RT Journal Article SR Electronic T1 LO-040 The efficacy of tacrolimus in antiphospholipid antibodies associated thrombocytopenia: a prospective cohort study JF Lupus Science & Medicine JO Lupus Sci Med FD Lupus Foundation of America SP A32 OP A34 DO 10.1136/lupus-2023-KCR.41 VO 10 IS Suppl 1 A1 Shi, Yu A1 Zhao, Jiuliang A1 Zeng, Xiaofeng YR 2023 UL http://lupus.bmj.com/content/10/Suppl_1/A32.3.abstract AB Background Thrombocytopenia is a common manifestation associated with the presence of antiphospholipid antibodies (aPLs). A specific guideline for management of aPLs associated thrombocytopenia is still absent.Methods This is a single-center observational prospective study. Patients with aPLs associated thrombocytopenia were recruited. Patients with systemic lupus erythematosus (SLE) related major organ involvement were excluded. Treatment response, adverse effects, bleeding events were monitored.Results A total of 61 patients were enrolled with a median treatment duration of 22 months. The overall response rate in this cohort was 80.3% (n = 49), including 49.2% of complete responses (n = 30) (table 1). Compared to commonly used second line therapy for immune thrombocytopenia like eltrombopag and rituximab, the response rate was similar.2 3 The median time to achieve a response was 3 months (IQR 1, 3). Within the first 3 months, the mean platelet count of patients with overall response elevated continuously (figure 1). A total of 8 (16.3%) patients with a response experienced a loss of response, 12.2% (n = 6) during treatment, the other in the process of tapering. The median duration of response under treatment was 24.5 months (IQR 9.8, 40.3). 11 (18%) patients had a sustained response after the termination of tacrolimus treatment. Patients diagnosed with SLE had a significantly higher rate of achieving overall response (91.3% vs 73.7%). Side effects were reported in 9.8% (n = 6) of the patients in this cohort and treatment was interrupted due to side effects in 3.3% (n = 2) of patients.Conclusions This study suggests that tacrolimus has adequate efficacy and is well tolerated for aPLs associated thrombocytopenia. Patients with mild to moderate SLE might benefit the most from tacrolimus treatment.Abstract LO-040 Figure 1 Percentages and mean platelet count of patients with different treatment response during follow-upView this table:Abstract LO-040 Table 1 Response characteristics of the studied patients