Effective Tacrolimus Treatment for Patients with Non-Severe Aplastic Anemia That is Refractory/Intolerant to Cyclosporine A: A Retrospective Study

BACKGROUND: For symptomatic non-severe aplastic anemia (NSAA) patients who cannot afford anti-thymocyte globulin (ATG) or allogeneic hematopoietic stem cell transplantation (HSCT), tacrolimus (FK) may be an option if these patients do not respond or become tolerant to cyclosporine A (CsA). METHODS: We enrolled 101 NSAA patients who were refractory or intolerant to CsA with no chance of HSCT or ATG treatment and treated these patients with tacrolimus for at least 6 months, with follow-up for at least one year. RESULTS: The overall response rate (ORR) was 38.6% (complete response: 9.9%; partial response: 28.7%), and the median time to optimal response was 6 (3～10) months. Thirty-two (31.7%) cases had elevated creatinine levels. Eight (7.9%) cases had elevations in AST/ALT. A total of 25.6% (10/39) of patients relapsed at the end of follow-up. Age (P=0.0005), FK concentration (4.0~12 ng/mL, P=0.0005) and intolerance to CsA (P=0.012) were the independent risk factors for ORR. Treg cell levels pre-FK treatment were much lower than those of healthy controls (3.7±0.6% vs 6.8±0.7%, P=0.0004) but increased significantly after FK treatment (3.7±0.6% vs 7.1±0.8%, P=0.0039). CONCLUSION: Our data suggest that tacrolimus is a salvage treatment for patients with NSAA that is refractory or intolerant to CsA.