Comparison of sequential and joint nonlinear mixed effects modeling of tumor kinetics and survival following Durvalumab treatment in patients with metastatic urothelial carcinoma.

Standard endpoints such as objective response rate are usually poorly correlated with overall survival (OS) for treatment with immune checkpoint inhibitors. Longitudinal tumor size may serve as a more useful predictor of OS, and establishing a quantitative relationship between tumor kinetics (TK) and OS is a crucial step for successfully predicting OS based on limited tumor size measurements. This study aims to develop a population TK model in combination with a parametric survival model by sequential and joint modeling approaches to characterize durvalumab phase I/II data from patients with metastatic urothelial cancer, and to evaluate and compare the performance of the two modeling approaches in terms of parameter estimates, TK and survival predictions, and covariate identification. The tumor growth rate constant was estimated to be greater for patients with OS ≤ 16 weeks as compared to that for patients with OS > 16 weeks with the joint modeling approach (kg= 0.130 vs. 0.0551 week-1, p-value < 0.0001), but similar for both groups (kg = 0.0624 vs.0.0563 week-1, p-value = 0.37) with the sequential modeling approach. The predicted TK profiles by joint modeling appeared better aligned with clinical observations. Joint modeling also predicted OS more accurately than the sequential approach according to concordance index and Brier score. The sequential and joint modeling approaches were also compared using additional simulated datasets, and survival was predicted better by joint modeling in the case of a strong association between TK and OS. In conclusion, joint modeling enabled the establishment of a robust association between TK and OS and may represent a better choice for parametric survival analyses over the sequential approach.

Exposure-response analysis for selection of optimal dosage regimen of anifrolumab in patients with systemic lupus erythematosus.

OBJECTIVES: The randomized, double-blind, phase 2 b MUSE study evaluated the efficacy and safety of the type I IFN receptor antibody anifrolumab (300 mg or 1000 mg every 4 weeks) compared with placebo for 52 weeks in patients with chronic, moderate to severe SLE. Characterizing the exposure-response relationship of anifrolumab in MUSE will enable selection of its optimal dosage regimen in two phase 3 studies in patients with SLE. METHODS: The exposure-response relationship, pharmacokinetics (PK) and SLE Responder Index (SRI(4)) efficacy data were analysed using a population approach. A dropout hazard function was also incorporated into the SRI(4) model to describe the voluntary patient withdrawals during the 1-year treatment period. RESULTS: The population PK model found that type I IFNGS-high patients, and patients with a higher body weight, had significantly greater clearance of anifrolumab. Stochastic clinical simulations demonstrated that doses <300 mg would lead to a greater-than-proportional reduction in drug exposure owing to type I IFN alpha receptor-mediated drug clearance (antigen-sink effect, more rapid drug clearance at lower concentrations) and suboptimal SRI(4) responses with wider confidence intervals. CONCLUSIONS: Based on PK, efficacy and safety considerations, anifrolumab 300 mg every 4 weeks was recommended as the optimal dosage for pivotal phase 3 studies in patients with SLE.

Chronic pharmacological antagonism of the GM-CSF receptor in mice does not replicate the pulmonary alveolar proteinosis phenotype but does alter lung surfactant turnover.

Granulocyte macrophage colony stimulating factor (GM-CSF) is a key participant in, and a clinical target for, the treatment of inflammatory diseases including rheumatoid arthritis (RA). Therapeutic inhibition of GM-CSF signalling using monoclonal antibodies to the α-subunit of the GM-CSF receptor (GMCSFRα) has shown clear benefit in patients with RA, giant cell arteritis (GCAs) and some efficacy in severe SARS-CoV-2 infection. However, GM-CSF autoantibodies are associated with the development of pulmonary alveolar proteinosis (PAP), a rare lung disease characterised by alveolar macrophage (AM) dysfunction and the accumulation of surfactant lipids. We assessed how the anti-GMCSFRα approach might impact surfactant turnover in the airway. Female C57BL/6J mice received a mouse-GMCSFRα blocking antibody (CAM-3003) twice per week for up to 24 weeks. A parallel, comparator cohort of the mouse PAP model, GM-CSF receptor ß subunit (GMCSFRß) knock-out (KO), was maintained up to 16 weeks. We assessed lung tissue histopathology alongside lung phosphatidylcholine (PC) metabolism using stable isotope lipidomics. GMCSFRß KO mice reproduced the histopathological and biochemical features of PAP, accumulating surfactant PC in both broncho-alveolar lavage fluid (BALF) and lavaged lung tissue. The incorporation pattern of methyl-D9-choline showed impaired catabolism and not enhanced synthesis. In contrast, chronic supra-pharmacological CAM-3003 exposure (100 mg/kg) over 24 weeks did not elicit a histopathological PAP phenotype despite some changes in lung PC catabolism. Lack of significant impairment of AM catabolic function supports clinical observations that therapeutic antibodies to this pathway have not been associated with PAP in clinical trials.

Comparison of autoinjector with accessorized prefilled syringe for benralizumab pharmacokinetic exposure: AMES trial results.

OBJECTIVE: We compared the pharmacokinetic exposure following a single subcutaneous dose of benralizumab 30 mg using either autoinjectors (AI) or accessorized prefilled syringes (APFS). APFS and AI functionality and reliability for at-home benralizumab delivery have been demonstrated in the GREGALE and GRECO studies, respectively. METHODS: In the open-label AMES study (NCT02968914), 180 healthy adult men and women were randomized to one of two device (AI or APFS) and three injection site (upper arm, abdomen, or thigh) combinations. Randomization was stratified by weight (<70 kg, 70-84.9 kg, and ≥85 kg). Blood eosinophil counts were measured on Days 1, 8, 29, and 57. RESULTS: Benralizumab pharmacokinetic exposure was similar between AI and APFS. Geometric mean ratios (AI/APFS) (90% CI) were 92.8% (87.4-98.6) and 94.5% (88.2-101.2) for two area under the concentration‒time curve measurements (AUClast and AUCinf). Benralizumab exposure was approximately 15-30% greater for thigh vs. abdomen or upper arm administration. Exposure was slightly greater for APFS vs. AI regardless of injection site or weight class. These differences were unlikely to be clinically relevant, as eosinophil depletion was achieved consistently with both devices at all injection sites. No device malfunctions were reported. No new or unexpected safety findings were observed. CONCLUSION: Benralizumab pharmacokinetic exposure was similar between AI and APFS, with consistent blood eosinophil count depletion observed with both devices. These results support benralizumab administration with either AI or APFS, providing patients and physicians increased choice, flexibility, and convenience for potential at-home delivery.

Patient-reported outcomes and inflammatory biomarkers in patients with locally advanced/metastatic urothelial carcinoma treated with durvalumab in phase 1/2 dose-escalation study 1108.

BACKGROUND: Durvalumab has shown meaningful clinical activity in patients with metastatic urothelial carcinoma (mUC) in Study 1108 (NCT01693562). An important focus in treatment is health-related quality of life (HRQOL). Here, patient-reported outcomes (PROs) from Study 1108 and their relationship with inflammatory biomarkers are explored. METHODS: Disease-related symptoms, functioning, and HRQOL were assessed with the Functional Assessment of Cancer Therapy-Bladder (FACT-Bl) and the European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire Core 30 (QLQ-C30). Relationships between PRO improvements and the best changes in the tumor size, albumin level, and neutrophil-lymphocyte ratio (NLR) were assessed with Spearman correlation analysis. RESULTS: The mean FACT-Bl total score improved from 107.5 (standard deviation [SD], 23.0) at the baseline to 115.4 (SD, 22.6) on day 113, with similar increases found for the Trial Outcome Index (TOI) and Bladder Cancer Subscale (BLCS) scores. The mean FACT-Bl total scores improved over time, and the FACT-Bl TOI scores significantly improved by day 113 (P < .05). The mean EORTC QLQ-C30 Global Health Status/Quality of Life score improved from 57.1 (SD, 24.8) at the baseline to 69.0 (SD, 21.4) on day 113; the functional scale and symptom scores (day 113) were higher than the baseline scores (P < .05) for EORTC Social Functioning. The FACT-Bl total, BLCS, and TOI scores improved in 32.6%, 34.9%, and 32.6% of the patients by day 113; 26.3% to 37.8% of the patients exhibited improvements in EORTC QLQ-C30 functional scores. The best tumor shrinkage and posttreatment improvements in serum albumin and NLR correlated with increases in FACT-Bl total, TOI, and BLCS scores and in EORTC Physical Functioning and Role Functioning scores (P < .05). CONCLUSIONS: Durvalumab was associated with improvements in disease-related symptoms, functioning, and HRQOL in patients with mUC. Improvements in systemic inflammation may contribute to PRO improvements in these patients.

Multifaceted Bioanalytical Methods for the Comprehensive Pharmacokinetic and Catabolic Assessment of MEDI3726, an Anti-Prostate-Specific Membrane Antigen Pyrrolobenzodiazepine Antibody-Drug Conjugate.

Complex biotherapeutic modalities, such as antibody-drug conjugates (ADC), present significant challenges for the comprehensive bioanalytical characterization of their pharmacokinetics (PK) and catabolism in both preclinical and clinical settings. Thus, the bioanalytical strategy for ADCs must be designed to address the specific structural elements of the protein scaffold, linker, and warhead. A typical bioanalytical strategy for ADCs involves quantification of the Total ADC, Total IgG, and Free Warhead concentrations. Herein, we present bioanalytical characterization of the PK and catabolism of a novel ADC. MEDI3726 targets prostate-specific membrane antigen (PMSA) and is comprised of a humanized IgG1 antibody site-specifically conjugated to tesirine (SG3249). The MEDI3726 protein scaffold lacks interchain disulfide bonds and has an average drug to antibody ratio (DAR) of 2. Based on the structural characteristics of MEDI3726, an array of 4 bioanalytical assays detecting 6 different surrogate analyte classes representing at least 14 unique species was developed, validated, and employed in support of a first-in-human clinical trial (NCT02991911). MEDI3726 requires the combination of heavy-light chain structure and conjugated warhead to selectively deliver the warhead to the target cells. Therefore, both heavy-light chain dissociation and the deconjugation of the warhead will affect the activity of MEDI3726. The concentration-time profiles of subjects dosed with MEDI3726 revealed catabolism of the protein scaffold manifested by the more rapid clearance of the Active ADC, while exhibiting minimal deconjugation of the pyrrolobenzodiazepine (PBD) warhead (SG3199).

Population pharmacokinetics, efficacy, and safety of moxetumomab pasudotox in patients with relapsed or refractory hairy cell leukaemia.

AIMS: To characterize the pharmacokinetics (PK) of moxetumomab pasudotox, an anti-CD22 recombinant immunotoxin, in adults with relapsed or refractory hairy cell leukaemia, we examined data from a phase 1 study (Study 1001; n = 49) and from the pivotal clinical study (Study 1053; n = 74). METHODS: Data from both studies were pooled (n = 123) to develop a population PK model. Covariates included demographics, disease state, liver and kidney function, prior treatment, and antidrug antibodies (ADAs). Exposure-response and exposure-safety were analysed separately by study. A 1-compartment model with linear elimination from the central compartment and 2 clearance (CL) rates was developed. RESULTS: Moxetumomab pasudotox was cleared more rapidly after cycle 1, day 1 (CL1 = 24.7 L/h) than subsequently (CL2 = 3.76 L/h), with high interindividual variability (116 and 109%, respectively). In Study 1053, patients with ADA titres >10 240 showed ~4-fold increase in CL. Higher exposures (≥median) were related to higher response rates, capillary leak syndrome and increased creatinine (Study 1053 only), or grade ≥3 adverse events (Study 1001 only). Clinical benefits were still observed in patients with lower exposure or high ADA titres. CONCLUSION: Despite a high incidence of immunogenicity with increased clearance, moxetumomab pasudotox demonstrated efficacy in hairy cell leukaemia.

Detecting bliss synergy in in vivo combination studies with a tumor kinetic model.

Linear models are generally reliable methods for analyzing tumor growth in vivo, with drug effectiveness being represented by the steepness of the regression slope. With immunotherapy, however, not all tumor growth follows a linear pattern, even after log transformation. Tumor kinetics models are mechanistic models that describe tumor proliferation and tumor killing macroscopically, through a set of differential equations. In drug combination studies, although an additional drug-drug interaction term can be added to such models, however, the drug interactions suggested by tumor kinetics models cannot be translated directly into synergistic effects. We have developed a novel statistical approach that simultaneously models tumor growth in control, monotherapy, and combination therapy groups. This approach makes it possible to test for synergistic effects directly and to compare such effects among different studies.

Prevalence of IgG and Neutralizing Antibodies against Staphylococcus aureus Alpha-Toxin in Healthy Human Subjects and Diverse Patient Populations.

Staphylococcus aureus causes an array of serious infections resulting in high morbidity and mortality worldwide. This study evaluated naturally occurring serum anti-alpha-toxin (anti-AT) antibody levels in human subjects from various age groups, individuals with S. aureus dialysis and surgical-site infections, and S. aureus-colonized versus noncolonized subjects. Anti-AT immunoglobulin G (IgG) and neutralizing antibody (NAb) levels in infants (aged ≤1 year) were significantly lower than those in other populations. In comparison to adolescent, adult, and elderly populations, young children (aged 2 to 10 years) had equivalent anti-AT IgG levels but significantly lower anti-AT NAb levels. Therefore, the development of anti-AT NAbs appears to occur later than that of AT-specific IgG, suggesting a maturation of the immune response to AT. Anti-AT IgG levels were slightly higher in S. aureus-colonized subjects than in noncolonized subjects. The methicillin susceptibility status of colonizing isolates had no effect on anti-AT antibody levels in S. aureus-colonized subjects. The highest anti-AT IgG and NAb levels were observed in dialysis patients with acute S. aureus infection. Anti-AT IgG and NAb levels were well correlated in subjects aged >10 years, regardless of colonization or infection status. These data demonstrate that AT elicits a robust IgG humoral response in infants and young children that becomes stable prior to adolescence, matures into higher levels of NAbs in healthy adolescents, and becomes elevated during S. aureus infection. These findings may assist in identifying subjects and patient populations that could benefit from vaccination or immunoprophylaxis with anti-AT monoclonal antibodies.

Blockade of GM-CSF pathway induced sustained suppression of myeloid and T cell activities in rheumatoid arthritis.

Objectives: Targeting the granulocyte-macrophage colony-stimulating factor (GM-CSF) pathway holds great potential in the treatment of inflammatory diseases. Mavrilimumab, a human monoclonal GM-CSF receptor-α antibody, has demonstrated clinical efficacy in RA. Our current study aimed to elucidate mechanisms of action and identify peripheral biomarkers associated with therapeutic responses of GM-CSF antagonism in RA. Methods: A 24-week placebo (PBO)-controlled trial was conducted in 305 RA patients who received mavrilimumab (30, 100 or 150 mg) or PBO once every 2 weeks. Serum biomarkers and whole blood gene expression profiles were measured by protein immunoassay and whole genome microarray. Results: Mavrilimumab treatment induced significant down-regulation of type IV collagen formation marker (P4NP 7S), macrophage-derived chemokine (CCL22), IL-2 receptor α and IL-6 compared with PBO. Both early and sustained reduction of P4NP 7S was associated with clinical response to 150 mg mavrilimumab treatment. Gene expression analyses demonstrated reduced expression of transcripts enriched in macrophage and IL-22/IL-17 signalling pathways after GM-CSF blockade therapy. Myeloid and T cell-associated transcripts were suppressed in mavrilimumab-treated ACR20 responders but not non-responders. While CCL22 and IL-6 down-regulation may reflect a direct effect of GM-CSFR blockade on the production of pro-inflammatory mediators by myeloid cells, the suppression of IL-2 receptor α and IL-17/IL-22 associated transcripts suggests an indirect suppressive effect of mavrilimumab on T cell activation. Conclusion: Our results demonstrated association of peripheral biomarker changes with therapeutic response to mavrilimumab in RA patients. The sustained efficacy of mavrilimumab in RA may result from both direct effects on myeloid cells and indirect effects on T cell activation after GM-CSFR blockade.

Statistical Models for the Analysis of Isobaric Tags Multiplexed Quantitative Proteomics.

Mass spectrometry is being used to identify protein biomarkers that can facilitate development of drug treatment. Mass spectrometry-based labeling proteomic experiments result in complex proteomic data that is hierarchical in nature often with small sample size studies. The generalized linear model (GLM) is the most popular approach in proteomics to compare protein abundances between groups. However, GLM does not address all the complexities of proteomics data such as repeated measures and variance heterogeneity. Linear models for microarray data (LIMMA) and mixed models are two approaches that can address some of these data complexities to provide better statistical estimates. We compared these three statistical models (GLM, LIMMA, and mixed models) under two different normalization approaches (quantile normalization and median sweeping) to demonstrate when each approach is the best for tagged proteins. We evaluated these methods using a spiked-in data set of known protein abundances, a systemic lupus erythematosus (SLE) data set, and simulated data from multiplexed labeling experiments that use tandem mass tags (TMT). Data are available via ProteomeXchange with identifier PXD005486. We found median sweeping to be a preferred approach of data normalization, and with this normalization approach there was overlap with findings across all methods with GLM being a subset of mixed models. The conclusion is that the mixed model had the best type I error with median sweeping, whereas LIMMA had the better overall statistical properties regardless of normalization approaches.

Choice of Starting Dose for Biopharmaceuticals in First-in-Human Phase I Cancer Clinical Trials.

BACKGROUND: First-in-human (FIH) trials of low-molecular-weight anticancer agents conventionally derive a safe start dose (SD) from one-tenth the severely toxic dose in 10% of rodents or one-sixth the highest nonseverely toxic dose (HNSTD) in nonrodent species. No consensus has been reached on whether this paradigm can be safely applied to biotechnology-derived products (BDPs). MATERIALS AND METHODS: A comprehensive search was conducted to identify all BDPs (excluding immune checkpoint inhibitors and antibody drug conjugates) with sufficient nonclinical and clinical data to assess the safety of hypothetical use of one-sixth HNSTD in an advanced cancer FIH trial. RESULTS: The search identified 23 BDPs, of which 21 were monoclonal antibodies. The median ratio of the maximum tolerated or maximum administered dose (MTD or MAD) to the actual FIH SD was 36 (range, 8-500). Only 2 BDPs reached the MTD. Hypothetical use of one-sixth HNSTD (allometrically scaled to humans) would not have exceeded the MTD or MAD for all 23 BDPs and would have reduced the median ratio of the MTD or MAD to a SD to 6.1 (range, 3.5-55.3). Pharmacodynamic (PD) markers were included in some animal toxicology studies and were useful to confirm the hypothetical SD of one-sixth HNSTD. CONCLUSION: One-sixth HNSTD would not have resulted in unacceptable toxicities in the data available. Supporting its use could reduce the number of dose escalations needed to reach the recommended dose. A low incidence of toxicities in animals and humans underscores the need to identify the pharmacokinetic and PD parameters to guide SD selection of BDPs for FIH cancer trials. IMPLICATIONS FOR PRACTICE: Start dose (SD) for biotechnology-derived products (BDPs) can be safely derived from one-sixth the highest nonseverely toxic dose in nonrodent species and may reduce the number of dose escalations needed to reach the recommended dose in first-in-human studies while limiting unnecessary exposure to high drug levels in humans. The use of this type of SD could improve the design of phase I studies of BDPs by making them more efficient. The role of preclinical pharmacodynamic markers was useful in confirming the hypothetical SD, and attempts should be explored in future animal studies to identify such parameters.

Quantitative measurement of the target-mediated internalization kinetics of biopharmaceuticals.

PURPOSE: Measurement of internalization of biopharmaceuticals targeting cell surface proteins can greatly facilitate drug development. The objective of this study was to develop a reliable method for determination of internalization rate constant (kint) and to demonstrate its utility. METHODS: This method utilized confocal imaging to record the internalization kinetics of fluorescence-tagged biopharmaceuticals in live-cells and a quantitative image-analysis algorithm for kint determination. Kint was incorporated into a pharmacokinetic-pharmacodynamic (PK-PD) model for simulation of the drug PK profiles, target occupancy and the displacement of endogenous ligand. RESULTS: The method was highly sensitive, allowing kint determination in cells expressing as low as 5,000 receptors/cell, and was amenable to adherent and suspension cells. Its feasibility in a mixed cell population, such as whole blood, was also demonstrated. Accurate assessment of the kint was largely attributed to continuous monitoring of internalization in live cells, rapid confocal image acquisition and quantitative image-analysis algorithm. Translational PK-PD simulations demonstrated that kint is a major determinant of the drug PK profiles, target occupancy, and the displacement of endogenous ligand. CONCLUSIONS: The developed method is robust for broad cell types. Reliable kint assessment can greatly expedite biopharmaceutical development by facilitating target evaluation, drug affinity goal setting, and clinical dose projection.

Non-normal random effects models for immunogenicity assay cut point determination.

Administration of biological therapeutics can generate undesirable immune responses that may induce anti-drug antibodies (ADAs). Immunogenicity can negatively affect patients, ranging from mild reactive effect to hypersensitivity reactions or even serious autoimmune diseases. Assessment of immunogenicity is critical as the ADAs can adversely impact the efficacy and safety of the drug products. Well-developed and validated immunogenicity assays are required by the regulatory agencies as tools for immunogenicity assessment. Key to the development and validation of an immunogenicity assay is the determination of a cut point, which serves as the threshold for classifying patients as ADA positive(reactive) or negative. In practice, the cut point is determined as either the quantile of a parametric or nonparametric empirical distribution. The parametric method, which is often based on a normality assumption, may lead to biased cut point estimates when the normality assumption is violated. The non-parametric method, which yields unbiased estimates of the cut point, may have low efficiency when the sample size is small. As the distribution of immune responses are often skewed and sometimes heavy-tailed, we propose two non-normal random effects models for cut point determination. The random effects, following a skew-t or log-gamma distribution, can incorporate the skewed and heavy-tailed responses and the correlation among repeated measurements. Simulation study is conducted to compare the proposed method with the current normal and nonparametric alternatives. The proposed models are also applied to a real dataset generated from assay validation studies.

Suppression of soluble T cell-associated proteins by an anti-interferon-α monoclonal antibody in adult patients with dermatomyositis or polymyositis.

OBJECTIVE: The aim of this study was to identify serum markers that are modulated by an investigational anti-IFN-α mAb, sifalimumab, in adult DM or PM patients. METHODS: In a phase 1b clinical trial, sera were collected from a total of 48 DM or PM adult patients receiving either placebo for 3 months or sifalimumab for 6 months. Samples were tested for 128 selected proteins using a multiplex luminex immunoassay. Muscle biopsies from selected patients were stained for T cell infiltration using an anti-CD3 antibody. RESULTS: A robust overexpression of multiple serum proteins in DM or PM patients was observed, particularly in patients with an elevated baseline type I IFN gene signature in the blood or muscle. Neutralization of the type I IFN gene signature by sifalimumab resulted in coordinated suppression of T cell-related proteins such as soluble IL-2RA, TNF receptor 2 (TNFR2) and IL-18. Muscle biopsies from two patients with the highest serum protein suppression were selected and found to have a pronounced reduction of muscle T cell infiltration. Down-regulation of IL-2RA correlated with favourable manual muscle test 8 (MMT-8) alterations in sifalimumab-dosed patients. CONCLUSION: A reduced level of multiple T cell-associated proteins after sifalimumab but not placebo administration suggests a suppressive effect of blocking type I IFN signalling on T cell activation and chemoattraction that may lead to a reduction of T cell infiltration in the muscle of myositis patients. Further, soluble IL-2RA changes from baseline may serve as a responsive and/or predictive marker for type I IFN-targeted therapy in adult DM or PM patients.

Nonclinical safety of mavrilimumab, an anti-GMCSF receptor alpha monoclonal antibody, in cynomolgus monkeys: relevance for human safety.

Mavrilimumab (CAM-3001) is an investigational human IgG4 monoclonal antibody (MAb) targeting GM-CSF receptor alpha which is currently being developed for the treatment of RA. GM-CSF plays a central role in the pathogenesis of rheumatoid arthritis (RA) through the activation, differentiation, and survival of macrophages and neutrophils. To support clinical development, the nonclinical safety of mavrilimumab was evaluated in several studies with cynomolgus monkeys as the pharmacologically relevant species. Comprehensive toxicity parameters were assessed in each study, and treatment duration ranged from 4 to 26weeks. Mavrilimumab has an acceptable safety profile in monkeys with no changes in any parameters other than microscopic findings in lung. In several studies, minimal accumulation of foamy alveolar macrophages was observed. This finding was only seen in studies of at least 11weeks duration, was reversible following a dose-free recovery period and was considered non-adverse. At higher dose levels (≥30mg/kg/week), in a 26-week repeat-IV dose study, the presence of lung foreign material, cholesterol clefts, and granulomatous inflammation was also observed in a few animals and was considered adverse. The dose- and time-related accumulation of foamy macrophages in lung following exposure to mavrilimumab observed in several NHP studies was expected based upon the known role of GM-CSFRα signaling in the function of alveolar macrophages. Overall, a clean no-observed-adverse-effect-level (NOAEL) without any effects in lung was established and provided adequate clinical safety margins. In clinical studies in RA patients, mavrilimumab has demonstrated good clinical activity with adequate safety to support further clinical development. A Phase 2b study of mavrilimumab in subjects with RA is in progress.

Cabozantinib exposure-response analysis for the phase 3 CheckMate 9ER trial of nivolumab plus cabozantinib versus sunitinib in first-line advanced renal cell carcinoma.

PURPOSE: In the phase 3 CheckMate 9ER trial, intravenous nivolumab (240 mg every 2 weeks) plus oral cabozantinib (40 mg/day) improved progression-free survival (PFS) versus sunitinib as first-line therapy for advanced renal cell carcinoma (RCC). To support cabozantinib dosing with the combination, this exposure-response analysis characterized the relationship of cabozantinib exposure with clinical endpoints. METHODS: Dose modification was allowed with cabozantinib (holds and reductions) to manage adverse events (AEs). The population pharmacokinetics analysis was updated and used to generate individual predicted cabozantinib exposure measures. Kaplan-Meier plots and time-to-event Cox proportional hazard (CPH) exposure-response models characterized the relationship of cabozantinib exposure with PFS, dose modifications, and selected AEs. RESULTS: Kaplan-Meier plots showed no clear difference in PFS across cabozantinib exposure quartiles. Cabozantinib exposure did not significantly affect the hazard of PFS in the CPH base model nor in the final model. In contrast, baseline albumin and nivolumab clearance had a significant effect on PFS. There was no significant relationship between cabozantinib clearance and risk of dose modification, but a significant relationship was identified between cabozantinib exposure and Grade ≥ 1 palmar-plantar-erythrodysesthesia and Grade ≥ 3 diarrhea in the exposure-response analysis. CONCLUSION: To optimize individual cabozantinib exposure, these data support the dose modification strategies in CheckMate 9ER for cabozantinib in patients with advanced RCC when combined with nivolumab.

Population Pharmacokinetics and Exposure-Response Analysis for the Phase 3 COSMIC-311 Trial of Cabozantinib for Radioiodine-Refractory Differentiated Thyroid Cancer.

BACKGROUND AND OBJECTIVE: In the USA, cabozantinib was approved for the treatment of patients aged ≥ 12 years with radioiodine-refractory differentiated thyroid cancer (DTC) who progressed on prior vascular endothelial growth factor (VEGFR)-targeted therapy based on the Phase 3 COSMIC-311 trial, which evaluated cabozantinib 60 mg/day versus placebo. Approved dosing is 60 mg/day for adults and for pediatric patients aged ≥ 12 years with body surface area (BSA) ≥ 1.2 m2, and 40 mg/day for pediatric patients aged ≥ 12 years with BSA < 1.2 m2. This report describes a population pharmacokinetic (PopPK) and exposure-response analysis of COSMIC-311. METHODS: A PopPK model was developed using concentration-time data from COSMIC-311 and 6 other cabozantinib studies. The final (full) PopPK model was used to simulate the effect of sex, body weight, race, and patient population. For exposure-response analysis, derived datasets from COSMIC-311 were constructed for time-to-event analyses of progression-free survival (PFS) and safety endpoints. RESULTS: The PopPK analysis included 4746 cabozantinib PK samples from 1745 patients and healthy volunteers. Body weight had minimal impact on cabozantinib exposure but increasing body weight was associated with increased apparent volume of distribution. Based on model-based simulation, adolescents < 40 kg had higher maximum plasma concentration at steady state of cabozantinib 60 mg/day compared to adults. Allometric scaling simulation in adolescents < 40 kg demonstrated higher exposure with 60 mg/day relative to adults receiving the same dose, while exposure with 40 mg/day in adolescents < 40 kg was similar to 60 mg/day in adults. The exposure-response analysis included 115 patients. There was no clear relationship between PFS or dose modification and cabozantinib exposure. A statistically significant relationship was demonstrated for cabozantinib exposure and hypertension (Grade ≥ 3) and fatigue/asthenia (Grade ≥ 3). CONCLUSIONS: These results support the dosing strategy implemented in COSMIC-311 and the BSA-based label recommendations for adolescents. The cabozantinib dose should be reduced to manage adverse events as indicated.

Combining pharmacometric models with predictive and prognostic biomarkers for precision therapy in Crohn's disease: A case study of brazikumab.

Pharmacometric models were used to investigate the utility of biomarkers in predicting the efficacy (Crohn's Disease Activity Index [CDAI]) of brazikumab and provide a data-driven framework for precision therapy for Crohn's disease (CD). In a phase IIa trial in patients with moderate to severe CD, treatment with brazikumab, an anti-interleukin 23 monoclonal antibody, was associated with clinical improvement. Brazikumab treatment effect was determined to be dependent on the baseline IL-22 (BIL22) or baseline C-reactive protein (BCRP; predictive biomarkers), and placebo effect was found to be correlated with the baseline CDAI (a prognostic biomarker). A maximal total inhibition on CDAI input function of 50.6% and 42.4% was predicted for patients with extremely high BIL22 or BCRP, compared to a maximal total inhibition of 20.9% and 17.8% for patients with extremely low BIL22 or BCRP, respectively, which were mainly due to the placebo effect. We demonstrated that model-derived baseline biomarker levels that achieve 50% of maximum unbound systemic concentration of 22.8 pg/mL and 8.03 mg/L for BIL22 and BCRP as the cutoffs to select subpopulations can effectively identify high-response subgroup patients with improved separation of responders when compared to using the median values as the cutoff. This work exemplifies the utility of pharmacometrics to quantify biomarker-driven responses in biologic therapies and distinguish between predictive and prognostic biomarkers, complementing clinical efforts of identifying subpopulations with higher likelihood of response to brazikumab.

Multiplex Bioanalytical Methods for Comprehensive Characterization and Quantification of the Unique Complementarity-Determining-Region Deamidation of MEDI7247, an Anti-ASCT2 Pyrrolobenzodiazepine Antibody-Drug Conjugate.

Deamidation, a common post-translational modification, may impact multiple physiochemical properties of a therapeutic protein. MEDI7247, a pyrrolobenzodiazepine (PBD) antibody-drug conjugate (ADC), contains a unique deamidation site, N102, located within the complementarity-determining region (CDR), impacting the affinity of MEDI7247 to its target. Therefore, it was necessary to monitor MEDI7247 deamidation status in vivo. Due to the low dose, a sensitive absolute quantification method using immunocapture coupled with liquid chromatography-tandem mass spectrometry (LBA-LC-MS/MS) was developed and qualified. We characterized the isomerization via Electron-Activated Dissociation (EAD), revealing that deamidation resulted in iso-aspartic acid. The absolute quantification of deamidation requires careful assay optimization in order not to perturb the balance of the deamidated and nondeamidated forms. Moreover, the selection of capture reagents essential for the correct quantitative assessment of deamidation was evaluated. The final assay was qualified with 50 ng/mL LLOQ for ADC for total and nondeamidated antibody quantification, with qualitative monitoring of the deamidated antibody. The impact of deamidation on the pharmacokinetic characteristics of MEDI7247 from clinical trial NCT03106428 was analyzed, revealing a gradual reduction in the nondeamidated form of MEDI7247 in vivo. Careful quantitative biotransformation analyses of complex biotherapeutic conjugates help us understand changes in product PTMs after administration, thus providing a more complete view of in vivo pharmacology.