PO:15:222 | Post-hoc analysis of the BeRLiSS-JS registry: efficacy of belimumab on thrombocytopenia

Greta Hulej¹, Margherita Zen¹, Marisol Bracalenti¹, Francesca Bottazzi², Rossella De Angelis³, Giacomo Emmi⁴, Roberto Gerli⁵, Marcello Govoni⁶, Renato Lo Gullo⁷, Simone Negrini⁸, Luca Quartuccio⁹, Maurizio Rossini¹⁰, Carlo Salvarani¹¹, Paola Tomietto⁴, Angelo Vacca¹², Andrea Doria¹, Luca Iaccarino¹. | ¹Università degli Studi di Padova, Padova, Italy; ²Università degli Studi di Pavia, Pavia, Italy; ³Università Politecnica delle Marche, Ancona, Italy; ⁴Università degli Studi di Trieste, Trieste, Italy; ⁵Università degli Studi Perugia, Perugia, Italy; ⁶Università degli Studi di Ferrara, Ferrara, Italy; ⁷Università degli Studi di Catania, Catania, Italy; ⁸Università degli Studi di Torino, Torino, Italy; ⁹Università degli Studi di Udine, Udine, Italy; ¹⁰Università degli Studi di Verona, Verona, Italy; ¹¹Università degli Studi di Modena e Reggio Emilia, Modena, Italy; ¹²Università degli Studi di Bari .

Background. We have seen clear evidence that belimumab is both effective and safe in treating systemic lupus erythematosus (SLE), showing good results across different disease domains. However, when it comes to hematologic manifestations, especially thrombocytopenia, the evidence remains limited.

Aim. To assess the efficacy of belimumab in hematologic manifestations, in particular thrombocytopenia, in a nationwide cohort of patients with SLE.

Methods. This study was based on a multicenter national cohort, involving 14 leading SLE referral centers across Italy. In particular, we enrolled 443 patients (n= 443) who met one of the following classification criteria for SLE: the ACR 1997 revised criteria, the SLICC 2012 criteria, or the EULAR/ACR 2019 criteria. In addition, all participants needed to be on either intravenous (10 mg/kg monthly) or subcutaneous treatment (200 mg weekly) with belimumab and have active disease at the time of enrollment. A positive serology was required, along with either joint or skin involvement. Among them we identified 44 patients with thrombocytopenia, defined as a platelet count <150,000/mm³ (Table 1). The efficacy of belimumab was assessed by evaluating the improvement in mean platelet count and the proportion of patients achieving platelet count normalization. The average daily dose of corticosteroids was also calculated at baseline and every 6 months. Univariate analyses were performed using paired t-tests and ANOVA for repeated measures, with SPSS version 29.

Results. Among patients with thrombocytopenia at baseline, platelet values increased significantly from a mean ± SD baseline value of 110.2±38.1×10⁹/l to 176.6 ± 88.7 ×109/L at 48 months (p=0.004) (Graph 1) and the rate of thrombocytopenic patients decreased to 45% at 48 months. Glucocorticoids users decreased numerically, but not significantly, from a baseline value of 93.2% to 80% at 48 months (Graph 2); specularly, the percentage of low-dose PDN users, defined as a daily dose of prednisone <5 mg, increased from baseline (36.4%) to month 48 (90%); statistical significance was found also at month 6 (68.3%, p=0.001) and month 12 (81.6%, p=0.033). Mean GC dose (expressed as PDN equivalents) declined significantly from a mean ± SD baseline value of 10.8 ± 9.6 mg/d to 4.4 ± 5.5 mg/d at 48 months. During follow up, platelet values did not differ significantly between patients on IS in addition to belimumab compared to those on belimumab alone (p=0.66). Moreover, IS use did not significantly influence platelet value changes during follow up (respectively, p=0.65 and p=0.53) (Graphs 3 and Graph 4).

Conclusion. Add-on therapy with belimumab led to clinical improvement in a significant proportion of patients with thrombocytopenia in a real-life setting. Therapy with belimumab was associated with a glucocorticoid-sparing effect. This effect does not appear to depend on the co-administration of a conventional immunosuppressant.