Pharmacokinetics of daclizumab high-yield process with repeated administration of the clinical subcutaneous regimen in patients with relapsing-remitting multiple sclerosis

Daclizumab: Mechanisms of Action, Therapeutic Efficacy, Adverse Events and Its Uncovering the Potential Role of Innate Immune System Recruitment as a Treatment Strategy for Relapsing Multiple Sclerosis

Daclizumab (DAC) is a humanized, monoclonal antibody that blocks CD25, a critical element of the high-affinity interleukin-2 receptor (IL-2R). DAC HYP blockade of CD25 inhibits effector T cell activation, regulatory T cell expansion and survival, and activation-induced T-cell apoptosis. Because CD25 blockade reduces IL-2 consumption by effector T cells, it increases IL-2 bioavailability allowing for greater interaction with the intermediate-affinity IL-2R, and therefore drives the expansion of CD56^bright natural killer (NK) cells. Furthermore, there appears to be a direct correlation between CD56^bright NK cell expansion and DAC HYP efficacy in reducing relapses and MRI evidence of disease activity in patients with RMS in phase II and phase III double-blind, placebo- and active comparator-controlled trials. Therapeutic efficacy was maintained during open-label extension studies. However, treatment was associated with an increased risk of rare adverse events, including cutaneous inflammation, autoimmune hepatitis, central nervous system Drug Reaction with Eosinophilia Systemic Symptoms (DRESS) syndrome, and autoimmune Glial Fibrillary Acidic Protein (GFAP) alpha immunoglobulin-associated encephalitis. As a result, DAC HYP was removed from clinical use in 2018. The lingering importance of DAC is that its use led to a deeper understanding of the underappreciated role of innate immunity in the potential treatment of autoimmune disease.

Daclizumab: Development, Clinical Trials, and Practical Aspects of Use in Multiple Sclerosis

Daclizumab is a humanized monoclonal antibody directed towards CD25, the alpha subunit of the high-affinity interleukin (IL)-2 receptor. Daclizumab exerts its effects via multiple mechanisms, including reduction of IL-2-mediated lymphocyte activation and upregulation of CD56-bright natural killer cells. Intravenous daclizumab (Zenapax™) was initially approved for prevention of rejection in renal transplant. In subsequent early testing, followed by larger-scale phase II and phase III trials, both intravenous and subcutaneous daclizumab have demonstrated clinical efficacy in the treatment of multiple sclerosis. The subcutaneous daclizumab prepared by high-yield process was utilized in the advanced phase II and phase III trials (SELECT and DECIDE). High-yield process daclizumab is now approved by the US Food and Drug Administration for relapsing-remitting multiple sclerosis, and is now formally termed daclizumab beta (DAC-beta; Zinbryta™). In this review, the early development of anti-IL-2 receptor alpha monoclonal antibodies and the properties of IL-2 and its receptor are discussed, and diverse mechanisms of action for daclizumab are presented. Results of the CHOICE, SELECT, and DECIDE clinical trials are discussed in detail. Adverse events observed in clinical trials included cutaneous reactions, liver enzyme elevations, infections, and autoimmune phenomena. DAC-beta is a monthly, patient-administered subcutaneous injection that requires enrollment in a safety monitoring (REMS) program for monthly liver function testing. Prescribers should be aware of the potential adverse events, as early recognition and management is important, particularly in cutaneous and hepatic reactions. Continued clinical experience with DAC-beta, including observations from the REMS program, will define its place in the armamentarium of immunotherapeutics for relapsing-remitting multiple sclerosis.

Pharmacodynamic effects of daclizumab in the intrathecal compartment

Objective

It was previously demonstrated that daclizumab therapy normalizes cellular cerebrospinal fluid (CSF) abnormalities typical of multiple sclerosis (MS) in the majority of treated patients. However, CSF cells represent only the mobile portion of intrathecal immune responses. Therefore, we asked whether daclizumab also reverses compartmentalized inflammation and if not, whether residual inflammation correlates with clinical response to the drug.

Methods

Forty MS patients treated with an intravenous or subcutaneous injection of daclizumab were followed for up to 16 years in two open‐label clinical trials. MRI contrast‐enhancing lesions (CELs), clinical scales, and CSF biomarkers quantified residual disease.

Results

Rapid decreases in CELs, sustained throughout the observation period, were observed with daclizumab treatment. Daclizumab therapy induced modest but statistically significant (P < 0.0001) decreases in CSF levels of T‐cell activation marker CD27 and IgG index. Interleukin 2 (IL‐2) CSF levels increased from baseline levels during treatment, consistent with reduced IL‐2 consumption by T cells, as a consequence of daclizumab's saturation of high‐affinity IL‐2 receptors. CSF levels of IL‐12p40, chitinase‐3‐like protein‐1 (CHI3L1), chemokine C‐X‐C motif ligand 13, and neurofilament light chain (NFL) were also significantly reduced by daclizumab. Among them, inhibition of CHI3L1 correlated with inhibition of NFL and with lack of disease progression.

Interpretation

These observations confirm daclizumab's direct pharmacodynamics effects on immune cells within central nervous system tissues and identify inhibition of CSF biomarkers of myeloid lineage as a stronger determinant of reduction in clinical MS activity than inhibition of biomarkers of adaptive immunity.

Daclizumab: A Review in Relapsing Multiple Sclerosis

Daclizumab (Zinbryta^®; previously known as daclizumab high-yield process) is a therapeutic monoclonal antibody that has recently been approved for the treatment of relapsing forms of multiple sclerosis (MS) in adults. Daclizumab is a humanized IgG1 monoclonal antibody directed against CD25, the alpha subunit of the high-affinity interleukin-2 receptor. As demonstrated in the phase III DECIDE trial, once-monthly subcutaneous daclizumab was superior to once-weekly intramuscular interferon (IFN) β-1a in reducing the clinical relapse rate and radiological measures of disease in patients with relapsing-remitting MS. In addition, daclizumab has demonstrated efficacy in reducing disability progression and in improving health-related quality of life in patients with relapsing MS. Ongoing open-label clinical trials indicate that daclizumab's efficacy is maintained in the longer term (3 years or more). Daclizumab appears to be generally well tolerated, with adverse events of interest (including hepatic, infectious and cutaneous events) generally manageable with regular monitoring and/or standard therapies. The place of daclizumab in MS treatment remains to be fully determined. However, based on available evidence, daclizumab provides a useful alternative option to other currently available disease-modifying therapies in the treatment of relapsing MS.

Daclizumab

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Spotlight on daclizumab: its potential in the treatment of multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory-demyelinating disease of the central nervous system of a putative autoimmune etiology. Although the exact pathogenic mechanisms underlying demyelination and axonal damage in MS are not fully understood, T-cells are believed to play a central role in the pathogenesis of the disease. Daclizumab is a humanized binding monoclonal antibody that binds to the Tac epitope on the α-subunit (CD25) of the interleukin-2 (IL-2) receptor, thus effectively blocking the formation of the high-affinity IL-2 receptor, which is expressed mainly on T-cells. A series of clinical trials in patients with relapsing MS demonstrated a profound effect of daclizumab on inflammatory disease activity and improved clinical outcomes compared with placebo or interferon-β, which led to the recent approval of daclizumab (Zinbryta™) for the treatment of relapsing forms of MS. Enhancement of endogenous mechanisms of immune regulation rather than inhibition of effector T-cells might explain the effects of daclizumab in MS. These include expansion and improved function of regulatory CD56bright NK cells, inhibition of the early activation of T-cells through blockade of IL-2 transpresentation by dendritic cells and reduction in the number of intrathecal proinflammatory lymphoid tissue inducer cells. The enhanced efficacy of daclizumab is accompanied by an increased frequency of adverse events and risks of serious adverse events, thus placing it as a second-line therapy and calling for the implementation of a strict risk management program. This review details the mechanisms of action of daclizumab, discusses its efficacy and safety in patients with MS, and provides an insight into the place of this novel therapy in the treatment of MS.

Daclizumab high-yield process in the treatment of relapsing-remitting multiple sclerosis

Daclizumab is a humanized monoclonal antibody that binds to the α subunit (CD25) of the interleukin-2 receptor and favorably modulates the immune environment in multiple sclerosis (MS). Blockage of CD25, among other effects, causes expansion and enhanced function of regulatory CD56^bright natural killer cells, which seems to be the leading mechanism of action in MS. Phase II and III clinical trials have demonstrated that monthly subcutaneous injections of daclizumab high yield process (DAC HYP) 150 mg in patients with relapsing MS led to a significant reduction of annualized relapse rate and decreased number of contrast-enhanced lesions on brain magnetic resonance imaging. Treatment with DAC HYP had efficacy superior to treatment with weekly injections of interferon β1a. This review summarizes the development of and clinical experience with daclizumab in MS.

Therapeutic efficacy of monthly subcutaneous injection of daclizumab in relapsing multiple sclerosis

Despite the availability of multiple disease-modifying therapies for relapsing multiple sclerosis (MS), there remains a need for highly efficacious targeted therapy with a favorable benefit-risk profile and attributes that encourage a high level of treatment adherence. Daclizumab is a humanized monoclonal antibody directed against CD25, the α subunit of the high-affinity interleukin 2 (IL-2) receptor, that reversibly modulates IL-2 signaling. Daclizumab treatment leads to antagonism of proinflammatory, activated T lymphocyte function and expansion of immunoregulatory CD56(bright) natural killer cells, and has the potential to, at least in part, rectify the imbalance between immune tolerance and autoimmunity in relapsing MS. The clinical pharmacology, efficacy, and safety of subcutaneous daclizumab have been evaluated extensively in a large clinical study program. In pivotal studies, daclizumab demonstrated superior efficacy in reducing clinical and radiologic measures of MS disease activity compared with placebo or intramuscular interferon beta-1a, a standard-of-care therapy for relapsing MS. The risk of hepatic disorders, cutaneous events, and infections was modestly increased. The monthly subcutaneous self-injection dosing regimen of daclizumab may be advantageous in maintaining patient adherence to treatment, which is important for optimal outcomes with MS disease-modifying therapy. Daclizumab has been approved in the US and in the European Union and represents an effective new treatment option for patients with relapsing forms of MS, and is currently under review by other regulatory agencies.

Therapeutic protein-drug interaction assessment for daclizumab high-yield process in patients with multiple sclerosis using a cocktail approach

AIMS

To characterize the potential effect of daclizumab high-yield process (DAC HYP), a monoclonal antibody that blocks the high-affinity interleukin-2 receptors for treatment of multiple sclerosis, on activity of cytochrome P450 (CYP) enzymes.

METHODS

Twenty patients with multiple sclerosis received an oral cocktail of probe substrates of CYP1A2 (caffeine 200 mg), CYP2C9 (warfarin 10 mg/vitamin K 10 mg), CYP2C19 (omeprazole 40 mg), CYP2D6 (dextromethorphan 30 mg) and CYP3A (midazolam 5 mg) on two sequential occasions: 7 days before and 7 days after subcutaneous administration of DAC HYP 150 mg every 4 weeks for three doses. Serial pharmacokinetic blood samples up to 96 h post dose and 12-h urine samples were collected on both occasions. Area under the curve (AUC) for caffeine, S-warfarin, omeprazole and midazolam, and urine dextromethorphan to dextrorphan ratio were calculated. Statistical analyses were conducted on log-transformed parameters using a linear mixed-effects model.

RESULTS

The 90% confidence intervals (CIs) for the geometric mean ratio (probe substrate with DAC HYP/probe substrate alone) for caffeine AUC from 0-12 h (0.93-1.15), S-warfarin AUC from 0 to infinity (AUC[0-inf]) (0.95-1.06), omeprazole AUC(0-inf) (0.88-1.13) and midazolam AUC(0-inf) (0.89-1.15) were within the no-effect boundary of 0.80-1.25. The geometric mean ratio for urine dextromethorphan to dextrorphan ratio was 1.01, with the 90% CI (0.76-1.34) extending slightly outside the no-effect boundary, likely due to high variability with urine collections and CYP2D6 activity.

CONCLUSIONS

DAC HYP treatment in patients with multiple sclerosis had no effect on CYP 1A2, 2C9, 2C19, 2D6 and 3A activity.

A monoclonal natural human IgM protects axons in the absence of remyelination

BACKGROUND

Whereas demyelination underlies early neurological symptoms in multiple sclerosis (MS), axonal damage is considered critical for permanent chronic deficits. Intracerebral infection of susceptible mouse strains with Theiler's murine encephalomyelitis virus (TMEV) results in chronic induced demyelinating disease (TMEV-IDD) with progressive axonal loss and neurologic dysfunction similar to progressive forms of MS. We previously reported that treatment of chronic TMEV-IDD mice with a neurite outgrowth-promoting natural human antibody, HIgM12, improved brainstem NAA concentrations and preserved functional motor activity. In order to translate this antibody toward clinical trial, we generated a fully human recombinant form of HIgM12, rHIgM12, determined the optimal in vivo dose for functional improvement in TMEV-IDD, and evaluated the functional preservation of descending spinal cord axons by retrograde labeling.

FINDINGS

SJL/J mice at 45 to 90 days post infection (dpi) were studied. A single intraperitoneal dose of 0.25 mg/kg of rHIgM12 per mouse is sufficient to preserve motor function in TMEV-IDD. The optimal dose was 10 mg/kg. rHIgM12 treatment protected the functional transport in spinal cord axons and led to 40 % more Fluoro-Gold-labeled brainstem neurons in retrograde transport studies. This suggests that axons are not only present but also functionally competent. rHIgM12-treated mice also contained more mid-thoracic (T6) spinal cord axons than controls.

CONCLUSIONS

This study confirms that a fully human recombinant neurite outgrowth-promoting monoclonal IgM is therapeutic in a model of progressive MS using multiple reparative readouts. The minimum effective dose is similar to that of a remyelination-promoting monoclonal human IgM discovered by our group that is presently in clinical trials for MS.