#2244 Safety and efficacy of daratumumab monotherapy in lupus nephritis refractory to conventional and rescue therapies
Authors: Roccatello Dario , Caniggia Ilaria , Ceruti Cecilia , Longo Roberta , Nescis Lorenzo , Sciascia Savino , Fenoglio Roberta 
Published: May 2024

Abstract

Background and Aims
Refractory lupus nephritis (LN) is defined as either no response to standard of care (SOC), i.e., failure to improve within 3–4 months or not achieving partial response within 12 months or complete response after 2 years of treatment. This condition is characterized by poor outcome, is often life-threatening, and represents a relatively unexplored clinical setting.
A dysregulation of CD38 expression has been reported in Systemic lupus Erythematosus, and highly expressing CD38 plasma cells relegated in bone marrow niches inaccessible to conventional and biological agents could represent a source of repowering of the immune dysregulation. The efficacy and safety of daratumumab, a monoclonal antibody specifically directed at CD38, given without any other immunosuppressant or agents targeting B-cell-activating factor, were assessed in a discrete cohort of patients with refractory LN, in whom both SOC and rescue treatments had failed.

Method
Six patients (1 male and 5 females) aged 41.3 years (range 20 to 61 years) were treated with Daratumumab monotherapy. The treatment protocol consisted of 16 mg/kg daratumumab administered intravenously weekly for 8 weeks, then every two weeks 8 more times, and lastly monthly for 8 times. All patients had failed previous treatments with both SOC including either mycophenolate mofetil or cyclophosphamide-azathioprine, and rescue therapies including Rituximab, Ocrelizumab, Belimumab, and iv IgG.

Results
One out of six patients did not show clinical response after 6 months of therapy, and Daratumumab was discontinued. Five patients continued to be treated (total treatment maximum 22 infusions) and reached a 12-month observation.
Renal biopsy performed before daratumumab administration revealed a class IV LN in 1 patient, class V LN in 1 patient, class III+V LN in 1 patient and class IV+V LN in the other 2. Three patients achieved a complete renal response and the other two a partial renal response. A significant decrease in proteinuria from 5.6 g per 24 h to 0.59 g per 24 h, 0.9 g per 24 h and 0.8 g per 24 h (P = 0.0010) at 3 months, 6 months and 12 months, respectively, was observed. The mean value of serum Creatinine (sCr) decreased from 2.3 to 1.5 mg/dl. The mean value of sCr decreased from 2.3 mg dl−1 to 1.5 mg/dl (P = 0.98) at 12 months. C3 and C4 levels increased from 72.8 (range, 0–99) to 101.6 (range, 78.0–135) mg/dl (P = 0.16) and from 9.4 (range, 5–14) to 20.4 (range, 13–30) mg/dl (P = 0.0182), respectively. A decrease in IgG mean levels from 971.7 mg dl−1 (range, 251–1546) to 512.3 mg/dl (range, 88–957), 481.7 (range, 84–878) mg/dl and 508.4 mg/dl (range, 192–685) at 3 months, 6 months and 12 months, respectively, was observed.
Improvement of clinical symptoms was paralleled by seroconversion of anti-double-stranded DNA antibodies (p = 0.03), significant decrease in interferon-gamma values (p = 0.0006), BMCA-B-cell maturation antigen (p = 0.0005) and soluble CD163 levels (p = 0.045), and IL 10 levels (p = 0.0006). Clinical remission was substantiated by improvement of SLEDAI-2K score (p = 0.03). Daratumumab was generally well tolerated.

Conclusion
These data suggest that Daratumumab administered alone (i.e., without any other immunosuppressant or agents targeting B-cell activating factor) is highly effective in refractory LN. The multifaced effects of Daratumumab on the inflammatory burden and the interferon gamma profile could provide a restoration of the immune balance.