Population Pharmacodynamic Model of Neutrophil Margination and Tolerance to Describe Effect of Sarilumab on Absolute Neutrophil Count in Patients with Rheumatoid Arthritis

Safety and effectiveness of sarilumab in Japanese patients with rheumatoid arthritis refractory to previous treatments: An interim analysis of a post-marketing surveillance

OBJECTIVES

An interim analysis of post-marketing surveillance data to assess the safety and effectiveness of sarilumab in Japanese patients with rheumatoid arthritis refractory to previous treatment.

METHODS

The interim analysis included patients who initiated sarilumab therapy between June 2018 and January 2021. The primary objective of this surveillance was safety.

RESULTS

In total, 1036 patients were enrolled and registered by 12 January 2021 (interim cut-off date). Of these, 678 were included in the safety analysis [75.4% female; mean age (± standard deviation) 65.8 ± 13.0 years]. Adverse drug reactions, defined as adverse events classified as possibly or probably related to sarilumab, were reported in 170 patients (incidence: 25.1%), with white blood cell count decreased (4.4%) and neutrophil count decreased (1.6%) most frequently reported. Serious haematologic disorders (3.4%) and serious infections (including tuberculosis) (2.5%) were the most frequently reported priority surveillance items. No malignant tumour was reported. An absolute neutrophil count (ANC) below the minimum standard value did not increase the incidence of serious infections.

CONCLUSIONS

Sarilumab was well tolerated, and no new safety signals were noted in this analysis. There was no difference in the frequency of serious infections between patients with an ANC below or above normal.

Immune-related adverse events of biological immunotherapies used in COVID-19

The use of biological immunotherapeutic drugs is one of the options currently being evaluated and employed to manage COVID-19, specifically monoclonal antibodies, which have shown benefit by regulating the excessive immune response seen in patients with severe infection, known as a cytokine storm. Tocilizumab has received particular importance for this clinical application, as has sarilumab. Both drugs share a substantial similarity in terms of pharmacodynamics, being inhibitors of the interleukin six receptor (IL-6Rα). Furthermore, sotrovimab, a neutralizing anti-SARS CoV-2 antibody, has gained the attention of the scientific community since it has recently been authorized under certain circumstances, positioning itself as a new therapeutic alternative in development. However, despite their clinical benefit, biological immunotherapies have the potential to generate life-threatening immune-related adverse events. Therefore it is essential to review their incidence, mechanism, and risk factors. This review aims to provide a comprehensive understanding of the safety of the biological immunotherapeutic drugs currently recommended for the treatment of COVID-19, provide a review of the known immune-mediated adverse events and explore the potential immune-related mechanisms of other adverse reactions.

Lessons learned from the preclinical discovery and development of sarilumab for the treatment of rheumatoid arthritis

INTRODUCTION

Rheumatoid arthritis (RA) pathogenesis is driven by a complex network of proinflammatory cytokines, among which interleukin-6 (IL-6) plays a key role in inducing and perpetuating chronic inflammation. Targeting the IL-6 pathway has shown to be an invaluable treatment strategy, as demonstrated by the results accrued in the last decade with the first IL-6 inhibitor, tocilizumab. More recently, a second monoclonal antibody blocking IL-6, sarilumab, has enriched our armamentarium by proving outstanding efficacy in RA treatment.

AREAS COVERED

After exploring the IL-6 pathway under physiological conditions and in the RA pathogenesis, in this review we discuss the pharmacologic properties of sarilumab and the clinical trials that constitute the sarilumab development program and have enabled its licensed application.

EXPERT OPINION

Results from clinical trials confirmed the efficacy and safety of sarilumab for the treatment of RA, similar to its precursor tocilizumab. Blocking IL-6 pathway results in comprehensive control of the disease, from both physician's and patient's perspective, and of RA comorbidities and extra-articular manifestations which are largely IL-6 driven. Finally, the proven efficacy of sarilumab as monotherapy arises the drug as a required therapeutic alternative considering the large proportion of patients intolerant or inadequate to receive conventional synthetic disease-modifying drugs (csDMARDs).

A whole-body circulatory neutrophil model with application to predicting clinical neutropenia from in vitro studies

A circulatory model of granulopoiesis and its regulation is presented that includes neutrophil trafficking in the lungs, liver, spleen, bone marrow, lymph nodes, and blood. In each organ, neutrophils undergo transendothelial migration from vascular to interstitial space, clearance due to apoptosis, and recycling via the lymphatic flow. The model includes cell cycling of progenitor cells in the bone marrow, granulocyte colony-stimulating factor (G-CSF) kinetics and its neutrophil regulatory action, as well as neutrophil margination in the blood. From previously reported studies, 111 In-labeled neutrophil kinetic data in the blood and sampled organs were used to estimate the organ trafficking parameters in the model. The model was further developed and evaluated using absolute neutrophil count (ANC), band cell, and segmented neutrophil time course data from healthy volunteers following four dose levels of pegfilgrastim (r2  = 0.77-0.99), along with ANC time course responses following filgrastim (r2  = 0.96). The baseline values of various cell types in bone marrow and blood, as well as G-CSF concentration in the blood, predicted by the model are consistent with available literature reports. After incorporating the mechanism of action of both paclitaxel and carboplatin, as determined from an in vitro bone marrow studies, the model reliably predicted the observed ANC time course following paclitaxel plus carboplatin observed in a phase I trial of 46 patients (r2  = 0.70). The circulatory neutrophil model may provide a mechanistic framework for predicting multi-organ neutrophil homeostasis and dynamics in response to therapeutic agents that target neutrophil dynamics and trafficking in different organs.

Base and Covariate Population Pharmacokinetic Analyses of Dupilumab in Adolescents and Children ≥6 to <12 Years of Age Using Phase 3 Data

Population pharmacokinetic (PK) base and covariate analyses were conducted using data from adolescents with moderate‐to‐severe atopic dermatitis (AD) and children ≥6 to <12 years of age with severe AD. Two phase 3 studies were analyzed (165 adolescents and 241 children on active treatment). A 2‐compartment model with linear and Michaelis‐Menten elimination and 3 transit compartments describing lag time in absorption was utilized. Weight, albumin, body mass index, and Eczema Area and Severity Index score were statistically significant covariates in at least 1 of the age populations. Only body weight had a consequential effect on central volume. Although an absorption rate and target‐mediated clearance somewhat decreased with age, no dose adjustment was needed in addition to the adjustment for weight already implemented in the phase 3 studies. Otherwise, population PK parameters and covariates were similar across the 2 pediatric subpopulations and in adults. No allometric changes in elimination rate and beta half‐life were observed with weight. Parameterization of models in terms of rates was a useful alternative to parameterization in terms of clearances, allowing for an absence of repeated covariates and preventing overparameterization. The model adequately described dupilumab pharmacokinetics in the pediatric populations.

Long-term safety and efficacy of sarilumab over 5 years in patients with rheumatoid arthritis refractory to TNF inhibitors

OBJECTIVE

To evaluate long-term safety and efficacy of sarilumab over 5 years in patients with RA refractory to TNF inhibitors (TNFi).

METHODS

Patients in the 24-week randomized controlled trial (RCT) TARGET (NCT01709578) whoreceived double-blind placebo or sarilumab 150 or 200 mg every 2 weeks (q2w), plus conventionalsynthetic DMARDs (csDMARDs), were eligible to receive open-label sarilumab 200 mg q2w pluscsDMARDs in the open-label extension (OLE), EXTEND (NCT01146652). OLE dose reduction to 150 mg q2w was permitted per investigators' judgement or protocol-mandated safety concerns. Safety and efficacy were assessed through treatment-emergent adverse events (AEs), laboratoryabnormalities and clinical disease activity scores. All statistics are descriptive.

RESULTS

Of 546 patients, 454 (83%) were treated with sarilumab in the OLE. Cumulative observation period was 1654.8 patient-years (PY; n = 521); 268 patients (51%) had ≥4 years' exposure. Incidencerates per 100 PY of AEs, AEs leading to discontinuation, infection and serious infection were 160.4, 8.1, 57.8 and 3.9, respectively. Neutropenia was the most common AE (15.3 per 100 PY). Absoluteneutrophil count <1000 cells/mm3 (Grade 3/4 neutropenia) was observed in 74 patients (14.2%) and normalized on treatment in 48. Clinical efficacy was sustained through 5 years' follow-up. Efficacy was similar for patients with 1 and >1 TNFi failure, and between patients who either remained on 200mg or reduced to 150 mg.

CONCLUSION

In patients with RA refractory to TNFi, sarilumab's long-term term safety profile was consistent with previous clinical studies and post-marketing reports. Efficacy was sustained over 5years.

Population Pharmacokinetic-Pharmacodynamic Relationships of Sarilumab Using Disease Activity Score 28-Joint C-Reactive Protein and Absolute Neutrophil Counts in Patients with Rheumatoid Arthritis

BACKGROUND

Sarilumab is a human monoclonal antibody blocking the interleukin-6 receptor alpha (IL-6Rɑ) approved for the treatment of moderately to severely active rheumatoid arthritis in adults with inadequate response or intolerance to other disease-modifying antirheumatic drugs.

OBJECTIVE

The aim of the current analysis was to describe sarilumab exposure-response relationships.

METHODS

Population pharmacokinetic/pharmacodynamic (PopPK/PD) models were developed describing the time course of the 28-joint disease activity score by C-reactive protein (DAS28-CRP) and absolute neutrophil count (ANC) using data from phase I-III studies (NCT01011959, NCT01061736, NCT01709578, NCT01768572) after subcutaneous sarilumab 50-150 mg every week or 100-200 mg every 2 weeks.

RESULTS

The time course of DAS28-CRP and ANC after sarilumab administration was described by semi-mechanistic, indirect-response models. Drug effect was predicted to be numerically greater at median exposure for the 200 mg every 2 weeks regimen versus the 150 mg every 2 weeks regimen, for both DAS28-CRP (50% vs. 47%) and ANC reduction from baseline (39% vs. 31%), with the latter showing less fluctuations within a dosing interval. Four covariates were retained in the final models: body weight, baseline rheumatoid factor status, anti-cyclic citrullinated peptide status, and concomitant methotrexate. There was no clinically meaningful influence of investigated covariates for either model.

CONCLUSION

The PopPK/PD models showed numerically greater reductions in DAS28-CRP and ANC with sarilumab 200 mg every 2 weeks than with 150 mg every 2 weeks. There was no clinically meaningful influence of investigated covariates. These data contribute to the totality of evidence that supports a sarilumab subcutaneous starting dose of 200 mg every 2 weeks, with a subsequent reduction to 150 mg every 2 weeks in the event of laboratory abnormalities such as neutropenia.