This retrospective single-center cohort study included 25 MN patients treated at the Department of Nephrology, Qilu Hospital of Shandong University, from April 2023 to April 2024. Inclusion criteria: (1) Adults aged 18–80 years; (2) Biopsy-proven MN or serum anti-PLA₂R antibody titer ≥14 RU/mL by ELISA; (3) Completion of ≥ 1 zuberitamab treatment cycle (mono- or combination therapy); (4) Follow-up time of no less than 12 months. Exclusion criteria: (1) Concurrent experimental drug use; (2) Uncontrolled conditions causing acute renal impairment; (3) Active malignancies; (4) Acute or chronic infections; (5) Comorbid autoimmune disorders; (6) Known drug hypersensitivity; (7) Pregnancy or lactation. This study has been approved by the Ethics Committee of Qilu Hospital of Shandong University.

Propensity scores were generated using a logistic regression model that included the following covariates: age, sex, baseline uPCR, baseline eGFR and baseline serum albumin level. One-to-one matching was performed using the nearest-neighbor algorithm without replacement, with a caliper width set to 0.2 of the standard deviation of the logit of the propensity score. Balance between the matched groups was assessed using standardized mean differences, with all covariates achieving a balance of < 0.1 after matching, indicating adequate balance. We concurrently collected clinical data from 25 PMN patients who received at least one dose of RTX treatment during the study period. All 50 enrolled patients completed a minimum 12-month follow-up.

All patients received zuberitamab therapy under inpatient supervision. The recommended dosage was 375 mg/m² body surface area (BSA). The specific infusion schedule (either 4×0.5g or 2×1g, both biweekly) and treatment intervals were determined through shared decision-making, incorporating established anti-CD20 protocols for PMN and individual clinical assessment. The use of concomitant immunosuppressants was at the treating physician’s discretion, based on the patient’s proteinuria severity and immunological profile. Following aseptic preparation, the calculated dose was reconstituted in 0.9% normal saline within a sterile, endotoxin-free infusion bag to achieve a final concentration of 1 mg/mL. Premedication included intravenous dexamethasone (5 mg) and intramuscular promethazine (25 mg). Infusions were initiated at 50 mg/hr, with incremental rate escalations of 50 mg/hr every 30 minutes (following an uneventful first hour) up to a maximum of 400 mg/hr, contingent upon tolerance assessment.

We evaluated clinical and laboratory parameters including complete blood count, liver/kidney function, anti-PLA₂R antibody titers, uPCR, and lymphocyte subsets at baseline (first treatment day with zuberitamab or RTX) and during follow-up visits. The data was collected retrospectively at 1, 3, 6, 9, and 12 months post-treatment. Due to financial constraints, lymphocyte count data were unavailable for six patients. Adverse events (e.g., acute infusion reactions, infections, pyrexia, cutaneous eruptions) were systematically documented and assessed by clinicians for severity and treatment-relatedness.

Clinical outcomes were the incidence of remission of proteinuria, including complete remission (CR), partial remission (PR) and nonresponse according to established criteria. The primary endpoint was the overall remission rate (CR + PR) at 12-month. CR was defined as uPCR <300 mg/g, serum albumin ≥30 g/L, and stable renal function without deterioration (15). PR was defined as uPCR between 300–3500 mg/g with ≥50% reduction from peak levels, accompanied by improved or normal serum albumin levels or stable serum creatinine (<30% increase from baseline) (15). Patients who did not meet these criteria were considered nonresponse.

Immunological outcomes were exclusively evaluated in PLA₂R-associated MN patients. Immunological remission was defined as serum anti-PLA₂R antibody (A-PLA₂R) titers <14 RU/ml, measured by enzyme-linked immunosorbent assay (ELISA) (16). Immunological complete remission was defined as A-PLA₂R <2 RU/ml (16). B cell depletion was defined as peripheral blood CD19⁺ B cell counts <5 cells/µl, monitored by flow cytometry (15).

Safety outcomes encompassed all adverse events occurring during monoclonal antibody administration and throughout the entire follow-up period. Adverse events were systematically analyzed, including incidence rates, specific nomenclature of serious adverse events, temporal occurrence patterns, and severity grading.

Normality of continuous variables was assessed using the Shapiro-Wilk test. Normally distributed data were expressed as mean ± standard error (SE) and analyzed using independent or paired t-tests. Non-normally distributed variables were presented as median (interquartile range [IQR]) with Mann-Whitney U or Wilcoxon signed-rank tests for comparisons. Categorical variables were reported as frequencies (percentages) and analyzed by chi-square test or Fisher’s exact test, as appropriate based on sample size and expected frequencies. Survival analysis for remission rates was performed using Kaplan-Meier curves with log-rank testing. All analyses were conducted using GraphPad Prism 8.0.2 (GraphPad Software, USA) and SPSS 25.0 (IBM Corp., USA), with statistical significance defined as two-tailed p<0.05.

This retrospective analysis evaluated 30 patients with immune-mediated glomerular diseases treated with zuberitamab at Qilu Hospital of Shandong University (April 2023-April 2024). After applying stringent inclusion/exclusion criteria, we excluded 5 patients for non-PMN glomerulonephritis diagnoses. The final cohort comprised 25 PMN patients (zuberitamab group). Using 1:1 propensity score matching, we selected 25 matched PMN controls treated with RTX (RTX group) during the identical observation period (Figure 1).

The median ages of the zuberitamab and RTX group were 59.0 (47.0-68.0) and 54.0 (43.5-60.0) years, respectively (P = 0.237). At baseline, the median uPCR was 6.8 (4.8-10.0) vs 5.6 (3.8-8.1) g/g (P = 0.286); the mean serum albumin was 28.8 ± 8.9 vs 30.7 ± 7.8 g/L (P = 0.418); the median serum creatinine was 82.0 (61.0-99.0) vs 80.0 (71.5-98.0) μmol/L (P = 0.637); the mean eGFR was 85.4 ± 32.2 vs 91.5 ± 22.7 mL/min/1.73m² (P = 0.439); the median A-PLA₂R was 52.6 (7.7-203.9) vs 62.3 (11.9-84.2) RU/mL (P = 0.821); and the mean peripheral blood CD19⁺ B cell counts were 312.1 ± 55.6vs 330.2 ± 35.4 cells/μL (P = 0.786). Both groups contained 11 anti-PLA₂R-positive patients. The dosing regimens between the two groups were comparable (all P>0.05) (Table 1).

Zuberitamab treatment induced progressive and sustained reductions in uPCR from month 1 onward (all P<0.001 versus baseline; Figure 2A). Concurrently, serum albumin levels demonstrated significant improvement beginning at month 3 (P<0.05), with progressively greater increases at subsequent timepoints (P<0.001 at 6/9/12 months; Figure 2B). Renal function parameters remained stable throughout follow-up, with neither serum creatinine nor eGFR showing clinically significant deviations from baseline values (Figures 2C, D).

Among the 11 baseline anti-PLA₂R-positive patients, antibody titers demonstrated a progressive temporal decline: 18.6 RU/mL (IQR, 9.1-21.3) at 1 month, 2.0 RU/mL (2.0-10.3) at 3 months, 2.0 RU/mL (2.0-3.3) at 6 months, and 2.3 ± 1.1 RU/mL (mean ± SD) at 9 months, with all patients achieving complete immunological remission (titer <2 RU/mL) by 12 months. These changes demonstrated statistically significant reductions from baseline at all evaluated timepoints (all P<0.001; Figure 2E).

In the 22 patients with complete follow-up data, peripheral blood CD19⁺ B-cell counts exhibited rapid and sustained depletion, decreasing to 0.0 cells/μL (IQR, 0.0-2.0) by month 1 and maintaining suppression throughout follow-up (3-month: 2.0 [1.0-6.0]; 6-month: 2.0 [1.0-3.0]; 9-month: 1.0 [0.8-15.8]; 12-month: 1.0 [0.0-60.0]). All patients achieved protocol-defined depletion (<5 cells/μL) by 6 months, with counts remaining significantly below baseline at all timepoints (all P<0.001; Figure 2F).

The zuberitamab group demonstrated 100.0% clinical remission (CR+PR) at 12 months, with 80.0% (20/25) achieving CR. Comparatively, the RTX group showed 96.0% (24/25) clinical remission, but only 32.0% CR. While overall remission rates did not differ significantly between groups (P = 1.000), zuberitamab yielded significantly higher complete remission rates (80.0% vs 32.0%, P<0.01; Table 2). Conversely, the PR rate was lower in the zuberitamab group (P<0.01), which is consistent with the shift of a greater proportion of patients achieving the higher response category (CR). It is noteworthy that, despite the favorable remission rates observed in the zuberitamab cohort, the findings should be interpreted with caution given the modest cohort size (n=25) and the single−center, observational design.

The Kaplan-Meier analysis revealed a significantly shorter time to overall response in the zuberitamab group compared to the RTX group (log-rank P<0.01; HR = 1.738; 95% CI [1.160-2.604]; Figure 3A). Furthermore, zuberitamab was associated with a higher complete response rate (log-rank P<0.001; HR = 4.187, 95% CI [2.285-7.672]; Figure 3B).

This study evaluated immunologic outcomes only in the 22 patients (11 in each treatment group) who were anti-PLA₂R-positive at baseline. At 6 months, all patients in the zuberitamab group achieved immunologic remission, with 9 patients (81.8%) reaching complete immunologic remission (A-PLA₂R < 2 RU/mL). In the RTX group, all 11 patients also achieved immunologic remission, with 8 patients (72.7%) reaching complete immunologic remission. At 12 months, all 22 patients achieved complete immunologic remission. No intergroup differences in remission rates were observed during follow-up (P = 1.000; Table 2).

Throughout the follow-up, the zuberitamab group maintained significantly lower UPCR than the RTX group (all P<0.05). At month 1, median UPCR was 2.43 (0.77-6.40) g/g with zuberitamab versus 4.75 (2.83-6.85) g/g with RTX (P<0.05). The benefit widened over time. By month 6, median UPCR reached 0.82 (0.29-1.99) g/g versus 2.44 (1.60-3.66) g/g (P<0.01). At month 12, zuberitamab achieved 0.11 (0.06-0.23) g/g compared to 1.41 (0.27-1.94) g/g with RTX (P<0.001) (Figure 4A).

Follow-up data showed no statistically significant intergroup differences in multiple parameters: serum albumin, serum creatinine, eGFR, A-PLA₂R titers, NK cell counts, or CD3⁺ T-cell counts (all P>0.05; Figures 4B–G).

Flow cytometry analysis demonstrated more profound early CD19⁺ B-cell depletion with zuberitamab versus RTX at 1 month (0.0 [0.0-2.0] vs 17.5 [3.0-53.3] cells/μL; P<0.001). During subsequent follow-up, no statistically significant differences in B-cell counts were observed between the two groups (all P>0.05; Figure 4H).

Both treatment groups demonstrated comparable safety profiles. One patient (4.0%) in each group experienced CTCAE grade 1 chills and fever during antibody administration. These mild infusion-related reactions resolved with temporary infusion interruption and physical cooling, without sequelae (Table 3). No other prespecified safety events—including infections, neutropenia, or hepatorenal dysfunction—were reported. It is important to note that in this retrospective study, routine surveillance of serum immunoglobulin levels (IgG, IgA, IgM) was not systematically performed. Key laboratory parameters (e.g., leukocytes, neutrophils, PCT, Hb, PLT, liver enzymes) remained stable and comparable between groups (all P>0.05; Figure 5). The study recorded no serious adverse events, malignancies, or deaths.