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

OBJECTIVE: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.