Selection of Nemolizumab Clinical Dosage for Atopic Dermatitis.

Nemolizumab is a monoclonal antibody directed against the interleukin-31 receptor A subunit, which is involved in the pathogenesis of pruritus and inflammation in atopic dermatitis (AD). Clinical trial results were combined with population PK (popPK) and pharmacokinetic/ pharmacodynamic (PK/PD) models to optimize nemolizumab dosing. Phase 1 and 2a clinical studies indicated that weight-based nemolizumab dosing reduced pruritus in patients with moderate-to-severe AD with good safety and tolerability even at the highest dose (3 mg/kg single dose and 2 mg/kg multiple doses). Nemolizumab PK profile was characterized by a slow absorption with peak serum concentrations reached 4.5-9.2 days post-dose, and a long terminal half-life ranging from 12.6 to 16.5 days. A change from weight-based dosing to flat dose was supported by an additional phase 2b study sponsored by Galderma. Flat dosing provides several practical advantages, including ease of preparation for self- or auto-injection and reduced chance of dosing errors. Doses of 10, 30, and 90 mg were selected based on popPK and PK/PD simulations to result in nemolizumab serum concentrations sufficient to achieve efficacy. Loading doses were administrated at the 2 lower doses in order to achieve target systemic concentrations from the first injection. The efficacy of Nemolizumab in improving cutaneous signs of inflammation and pruritus in AD and its safety profile, combined with popPK and PK/PD analyses, supported selection of the flat-dose regimen of 30 mg (with a 60 mg loading dose) given every 4 weeks subcutaneously for 16 weeks in the phase 3 ARCADIA studies sponsored by Galderma. J Drugs Dermatol. 2023;22(10):1017-1020 doi:10.36849/JDD.7437R1.

Clinical Efficacy of Pre-Hospital Electrocardiogram Transmission in Patients Undergoing Primary Percutaneous Coronary Intervention for ST-Segment Elevation Myocardial Infarction.

Rapid reperfusion by primary percutaneous coronary intervention (pPCI) is an established strategy for the treatment of patients with ST-segment elevation myocardial infarction (STEMI). Pre-hospital electrocardiogram (PH-ECG) transmission by the emergency medical services (EMS) facilitates timely reperfusion in these patients. However, evidence regarding the clinical benefits of PH-ECG in individual hospitals is limited.This retrospective, observational study investigated the clinical efficacy of PH-ECG in STEMI patients who underwent pPCI. Of a total of 382 consecutive STEMI patients, 237 were enrolled in the study and divided into 2 groups: a PH-ECG group (n = 77) and non-PH-ECG group (n = 160). Door-to-balloon time (D2BT) was significantly shorter in the PH-ECG group (66 [52-80] min), compared to the non-PH-ECG group (70 [57-88] minutes, P = 0.01). The 30-day all-cause mortality rate was 6% in the PH-ECG group, which was significantly lower than that in the non-PH-ECG group (16%) (P = 0.037, hazard ratio [HR]: 0.38, 95% CI: 0.15-0.98). This trend was particularly evident in severely ill patients when stratified by GRACE score.The use of PH-ECG improved the survival rate of STEMI patients undergoing pPCI due to the improved pre-arrival preparation based on the EMS information. Coordination between EMS and PCI-capable institutes is essential for the management of PH-ECG.

A phase 2 study of polatuzumab vedotin + bendamustine + rituximab in relapsed/refractory diffuse large B-cell lymphoma.

Polatuzumab vedotin (pola) is a CD79b-targeted antibody-drug conjugate delivering a potent antimitotic agent (monomethyl auristatin E) to B cells. This was an open-label, single-arm study of pola 1.8 mg/kg, bendamustine 90 mg/m2 , rituximab 375 mg/m2 (pola + BR) Q3W for up to six cycles in patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL) who received ≥1 prior line of therapy and were ineligible for autologous stem cell transplantation (ASCT) or experienced treatment failure with prior ASCT. Primary endpoint was complete response rate (CRR) at the end of the treatment (EOT) by positron emission tomography-computed tomography (PET-CT) using modified Lugano Response Criteria. Secondary endpoints included efficacy, safety, and pharmacokinetics. Thirty-five patients (median age 71 [range 46-86] years) were enrolled. Twenty-three (66%) patients had refractory disease, and 23 (66%) had ≥2 prior lines of therapy. At a median follow-up of 5.4 (0.7-11.9) months, patients received a median of five treatment cycles. CRR was 34.3% (95% confidence interval [CI] 19.1-52.2) at EOT. Overall response rate was 42.9% at EOT, and median progression-free survival was 5.2 months (95% CI 3.6-not evaluable). Median overall survival was not reached. No fatal adverse events (AEs) were observed. Grade 3-4 AEs were mainly hematological: anemia (37%), neutropenia (31%), white blood cell count decreased (23%), thrombocytopenia/platelet count decreased/neutrophil count decreased (20% each), and febrile neutropenia (11%). Grade 1-2 peripheral neuropathy (PN; sensory and/or motor) was reported in 14% of patients; there were no ≥grade 3 PN events. This study (JapicCTI-184048) demonstrated the efficacy and safety of pola + BR in Japanese patients with R/R DLBCL who were ineligible for ASCT.

Safety and pharmacokinetics of polatuzumab vedotin in Japanese patients with relapsed/refractory B-cell non-Hodgkin lymphoma: a phase 1 dose-escalation study.

OBJECTIVE: A phase 1 dose-escalation study of polatuzumab vedotin (pola) was conducted to assess safety, pharmacokinetics and preliminary antitumor activity of pola in Japanese patients with relapsed/refractory B-cell non-Hodgkin lymphoma. METHODS: Patients received pola (1.0 or 1.8 mg/kg) intravenously every 21 days until disease progression or intolerance. Intra-patient dose escalation was prohibited. Tolerability was determined by the standard 3 + 3 rule. Blood sampling was performed to characterize pharmacokinetics. Antitumor activity was evaluated through computed tomography and bone marrow sampling. RESULTS: Four patients received pola 1.0 mg/kg; three received 1.8 mg/kg. Patients had follicular lymphoma (n = 4) or diffuse large B-cell lymphoma (n = 3), median age of 62 years, received a median of 3 prior therapies; six were female. Pola was well tolerated in both cohorts, with no dose-limiting toxicities observed. The most common adverse event was peripheral sensory neuropathy (n = 4). Grade 3 adverse events were cholecystitis and neutrophil count decreased (one each; both 1.0 mg/kg), and syncope and cataract (one each; both 1.8 mg/kg). The plasma half-life of antibody-conjugate monomethyl auristatin E was 4.43-7.98 days, and systemic exposure of unconjugated monomethyl auristatin E was limited in both cohorts. Four patients achieved objective responses (three complete, one partial) without disease progression during the study. CONCLUSIONS: This phase 1 dose-escalation study demonstrated that pola has an acceptable safety profile and offers encouraging antitumor activity to Japanese patients with relapsed/refractory B-cell non-Hodgkin lymphoma. Pola 1.8 mg/kg, the recommended phase 2 dose, was tolerable in Japanese patients.

Phase II study of TP300 in patients with advanced gastric or gastro-oesophageal junction adenocarcinoma.

BACKGROUND: TP300, a recently developed synthetic camptothecin analogue, is a highly selective topoisomerase I inhibitor. A phase I study showed good safety and tolerability. As camptothecins have proven active in oesophago-gastric adenocarcinomas, in this phase II study we assessed the efficacy and safety of TP300 in patients with gastric or gastro-oesophageal junction (GOJ) adenocarcinomas. METHODS: Eligible patients had metastatic or locally advanced gastric or Siewert Types II or III GOJ inoperable adenocarcinoma. Patients were chemotherapy naïve unless this had been administered in the perioperative setting. TP300 was administered as a 1-h intravenous infusion every 3 weeks (a cycle) for up to 6 cycles at a starting dose of 8 mg/m2 with intra-patient escalation to 10 mg/m2 from cycle 2 in the absence of dose-limiting toxicity. Tumour responses (RECIST 1.1) were assessed every 6 weeks. Toxicity was recorded by NCI-CTCAE version 3.0. Using a modified two-stage Simon design (Stage I and II), a total of 43 patients were to be included providing there were 3 of 18 patients with objective response in Stage I of the study. RESULTS: In Stage I of the study 20 patients (14 males, 6 females), median age 67 years (range 40 - 82), performance status ECOG 0/1, with GC [14] or GOJ carcinoma [6] were enrolled. Of the 16 evaluable patients, 11 received the planned dose increase to 10 mg/m2 at cycle 2, 2 decreased to 6 mg/m2, and 3 continued on 8 mg/m2. There were no objective responses after 2 cycles of treatment. Twelve patients had stable disease for 1 - 5 months and 4 had progressive disease. Median progression free survival (PFS) was 4.1 months (CI [1.6 - 4.9]), median time to progression (TTP) was 2.9 months (CI [1.4 - 4.2]). Grade 3/4 toxicities (worst grade all cycles) included 7 patients (35 %) with neutropenia, 4 patients (20 %) with anaemia, 2 patients (10 %) with thrombocytopenia, and 3 patients (15 %) with fatigue. This study was terminated at the end of Stage I due to a lack of the required (3/18) responders. CONCLUSIONS: This study of TP300 showed good drug tolerability but it failed to demonstrate sufficient efficacy as measured by radiological response. TRIAL REGISTRATION: EU-CTR 2009-012097-12 2009-09-03.

Epstein-Barr virus-associated primary central nervous system cytotoxic T-cell lymphoma.

Primary central nervous system lymphoma (PCNSL) expressing T-cell markers is rare, among which nasal-type extranodal NK/T-cell lymphoma is an extremely rare subtype associated with Epstein-Barr virus (EBV) infection. Here we report the clinicopathologic features of a case of EBV-associated PCNSL showing a cytotoxic T-cell phenotype. The patient, a 73-year-old woman, presented with rapidly progressive mental deterioration. Brain MRI revealed multiple lesions with swelling in the bilateral cerebral hemispheres, which were hypointense on T1-weighted images, hyperintense on T2-weighted and fluid-attenuated inversion recovery images, and slightly hyperintense on diffusion-weighted images. Biopsy specimens from the temporal region showed many medium-sized anaplastic lymphocytic cells with perivascular and angio-invasive patterns in the cortex. Immunohistochemically, the cells were positive for CD3, CD8, T-cell-restricted intracellular antigen-1 (TIA-1), granzyme B and perforin, but negative for CD56 and CD20. In situ hybridization revealed EBV-encoded RNAs in the tumor cell nuclei. A rearrangement study showed T-cell receptor γ-chain gene rearrangement with a clonal appearance. The patient died 6 months after surgery, and a general autopsy revealed no lymphoma cells outside the brain. These cellular profiles are inconsistent with those of extranodal NK/T-cell lymphoma, and have not been previously described. This case appears to represent an unusual CNS manifestation of EBV-associated T-cell lymphoma.

Phase I study of TP300 in patients with advanced solid tumors with pharmacokinetic, pharmacogenetic and pharmacodynamic analyses.

BACKGROUND: A Phase I dose escalation first in man study assessed maximum tolerated dose (MTD), dose-limiting toxicity (DLT) and recommended Phase II dose of TP300, a water soluble prodrug of the Topo-1 inhibitor TP3076, and active metabolite, TP3011. METHODS: Eligible patients with refractory advanced solid tumors, adequate performance status, haematologic, renal, and hepatic function. TP300 was given as a 1-hour i.v. infusion 3-weekly and pharmacokinetic (PK) profiles of TP300, TP3076 and TP3011 were analysed. Polymorphisms in CYP2D6, AOX1 and UGT1A1 were studied and DNA strand-breaks measured in peripheral blood mononuclear cells (PBMCs). RESULTS: 32 patients received TP300 at 1, 2, 4, 6, 8, 10, 12 mg/m(2). MTD was 10 mg/m(2); DLTs at 12 (2/4 patients) and 10 mg/m(2) (3/12) included thrombocytopenia and febrile neutropenia; diarrhoea was uncommon. Six patients (five had received irinotecan), had stable disease for 1.5-5 months. TP3076 showed dose proportionality in AUC and Cmax from 1-10 mg/m(2). Genetic polymorphisms had no apparent influence on exposure. DNA strand-breaks were detected after TP300 infusion. CONCLUSIONS: TP300 had predictable hematologic toxicity, and diarrhoea was uncommon. AUC at MTD is substantially greater than for SN38. TP3076 and TP3011 are equi-potent with SN38, suggesting a PK advantage. TRIAL REGISTRATION: EU-CTR2006-001345-33.

Maxacalcitol Pharmacokinetic-Pharmacodynamic Modeling and Simulation for Secondary Hyperparathyroidism in Patients Receiving Maintenance Hemodialysis.

BACKGROUND: Maxacalcitol was approved in Taiwan in 2018 as the first active vitamin D3 injection for secondary hyperparathyroidism (SHPT) in patients on maintenance hemodialysis. However, no data from any clinical study with maxacalcitol in Taiwanese patients is available. OBJECTIVES: This analysis aimed to evaluate the profiles of parathyroid hormone (PTH) and calcium (Ca) concentrations in Taiwanese SHPT patients on hemodialysis and maxacalcitol. METHODS: We developed population pharmacokinetic (PK) and pharmacodynamic (PD) models using a modeling and simulation approach. The data for these analyses were obtained from two studies: a clinical pharmacology study in Japanese patients and an ethnic comparison study in healthy Japanese and -Taiwanese volunteers. We then conducted a simulation study with a PK-PD model comprising the PK and PD models developed here. RESULTS: Serum maxacalcitol concentration profile was modeled using a two-compartment model that took into consideration the distribution of concentrations below the lower limit of quantification. An ethnic difference in clearance was included in the PK model as a covariate. A PD model that used a PTH/Ca feedback loop best described the observed data. There were no significant differences in Ca or PTH concentrations between Taiwanese and Japanese based on the simulation results from our PK-PD model, even though maxacalcitol exposure was approximately 40% higher in Taiwanese than in Japanese. CONCLUSIONS: On the basis of these population PK and PD analyses and the clinical study conducted in Japan, there is no clinically relevant difference between Taiwanese and Japanese in terms of serum Ca or PTH levels.

Prediction of human blood-to-plasma drug concentration ratio.

The objective of this study was to predict R(b) (blood/plasma ratio) in humans using a simple method. Human and rat R(b) and free fraction in plasma (f(p)) values were obtained from the literature. The ratio of total red blood cell concentration to the free concentration in plasma (K(b)) was calculated using f(p) and R(b). Four methods were used for the prediction of R(b): (A) use of rat R(b); (B) use of R(b) calculated from rat K(b) and human f(p); (C) correlation of human log ((1-f(p))/f(p)) and human log K(b); and (D) correlation of log D with human log K(b). The R(b) of 96 compounds in humans ranged from 0.52 to 2.00, with an average of 0.89. A significant correlation was observed among human log K(b), human log ((1-f(p))/f(p)), and log D; however, no obvious correlation was observed among human R(b), human log ((1-f(p))/f(p)), and log D. The errors within 1.25-fold for methods A-D were 68.3%, 77.6%, 61.5% and 64.8%, respectively. All predictive methods considered here were superior to the use of the average value of human R(b) or R(b)=1. Rat R(b) corrected by human f(p) improved the accuracy of the prediction. Method B was the most accurate of the four methods.

Effects of Child-Pugh B Cirrhosis on Pharmacokinetics of Tofogliflozin, a New Sodium-Glucose Co-Transporter (SGLT2) Inhibitor.

BACKGROUND: Tofogliflozin is a highly selective sodium-glucose co-transporter 2 (SGLT2) inhibitor. A mass balance study with combinations of microdoses revealed that tofogliflozin has high oral bioavailability (97.5%) and that tofogliflozin in circulation is eliminated primarily by metabolic pathways, with the liver playing a prominent role in elimination. OBJECTIVES: This study aimed to evaluate the effect of moderate hepatic impairment on the pharmacokinetics of tofogliflozin and on the pharmacodynamics (urinary glucose excretion [UGE]). METHODS: In an open-label, parallel-group study, 17 subjects (9 with moderate hepatic impairment [Child-Pugh Class B, score 7-9] and 8 healthy) received a single oral dose of 40 mg tofogliflozin. Plasma and urine concentrations of tofogliflozin were determined. Accumulated UGE, adverse events, and physiological and laboratory test data were monitored. RESULTS: Geometric mean ratio (GMR; geometric mean value for subjects with moderate hepatic impairment / geometric mean value for healthy subjects) of Cmax was 1.47 and GMR of AUCinf was 1.70. Moderate hepatic impairment had only a little effect on tmax and CLR but it prolonged MRT. The levels of cumulative UGE were similar between the 2 groups. No clinically significant adverse events, laboratory test values, or physiological test values were observed in any subject. CONCLUSIONS: Moderate hepatic impairment increased Cmax and AUCinf of tofogliflozin by 47% and 70%, respectively. This increase in tofogliflozin exposure did not increase UGE in hepatically impaired subjects. A single oral dose of 40 mg tofogliflozin was well tolerated, supporting dose adjustment is unnecessary even in moderately hepatically impaired subjects.

Asian race and origin have no clinically meaningful effects on polatuzumab vedotin pharmacokinetics in patients with relapsed/refractory B-cell non-Hodgkin lymphoma.

PURPOSE: The CD79b-targeted antibody-drug conjugate polatuzumab vedotin (pola), alone and with chemoimmunotherapy, has clinical efficacy and a tolerable safety profile in B-cell non-Hodgkin lymphoma (B-NHL). We assessed (a) whether exposure from global studies of pola is comparable to Asian patients, and (b) if the recommended pola dose is appropriate in Asian patients based on exposure. METHODS: The pharmacokinetics (PK) of pola in Asian and global populations was characterized for three analytes (antibody-conjugated monomethyl auristatin E (MMAE) [acMMAE], total antibody, and unconjugated MMAE) in five phase 1b/2 single-agent and combination studies in B-NHL patients (JO29138 [JAPICCTI-142580], DCS4968g [NCT01290549], GO27834 [NCT01691898], GO29044 [NCT01992653], and GO29365 [NCT02257567]). PK data were compared between Japanese phase 1 JO29138 (JAPICCTI-142580) and global phase 1 DCS4968g (NCT01290549) studies and between Asian and non-Asian patients in the randomized relapsed/refractory B-NHL cohorts of the phase 1b/2 study GO29365 (NCT02257567). A population PK (popPK) model was used to assess the effects of Asian race and region on acMMAE and unconjugated MMAE exposure. RESULTS: PK non-compartmental analysis (NCA) parameters for the key analyte acMMAE in the Japanese JO29138 (JAPICCTI-142580) and global phase 1 DCS4968g (NCT01290549) studies were similar. In GO29365 (NCT02257567), the phase 1b/2 combination study, mean exposure to the analytes was generally lower in Asian patients (by ~ 9.9 to 17.5%), but not to a clinically meaningful extent. Overall, the popPK model further suggested comparable PK in Asian patients with B-NHL (race or region) versus non-Asian patients. CONCLUSION: Race has no clinically meaningful effect on pola PK. These results (and observations from efficacy/safety exposure-response analyses) support no pola dose adjustments are warranted for Asian patients with DLBCL.

A simulation study to evaluate limited sampling strategies to estimate area under the curve of drug concentration versus time following repetitive oral dosing: limited sampling model versus naive trapezoidal method.

The area under the curve (AUC) can be associated with the therapeutic or toxic effect of a drug. The limited sampling model (LSM) is an approach that is gaining popularity due to its simplicity for the estimation of AUC using 1-3 blood samples. The aim of the present simulation study was to compare the performance of LSM for various hypothetical drugs with that of the naive trapezoidal method (Trap). The 3-point (trough, peak, and downhill) sampling design following repetitive oral dosing was assumed for LSM (LSM3) and Trap (Trap3). The 2-point (trough and peak) sampling design was also assumed for LSM (LSM2) and Trap (Trap2). In addition, trough-sampling and peak-sampling designs for LSM were designated as LSM1 and LSM1', respectively. As a result, the rank order of precision of the AUC estimation designs/methods was summarized as follows: LSM3 asymptotically equal to Trap3> or =LSM2> or =Trap2 asymptotically equal to LSM1>LSM1'. The finding suggested that LSM can not always improve the estimation performance of AUC in the 3-point sampling design, and that LSM1' is insufficient to estimate the performance of AUC for the hypothetical drugs evaluated in the present study. Accordingly, LSM2 and LSM1 may be an efficient approach for estimating AUC following repetitive oral dosing. In addition, Trap3 and Trap2 may be promising alternatives, because Trap does not require a high investment to recruit a full-sampling model-development group.

Effect of Renal Impairment on the Pharmacokinetics and Pharmacodynamics of Tofogliflozin (A SELECTIVE SGLT2 Inhibitor) in Patients with Type 2 Diabetes Mellitus.

PURPOSE: Tofogliflozin is an orally available selective inhibitor of sodium-glucose co-transporter 2 for treatment of type 2 diabetes mellitus (T2DM). Two studies were conducted to evaluate the effect of renal impairment on pharmacokinetics and pharmacodynamics of tofogliflozin. METHODS: The studies were: 1) single dose study in T2DM patients with normal renal function and mild, moderate and severe renal impairment, and 2) multiple dose study for 24 weeks in T2DM patients with normal renal function and moderate renal impairment. RESULTS: Renal function did not have a clinically relevant effect on the PK of tofogliflozin. Urinary glucose excretion up to 24 h after administration of tofogliflozin (UGE24h) decreased with decreasing glomerular filtration rate. Lowering UGE24h resulted in waning glycemic control but not body weight reduction. CONCLUSIONS: Single and multiple administrations of tofogliflozin were generally well tolerated in T2DM patients with various renal functions. As far as investigated here, these studies indicate no dose adjustment is required for patients with renal impairment.

Reversible mechanochromic luminescence of [(C6F5Au)2(mu-1,4-diisocyanobenzene)].

Reversible mechanochromic luminescence of [(C6F5Au)2(mu-1,4-diisocyanobenzene)] is reported. Grinding of the complex induced a photoluminescent color change, which was restored by exposure to a solvent. This cycle was repeated 20 times with no color degradation in the emissions. Their optical properties, X-ray crystallographic analysis, IR, and XRD measurements strongly suggested that the change in the molecular arrangement is responsible for this mechanochromic property. Intermolecular aurophilic bondings presumably play a key role in the altered emission.

Dosage Optimization of Nemolizumab Using Population Pharmacokinetic and Pharmacokinetic-Pharmacodynamic Modeling and Simulation.

Nemolizumab is a humanized anti-interleukin-31 receptor A monoclonal antibody for treating atopic dermatitis, and it especially improves pruritus. The objective of the simulation study was to optimize the dose regimen using a flat dose. The serum nemolizumab concentration and pruritus visual analog scale as an efficacy end point were modeled using the population analysis approach in 299 patients with atopic dermatitis who received placebo or doses between 0.1 and 3 mg/kg as a single dose once every 4 weeks or 2 mg/kg once every 8 weeks. A 1-compartment model with first-order absorption was employed as the pharmacokinetic model. An indirect turnover model with an inhibition component was employed as the main part of the pharmacokinetic-pharmacodynamic model. The models well described the observations. Therefore, simulations with several dose regimens were performed to optimize the dose regimen including a flat dose. The simulated area under the concentration-time curve at a steady state around 75 mg in the every-4-week regimen corresponds to that associated with the dose range of 0.5 to 2 mg/kg in the 4-week regimen. The simulated pruritus visual analog scale also showed a similar tendency. These simulation results support dose optimization during the clinical development program of nemolizumab.

Pharmacokinetics and Pharmacodynamics of Tofogliflozin (a Selective SGLT2 Inhibitor) in Healthy Male Subjects.

Tofogliflozin is a selective oral inhibitor of sodium-glucose co-transporter 2 for treatment of type 2 diabetes mellitus. The pharmacokinetics, pharmacodynamics, and safety of tofogliflozin were investigated in healthy male subjects. Three studies were conducted: single-ascending dose study (10-640 mg) in 56 Japanese and 24 Caucasian subjects; multiple-ascending dose study (2.5-80 mg once daily for 7 days) in 24 Japanese subjects; and food-effect study (20-40 mg) in 30 Japanese subjects. Tofogliflozin was absorbed rapidly and eliminated from the systemic circulation with a t1/2 of 5-6 h. Exposure increased dose-proportionally up to 320 mg. Body weight-corrected exposure was similar between Japanese and Caucasian subjects. Urinary excretion of tofogliflozin ranged from 17.1 to 27.4% of dose. Tofogliflozin did not accumulate with once daily administration. Food intake decreased Cmax by approximately 30% but did not change AUC0-inf. Tofogliflozin caused dose-dependent daily urinary glucose excretion (UGE0-24h), but food intake condition at administration did not affect it. The exposure-response relationship between plasma average concentration of tofogliflozin (Cavg) and UGE0-24h fitted Emax model well. There were no serious adverse events leading to discontinuation or episodes of hypoglycemia. Single and multiple administration of tofogliflozin were generally well tolerated. Exposure to tofogliflozin was dose-proportional up to 320 mg and did not accumulate with multiple once-a-day administration. The model suggests more than 100 ng/mL Cavg corresponding to the dose of between 20 and 40 mg leads to almost maximum effect of tofogliflozin.

Combining 'Bottom-Up' and 'Top-Down' Methods to Assess Ethnic Difference in Clearance: Bitopertin as an Example.

BACKGROUND AND OBJECTIVES: We propose a strategy for studying ethnopharmacology by conducting sequential physiologically based pharmacokinetic (PBPK) prediction (a 'bottom-up' approach) and population pharmacokinetic (popPK) confirmation (a 'top-down' approach), or in reverse order, depending on whether the purpose is ethnic effect assessment for a new molecular entity under development or a tool for ethnic sensitivity prediction for a given pathway. The strategy is exemplified with bitopertin. METHODS: A PBPK model was built using Simcyp(®) to simulate the pharmacokinetics of bitopertin and to predict the ethnic sensitivity in clearance, given pharmacokinetic data in just one ethnicity. Subsequently, a popPK model was built using NONMEM(®) to assess the effect of ethnicity on clearance, using human data from multiple ethnic groups. A comparison was made to confirm the PBPK-based ethnic sensitivity prediction, using the results of the popPK analysis. RESULTS: PBPK modelling predicted that the bitopertin geometric mean clearance values after 20 mg oral administration in Caucasians would be 1.32-fold and 1.27-fold higher than the values in Chinese and Japanese, respectively. The ratios of typical clearance in Caucasians to the values in Chinese and Japanese estimated by popPK analysis were 1.20 and 1.17, respectively. The popPK analysis results were similar to the PBPK modelling results. CONCLUSION: As a general framework, we propose that PBPK modelling should be considered to predict ethnic sensitivity of pharmacokinetics prior to any human data and/or with data in only one ethnicity. In some cases, this will be sufficient to guide initial dose selection in different ethnicities. After clinical trials in different ethnicities, popPK analysis can be used to confirm ethnic differences and to support dose justification and labelling. PBPK modelling prediction and popPK analysis confirmation can complement each other to assess ethnic differences in pharmacokinetics at different drug development stages.

Clinical pharmacology of tocilizumab for the treatment of systemic juvenile idiopathic arthritis.

Tocilizumab is a humanized anti-IL-6 receptor monoclonal antibody approved for the treatment of rheumatoid arthritis and systemic juvenile idiopathic arthritis. Biweekly doses of 8 mg/kg for patients who weigh ≥ 30 kg and 12 mg/kg for patients who weigh <30 kg produce adequate blockade of IL-6 receptors and normalization of C-reactive protein levels. The mean area under the curve during a 2-week dosing interval, maximum and minimum serum concentrations for both doses were 1341 ± 415 µg·day/ml, 245 ± 57.2 and 57.5 ± 23.3 µg/ml, respectively. Tocilizumab pharmacokinetic exposure parameters and clinical end points were comparable between these two dose groups. Proportions of patients achieving clinical end points were comparable across exposure quartiles, suggesting that pharmacokinetic exposures are within the plateau of the exposure-response curve.

Population pharmacokinetic-pharmacodynamic modelling and simulation of neutropenia induced by TP300, a novel topoisomerase I inhibitor.

OBJECTIVES: TP300 is a novel topoisomerase I inhibitor with neutropenia as a significant toxicity. We developed and evaluated a pharmacokinetic-pharmacodynamic (PK-PD) model, using data from Phase I and II trials to predict neutrophil decrease in patients treated with TP300. METHODS: Plasma drug concentrations of TP300, its active form TP3076 and active metabolite TP3011 and absolute neutrophil counts (ANCs) from a Phase I trial were analysed as a training dataset. A two-plus-two-compartment model was applied to the pharmacokinetics of TP3076 and TP3011. A semi-mechanistic model was used to describe the PK-PD relationship between the plasma concentration of TP3076 and TP3011, and changes in ANC. KEY FINDINGS: The model fitted well to plasma concentrations of TP3076 and TP3011. Model appropriateness was confirmed in a Phase II trial validation dataset. Body weight and liver biochemistry values were identified as covariates. A semi-mechanistic PK-PD model was applied and the longitudinal decrease in ANC was simulated. Neutrophil counts reached their nadir approximately 2 weeks after administration of TP300, and the proportion of subjects affected increased with dose. CONCLUSIONS: This PK-PD model to predict neutropenia following treatment with TP300 fitted well the decrease in ANC with total concentration of TP3076 and TP3011.