Single low-dose daratumumab enhances rituximab efficacy for sustained remission in treatment-refractory autoimmune cytopenias

Abstract

Treatment-refractory autoimmune cytopenias (AIC) including immune thrombocytopenia (ITP), autoimmune hemolytic anemia (AIHA), and Evans syndrome (ES) lack therapies providing durable remission. We conducted a retrospective cohort study of 22 adults with refractory primary AIC who received single low-dose daratumumab (100 mg, day 0) combined with rituximab (100 mg weekly ×4 doses) and glucocorticoids. Primary endpoints were overall response rate (ORR), complete response rate (CRR), relapse-free survival (RFS), and safety. Among participants (median age 63.0 years; 81.8% female), 95.5% achieved initial response (CRR 27.3%; partial response rate 68.2%) with median time-to-response 7 days. At median follow-up 322 days, sustained ORR was 81.8% with CRR 59.1%. with disease-specific rates: CRR/ORR of 60.0%/80.0% (AIHA), 60.0%/70.0% (ITP), and 57.1%/100.0% (ES). Cumulative CRR by subtype were 75% (AIHA), 80% (ITP), and 65.7% (ES) (P = 0.031). The median RFS was not reached during the follow-up period. Averse events occurred in 36.4% of patients, primarily infections (27.8%; herpesvirus, urinary/respiratory tract) and rash (9.1%); all resolved with intervention. In conclusion, this dual-pathway targeting regimen induced rapid, durable hematologic responses in refractory AIC with manageable toxicity. The single low-dose daratumumab approach demonstrates significant clinical feasibility, potentially redefining therapeutic paradigms for antibody-mediated autoimmune disorders.