Comparative effectiveness and predictors of SRI-4 and LLDAS attainment in active systemic lupus erythematosus: a real-world study of telitacicept versus belimumab.

To compare the attainment of Systemic Lupus Erythematosus Responder Index 4 (SRI-4) and lupus low disease activity state (LLDAS) between telitacicept and belimumab in patients with active systemic lupus erythematosus (SLE), and to identify baseline clinical predictors of treatment response. This retrospective observational cohort study was conducted at a single center in China between 2020 and 2024. A total of 115 patients with active SLE received either telitacicept (n = 60, 80 mg or 160 mg weekly) or belimumab (n = 55, 10 mg/kg every 4 weeks) alongside standard therapy. The primary outcome was the SRI-4 response rate at week 24. Baseline predictors were identified using LASSO and multivariable Cox proportional hazards models. Telitacicept demonstrated a significantly higher early SRI-4 response at week 4 (16.7% [10/60] vs. 3.6% [2/55]; OR 5.30, 95% CI 1.11-25.39, P = 0.037). At week 24, the SRI-4 response was 56.7% (34/60) for telitacicept compared to 40.0% (22/55) for belimumab (OR 1.96, 95% CI 0.93-4.12, P = 0.075). Univariate Cox analysis indicated a superior cumulative SRI-4 incidence for telitacicept (HR 3.03, 95% CI 1.30-7.08, P = 0.011). Multivariable analysis confirmed baseline SLEDAI-2 K (HR 1.29, 95% CI 1.17-1.42, P = 0.001) and serum albumin levels (HR 1.16, 95% CI 1.08-1.24, P = 0.001) as independent predictors of SRI-4 achievement. The incidence of total adverse events was comparable between the telitacicept and belimumab groups (38.3% [23/60] vs. 34.6% [19/55], P = 0.675). In clinical practice, telitacicept is associated with earlier SRI-4 attainment compared to belimumab in patients with active SLE. Baseline disease activity scores and serum albumin levels are key prognostic markers for achieving therapeutic response. Key Points • Telitacicept is associated with a significantly more rapid attainment of the SRI-4 response compared to belimumab in patients with active systemic lupus erythematosus in a real-world setting. • Baseline SLEDAI-2 K scores and serum albumin levels are identified as independent predictors for achieving early therapeutic responses. • The two BAFF/APRIL inhibitors exhibit distinct hematological impacts: telitacicept significantly improves hemoglobin levels, while belimumab is more effective at increasing platelet counts. • A higher dose of telitacicept (160 mg) may facilitate superior long-term attainment of the lupus low disease activity state (LLDAS) compared to the standard dose.