#2748 Combined rituximab and daratumumab treatment in difficult to treat nephrotic syndrome cases
Authors: Bigatti Carolina , Cravedi Paolo , Ghiggeri Gian Marco , Angeletti Andrea 
Published: May 2024

Abstract

Background and Aims
Common treatments for multidrug-resistant and multidrug-dependent nephrotic syndrome (NS) are inconsistently effective and burdened by long-term toxicities. Moreover, affected patients are at high risk of progression to end-stage kidney failure.

Objective
To test the safety/efficacy profile of combined single infusion of rituximab and daratumumab in inducing proteinuria remission in multidrug resistant nephrotic syndrome and maintaining drug free disease remission in patients with multidrug-dependent nephrotic syndrome after removal of oral immunosuppression.

Method
We here present a Phase 2 Proof-of-Concept single-arm clinical trial, that enrolled consecutive participants at the Nephrology Unit of the IRCCS Giannina Gaslini Children's Hospital in Genoa, Italy, between September 2021 and March 2023. Enrolled patients, aged between 3 and 24 years, were multidrug-dependent or multidrug-resistant nephrotic syndrome for at least 12 months before enrolment. Multidrug-dependency was defined by the need of at least 2 oral immunosuppressive drugs (prednisone and/or calcineurin inhibitors and/or mycophenolate mofetil) and by the occurrence of at least two consecutive relapses on two immunosuppressive drugs. Multidrug-resistance nephrotic syndrome was defined by the lack of antiproteinuric effect of a double immunosuppressive therapy. Exclusion criteria included genetic forms of NS and administration of monoclonal therapies in the last 9 months before enrolment.
Interventions: Rituximab and daratumumab were administered as single doses at 375 mg/m2 and 16 mg/kg, respectively, 15 days apart.
Main Outcomes and Measures:Proteinuria, serum albumin, Immunoglobulin M and G, B and T lymphocyte subsets, safety, Quality of Life.

Results
A total of 7 consecutive multidrug-resistant and 16 multidrug-dependent NS, respectively, were enrolled. In multidrug-resistant NS, combined rituximab and daratumumab promoted complete or partial remission in 6 patients (Fig. 1A). Five subjects experienced proteinuria relapse, that was effectively treated with a second course of combined treatment. Decreased of I'm, but not IgG, correlated with improvement of proteinuria (Fig. 1B).These treatment allowed to reduce the chronic immunosuppressive treatment daily administered (Fig. 1C). In multidrug-dependent NS, combined rituximab and daratumumab extended the relapse-free time, allowing us to remove oral immunosuppressant (Fig. 1D). Disease relapse was invariably anticipated by a recovery of circulating IgM:patients with IgM levels below median values measured at 3 mo post-treatment had a significantly lower rate of relapse at 9 mo than patients with higher IgM levels at 3 mo (Fig. 1E). Combined treatment induced significative reduction of CD38+ plasma cells (Fig. 1F) and IgM, but not IgG.
Treatment was well tolerated and significantly increased quality of life.

Conclusion
Combined rituximab and daratumumab was safe and effective in the treatment of complicated forms of NS, offering a new therapeutic option for this severe condition.