Pharmacodynamics and molecular correlates of response to glofitamab in relapsed/refractory non-Hodgkin lymphoma.

Glofitamab, a novel CD20xCD3, T-cell-engaging bispecific antibody, exhibited single-agent activity in Study NP30179, a first-in-human, phase 1 trial in relapsed/refractory B-cell non-Hodgkin lymphoma. Preclinical studies showed that glofitamab leads to T-cell activation, proliferation, and tumor cell killing upon binding to CD20 on malignant cells. Here, we provide evidence of glofitamab's clinical activity, including pharmacodynamic profile, mode of action, and factors associated with clinical response, by evaluating biomarkers in patient samples from the dose-escalation part of this trial. Patients enrolled in Study NP30179 received single-dose obinutuzumab pretreatment (1000 mg) 7 days before IV glofitamab (5 µg-25 mg). Glofitamab treatment lasted ≤12 cycles once every 2 or 3 weeks. Blood samples were collected at predefined time points per the clinical protocol; T-cell populations were evaluated centrally by flow cytometry, and cytokine profiles were analyzed. Immunohistochemical and genomic biomarker analyses were performed on tumor biopsy samples. Pharmacodynamic modulation was observed with glofitamab treatment, including dose-dependent induction of cytokines, and T-cell margination, proliferation, and activation in peripheral blood. Gene expression analysis of pretreatment tumor biopsy samples indicated that tumor cell intrinsic factors such as TP53 signaling are associated with resistance to glofitamab, but they may also be interlinked with a diminished effector T-cell profile in resistant tumors and thus represent a poor prognostic factor per se. This integrative biomarker data analysis provides clinical evidence regarding glofitamab's mode of action, supports optimal biological dose selection, and will further guide clinical development. This trial was registered at www.clinicaltrials.gov as #NCT03075696.

Glofitamab, a Novel, Bivalent CD20-Targeting T-Cell-Engaging Bispecific Antibody, Induces Durable Complete Remissions in Relapsed or Refractory B-Cell Lymphoma: A Phase I Trial.

PURPOSE: Glofitamab is a T-cell-engaging bispecific antibody possessing a novel 2:1 structure with bivalency for CD20 on B cells and monovalency for CD3 on T cells. This phase I study evaluated glofitamab in relapsed or refractory (R/R) B-cell non-Hodgkin lymphoma (B-NHL). Data for single-agent glofitamab, with obinutuzumab pretreatment (Gpt) to reduce toxicity, are presented. METHODS: Seven days before the first dose of glofitamab (0.005-30 mg), all patients received 1,000 mg Gpt. Dose-escalation steps were determined using a Bayesian continuous reassessment method with overdose control. Primary end points were safety, pharmacokinetics, and the maximum tolerated dose of glofitamab. RESULTS: Following initial single-patient cohorts, 171 patients were treated within conventional multipatient cohorts and received at least one dose of glofitamab. This trial included heavily pretreated patients with R/R B-NHL; most were refractory to prior therapy (155; 90.6%) and had received a median of three prior therapies. One hundred and twenty-seven patients (74.3%) had diffuse large B-cell lymphoma, transformed follicular lymphoma, or other aggressive histology, and the remainder had indolent lymphoma subtypes. Five (2.9%) patients withdrew from treatment because of adverse events. Cytokine release syndrome occurred in 86 of 171 (50.3%) patients (grade 3 or 4: 3.5%); two (1.2%) patients experienced grade 3, transient immune effector cell-associated neurotoxicity syndrome-like symptoms. The overall response rate was 53.8% (complete response [CR], 36.8%) among all doses and 65.7% (CR, 57.1%) in those dosed at the recommended phase II dose. Of 63 patients with CR, 53 (84.1%) have ongoing CR with a maximum of 27.4 months observation. CONCLUSION: In patients with predominantly refractory, aggressive B-NHL, glofitamab showed favorable activity with frequent and durable CRs and a predictable and manageable safety profile.

Population Pharmacokinetic and Exposure-Response Analysis of Selumetinib and Its N-desmethyl Metabolite in Patients With Non-Small Cell Lung Cancer.

Selumetinib (AZD6244, ARRAY-142886) is a mitogen-activated protein kinase kinase inhibitor that has been tested for treatment of non-small cell lung cancer (NSCLC). Selumetinib (75 mg twice daily) plus docetaxel in patients with advanced NSCLC has been assessed in phase 2 (SELECT-2) and phase 3 (SELECT-1) clinical trials. The objective of the current analysis was to investigate the exposure-response relationship of selumetinib in these 2 clinical trials, based on the development of a population pharmacokinetic (PopPK) model for selumetinib and its active metabolite, N-desmethyl selumetinib, in patients with NSCLC. A PopPK model using data from seven phase 1 studies was first developed and served as prior information for the development of the patient PopPK model. The pharmacokinetics (PK) of selumetinib and N-desmethyl selumetinib were modeled simultaneously. A two-compartment model with zero-first order absorption and first-order elimination reasonably described the selumetinib PK. The N-desmethyl metabolite of selumetinib was described by a one-compartment model with first-order elimination. The final PK parameter estimates were similar between patients with NSCLC and patients in the phase 1 population. Selumetinib apparent clearance and central volume of distribution were 11.9 L/h and 32.1 L, respectively, in patients. Individual selumetinib exposure metrics were estimated to investigate the correlation between exposure and efficacy/safety endpoints observed in NSCLC studies. There was no significant difference in progression-free survival (the primary endpoint) among the different quartiles of exposure. Similarly, no significant correlation was observed between selumetinib exposure and other secondary efficacy or safety endpoints. The conclusions are in accordance with the reported clinical findings.

Population pharmacokinetics of the MEK inhibitor selumetinib and its active N-desmethyl metabolite: data from 10 phase I trials.

AIMS: The aims of the study were to characterize the pharmacokinetics (PK) of selumetinib (AZD6244; ARRY-142886), a mitogen-activated protein kinase kinase (MEK) 1/2 inhibitor in clinical development for various indications, and its N-desmethyl metabolite in healthy volunteers, and evaluate clinically important covariates. METHODS: A pooled-population PK analysis was performed using a nonlinear mixed-effects approach with plasma concentration data from 346 subjects who received single oral doses of selumetinib 20-75 mg across 10 phase I studies. Absolute bioavailability was determined using intravenous [14 C] selumetinib. RESULTS: A two-compartment linear model with sequential zero-first order absorption and a lag time for the zero-order process was described for selumetinib PK. N-desmethyl metabolite disposition was described by a single compartment with linear elimination, without back transformation. The parent-only and joint models generally described pooled data adequately. For the median subject, not taking interacting drugs, estimates for clearance (CL) and central volume of distribution (V2) for selumetinib in the final joint model were 12.7 l h-1 and 35.6 l, respectively. Food effects, comedication with itraconazole [a cytochrome P450 (CYP) 3A4 inhibitor], fluconazole (a CYP2C19 inhibitor) and rifampicin (a CYP3A4 inducer) and formulation effects were incorporated into the base model a priori. Race and hepatic function were also influential in the PK model. Additional covariates affecting selumetinib disposition identified from covariate analysis were age on V2, bilirubin on CL, and weight on CL and V2. CONCLUSIONS: Analysis confirmed previous clinical pharmacology study findings of drug-drug interactions and food effects, with additional covariates that influence selumetinib and N-desmethyl selumetinib PK identified. Dose modifications based on these additional covariates were not considered necessary.

Selumetinib Plus Docetaxel Compared With Docetaxel Alone and Progression-Free Survival in Patients With KRAS-Mutant Advanced Non-Small Cell Lung Cancer: The SELECT-1 Randomized Clinical Trial.

Importance: There are no specifically approved targeted therapies for the most common genomically defined subset of non-small cell lung cancer (NSCLC), KRAS-mutant lung cancer. Objective: To compare efficacy of the mitogen-activated protein kinase kinase (MEK) inhibitor selumetinib + docetaxel with docetaxel alone as a second-line therapy for advanced KRAS-mutant NSCLC. Design, Setting, and Participants: Multinational, randomized clinical trial conducted at 202 sites across 25 countries from October 2013 through January 2016. Of 3323 patients with advanced NSCLC and disease progression following first-line anticancer therapy tested for a KRAS mutation, 866 were enrolled and 510 randomized. Primary reason for exclusion was ineligibility. The data cutoff date for analysis was June 7, 2016. Interventions: Patients were randomized 1:1; 254 to receive selumetinib + docetaxel and 256 to receive placebo + docetaxel. Main Outcomes and Measures: Primary end point was investigator assessed progression-free survival. Secondary end points included overall survival, objective response rate, duration of response, effects on disease-related symptoms, safety, and tolerability. Results: Of 510 randomized patients (mean age, 61.4 years [SD, 8.3]; women, 207 [41%]), 505 patients (99%) received treatment and completed the study (251 received selumetinib + docetaxel; 254 received placebo + docetaxel). At the time of data cutoff, 447 patients (88%) had experienced a progression event and 346 deaths (68%) had occurred. Median progression-free survival was 3.9 months (interquartile range [IQR], 1.5-5.9) with selumetinib + docetaxel and 2.8 months (IQR, 1.4-5.5) with placebo + docetaxel (difference, 1.1 months; hazard ratio [HR], 0.93 [95% CI, 0.77-1.12]; P = .44). Median overall survival was 8.7 months (IQR, 3.6-16.8) with selumetinib + docetaxel and 7.9 months (IQR, 3.8-20.1) with placebo + docetaxel (difference, 0.9 months; HR, 1.05 [95% CI, 0.85-1.30]; P = .64). Objective response rate was 20.1% with selumetinib + docetaxel and 13.7% with placebo + docetaxel (difference, 6.4%; odds ratio, 1.61 [95% CI, 1.00-2.62]; P = .05). Median duration of response was 2.9 months (IQR, 1.7-4.8; 95% CI, 2.7-4.1) with selumetinib + docetaxel and 4.5 months (IQR, 2.3-7.3; 95% CI, 2.8-5.6) with placebo + docetaxel. Adverse events of grade 3 or higher were more frequent with selumetinib + docetaxel (169 adverse events [67%] for selumetinib + docetaxel vs 115 adverse events [45%] for placebo + docetaxel; difference, 22%). Conclusions and Relevance: Among patients with previously treated advanced KRAS-mutant non-small cell lung cancer, addition of selumetinib to docetaxel did not improve progression-free survival compared with docetaxel alone. Trial Registration: clinicaltrials.gov: NCT01933932.

Pharmacokinetics and pharmacogenetics of the MEK1/2 inhibitor, selumetinib, in Asian and Western healthy subjects: a pooled analysis.

PURPOSE: Emerging data on selumetinib, a MEK1/2 inhibitor in clinical development, suggest a possible difference in pharmacokinetics (PK) between Japanese and Western patients. This pooled analysis sought to assess the effect of ethnicity on selumetinib exposure in healthy Western and Asian subjects, and to identify any association between genetic variants in the UGT1A1, CYP2C19 and ABCG2 genes and observed differences in selumetinib PK. METHODS: A pooled analysis of data from ten Phase I studies, one in Asian subjects (encompassing Japanese, non-Japanese Asian and Indian Asian subjects) and nine in Western subjects, was conducted. Key findings were derived from the collective exposure data across doses of 25, 35, 50 and 75 mg selumetinib; primary variables were dose-normalized AUC and Cmax. RESULTS: PK data from 308 subjects (10 studies) were available for the pooled analysis; genetic data from 87 subjects (3 studies) were available for the pharmacogenetic analysis. Dose-normalized AUC and Cmax were 35% (95% CI: 25-47%) and 39% (95% CI: 24-56%) higher in the pooled Asian group, respectively, compared with Western subjects. PK exposure parameters were similar between the Japanese, non-Japanese Asian and Indian groups. There was no evidence that the polymorphisms assessed in the genes UGT1A1, CYP2C19 and ABCG2 account for observed PK differences. CONCLUSIONS: Selumetinib exposure was higher in healthy Asian subjects compared with Western subjects, and these data provide valuable insight for clinicians to consider when treating patients of Asian ethnicity with selumetinib.

Randomized phase 2 study of obinutuzumab monotherapy in symptomatic, previously untreated chronic lymphocytic leukemia.

Obinutuzumab is a glycoengineered, type 2 anti-CD20 humanized antibody with single-agent activity in relapsed chronic lymphocytic leukemia (CLL). With other CD20 antibodies, a dose-response relationship has been shown. We therefore performed a randomized phase 2 study in symptomatic, untreated CLL patients to evaluate if an obinutuzumab dose response exists. Obinutuzumab was given at a dose of 1000 mg (100 mg IV day 1, 900 mg day 2, 1000 mg day 8 and day 15 of cycle 1; 1000 mg day 1 of cycles 2-8) or 2000 mg (100 mg IV day 1, 900 mg day 2, 1000 mg day 3, 2000 mg day 8 and day 15 of cycle 1; 2000 mg day 1 of cycles 2-8). The primary end point was overall response rate (ORR). Eighty patients were enrolled with similar demographics: median age 67 years, 41% high-risk Rai disease, and 10% del(17p)(13.1). ORR (67% vs 49%, P = .08) and complete response (CR) or CR with incomplete cytopenia response (20% vs 5%) favored 2000 mg obinutuzumab. Overall, therapy was well tolerated, and infusion events were manageable. This study demonstrates significant efficacy of obinutuzumab monotherapy, for 1000 mg as well as for 2000 mg, in untreated CLL patients with acceptable toxicity. Although exploratory, a dose-response relationship may exist, but its relevance to improving progression-free survival is uncertain and will require further follow-up. This trial was registered at www.clinicaltrials.gov as #NCT01414205.

Rationale for optimal obinutuzumab/GA101 dosing regimen in B-cell non-Hodgkin lymphoma.

Obinutuzumab (GA101) is a type II, glycoengineered anti-CD20 monoclonal antibody for the treatment of hematologic malignancies. Obinutuzumab has mechanisms of action that are distinct from those of rituximab, potentially translating into improved clinical efficacy. We present the pharmacokinetic and clinical data from the phase I/II GAUGUIN and phase I GAUDI studies that were used to identify the obinutuzumab dose and regimen undergoing phase III assessment. In phase I (GAUGUIN and GAUDI), non-Hodgkin lymphoma patients received up to a maximum 9 fixed doses (obinutuzumab 50-2000 mg). In GAUGUIN phase II, patients received obinutuzumab 400/400 mg or 1600/800 mg [first dose day (D)1, D8, cycle (C) 1; second dose D1, C2-C8]. The influence of demographic factors on pharmacokinetics and drug exposure on tumor response and toxicity were analyzed using exploratory graphical analyses. Obinutuzumab serum concentrations with 1600/800 mg were compared with a 1000 mg fixed-dose regimen (D1, D8 and D15, C1; D1, C2-C8) using pharmacokinetic modeling simulations. Factors related to CD20-antigenic mass were more influential on obinutuzumab pharmacokinetics with 400/400 versus 1600/800 mg. Higher serum concentrations were observed with 1600/800 versus 400/400 mg, irrespective of CD20-antigenic mass. Tumor shrinkage was greater with 1600/800 versus 400/400 mg; there was no significant increase in adverse events. Fixed dose 1000 mg with an additional C1 infusion resulted in similar serum concentrations to 1600/800 mg in model-based analyses. The obinutuzumab 1000 mg fixed-dose regimen identified in this exploratory analysis was confirmed in a full covariate analysis of a larger dataset, and is undergoing phase III evaluation. GAUGUIN and GAUDI are registered at www.clinicaltrials.gov (clinicaltrials.gov identifier:00517530 and 00825149, respectively).

Effect of hepatic and renal impairment on the pharmacokinetics of dalcetrapib: altered distribution of the active thiol?

BACKGROUND AND OBJECTIVE: Dalcetrapib, a cholesteryl ester transfer protein (CETP) modulator, is a thioester pro-drug that is rapidly hydrolysed to generate a pharmacologically active thiol. The thiol covalently binds to plasma proteins as mixed disulfides, extensively distributes into plasma lipoprotein fractions, and is principally cleared by metabolism, including extensive first-pass metabolism. Here we report two studies assessing the effects of hepatic and renal impairment on the pharmacokinetics of the thiol and its primary metabolites. METHODS: Adults with hepatic or renal impairment and healthy controls were recruited in two separate non-randomized, open-label studies. Eligible subjects were aged 18-70 years (hepatic impairment study) or 18-75 years (renal impairment study) with a body mass index 18-40 kg/m(2). Healthy controls were matched by age, bodyweight and sex. Each participant received a single 600 mg oral dose of dalcetrapib. Plasma and urine sampling was performed up to 3-4 days post-dalcetrapib administration for analysis of the pharmacokinetics of the thiol and its primary S-methyl and S-glucuronide metabolites. In the renal impairment study, CETP activity and mass, and lipid profiles were also assessed. RESULTS: Twenty-eight subjects were enrolled in the hepatic impairment study (mild or moderate hepatic impairment, n = 8 in each group; controls, n = 12). Thirty-five subjects participated in the renal impairment study (mild, moderate or severe renal impairment, n = 8 in each group; controls, n = 11). In patients with moderate hepatic impairment, the area under the plasma concentration-time curve from time zero to infinity (AUC(∞)) for thiol exposure was increased 34 % (geometric mean ratio [GMR] 1.34, 90 % CI 1.02-1.76), compared with matched controls. Regression analysis revealed a weak inverse relationship between thiol exposure and creatinine clearance (p = 0.0137, r(2) = 17.1 %). In patients with moderate or severe renal impairment, thiol exposures were 62 % (AUC(∞) GMR 1.62, 90 % CI 0.81-3.27) and 81 % (AUC(∞) GMR 1.81, 90 % CI 1.21-2.71) higher, respectively, than matched controls. Exposures of the S-glucuronide and S-methyl metabolites were also higher in hepatic and renal impairment groups. In the renal impairment study, CETP activity was decreased following administration of dalcetrapib, with no clear differences between groups. CONCLUSION: Hepatic and renal impairment both altered dalcetrapib pharmacokinetics and increased thiol exposure, with the extent of the effect dependent on the severity of impairment. The effect of renal impairment may be linked to altered distribution of the thiol, which illustrates the importance of assessing distribution to understand the causes and consequences of altered pharmacokinetics of thiol drugs in patient populations.

A phase 1 study of obinutuzumab induction followed by 2 years of maintenance in patients with relapsed CD20-positive B-cell malignancies.

This phase 1 study evaluated the safety, tolerability, pharmacokinetics, and antitumor activity of obinutuzumab (GA101), a glycoengineered type II anti-CD20 monoclonal antibody administered as induction followed by 2 years of maintenance. Cohorts of 3 to 6 patients received obinutuzumab (200-2000 mg) intravenously weekly for 4 weeks. Patients with a complete or partial response (or stable disease and clinical benefit) continued to receive obinutuzumab every 3 months, for a maximum of 8 doses. Twenty-two patients with relapsed CD20-positive non-Hodgkin lymphoma or chronic lymphocytic leukemia with an indication for treatment and no therapy of higher priority were enrolled. Patients received a median of 4 prior regimens; 86% had received at least 1 rituximab-containing regimen. No dose-limiting or unexpected AEs were observed. Infusion-related reactions were most common (all grades, 73%; grade 3/4, 18%), followed by infection (32%), pyrexia (23%), neutropenia (23%), headache (18%), and nausea (18%). At end of induction, 5 (23%) patients achieved partial responses and 12 (54%) had stable disease. Eight patients received maintenance; best overall response was 32% (6 partial responses/1 complete response). Obinutuzumab induction and maintenance therapy was well tolerated with promising efficacy in this heterogeneous, highly pretreated population and warrants further investigation. This study was registered at www.clinicaltrials.gov (identifier NCT00576758).

Scaling factors for the extrapolation of in vivo metabolic drug clearance from in vitro data: reaching a consensus on values of human microsomal protein and hepatocellularity per gram of liver.

Reported predictions of human in vivo hepatic clearance from in vitro data have used a variety of values for the scaling factors human microsomal protein (MPPGL) and hepatocellularity (HPGL) per gram of liver, generally with no consideration of the extent of their inter-individual variability. We have collated and analysed data from a number of sources, to provide weighted meangeo values of human MPPGL and HPGL of 32 mg g-1 (95% Confidence Interval (CI); 29-34 mg.g-1) and 99x10(6) cells.g-1 (95% CI; 74-131 mg.g-1), respectively. Although inter-individual variability in values of MPPGL and HPGL was statistically significant, gender, smoking or alcohol consumption could not be detected as significant covariates by multiple linear regression. However, there was a weak but statistically significant inverse relationship between age and both MPPGL and HPGL. These findings indicate the importance of considering differences between study populations when forecasting in vivo pharmacokinetic behaviour. Typical clinical pharmacology studies, particularly in early drug development, use young, fit, healthy male subjects of around 30 years of age. In contrast, the average age of patients for many diseases is about 60 years of age. The relationship between age and MPPGL observed in this study estimates values of 40 mg.g-1 for a 30 year old individual and 31 mg.g-1 for a 60 year old individual. Investigators may wish to consider the reported covariates in the selection of scaling factors appropriate for the population in which estimates of clearance are being predicted. Further studies are required to clarify the influence of age (especially in paediatric subjects), donor source and ethnicity on values of MPPGL and HPGL. In the meantime, we recommend that the estimates (and their variances) from the current meta-analysis be used when predicting in vivo kinetic parameters from in vitro data.

Determination of a human hepatic microsomal scaling factor for predicting in vivo drug clearance.

PURPOSE: To determine a microsomal scaling factor for human liver suitable for prediction of in vivo drug clearance from in vitro data and to explore the role of inter-liver variability in this factor on the reported underprediction from microsomal parameters. METHODS: Cytochrome P450 (henceforth P450) content in whole homogenates and microsomes from 38 donor livers was used to determine a microsomal scaling factor. In a subset (n = 20) of these preparations, individual P450 enzymes were examined by Western blotting and selective probe activities were determined. RESULTS: The scaling factor from 38 livers averaged 40 mg microsomal protein per gram liver with a coefficient of variation of 31%. Western blotting experiments indicated that there was no P450 enzyme-specific trend in the distribution of individual P450 enzymes in liver microsomes relative to whole homogenate. Predictions based on an average scaling factor resulted in a satisfactory prediction of intrinsic clearance of three benzodiazepines similar to that obtained using individual factors for the same livers. CONCLUSION: A value for human liver microsomal scaling of 40 mg microsomal protein per gram liver has been established. The reason for underprediction previously reported for 52 different drug substrates was not the use of an incorrect value for the scaling factor.