OBJECTIVETo evaluate the effects of cyclosporine A (CsA) whole-blood concentration on the early response to immunosuppressive therapy (IST) in severe and very severe aplastic anemia (SAA/VSAA).

METHODSNinety SAA/VSAA patients treated with rabbit antithymocyte globulin (ATG) plus CsA as first line therapy in our hospital were retrospectively analysed. CsA levels between the response group and non-response group, and response rates of patients with variant CsA levels were compared respectively.

RESULTS(1) There was no significant difference in the beginning unmodified CsA blood concentration between IST responded and non-responded SAA/VSAA patients. The beginning unmodified C(0) 133.91 ug/L in IST 2-month responders was higher than that of 49.9 ug/L in non-responded SAA patients (P = 0.009); (2) The mean CsA C(0) and C(2) levels during the third month following IST were significantly different in responders and non-responders(197.52 µg/L vs 161.49 µg/L, P = 0.024, and 738.76 µg/L vs 615.46 µg/L, P = 0.009), and no significant difference in other periods of IST (P > 0.05); (3) The response rate (87.5%) was significantly higher in patients with CsA C(0) ≥ 200µg/L the third month following IST than those of 55.6% in patients with CsA C(0) 150 - 200 µg/L (P = 0.023) and 59.3% in patients with CsA C(0) < 150 µg/L (P = 0.046), respectively. The response rate was significantly higher of C(2) ≥ 700 µg/L group than that of C(2) < 700 µg/L group (80.5%vs 55.3%, P = 0.012).

CONCLUSIONSThe CsA concentration related to the early IST response. The third month CsA concentrations was the most important for the response and maintaining CsA levels with C(0) ≥ 200 µg/L and C(2) ≥ 700 µg/L may improve the response to IST in SAA/VSAA.