MO007A PHASE 1B MULTIPLE ASCENDING-DOSE STUDY OF A CD6 TARGETED THERAPY, ITOLIZUMAB, IN SUBJECTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS WITH OR WITHOUT ACTIVE PROLIFERATIVE LUPUS NEPHRITIS

Background and Aims Lupus nephritis (LN) is a leading cause of morbidity and mortality in systemic lupus erythematosus (SLE) patients. T cells are believed to play a central role in the pathogenesis of both SLE and LN. CD6 is a co-stimulatory receptor, predominantly expressed on T cells, that binds to activated leukocyte cell adhesion molecule (ALCAM), a ligand expressed on antigen presenting cells and various epithelial and endothelial tissues. The CD6-ALCAM pathway plays an integral role in modulating T cell activation, proliferation, differentiation and trafficking, and is central to immune mediated inflammation. Itolizumab (EQ001) is a humanized IgG1 monoclonal antibody that binds CD6, blocks the interaction between CD6 and ALCAM, and inhibits both the activation and trafficking of T cells. Inhibiting the CD6-ALCAM pathway with itolizumab potentially represents a promising therapeutic approach for the treatment of LN. The aim of this study is to assess the safety and tolerability, pharmacokinetics, pharmacodynamics, and clinical activity of subcutaneously administered itolizumab in patients with SLE with and without active proliferative lupus nephritis (apLN). Method This cohort-based dose escalation study includes two types of patients: The Type A cohort will enroll ∼24 patients with SLE without apLN (all treated with itolizumab) and the Type B cohort will randomize in a blinded manner ∼36 patients (3:1, itolizumab:placebo) with biopsy-proven ISN/RPS class III or IV (+ V) apLN who have had inadequate response to induction and/or post-induction maintenance treatment, exhibiting urine protein to creatinine ratio [UPCR] ≥1 g/g and active serology. Within both the Type A and Type B cohorts, up to 4 dose groups will be tested (Figure). Background treatments for SLE or LN are allowed. Following 4 weeks of treatment in a new higher dose Type A cohort and recommendation by an independent safety data review committee (DRC), the dose studied in the Type A cohort may then be studied in a Type B Cohort for a 12-week treatment duration (Figure). The primary endpoint is the safety and tolerability of itolizumab. Efficacy endpoints (in the Type B cohorts) include UPCR, estimated glomerular filtration rate, prednisone dose requirements, renal response, Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K), FACIT Fatigue Scale, serologic markers, and other patient reported outcomes. In Type A cohort patients, clinical responses and pharmacologic activity will be assessed based on changes in serologic markers, SLEDAI-2K, FACIT Fatigue Scale. Pharmacodynamic markers, including markers that may allow future risk stratification, urinary ALCAM and CD6, will be examined in both cohort types. Results The study is ongoing. Six patients have been enrolled in Type A Cohort 1 (0.4 mg/kg dose) and completed both treatment and 4 weeks of post-treatment follow-up. The mean age was 59.5 (12.9) years, 100% were female; 67% were Hispanic/Latino; and 50% were White, and 50% were Black. Duration of SLE ranged from 3 years to 31 years. Concomitant medications for lupus included prednisone (83%, dose range 2.5 mg – 10 mg), methotrexate (33%), and anti-malarials (33%). Baseline SLEDAI-2K (mean 7.5 [2.2]) was based on findings of alopecia (83%); arthritis (67%); mucosal ulcers and rash (50% each); fever, increased dsDNA, and low complement (17% each). There were no adverse events. Additional data from this ongoing study will be presented. Conclusion Itolizumab, a monoclonal antibody blocking the CD6-ALCAM pathway, is a novel experimental treatment for LN. This is the first trial of itolizumab in patients with SLE and apLN. Data from the first cohort of patients suggest that the drug is safe and well-tolerated at a dose of 0.4 mg/kg over a 4-week treatment period. Additional cohorts of patients with SLE and apLN are currently being enrolled.