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Evidence suggests that effects of interleukin-6 pathway inhibitors sarilumab, tocilizumab, and sirukumab on absolute neutrophil count (ANC) are due to margination of circulating neutrophils into rapidly mobilizable noncirculating pools. We developed a population pharmacodynamic model using compartments for neutrophil margination and ANC-specific tolerance to describe rapid, transient ANC changes in blood following administration of subcutaneous sarilumab and intravenous/subcutaneous tocilizumab based on data from 322 patients with rheumatoid arthritis in two single-dose (NCT02097524 and NCT02404558) and one multiple-dose (NCT01768572) trials. The model incorporated a tolerance compartment to account for ANC nadir and beginning of recovery before maximal drug concentration after subcutaneous dosing, and absence of a nadir plateau when the ANC response is saturated after subcutaneous or intravenous dosing. The model effectively describes the ANC changes and supports neutrophil margination and tolerance as an explanation for the absence of increased infection risk associated with low ANC due to interleukin-6 pathway inhibitor treatment.

The population pharmacokinetics of sirukumab, a human immunoglobulin G1κ monoclonal antibody against interleukin-6, were characterized in patients with moderately to severely active rheumatoid arthritis in 4 phase 3 studies (SIRROUND-D, -T, -H, and -M). A total of 17 034 serum concentrations were analyzed from 1991 rheumatoid arthritis patients who received subcutaneous administration of sirukumab 50 mg every 4 weeks or 100 mg every 2 weeks. A stepwise confirmatory population PK analysis was conducted to accommodate the staged data release and the sparse sampling nature of phase 3 studies and to assess the potential covariate influences in an unbiased and timely manner. The base model, that is, a 1-compartment linear model with first-order absorption and first-order elimination, was prespecified based on prior information from a phase 2 study along with information about phase 3 study design. The covariate model was also prespecified based on pharmacological/physiological relevance and sample size. After the primary covariate analysis, a simplified model was produced by removing covariates with effect sizes

This phase 1, randomized, open-label study assessed the absolute bioavailability and pharmacokinetic comparability of sirukumab, a human anti-interleukin-6 monoclonal antibody, following subcutaneous (SC) administration via Prefilled Syringe-UltraSafe Passive® Delivery System (PFS-U) or Prefilled Syringe-SmartJect® Autoinjector (PFS-AI; Janssen Research & Development, LLC, Spring House, Pennsylvania). A total of 144 healthy male subjects were randomized to 5 single-dose treatment groups: sirukumab 50 mg and 100 mg (each by PFS-U and PFS-AI) and sirukumab 100 mg intravenous (IV) infusion. Pharmacokinetic parameters were calculated using noncompartmental analysis. Following SC administration, maximum serum concentrations (Cmax ) and area under the concentration-vs-time curve (AUC) increased in an approximately dose-proportional manner. Median time to reach Cmax was 5 days, and mean half-life ranged from 16 to 19 days. Mean absolute bioavailability of sirukumab by PFS-AI and PFS-U, respectively, was estimated at 92.4% and 81.4% with 100 mg and 88.4% and 94.7% with 50 mg. Ratios of geometric means (90% confidence intervals) of Cmax and AUC0-77d for PFS-AI:PFS-U were 1.13 (1.03, 1.25) and 1.14 (1.05, 1.24), respectively, indicating comparable systemic exposures of sirukumab following a single 100-mg SC dose by PFS-U or PFS-AI. The incidence of antibodies to sirukumab was low (1.4%). No new safety concerns associated with sirukumab were identified at either dose.

Objective To assess the efficacy and safety of sirukumab, an anti-interleukin-6 monoclonal antibody, for the treatment of patients with active lupus nephritis (LN). Methods Patients with class III or class IV LN (as determined by renal biopsy within 14 months of randomization) who had persistent proteinuria (>0.5 gm/day) despite receiving immunosuppressive therapy and who were being treated with stable doses of a renin-angiotensin system blocker were randomized (5:1) to receive treatment with sirukumab at a dose of 10 mg/kg intravenously (n = 21) or placebo (n = 4) every 4 weeks through week 24. The primary end point was the percent reduction in proteinuria (measured as the protein-to-creatinine [P:C] ratio in a 12-hour urine collection) from baseline to week 24. Results Twenty-five patients were enrolled, of whom 19 (76.0%) completed treatment through week 24 and 6 (24.0%) discontinued the study agent early, with 5 of the 6 discontinuing due to adverse events. At week 24, the median percent change in proteinuria from baseline to week 24 in sirukumab-treated patients was 0.0% (95% confidence interval -61.8, 39.6). In contrast, the 4 placebo-treated patients showed an increase in proteinuria (median percent reduction -43.3%) at week 24. Of note, a subset of 5 sirukumab-treated patients had ≥50% improvement in their P:C ratio through week 28. In the sirukumab group, 47.6% of patients experienced ≥1 serious adverse event through week 40; most were infection-related. No deaths or malignancies occurred. No serious adverse events were observed in the 4 placebo-treated patients. Conclusion This proof-of-concept study did not demonstrate the anticipated efficacy nor did it demonstrate an acceptable safety profile for sirukumab treatment in this population of patients with active LN receiving concomitant immunosuppressive treatment.

AIMS To assess the safety, tolerability, pharmacokinetics (PK) and immunogenicity of sirukumab (CNTO 136) following intravenous (i.v.) infusion in healthy subjects.

ObjectiveWe undertook a 2-part, phase I, double-blind, placebo-controlled study to evaluate the safety and pharmacokinetics of multiple intravenous infusions of sirukumab, a human anti-interleukin-6 monoclonal antibody, in patients with cutaneous lupus erythematosus (CLE) or systemic lupus erythematosus (SLE). MethodsIn part A, patients with histologically confirmed CLE were randomized to 4 infusions of placebo or 1, 4, or 10 mg/kg sirukumab every 2 weeks. In part B, SLE patients diagnosed according to American College of Rheumatology criteria with a score of 5-12 on the Safety of Estrogens in Lupus Erythematosus National Assessment version of the SLE Disease Activity Index were randomized to 4 infusions of placebo or 10 mg/kg sirukumab every 2 weeks. ResultsWe treated 31 CLE patients (23 with sirukumab, 8 with placebo) and 15 SLE patients (10 with sirukumab, 5 with placebo). Adverse events (AEs) occurred more often with sirukumab than placebo in CLE patients (91% versus 63%) and in SLE patients (90% versus 80%). Sirukumab led to sustained, dose-independent decreases in white blood cell counts, absolute neutrophil counts (neutropenia), and platelet counts (thrombocytopenia) and to minor elevations in total cholesterol levels. The majority of infections were mild respiratory infections. which were reported similarly across CLE cohorts but more often in sirukumab-treated than in placebo-treated SLE patients. Two serious AEs of infection occurred (pneumonia in the 10 mg/kg-treated group and iatrogenic wound infection in the 4 mg/kg-treated group). Sirukumab showed linear pharmacokinetics in CLE patients. Systemic exposure and half-life were comparable between CLE and SLE patients. No patient developed antibodies to sirukumab through 22 weeks. C-reactive protein and serum amyloid A mean concentrations were suppressed with sirukumab from week 1 to week 14. ConclusionTreatment with intravenous sirukumab infusions was generally well tolerated in both CLE and SLE patients with mild, stable, active disease. Sirukumab demonstrated linear pharmacokinetics over the dose range studied and comparable systemic exposure and half-life in CLE and SLE patients. (Less)