Objective: To investigate the long-term clinical, histological and serological affects of B-cell-depleting therapy (BCDT) in patients with LN refractory to conventional treatment.
Methods: Twenty-five patients, followed for a mean time of 36 months (9-95 months), were included. Renal disease activity was evaluated with the BILAG index and renal response was determined according to the LN European consensus statement. Renal biopsies were performed for histological evaluation at baseline and follow-up.
Results: Partial response (PR) or complete renal response (CR) was observed in 22 of 25 after a median of 12 months. Sixteen patients achieved CR after a median of 24 months. Six patients experienced a renal relapse. Proteinuria decreased significantly (P = 0.0002) from baseline to 36 months. A noteworthy histological improvement was seen in nearly all patients with a significant reduction in activity index (P = 0.01). Longer depletion time and low baseline values of IgM were indicative of achieving clinical remission during the first year after treatment (P = 0.03 and P = 0.04, respectively).
Conclusion: In therapy-resistant LN, BCDT induced clinical and histological improvements in the majority of patients. Transition from PR to CR was mainly seen during the second year of follow-up. Patients with longer depletion time and low baseline levels of IgM were more likely to gain a faster remission, suggesting that the clinical benefit may be linked to suppression of autoreactive plasmablasts. Although formal evidence of BCDT in LN is lacking, our data may provide guidance to clinicians considering therapeutic options in patients with refractory LN.