**5. Anticytokine monoclonal antibodies**

262 Autoimmune Disorders – Current Concepts and Advances from Bedside to Mechanistic Insights

days apart. The incidence of adverse events and laboratory abnormalities was similar among the belimumab and placebo groups. A significant reduction in the median percentage of CD20+ B-cells was noted with a one and two doses of belimumab versus

Wallace et al. assessed the safety, tolerability, biological activity, and efficacy of belimumab in combination with standard of care therapy in patients with active SLE (Wallace, Stohl et al. 2009). In this phase II, randomized trial 449 patients with SELENA-SLEDAI score ≥ 4 were randomly assigned to belimumab (1, 4, 10 mg/kg) or placebo in a 52-week study. In this study, belimumab treatment did not result in significant improvement compared with placebo. Percentage change in the SELENA-SLEDAI score at week 24, the primary endpoint of the study, was similar in both arms (19.5% in the belimumab group versus 17.2% in the placebo group). There was no significant difference in time to first SFI-defined flare over 52 weeks between the belimumab and placebo groups (67 versus 83 days, respectively). However, the median time to first SLE flare during weeks 24–52 was significantly longer with belimumab treatment (154 versus 108 days; P=0.0361). During the 52-week study and 8-week follow-up period, the incidence of AEs were similar in all treatment groups, including placebo. Only

urticaria was statistically more frequent in belimumab-treated patients (4% versus 0%).

day were reported in four patients.

(ClinicalTrials.gov Identifier: NCT01205438).

**4. Monoclonal antibodies inhibiting T cell costimulation** 

**3.2.2 LY2127399** 

The efficacy and safety of belimumab in patients with active SLE was also assessed in a large, randomized, multicenter study recently reported by Navarra et al 2011 (Navarra, Guzmán et al. 2011). In this trial, 865 patients with scores of at least 6 on the Safety of Estrogens in Lupus Erythematosus National Assessment-Systemic Lupus Erythematosus Disease Activity Index (SELENA-SLEDAI) were randomly assigned to belimumab 1 mg/kg or 10 mg/kg, or placebo by intravenous infusion in 1 h on days 0, 14, and 28, and then every 28 days until 48 weeks, with standard of care. Significantly higher Systemic Lupus Erythematosus Responder Index (SRI) rates were noted with belimumab 1 mg/kg (51%, P=0.0129) and 10 mg/kg (58%, p=0.006) than with placebo (44%) at week 52. In addition, more patients had SELENA-SLEDAI score reduced by at least 4 points during 52 weeks with belimumab 1 mg/kg (53%, P=0.0189) and 10 mg/kg (58%, P=0.0024) than with placebo (46%). Moreover, more patients receiving belimumab 1 mg/kg (78%, P=0.1064) and 10 mg/kg (81%, P=0.0181) had no new BILAG A or no more than 1 new B flare than did those receiving placebo (73%). There was no difference in rates of adverse events in patients given belimumab 1 mg/kg and 10 mg/kg, and placebo. Serious infection was noted in 8%, 4%, and 6% patients, respectively. Severe or serious hypersensitivity reactions on an infusion

Anti-BAFF monoclonal antibody LY2127399 (Eli Lilly & Company Limited) is a fully human IgG4 antibody with neutralizing activity against both membrane-bound and soluble BAFF. This may reduce the activity, proliferation and survival of B-cells. The ongoing study evaluates the efficacy, safety and tolerability of two different doses of LY2127399 administered in addition to standard of care therapy in patients with active SLE

Cytotoxic lymphocyte-associated antigen-4 (CTLA-4) is a potent inhibitor of the costimulation pathway necessary to activate T cells. Abatacept (CTLA-4 immunoglobulin; CTLA4-Ig,

placebo. However, SLE activity did not change after treatment with this mAb.

In the course of SLE, a wide variety of cytokines is dysregulated, many of which are likely to influence autoimmunity and lupus tissue inflammation (La Cava. 2010; Robak, Kulczycka et al. 2007). They are not only involved in the immune dysregulation of SLE, but also in the local inflammatory response which ultimately leads to tissue injury. Proinflammatory cytokines such as tumor necrosis factor (TNF), iterleukin-6 (IL-6), IL-1 and interferon- (IFN-) may play an important role in propagating the inflammatory process responsible for tissue damage. IL-12, IL-15 and IL-18 are probably also involved in pathogenesis of SLE. The possibility of blocking the proinflammatory cascade by selective inactivation of cytokines can be a successful therapy for patients with SLE.

#### **5.1 Anti-IL-6 monoclonal antibodies**

Data from several studies suggests that IL-6 plays an important role in the B-cell hyperactivity and immunopathology of SLE (Klashman, Martin et al. 1991). One of the most important effects of IL-6 is to induce the maturation of B lymphocytes into plasma cells and augment the imunoglobulin secretion. IL-6 binds to the IL-6 receptors which belong to the type 1 cytokine receptor superfamily that consists of two subunits, namely the IL-6 R and the gp 130. This cytokine may have a direct influence in mediating tissue damage. Elevated levels of IL-6 were detected in the serum, urine and renal glomerulli of patients with active SLE and in murine models of SLE (Grondal, Gunnarsson et al. 2000).

Tocilizumab (ACTEMRA, MRA, Roche Pharmaceuticals) is a humanized anti-human IL-6R mAb considered as a therapeutic option for patients with SLE. It is an antibody which inhibits the interleukin-6 receptor. It binds to both soluble IL-6R and transmembrane IL-6R

The Emerging Role of Monoclonal Antibodies in the Treatment of Systemic Lupus Erythematosus 265

prednisone were used. The study indicates that the use of IL-10 antagonists may be beneficial

CD40, a member of the tumor necrosis factor receptor super family, is highly expressed in normal B-cells and a variety of B-cell malignancies. CD40 ligand, also called CD154 or gp39, is a protein expressed on activated CD4+ T cells as well as on platelets, mast cells, macrophages, basophils, NK cells and B lymphocytes. An increased expression of CD40L has been found in the peripheral lymphocytes of patients with active SLE (Devi, Van Noordin et al. 1998). Moreover, serum levels of CD154 (CD40L) are higher in lupus patients than in normal persons (van Kooten & Banchereau 2000). The high expression of CD154 on T and B cells may increase production of potentially harmful auto-antibodies. The results of preclinical studies indicate that lupus-prone mice treated with anti-CD40L Abs had diminished inflammation, reduced anti-DNA autoantibody production and prolonged survival. Prolonged administration was particularly helpful in preventing fibrosis in severely nephritic mice (Kalled, Cutler et al. 2001). These results prompted the testing of

Two mAbs directed against CD40 have been developed and investigated in preclinical studies and clinical trials, lucatumumab (HCD122) and dacetuzumab (SGN-40) (Kelley,

Lucatumumab ((HCD122, CHIR-0.12.12; Novartis Pharmaceuticals) is a fully human anti-CD40 mAb directed against the B-cell surface antigen CD40. It blocks CD40/CD40L interactions *in vitro* and inhibits CD40L-induced proliferation of human peripheral blood lymphocytes without disturbing baseline lymphocyte proliferation. Lucatumumab triggers

Dacetuzumab (Seattle Genetics, Inc), is another humanized anti-CD40 IgG1 mAb, which induces ADCC and apoptosis of normal and malignant B-cells (Kelley, Gelzleichter et al. 2006). Dacetuzumab is able to initiate multiple signalling cascades upon ligation of CD40 on NHL cell lines. Dacetuzumab-mediated cytotoxicity is associated with up-regulation of cytotoxic ligands of the tumor necrosis factor (TNF) family including Fas/FasL, TNF-related

IDEC-131/E6040 (Idec Pharmaceuticals Corp. San Diego) is a humanized mAb against human CD154, comprising human 1 heavy chains and human light chains with complementarity-determining regions of murine mAb clone 24-31. In Phase I clinical trial, IDEC-131 was administered in a single intravenous infusion at doses of 0.05-15.0 mg/kg in patients with SLE. Patients were followed for 3 months to evaluate toxicity and

cell lysis via ADCC in cells overexpressing CD40 (Luqman, Klabunde et al. 2008).

in the management of refractory SLE.

anti-CD40L mAbs in human SLE.

Gelzleichter et al. 2006).

**6.1.1 Lucatumumab** 

**6.1.2 Dacetuzumab** 

**6.2.1 IDEC-131** 

**6.1 Anti-CD40 monoclonal antibodies** 

apoptosis-inducing ligand, and TNFalpha.

**6.2 Anti-CD40L monoclonal antibodies** 

**6. Anti-CD40 and anti-CD40L monoclonal antibodies** 

and inhibit IL-6 binding to its receptors, leading to the blockade of IL-6 signaling through both receptors (Jones and Ding 2010). Tocilizumab suppresses the biological activity of IL-6 and is now being used in clinical trials for RA and SLE (ClinicalTrials.gov Identifier: NCT00046774). An intraperitoneal administration of an anti-IL-6 mAb decreased the production of anti-ds DNA antibodiess in murine model of SLE and prevented the development of severe kidney disease. These results suggest that treatment with anti-IL-6 mAb has a beneficial effect on autoimmunity in murine SLE and that autoreactive B cells may be the primary target for anti-IL-6 antibody treatment (Liang, Gardner et al. 2006).

Tocilizumab is an effective agent in all the stages of RA (Jones, Sebba et al. 2010). Tocilizumab is the first agent that has been shown to be superior to methotrexate (MTX) as monotherapy for the signs and symptoms of this disease. It is also an active drug in SLE patients. Tocilizumab when used in mild to moderate lupus patient has demonstrated preliminary success and good tolerability in an open-label phase I dosage-escalation study (Illei, Shirota et al. 2010). In this trial 16 patients with mild-to-moderate disease activity were assigned to receive 1 of 3 doses of tocilizumab given intravenously every other week for total of 7 infusions: 2 mg/kg in 4 patients, 4 mg/kg in 6 patients, or 8 mg/kg in 6 patients. Patients were then monitored for an additional 8 weeks. The median decrease in anti-dsDNA antibody levels at week 14 was −9 IU/ml (P = 0.03). There was improvement in overall disease activity over the course of treatment. Mean SLAM scores decreased from 7.1 at baseline to 5.0 at week 14 (P = 0.002), and mean mSELENA–SLEDAI scores decreased from 9.5 to 5.5 (P = 0.001). In addition, there was no SLE flare during the treatment period. The infusions were well tolerated, without any clinically significant infusion reactions. However, the treatment induced dosage-related decreases in the absolute neutrophil count, with a median decrease of 38% in the 4 mg/kg dosage group and 56% in the 8 mg/kg dosage group. Infections were observed in 11 patients between the start of study treatment and the end of the follow up period. This study provides the first evidence that treatment with tocilizumab has an acceptable safety profile and suggests a possible immunologic and clinical benefit in SLE.

#### **5.2 Anti-IL 10 monoclonal antibody**

Interleukin-10 (IL-10) is a cytokine produced mainly by monocytes and lymphocytes. It impedes the activation of antigen presenting cells, down-regulates the expression of costimulatory molecules and blunts T cell activation and TNF-α secretion. IL-10 boosts B cell proliferation and immunoglobulin class switching resulting in enhanced antibody secretion with the capacity to enter extravascular compartments and promote inflammation in SLE (Yap & Lai 2010). The levels of IL-10 increase in the serum of patients with active SLE and correlates with disease activity. Alteration in IL-10 regulation may result in accelerated T-cell apoptosis and aberrant T-cell dependent B-cell function. In animal models of lupus nephritis, anti-IL 10 blockade offered some benefits in limiting renal damage (Ravirajan, Wang et al. 2004). The beneficial effect of a combined therapy using both anti-IL-10 and anti-C5 mAb to prevent or reduce the effect of the humoral immune response in lupus disease was also suggested. Preliminary data has shown that anti-IL-10 monoclonal antibody improved cutaneous lesions, joint symptoms, and SLEDAI in lupus patients (Llorente, Richaud-Patin et al. 2000). The anti-IL-10 monoclonal antibody was administered to six patients with steroid resistant SLE in an open label pilot study. Treatment consisted of an 20 mg/day intravenous administration of an anti-IL-10 murine mAb (B-N10) for 21 consecutive days, with a follow-up period of 6 months. Therapy was well tolerated and marked improvement in skin lesions and joint symptoms was observed in all patients over the next 6 months. Furthermore, three times lower doses of prednisone were used. The study indicates that the use of IL-10 antagonists may be beneficial in the management of refractory SLE.
