Effective treatment with tacrolimus for patients with non-severe aplastic anemia refractory/ intolerant to cyclosporine A: a retrospective study

Background: For the symptomatic non-severe aplastic anemia (NSAA) patients who cannot afford anti-thymocyte globulin (ATG) or allogeneic hematopoietic stem cell transplantation (HSCT), tacrolimus (FK) was occasionally reported to be an option if they were not response or tolerant to the cyclosporine A (CsA). Method: We collected and analyzed respectively 101 NSAA patients refractory or intolerant to CsA with no chance of HSCT or ATG, and treated them with tacrolimus for at least 6 months and followed up for at least one year. Results: : The overall response (ORR) was 38.6% (complete response: 9.9%; partial response: 28.7%) and the median time to optimal response was 6 (3～10) months. 32 (31.7%) cases had elevated creatinine level. 8 (7.9%) cases had elevation of AST/ALT. 25.6% (10/39) of patients relapsed at the end of follow-up. Age (P=0.0005), FK concentration (4.0~12ng/ml, P=0.0005) and intolerance to CsA (P=0.012) were the independent risk factors for ORR. Treg cells level pre-FK treatment was much lower than 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 provide a possibility of tacrolimus as a salvage treatment for patients with NSAA refractory or intolerant to CsA.