advanced or metastatic solid tumors

PURPOSE

Entrectinib is an anti-cancer agent that inhibits TRKA/B/C, ROS1, and ALK. Secondary pharmacokinetic (PK) exposure parameters for entrectinib derived from a previously described population PK model were used to characterize exposure-response relationships in patients treated with entrectinib.

METHODS

Data were pooled from Phase 1 and 2 studies of entrectinib (600-800 mg/day in adults, 250-750 mg/m²/day in children) in 293 patients with NTRK-, ROS1-, or ALK-positive, locally advanced or metastatic tumors. Efficacy was evaluated by the changes in sum of target lesion diameters and best overall response defined by RECIST1.1. A longitudinal nonlinear mixed-effect model described the relationship between entrectinib exposure and tumor size data in patients with ROS1-positive non-small-cell lung cancer (NSCLC) or NTRK fusion-positive solid tumors. The relationship between exposure and treatment-emergent (TEAEs) or serious (SAEs) adverse events was assessed by logistic regression in all patients for whom secondary PK parameter estimates were derived.

RESULTS

Among the 89 patients with evaluable efficacy data included in the exposure-efficacy analysis, 73% (65/89) achieved a complete or partial response. Entrectinib exposure distribution was similar in responders and non-responders. Model-described tumor shrinkage rates were 8-12 times greater than growth rates in both ROS-1-positive NSCLC patients and NTRK fusion-positive solid tumor patients, with no relationship between exposure and these rates. The probability of experiencing a Grade ≥ 3 TEAE or SAE increased with exposure, primarily at doses > 600 mg/day.

CONCLUSION

These analyses supported that entrectinib at 600 mg/day provides an acceptable benefit-risk ratio in adults with NTRK-, ROS1-, or ALK-positive tumors, considered as rare disease.

BioRssay: an R package for analyses of bioassays and probit graphs

Dose-response relationships reflect the effects of a substance on organisms, and are widely used in broad research areas, from medicine and physiology, to vector control and pest management in agronomy. Furthermore, reporting on the response of organisms to stressors is an essential component of many public policies (e.g. public health, environment), and assessment of xenobiotic responses is an integral part of World Health Organization recommendations. Building upon an R script that we previously made available, and considering its popularity, we have now developed a software package in the R environment, BioRssay, to efficiently analyze dose-response relationships. It has more user-friendly functions and more flexibility, and proposes an easy interpretation of the results. The functions in the BioRssay package are built on robust statistical analyses to compare the dose/exposure-response of various bioassays and effectively visualize them in probit-graphs.

Integrated exposure-response analysis of efficacy and safety of lurbinectedin to support the dose regimen in small-cell lung cancer

Purpose

These exposure–response (E–R) analyses integrated lurbinectedin effects on key efficacy and safety variables in relapsed SCLC to determine the adequacy of the dose regimen of 3.2 mg/m² 1-h intravenous infusion every 3 weeks (q3wk).

Methods

Logistic models and Cox regression analyses were applied to correlate lurbinectedin exposure metrics (AUC_tot and AUC_u) with efficacy and safety endpoints: objective response rate (ORR) and overall survival (OS) in SCLC patients (n = 99) treated in study B-005 with 3.2 mg/m² q3wk, and incidence of grade 4 (G4) neutropenia and grade 3–4 (G ≥ 3) thrombocytopenia in a pool of cancer patients from single-agent phase I to III studies (n = 692) treated at a wide range of doses. A clinical utility index was used to assess the appropriateness of the selected dose.

Results

Effect of lurbinectedin AUC_u on ORR best fitted to a sigmoid-maximal response (E_max) logistic model, where E_max was dependent on chemotherapy-free interval (CTFI). Cox regression analysis with OS found relationships with both CTFI and AUC_u. An E_max logistic model for G4 neutropenia and a linear logistic model for G ≥ 3 thrombocytopenia, which retained platelets and albumin at baseline and body surface area, best fitted to AUC_tot and AUC_u. AUC_u between approximately 1000 and 1700 ng·h/L provided the best benefit/risk ratio, and the dose of 3.2 mg/m² provided median AUC_u of 1400 ng·h/L, thus maximizing the proportion of patients within that lurbinectedin target exposure range.

Conclusions

The relationships evidenced in this integrated E–R analysis support a favorable benefit-risk profile for lurbinectedin 3.2 mg/m² q3wk.

Trial registration

Clinicaltrials.gov: NCT02454972; registered May 27, 2015.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00280-021-04366-3.

A randomized, double-blind, phase 2b study to investigate the efficacy, safety, tolerability and pharmacokinetics of a single-dose regimen of ferroquine with artefenomel in adults and children with uncomplicated Plasmodium falciparum malaria

Background

For uncomplicated Plasmodium falciparum malaria, highly efficacious single-dose treatments are expected to increase compliance and improve treatment outcomes, and thereby may slow the development of resistance. The efficacy and safety of a single-dose combination of artefenomel (800 mg) plus ferroquine (400/600/900/1200 mg doses) for the treatment of uncomplicated P. falciparum malaria were evaluated in Africa (focusing on children ≤ 5 years) and Asia.

Methods

The study was a randomized, double-blind, single-dose, multi-arm clinical trial in patients aged > 6 months to < 70 years, from six African countries and Vietnam. Patients were followed up for 63 days to assess treatment efficacy, safety and pharmacokinetics. The primary efficacy endpoint was the polymerase chain reaction (PCR)-adjusted adequate clinical and parasitological response (ACPR) at Day 28 in the Per-Protocol [PP] Set comprising only African patients ≤ 5 years. The exposure–response relationship for PCR-adjusted ACPR at Day 28 and prevalence of kelch-13 mutations were explored.

Results

A total of 373 patients were treated: 289 African patients ≤ 5 years (77.5%), 64 African patients > 5 years and 20 Asian patients. None of the treatment arms met the target efficacy criterion for PCR-adjusted ACPR at Day 28 (lower limit of 95% confidence interval [CI] > 90%). PCR-adjusted ACPR at Day 28 [95% CI] in the PP Set ranged from 78.4% [64.7; 88.7%] to 91.7% [81.6; 97.2%] for the 400 mg to 1200 mg ferroquine dose. Efficacy rates were low in Vietnamese patients, ranging from 20 to 40%. A clear relationship was found between drug exposure (artefenomel and ferroquine concentrations at Day 7) and efficacy (primary endpoint), with higher concentrations of both drugs resulting in higher efficacy. Six distinct kelch-13 mutations were detected in parasite isolates from 10/272 African patients (with 2 mutations known to be associated with artemisinin resistance) and 18/20 Asian patients (all C580Y mutation). Vomiting within 6 h of initial artefenomel administration was common (24.6%) and associated with lower drug exposures.

Conclusion

The efficacy of artefenomel/ferroquine combination was suboptimal in African children aged ≤ 5 years, the population of interest, and vomiting most likely had a negative impact on efficacy.

Trial registration ClinicalTrials.gov, NCT02497612. Registered 14 Jul 2015, https://clinicaltrials.gov/ct2/show/NCT02497612?term=NCT02497612&draw=2&rank=1

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-03749-4.

Population pharmacokinetics and exposure-response of selumetinib and its N-desmethyl metabolite in pediatric patients with neurofibromatosis type 1 and inoperable plexiform neurofibromas

PURPOSE

Selumetinib (ARRY-142886) is a potent, selective, MEK1/2 inhibitor approved in the US for the treatment of children (≥ 2 years) with neurofibromatosis type 1 (NF1) and symptomatic, inoperable plexiform neurofibromas (PN). We characterized population pharmacokinetics (PK) of selumetinib and its active N-desmethyl metabolite, evaluated exposure-safety/efficacy relationships, and assessed the proposed therapeutic dose of 25 mg/m² bid based on body surface area (BSA) in this patient population.

METHODS

Population PK modeling and covariate analysis (demographics, formulation, liver enzymes, BSA, patients/healthy volunteers) were based on pooled PK data from adult healthy volunteers (n = 391), adult oncology patients (n = 83) and pediatric patients with NF1-PN (n = 68). Longitudinal selumetinib/metabolite exposures were predicted with the final model. Exposure-safety/efficacy analyses were applied to pediatric patients (dose levels: 20, 25, 30 mg/m² bid).

RESULTS

Selumetinib and metabolite concentration-time courses were modeled using a joint compartmental model. Typical selumetinib plasma clearance was 11.6 L/h (95% CI 11.0-12.2 L/ h). Only BSA had a clinically relevant (> 20%) impact on exposure, supporting BSA-based administration in children. Selumetinib and metabolite exposures in responders (≥ 20% PN volume decrease from baseline) and non-responders were largely overlapping, with medians numerically higher in responders. No clear relationships between exposure and safety events were established; exposure was not associated with key adverse events (AEs) including rash acneiform, diarrhea, vomiting, and nausea.

CONCLUSION

Findings support continuous selumetinib 25 mg/m² bid in pediatric patients. Importantly, the updated dosing nomogram ensures that patients will receive a clinically active, yet tolerable, dose regardless of differences in BSA and allows dose reductions, if necessary.

Associations between model-predicted rivaroxaban exposure and patient characteristics and efficacy and safety outcomes in the prevention of venous thromboembolism

Anticoagulant plasma concentrations and patient characteristics might affect the benefit–risk balance of therapy. The study objective was to assess the impact of model-predicted rivaroxaban exposure and patient characteristics on outcomes in patients receiving rivaroxaban for venous thromboembolism (VTE) prophylaxis (VTE-P) after hip/knee replacement surgery. Post hoc exposure–response analyses were conducted using data from the phase 3 RECORD1–4 studies, in which 12,729 patients were randomized to rivaroxaban 10 mg once daily or enoxaparin for ≤ 39 days. Multivariate regression approaches were used to correlate model-predicted individual rivaroxaban exposures and patient characteristics with outcomes. In the absence of measured rivaroxaban exposure, exposure estimates were predicted based on individual increases in prothrombin time (PT) and by making use of the known correlation between rivaroxaban plasma concentration and dynamics of PT. No significant associations between rivaroxaban exposure and total VTE or major bleeding were identified. A significant association between exposure and a composite of major or non-major clinically relevant (NMCR) bleeding from day 4 after surgery was observed. The relationship was shallow, with an approximate predicted absolute increase in a composite of major or NMCR bleeding from 1.08 [95% confidence interval (CI) 0.76–1.54] to 2.18% (95% CI 1.51–3.17) at the 5th and 95th percentiles of trough plasma concentration, respectively. In conclusion, based on the underlying data and analysis, no reliable target window for exposure with improved benefit–risk could be identified within the investigated exposure range. Hence, monitoring rivaroxaban levels is unlikely to be beneficial in VTE-P.

Associations between model-predicted rivaroxaban exposure and patient characteristics and efficacy and safety outcomes in the treatment of venous thromboembolism

Anticoagulant plasma concentrations and patient characteristics might affect the benefit–risk balance of therapy. This study assessed the impact of model-predicted rivaroxaban exposure and patient characteristics on outcomes in patients receiving rivaroxaban for venous thromboembolism treatment (VTE-T) using data from the phase 3 EINSTEIN–DVT and EINSTEIN–PE studies. In the absence of measured rivaroxaban exposure, exposure estimates were predicted based on individual increases in prothrombin time (PT) and the known correlation between rivaroxaban plasma concentrations and PT dynamics. The composite efficacy outcomes evaluated were recurrent deep-vein thrombosis (DVT) and pulmonary embolism (PE) and recurrent DVT, PE and all-cause death; safety outcomes were major bleeding and the composite of major or non-major clinically relevant (NMCR) bleeding. Exposure–response relationships were evaluated using multivariate logistic and Cox regression for the twice-daily (BID) and once-daily (OD) dosing periods, respectively. Predicted rivaroxaban exposure and CrCl were significantly associated with both efficacy outcomes in the BID period. In the OD period, exposure was significantly associated with recurrent DVT and PE but not recurrent DVT, PE and all-cause death. The statistically significant exposure–efficacy relationships were shallow. Exposure–safety relationships were absent within the investigated exposure range. During both dosing periods, low baseline hemoglobin and prior bleeding were associated with the composite of major or NMCR bleeding. In conclusion, based on the underlying data and analysis, no reliable target window for exposure with improved benefit–risk could be identified within the investigated exposure range. Therefore, monitoring rivaroxaban levels is unlikely to be beneficial in VTE-T.

Pharmacokinetics of the oral multikinase inhibitor regorafenib and its association with real-world treatment outcomes

Purpose Despite the established activity of regorafenib in metastatic colorectal cancer (CRC), gastrointestinal stromal tumor (GIST), and hepatocellular carcinoma (HCC), its toxicity profile has limited clinical use. We aimed to evaluate the pharmacokinetics of regorafenib and its active metabolites M-2/M-5, and to clarify the relationships between total drug-related exposure and clinical outcomes in real-world practice. Methods Blood samples at steady state were obtained during Cycle 1 from patients treated with regorafenib. Plasma concentrations of regorafenib and its metabolites were measured by liquid chromatography-tandem mass spectrometry. The efficacy and safety endpoints were progression-free survival (PFS) and dose-limiting toxicities (DLTs), respectively. The exposure-response relationships were assessed. Results Thirty-four Japanese patients with advanced cancers were enrolled (CRC, n = 26; GIST and HCC, each n = 4). Nine patients started regorafenib treatment at the recommended dose of 160 mg once daily (3 weeks on / 1 week off), while the other patients received a reduced starting dose to minimize toxicities. The median PFS was significantly longer in patients achieving total trough concentrations (C_trough) of regorafenib and M-2/M-5 ≥2.9 µg/mL than those who did not (112 vs. 57 days; p = 0.044). Furthermore, the cumulative incidence of DLTs during the first 2 cycles was significantly higher in patients with summed C_trough levels ≥4.3 µg/mL than in others (p = 0.0003). Conclusions Dose titration of regorafenib to achieve drug-related C_trough levels between 2.9 and 4.3 µg/mL in Cycle 1 may improve efficacy and safety, warranting further investigation in a larger patient population.Clinical trial registry: Not applicable.

Selinexor population pharmacokinetic and exposure-response analyses to support dose optimization in patients with diffuse large B-cell lymphoma

PURPOSE

Characterize the population PK and exposure-response (ER) relationships of selinexor in patients with diffuse large B-cell lymphoma (DLBCL) (efficacy endpoints) or other non-Hodgkin's lymphoma (NHL) patients (safety endpoints) to determine the optimal dose in patients with DLBCL.

METHODS

This work included patients from seven clinical studies, with 800 patients for PK, 175 patients for efficacy and 322 patients for safety analyses. Logistic regression models and Cox-regression models were used for binary and time-to-event endpoints, respectively. Model-based simulations were performed to justify dose based on balance between efficacy and safety outcome.

RESULTS

Selinexor pharmacokinetics were well-described by a two-compartment model with body weight as a significant covariate on clearance and central volume of distribution and gender on clearance. Overall response rate (ORR) in patients with DLBCL increased with day 1 C_max and decreased in patients with higher baseline tumor size (p < 0.05). Significant exposure-safety relationships (p < 0.05) in NHL patients were identified for the frequency of the following safety endpoints: dose modifications, decreased appetite Grade ≥ 3 (Gr3+), fatigue Gr2+, vision blurred Gr1+, and vomiting Gr2+. Similar exposure-safety relationships were found for time-to-onset of the adverse events.

CONCLUSIONS

Simulations of the safety and efficacy ER models suggested that, compared to a starting dose of 60 mg twice weekly (BIW), a 40 mg BIW regimen resulted in an absolute decrease in AE probabilities between 1.9 and 5.3%, with a clinically significant absolute efficacy decrease of 4.7% in ORR. The modeling results support that 60 mg BIW is the optimal dose in patients with DLBCL.

Detection and impact of hysteresis when evaluating a drug's QTc effect using concentration-QTc analysis

Early-phase studies quantifying the QTc prolongation potential for a new drug often use linear concentration-QTc (C-QTc) models, assuming no delay between plasma concentrations and QTc changes. However, that assumption is not always correct. The term "hysteresis" has been utilized to describe a time lag present between a measurable concentration and a measurable effect. To detect and quantify hysteresis and its impact on study interpretation, studies with hysteresis of 0.25-4 h were simulated with different doses, half-lives, and sampling schedules in a crossover design. Hysteresis was quantified using a novel method termed exposure-normalized GRI (enGRI), a proposed modification of the Glomb-Ring Index (GRI), to account for delay and magnitude of QTc effects. With realistic sampling, the rate of false negative studies (FN) increased proportionally to the delay, even for delays shorter than 1 h. Using an enGRI threshold (γ) of 2 ms resulted in FN with undetected delay and FN without hysteresis at approximately the same rate. For γ = 2 ms, the specificity of enGRI was > 90% throughout the investigated scenarios. We therefore propose the incorporation of enGRI when interpreting results from C-QTc analysis with the intent of characterizing QTc effects.

The application of extreme value theory to pharmacometrics

Clinical trials are often analyzed by examining the means, e.g., what is the mean treatment effect or what is the mean treatment difference, but there are times when analysis of the maximums (or minimums) are of interest. For instance, what is the highest heart rate that could be observed or what the smallest treatment effect that could be expected? While inference on the means is based on the central limit theorem, the corresponding theorem for maximums or minimums is the Fisher-Tippett theorem, also called the extreme value theorem (EVT). This manuscript will introduce EVT to pharmacometricians, particularly block maxima analysis and peak over threshold analysis, and provide examples for how it can be applied to pharmacometric data, particularly the analysis of pharmacokinetics and ECG safety data, like QTcF intervals.

An evaluation of overall survival in patients with newly diagnosed acute myeloid leukemia and the relationship with glasdegib treatment and exposure

PURPOSE

Glasdegib, an oral inhibitor of the Hedgehog signaling pathway, is approved in the United States in combination with low-dose cytarabine (LDAC) to treat patients with newly diagnosed acute myeloid leukemia (AML) ineligible to receive intensive chemotherapy. This population pharmacokinetic/pharmacodynamic analysis characterized the time course of survival with glasdegib + LDAC relative to LDAC alone, and explored whether the differences in glasdegib exposure at the clinical dose of 100 mg once daily (QD) significantly affected overall survival (OS).

METHODS

Data from the BRIGHT AML 1003 trial in patients with AML were included in treatment-response (glasdegib + LDAC, n = 78; LDAC alone, n = 38) and exposure-response (glasdegib + LDAC, n = 75) analyses.

RESULTS

The analyses demonstrate that patients treated with glasdegib + LDAC (vs LDAC alone) at any time point during the study period were 58% less likely to die, translating to prolonging of median OS by ~ 5 months (hazard ratio 0.42 [95% confidence interval 0.28-0.66]). Variability in glasdegib exposures did not impact the risk of death. Additionally, potential covariates such as patient demographics, prior treatment with a hypomethylating agent, baseline safety laboratory values, and disease characteristics, did not impact the probability of OS.

CONCLUSION

Together these results confirm that glasdegib + LDAC treatment (vs. LDAC alone) is associated with a significant survival benefit in patients with newly diagnosed AML, and that variability in glasdegib doses (e.g., for dose reductions) and exposures do not compromise the survival benefit of glasdegib 100 mg QD.

CLINICAL TRIAL NUMBER

NCT01546038.

Model-based Prediction of the Long-term Glucose-Lowering Effects of Ipragliflozin, a Selective Sodium-Glucose Cotransporter 2 (SGLT2) Inhibitor, in Patients with Type 2 Diabetes Mellitus

INTRODUCTION

Sodium-dependent glucose cotransporter 2 (SGLT2) inhibitors inhibit the reabsorption of glucose from the kidneys and increase urinary glucose excretion (UGE), thereby lowering the blood glucose concentration in people suffering from type 1 and type 2 diabetes mellitus (T2DM). In a previous study, we reported a pharmacokinetics/pharmacodynamics model to estimate individual change in UGE (ΔUGE), which is a direct pharmacological effect of SGLT2 inhibitors. In this study, we report our enhancement of the previous model to predict the long-term effects of ipragliflozin on clinical outcomes in patients with T2DM.

METHODS

The time course of fasting plasma glucose (FPG) and hemoglobin A1c (HbA1c) in patients with T2DM following ipragliflozin treatment that had been observed in earlier clinical trials was modeled using empirical models combined with the maximum drug effect (E_max) model and disease progression model. As a predictive factor of drug effect, estimated ΔUGE was introduced into the E_max model, instead of ipragliflozin exposure. The developed models were used to simulate the time course of FPG and HbA1c following once-daily treatment with placebo or ipragliflozin at doses of 12.5, 25, 50 and 100 mg, and the changes at 52 weeks at the approved dose of 50 mg were summarized by renal function category.

RESULTS

The developed models that included UGE as a dependent variable of response were found to well describe observed time courses in FPG and HbA1c. Baseline blood glucose level and renal function had significant effects on the glucose-lowering effect of ipragliflozin, and these models enabled quantification of these impacts on clinical outcomes. Simulated median changes in HbA1c in T2DM patients with mild and moderate renal impairment were 25 and 63% lower, respectively, than those in T2DM patients with normal renal function. These results are consistent with the observed clinical data from a previous renal impairment study.

CONCLUSIONS

Empirical models established based on the effect of UGE well predicted the renal function-dependent long-term glucose-lowering effects of ipragliflozin in patients with T2DM.

A time-to-event analysis of the exposure-response relationship for bezlotoxumab concentrations and CDI recurrence

Bezlotoxumab is a monoclonal antibody approved for the prevention of recurrent Clostridium difficile infection (rCDI). In a previous exposure-response (E-R) analysis of bezlotoxumab exposure and rCDI, based on data from two phase 3 trials in participants who received placebo or bezlotoxumab 10 mg/kg, rCDI was treated as a binary endpoint and discontinued subjects were imputed as not having rCDI, resulting in an apparent positive E-R trend between rCDI rates and bezlotoxumab exposure. Therefore, a time-to-event (TTE) analysis was applied to investigate the E-R relationship, accounting for the time to rCDI occurrence and participant discontinuation. A TTE model, applying a time-dependent hazard function and right-censoring of data based on rCDI, discontinuation, or study end was developed. Exposure effects and covariates effects were evaluated as predictors affecting the hazard. The TTE model consisted of a Gompertz function with age, endogenous immunoglobulin G to C. difficile toxin B (IgG-B), history of CDI, hospitalization, sex, Charlson Comorbidity Index, and concomitant use of systemic antibiotics affecting the hazard. Exposure effects were characterized with a maximum effect (E_max) E-R relationship on the baseline parameter, and bezlotoxumab exposures achieved at the 10 mg/kg dose were found to be on the plateau of the E-R curve. Endogenous IgG-B significantly impacted the E_max, indicating that low-titer participants derive a greater benefit from bezlotoxumab treatment compared with high-titer participants. The results support the conclusions of the previous E-R analysis, where exposures achieved at the 10 mg/kg dose are on the plateau of the E-R curve.

Population Pharmacokinetics and Exposure-Response Modeling of Golimumab in Adults With Moderately to Severely Active Ulcerative Colitis

PURPOSE

Golimumab is a fully human monoclonal antibody to tumor necrosis factor-α and is indicated for the treatment of moderately to severely active ulcerative colitis (UC). This study analyzed the population pharmacokinetic (PK) properties of golimumab and exposure-response for efficacy and safety, using data from combined Phase II/III UC studies.

METHODS

Data on serum golimumab concentration following IV and subcutaneous (SC) administration were fitted simultaneously using nonlinear mixed-effects modeling for the development of a population PK model. Logistic regression models were used for assessing relationships between serum golimumab concentrations and clinical efficacy outcomes in SC induction and maintenance studies. The percentages of patients developing infections, serious infections, and serious adverse events were assessed by golimumab exposure metric quartiles.

FINDINGS

The PK properties of golimumab are well described by a 2-compartment model with first-order absorption and elimination. Typical values of PK parameters in a 70-kg patient were clearance, 0.544 L/d; central and peripheral compartment V_d, 3.43 and 2.27 L, respectively; and intercompartmental clearance, 0.291 L/d. Golimumab t_1/2 was 10.5 days; bioavailability following SC administration was 52.2%. Body weight, anti-golimumab antibodies, serum albumin, C-reactive protein, and alkaline phosphatase affected golimumab disposition. A positive exposure-response relationship was established between golimumab concentration and efficacy outcomes. No apparent correlation between golimumab exposure and rate of infections, serious infections, or serious adverse events was observed in patients receiving golimumab 50 or 100 mg SC every 4 weeks through 1 year.

IMPLICATIONS

Body weight, serum albumin, and anti-golimumab antibodies explain some of the variability observed in the PK properties of golimumab, and exposure-response findings support the recommended posology of golimumab in UC. ClinicalTrials.gov identifiers: NCT00488774, NCT00487539, and NCT00488631.

Alternative dosing regimens for atezolizumab: an example of model-informed drug development in the postmarketing setting

PURPOSE

To determine the exposure-response (ER) relationships between atezolizumab exposure and efficacy or safety in patients with advanced non-small cell lung cancer (NSCLC) or urothelial carcinoma (UC) and to identify alternative dosing regimens.

METHODS

ER analyses were conducted using pooled NSCLC and UC data from phase 1 and 3 studies (PCD4989g, OAK, IMvigor211; ClinicalTrials.gov IDs, NCT01375842, NCT02008227, and NCT02302807, respectively). Objective response rate, overall survival, and adverse events were evaluated vs pharmacokinetic (PK) metrics. Population PK-simulated exposures for regimens of 840 mg every 2 weeks (q2w) and 1680 mg every 4 weeks (q4w) were compared with the approved regimen of 1200 mg every 3 weeks (q3w) and the maximum assessed dose (MAD; 20 mg/kg q3w). Phase 3 IMpassion130 (NCT02425891) data were used to validate the PK simulations for 840 mg q2w. Observed safety data were evaluated by exposure and body weight subgroups.

RESULTS

No significant ER relationships were observed for safety or efficacy. Predicted exposures for 840 mg q2w and 1680 mg q4w were comparable to 1200 mg q3w and the MAD and consistent with observed PK data from IMpassion130. Observed safety was similar between patients with a C_max above and below the predicted C_max for 1680 mg q4w and between patients in the lowest and upper 3 body weight quartiles.

CONCLUSION

Atezolizumab regimens of 840 mg q2w and 1680 mg q4w are expected to have comparable efficacy and safety as the approved regimen of 1200 mg q3w, supporting their interchangeable use and offering patients greater flexibility.

Pharmacokinetic and exploratory exposure-response analysis of pertuzumab in patients with operable HER2-positive early breast cancer in the APHINITY study

Purpose

To characterize the pharmacokinetics (PK) of, and perform an exploratory exposure–response (E–R) analysis for, pertuzumab in patients with HER2-positive early breast cancer (EBC) within the APHINITY study (NCT01358877, BIG 4–11/BO25126/TOC4939G).

Methods

A previously developed pertuzumab two-compartment linear population pharmacokinetic (popPK) model was subjected to external validation to examine appropriateness for describing pertuzumab concentrations from the APHINITY study. Pharmacokinetic drug–drug interactions (DDIs) between pertuzumab, trastuzumab, and chemotherapy were assessed by comparing observed serum or plasma C_max, C_min, and AUC_last geometric mean ratios with 90% CIs. Predictions of pertuzumab C_max,ss, C_min,ss, and AUC_ss were derived from individual parameter estimates and used in an exploratory E–R analysis.

Results

Using data from 72 patients, based on goodness-of-fit, the popPK model was deemed appropriate for predictions of individual exposures for subsequent comparisons to historical data, assessment of DDIs, and E–R analyses. No evidence of DDIs for pertuzumab on trastuzumab, trastuzumab on pertuzumab, or pertuzumab on chemotherapy PK was observed. Analyses of differences in exposure between patients with and without invasive disease-free survival events did not indicate improved efficacy with increased exposure. Overall Grade ≥ 3 diarrhea prevalence was higher with pertuzumab versus placebo, but was not greater with increasing pertuzumab exposure. No apparent E–R relationship was suggested with respect to other grade ≥ 3 AEs.

Conclusion

Overall, the limited available data from this exploratory study suggest that no dose adjustments are needed for pertuzumab when administered in combination with trastuzumab and an EBC chemotherapy regimen.

Electronic supplementary material

The online version of this article (10.1007/s00280-019-03826-1) contains supplementary material, which is available to authorized users.

Rituximab dosing in hematological malignancies: an old question, revisited

Rituximab is the standard of care for most B-cell malignancies. Its rapid clinical development enabled patients to receive this life-prolonging medicine sooner; however, it precluded a thorough assessment of dose selection. Extensive clinical pharmacology data collected from the recent subcutaneous development program enabled re-examination of this old question and support that the approved rituximab dosing regimens in non-Hodgkin's lymphoma and chronic lymphocytic leukemia appear to maximize the clinical benefit in the majority of patients.

Exposure-response relationship for ramucirumab from the randomized, double-blind, phase 3 REVEL trial (docetaxel versus docetaxel plus ramucirumab) in second-line treatment of metastatic non-small cell lung cancer

PURPOSE

Ramucirumab plus docetaxel improved survival in REVEL, a randomized phase 3 trial for patients with Stage IV non-small cell lung cancer after standard platinum-based chemotherapy. This exploratory analysis evaluated the exposure-response relationship of ramucirumab from REVEL.

METHODS

Patients received ramucirumab (10 mg/kg) or placebo plus docetaxel (75 mg/m2) every 3 weeks. Pharmacokinetic samples were collected. A population pharmacokinetic analysis predicted ramucirumab minimum concentration after first-dose administration (Cmin,1) and average concentration at steady state (Cave,ss). Predicted Cmin,1 and Cave,ss were used to evaluate the relationship between ramucirumab exposure and efficacy and safety, respectively. Exposure-efficacy was assessed by Kaplan-Meier and Cox regression analyses; exposure-safety was assessed by ordered categorical analyses.

RESULTS

Analyses included 376 patients treated with ramucirumab plus docetaxel and 366 patients treated with placebo plus docetaxel (364 for safety population). After adjusting for corresponding prognostic factors, the association between overall survival (OS) and Cmin,1 was statistically significant (p = 0.0110), although progression-free survival (PFS) showed a marginal association (p = 0.0515). At high ramucirumab exposures (Cmin,1), greater improvements (smaller hazard ratios) were seen for OS and PFS when stratified by Cmin,1 exposure quartiles. A statistically significant correlation was observed between ramucirumab Cave,ss and grade ≥ 3 febrile neutropenia and hypertension.

CONCLUSIONS

An association was observed between ramucirumab exposure and efficacy. Higher ramucirumab exposure was associated with improved clinical outcomes and increased toxicity in this analysis. Two exposure-response prospective randomized trials are being conducted to address causation (NCT02443883 and NCT02514551), with encouraging preliminary results (Ajani et al. in Ann Oncol 28:abstr 698P, 2017).

Population pharmacokinetics and exposure-response modeling and simulation for evolocumab in healthy volunteers and patients with hypercholesterolemia

Evolocumab, a novel human monoclonal antibody, inhibits proprotein convertase subtilisin/kexin type 9, a protein that targets low-density lipoprotein-cholesterol (LDL-C) receptors for the treatment of hyperlipidemia. The primary objective of this analysis was to characterize the population pharmacokinetics (popPK) and exposure-response relationship of evolocumab to assess if dose adjustment is needed across differing patient populations. Data were pooled for 5474 patients in 11 clinical studies who received evolocumab doses of 7-420 mg at various frequencies, either intravenously or subcutaneously. Evolocumab area under concentration-time curve from 8 to 12 weeks (AUC_wk8-12) was simulated for individuals using the popPK model and was used to predict the LDL-C response in relation to AUC_wk8-12. Evolocumab was eliminated through nonspecific (linear) and target-mediated (nonlinear) clearance. PopPK parameters and associated variabilities of evolocumab were similar to those of other monoclonal antibodies. The exposure-response model predicted a maximal 66% reduction in LDL-C from baseline to the mean of weeks 10 and 12 for doses of evolocumab 140 mg subcutaneously every 2 weeks or 420 mg subcutaneously once monthly. After inclusion of statistically significant covariates in an uncertainty-based simulation, LDL-C reduction from baseline at the mean of weeks 10 and 12 was predicted to be within 74% to 126% of the reference patient for all simulated patient groups. Evolocumab had nonlinear pharmacokinetics. The range of responses based on intrinsic and extrinsic factors was not predicted to be sufficiently different from the reference patient to warrant evolocumab dose adjustment.

Leveraging model-informed approaches for drug discovery and development in the cardiovascular space

Cardiovascular disease remains a significant global health burden, and development of cardiovascular drugs in the current regulatory environment often demands large and expensive cardiovascular outcome trials. Thus, the use of quantitative pharmacometric approaches which can help enable early Go/No Go decision making, ensure appropriate dose selection, and increase the likelihood of successful clinical trials, have become increasingly important to help reduce the risk of failed cardiovascular outcomes studies. In addition, cardiovascular safety is an important consideration for many drug development programs, whether or not the drug is designed to treat cardiovascular disease; modeling and simulation approaches also have utility in assessing risk in this area. Herein, examples of modeling and simulation applied at various stages of drug development, spanning from the discovery stage through late-stage clinical development, for cardiovascular programs are presented. Examples of how modeling approaches have been utilized in early development programs across various therapeutic areas to help inform strategies to mitigate the risk of cardiovascular-related adverse events, such as QTc prolongation and changes in blood pressure, are also presented. These examples demonstrate how more informed drug development decisions can be enabled by modeling and simulation approaches in the cardiovascular area.

Exposure-response relationship of ramucirumab in patients with advanced second-line colorectal cancer: exploratory analysis of the RAISE trial

PURPOSE

To characterize ramucirumab exposure-response relationships for efficacy and safety in patients with metastatic colorectal cancer (mCRC) using data from the RAISE study.

METHODS

Sparse pharmacokinetic samples were collected; a population pharmacokinetic analysis was conducted. Univariate and multivariate Cox proportional hazards models analyzed the relationship between predicted ramucirumab minimum trough concentration at steady state (C min,ss) and survival. Kaplan-Meier analysis was used to evaluate survival from patients in the ramucirumab plus folinic acid, 5-fluorouracil, and irinotecan (FOLFIRI) treatment arm stratified by C min,ss quartiles (Q). An ordered categorical model analyzed the relationship between C min,ss and safety outcomes.

RESULTS

Pharmacokinetic samples from 906 patients were included in exposure-efficacy analyses; samples from 905 patients were included in exposure-safety analyses. A significant association was identified between C min,ss and overall survival (OS) and progression-free survival (PFS) (p < 0.0001 for both). This association remained significant after adjusting for baseline factors associated with OS or PFS (p < 0.0001 for both). Median OS was 11.5, 12.9, 16.4, and 16.7, and 12.4 months for ramucirumab C min,ss Q1, Q2, Q3, Q4, and placebo group, respectively. Median PFS was 5.4, 4.6, 6.8, 8.5, and 5.2 months for ramucirumab C min,ss Q1, Q2, Q3, Q4, and placebo group, respectively. The risk of Grade ≥3 neutropenia was associated with an increase in ramucirumab exposure.

CONCLUSIONS

Exploratory exposure-response analyses suggested a positive relationship between efficacy and ramucirumab exposure with manageable toxicities in patients from the RAISE study with mCRC over the ranges of exposures achieved by a dose of 8 mg/kg every 2 weeks in combination with FOLFIRI.

Exposure-response relationship of regorafenib efficacy in patients with hepatocellular carcinoma

PURPOSE

To explore the relationship between regorafenib exposure and efficacy in patients with hepatocellular carcinoma (HCC) who had disease progression during sorafenib treatment (RESORCE).

METHODS

Exposure-response (ER) analyses for regorafenib were performed using data from a phase 3, randomized, placebo-controlled trial (RESORCE). Patients received 160mg regorafenib or placebo once daily (3weeks on/1week off in a 4-week cycle) with best supportive care until disease progression, death, or unacceptable toxicity. Kaplan-Meier analyses for overall survival (OS) and time-to-progression (TTP) were performed in which regorafenib-treated patients were grouped into four categories according to their estimated average exposure over 4weeks in cycle 1. While this analysis primarily focused on efficacy, a potential correlation between exposure and treatment-emergent adverse events (TEAEs) was also evaluated. If any differences were observed between Kaplan-Meier plots, the ER analysis continued with a multivariate Cox regression analysis to evaluate the correlation between exposure quartile categories and the efficacy and safety parameters while taking into consideration the effect of the predefined clinically relevant demographic and baseline covariates. The functional form of the ER relationship within the regorafenib treatment group was subsequently evaluated.

RESULTS

Based on visual assessment of the Kaplan-Meier plots, no meaningful relationship between the exposure categories and TEAEs were observed, although median OS and TTP tended to be longer in the higher exposure categories. Further ER analyses, which considered the effects of predefined covariates and the different shapes of the ER relationship, focused on efficacy. The baseline risk factors Eastern Cooperative Oncology Group (ECOG) performance status ≥1, alpha-fetoprotein levels ≥400ng/ml, and aspartate transaminase or alanine transaminase levels >3×upper limit of normal were significantly associated with OS (P<0.01) and age was associated with TTP. A statistically significant difference was found for OS and TTP between patients receiving regorafenib compared with those receiving placebo in the multivariate ER analysis (P<0.01) in favor of regorafenib. However, within the group of regorafenib-treated patients, the effect of regorafenib exposure on efficacy, either by estimating four effect sizes for each quartile, or by including a continuous linear or nonlinear relationship between individual exposure and efficacy, was not significant (P>0.01) and relatively flat. This suggests that increasing regorafenib exposure would not result in a meaningful increase in OS or TTP.

CONCLUSION

After considering the baseline risk factors: ECOG performance status, alpha-fetoprotein levels, and hepatic function for OS and age for TTP, the ER analysis in regorafenib-treated patients showed similar efficacy over the entire predicted exposure range in RESORCE. This supports the selected regorafenib dose of 160mg once daily (3weeks on/1week off in a 4-week cycle) in patients with intermediate or advanced HCC who have experienced disease progression on sorafenib.

Pharmacokinetic and exposure-response analyses of pertuzumab in combination with trastuzumab and docetaxel during neoadjuvant treatment of HER2+ early breast cancer

Purpose

The NeoSphere trial evaluated pertuzumab in the neoadjuvant setting [early breast cancer (EBC)] with pathological complete response (pCR) as the primary efficacy end point. This analysis of pertuzumab aimed to (1) compare its pharmacokinetics (PK) in patients with EBC versus advanced cancers, (2) to further evaluate PK drug–drug interactions (DDIs) when given in combination with trastuzumab, and (3) to assess the relationship between exposure and efficacy to assess the clinical dosing regimen in the EBC patients.

Methods

Pertuzumab serum concentration data from 180 patients in NeoSphere were compared to historical observations and potential DDI was assessed, by applying simulation techniques using a population PK model. The impact of pertuzumab exposure on pCR rate was evaluated using a logit response model (n = 88).

Results

The observed PK matched the population PK model simulations, confirming that the PK in neoadjuvant EBC appear to be in agreement with the historical observations. No evidence of a DDI effect of trastuzumab or docetaxel on pertuzumab was observed supporting the doses when given in combination. In NeoSphere >90% of EBC patients achieved the non-clinical target serum concentration. There was no association between the pertuzumab serum concentration and pCR within the range observed in this study (20–100 μg/mL) supporting no dose adjustments needed for patients with lower exposure.

Conclusions

This analysis further supports the lack of DDI between the two therapeutic proteins and the appropriateness of the approved fixed non-body-weight-adjusted pertuzumab dose in the treatment of neoadjuvant EBC with pertuzumab in combination with trastuzumab and docetaxel.

Electronic supplementary material

The online version of this article (doi:10.1007/s00280-016-3218-0) contains supplementary material, which is available to authorized users.

Population Pharmacokinetics and Exposure-Response (Efficacy and Safety/Tolerability) of Empagliflozin in Patients with Type 2 Diabetes

INTRODUCTION

The aim of the analysis was to characterize the population pharmacokinetics (PKs) and exposure-response (E-R) for efficacy (fasting plasma glucose, glycated hemoglobin) and safety/tolerability [hypoglycemia, genital infections, urinary tract infection (UTI), and volume depletion] of the sodium glucose cotransporter 2 inhibitor, empagliflozin, in patients with type 2 diabetes mellitus. This study extends the findings of previous analyses which described the PK and pharmacodynamics (PD) using early clinical studies of up to 12 weeks in duration.

METHODS

Population pharmacokinetic and E-R models were developed based on two Phase I, four Phase II, and four Phase III studies.

RESULTS

Variability in empagliflozin exposure was primarily affected by estimated glomerular filtration rate (eGFR) (less than twofold increase in exposure in patients with severe renal impairment). Consistent with its mode of action, the efficacy of empagliflozin was increased with elevated baseline plasma glucose levels and attenuated with decreasing renal function, but was still maintained to nearly half the maximal effect with eGFR as low as 30 mL/min/1.73 m(2). All other investigated covariates, including sex, body mass index, race, and age did not alter the PK or efficacy of empagliflozin to a clinically relevant extent. Compared with placebo, empagliflozin administration was associated with an exposure-independent increase in the incidence of genital infections and no significant change in the risk of UTI, hypoglycemia, or volume depletion.

CONCLUSION

Based on the results from the PK and E-R analysis, no dose adjustment is required for empagliflozin in the patient population for which the drug is approved.

FUNDING

Boehringer Ingelheim.

Venetoclax does not prolong the QT interval in patients with hematological malignancies: an exposure-response analysis

PURPOSE

Venetoclax (ABT-199/GDC-0199) is a selective first-in-class B cell lymphoma-2 inhibitor being developed for the treatment of hematological malignancies. The aim of this study was to determine the potential of venetoclax to prolong the corrected QT (QTc) interval and to evaluate the relationship between systemic venetoclax concentration and QTc interval.

METHODS

The study population included 176 male and female patients with relapsed or refractory chronic lymphocytic leukemia/small lymphocytic lymphoma (n = 105) or non-Hodgkin's lymphoma (n = 71) enrolled in a phase 1 safety, pharmacokinetic, and efficacy study. Electrocardiograms were collected in triplicate at time-matched points (2, 4, 6, and 8 h) prior to the first venetoclax administration and after repeated venetoclax administration to achieve steady state conditions. Venetoclax doses ranged from 100 to 1200 mg daily. Plasma venetoclax samples were collected after steady state electrocardiogram measurements.

RESULTS

The mean and upper bound of the 2-sided 90 % confidence interval (CI) QTc change from baseline were <5 and <10 ms, respectively, at all time points and doses (<400, 400, and >400 mg). Three subjects had single QTc values >500 ms and/or ΔQTc > 60 ms. The effect of venetoclax concentration on both ΔQTc and QTc was not statistically significant (P > 0.05). At the mean maximum concentrations achieved with therapeutic (400 mg) and supra-therapeutic (1200 mg) venetoclax doses, the estimated drug effects on QTc were 0.137 (90 % CI [-1.01 to 1.28]) and 0.263 (90 % CI [-1.92 to 2.45]) ms, respectively.

CONCLUSION

Venetoclax does not prolong QTc interval even at supra-therapeutic doses, and there is no relationship between venetoclax concentrations and QTc interval.

Analysis of peginterferon β-1a exposure and Gd-enhanced lesion or T2 lesion response in relapsing-remitting multiple sclerosis patients

The effect of subcutaneous (SC) peginterferon β-1a exposure on reduction of gadolinium-enhanced (Gd+) lesion count over time was evaluated in patients with relapsing-remitting multiple sclerosis (RRMS) in a Phase 3 study (ADVANCE). Patients were randomized to receive SC injections of placebo (n = 500), 125 mcg every-2-weeks (n = 512), or 125 mcg every-4-weeks (n = 500) for 1 year, and then active treatment in the second year. Steady state 4-week AUC (AUCss) was derived for each individual based on sparse pharmacokinetic (PK) sample and a population PK model. Several longitudinal count models, including marginal, mixed effect, and mixture models, were compared to explore the relationship between AUC_ss and Gd+ lesion count (or T2 lesion count). A mixture model which divided subjects into two subpopulations by low and high baseline lesion activity was found to yield best goodness-of-fit for the data. In this model, the point estimate and 95 % CI for drug effect slope on log(λ) are −0.0256 (−0.0304, −0.0216) for Gd+ lesion and −0.0147 (−0.0170, −0.0124) for T2 lesion. This suggested that reduction of Gd+ lesion (or T2 lesion) count over time is significantly related to SC peginterferon β-1a exposure, and that the increased reduction lesion count with the every-2-week regimen versus the every-4-week regimen was driven by the higher exposure achieved in that treatment arm (mean Gd+ lesion count 0.2 and 0.7 at Year 2, respectively). The every-2-week regimen produced an exposure range that was close to the plateau range of the exposure–response curve, supporting its selection as the regulatory approved dosage.

Exposure-safety-efficacy analysis of single-agent ixazomib, an oral proteasome inhibitor, in relapsed/refractory multiple myeloma: dose selection for a phase 3 maintenance study

Background Ixazomib is the first oral, small molecule proteasome inhibitor to reach phase 3 trials. The current analysis characterized the exposure-safety and exposure-efficacy relationships of ixazomib in patients with relapsed/refractory multiple myeloma (MM) with a purpose of recommending an approach to ixazomib dosing for maintenance therapy. Methods Logistic regression was used to investigate relationships between ixazomib plasma exposure (area under the curve/day; derived from individual apparent clearance values from a published population pharmacokinetic analysis) and safety/efficacy outcomes (hematologic [grade ≥ 3 vs ≤ 2] or non-hematologic [grade ≥ 2 vs ≤ 1] adverse events [AEs], and clinical benefit [≥stable disease vs progressive disease]) using phase 1 data in relapsed/refractory MM (NCT00963820; N = 44). Results Significant relationships to ixazomib exposure were observed for five AEs (neutropenia, thrombocytopenia, rash, fatigue, and diarrhea) and clinical benefit (p < 0.05). Dose–response relationships indicated a favorable benefit/risk ratio at 3 mg and 4 mg weekly, which are below the maximum tolerated dose of 5.5 mg. At 3 mg, the model predicted that: 37 % of patients will achieve clinical benefit; incidence of grade ≥ 3 neutropenia and thrombocytopenia will be 10 % and 23 %, respectively; and incidence of grade ≥ 2 rash, fatigue, and diarrhea will be 8 %, 19 %, and 19 %, respectively. Conclusions Based on the findings, patients in the phase 3 maintenance trial will initiate ixazomib at a once-weekly dose of 3 mg, increasing to 4 mg if acceptable tolerability after 4 cycles, to provide maximum clinical benefit balanced with adequate tolerability.

Population pharmacokinetics and exposure-response of trametinib, a MEK inhibitor, in patients with BRAF V600 mutation-positive melanoma

PURPOSE

To characterize the pharmacokinetics of oral trametinib, a first in class MEK inhibitor, identify covariates, and describe the relationship between exposure and clinical effects in patients with BRAF V600 metastatic melanoma.

EXPERIMENTAL DESIGN

Trametinib concentrations obtained in three clinical studies were included in the population pharmacokinetic analysis. Trametinib 2 mg once daily was administered in the Phase 2 and 3 studies. The impact of exposure [trough (C min) or average concentration] on response rates and progression-free survival (PFS) was examined.

RESULTS

Plasma concentrations (n = 3120) obtained in 493 patients were described using a two-compartment model. Trametinib oral clearance was lower in women relative to men (1.26-fold) and increased with body weight. There was no significant effect of age, mild or moderate renal impairment, or mild hepatic impairment on oral clearance. Between-subject variability was low (24 %). The number of responders was consistent across median exposure range, although tended to be lower at trough concentration <10 ng/mL. Disease stage was found to be a significant predictor of response with a lower response rate in patients with disease stage of M1c. Lactate dehydrogenase was significant in the analysis of PFS. Patients with observed C min above the median had longer PFS than those below median based on Phase 2 study (median 10.6 ng/mL), while the effect of exposure was not statistically significant in the Phase 3 study (median 13.6 ng/mL).

CONCLUSIONS

No dosage adjustments are required with any of the covariates tested. Clinical efficacy was associated with trametinib trough concentrations greater than 10 ng/mL.

Fluoride exposure from groundwater as reflected by urinary fluoride and children's dental fluorosis in the Main Ethiopian Rift Valley

This cross-sectional study explores the relationships between children's F(-) exposure from drinking groundwater and urinary F(-) concentrations, combined with dental fluorosis (DF) in the Main Ethiopian Rift (MER) Valley. We examined the DF prevalence and severity among 491 children (10 to 15 years old) who are life-long residents of 33 rural communities in which groundwater concentrations of F(-) cover a wide range. A subset of 156 children was selected for urinary F(-) measurements. Our results showed that the mean F(-) concentrations in groundwater were 8.5 ± 4.1 mg/L (range: 1.1-18 mg/L), while those in urine were 12.1±7.3 mg/L (range: 1.1-39.8 mg/L). The prevalence of mild, moderate, and severe DF in children's teeth was 17%, 29%, and 45%, respectively, and the majority (90%; n=140) of the children had urinary F(-) concentrations above 3 mg/L. Below this level most of the teeth showed mild forms of DF. The exposure-response relationship between F(-) and DF was positive and non-linear, with DF severity tending to level off above a F(-) threshold of ~6 mg/L, most likely due to the fact that at ~6 mg/L the enamel is damaged as much as it can be clinically observed in most children. We also observed differential prevalence (and severity) of DF and urinary concentration, across children exposed to similar F(-) concentrations in water, which highlights the importance of individual-specific factors in addition to the F(-) levels in drinking water. Finally, we investigated urinary F(-) in children from communities where defluoridation remediation was taking place. The lower F(-) concentration measured in urine of this population demonstrates the capacity of the urinary F(-) method as an effective monitoring and evaluation tool for assessing the outcome of successful F(-) mitigation strategy in relatively short time (months) in areas affected with severe fluorosis.

Voriconazole pharmacokinetics and exposure-response relationships: assessing the links between exposure, efficacy and toxicity

The triazole antifungal voriconazole (VCZ) exhibits broad-spectrum antifungal activity and is the first-line treatment for invasive aspergillosis. Highly variable, non-linear pharmacokinetics, metabolism via the polymorphic drug-metabolising enzyme CYP2C19, and a range of serious adverse events (AEs) including hepatotoxicity and neurotoxicity complicate the clinical utility of VCZ. As interest in optimising VCZ treatment has increased, a growing number of studies have examined the relationships between VCZ exposure and efficacy in the treatment and prevention of invasive fungal infections, as well as associations with VCZ-related AEs. This review provides a critical analysis of VCZ pharmacokinetics and exposure-response (E-R) relationships, assessing the links between VCZ exposure, efficacy and toxicity. Low VCZ exposure has frequently been associated with a higher incidence of treatment failure; fewer studies have addressed E-R relationships with prophylactic VCZ. VCZ-related neurotoxicity appears common at high VCZ concentrations and can be minimised by maintaining concentrations below the recommended upper concentration thresholds; hepatotoxicity appears to be associated with increased VCZ exposure but is also prevalent at low concentrations. Further research should aim to inform and optimise the narrow therapeutic range of VCZ as well as develop interventions to individualise VCZ dosing to achieve maximal efficacy with minimal toxicity.