THU0042 Preclinical Characterization of Sirukumab, a Human Monoclonal Antibody that Targets Human Interleukin-6 Signaling

A Multicenter, Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Efficacy and Safety of Treatment With Sirukumab (CNTO 136) in Patients With Active Lupus Nephritis

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.

Development of a Physiologically Based Pharmacokinetic Model to Predict Disease-Mediated Therapeutic Protein-Drug Interactions: Modulation of Multiple Cytochrome P450 Enzymes by Interleukin-6

Disease-mediated therapeutic protein-drug interactions have recently gained attention from regulatory agencies and pharmaceutical industries in the development of new biological products. In this study, we developed a physiologically based pharmacokinetic (PBPK) model using SimCYP to predict the impact of elevated interleukin-6 (IL-6) levels on cytochrome P450 (CYP) enzymes and the treatment effect of an anti-IL-6 monoclonal antibody, sirukumab, in patients with rheumatoid arthritis (RA). A virtual RA patient population was first constructed by incorporating the impact of systemic IL-6 level on hepatic and intestinal expression of multiple CYP enzymes with information from in vitro studies. Then, a PBPK model for CYP enzyme substrates was developed for healthy adult subjects. After incorporating the virtual RA patient population, the PBPK model was applied to quantitatively predict pharmacokinetics of multiple CYP substrates in RA patients before and after sirukumab treatment from a clinical cocktail drug interaction study. The results suggested that, compared with observed clinical data, changes in systemic exposure to multiple CYP substrates by anti-IL-6 treatment in virtual RA patients have been reasonably captured by the PBPK model, as manifested by modulations in area under plasma concentration versus time curves for midazolam, omeprazole, S-warfarin, and caffeine. This PBPK model reasonably captured the modulation effect of IL-6 and sirukumab on activity of CYP3A, CYP2C9, CYP2C19, and CYP1A2 and holds the potential to be utilized to assess the modulation effect of sirukumab on the metabolism and pharmacokinetics of concomitant small-molecule drugs in RA patients.