Objective: To evaluate the efficacy and safety of human recombinant thrombopoietin (rhTPO, a product of Sunshine Pharmaceutical Co Ltd, China) in chronic refractory idiopathic thrombocytopenic purpura.

Methods: Eighty-two patients with chronic refractory idiopathic purpura received daily subcutaneous administration of rhTPO at a dose of 1.0 micro g/kg for a maximum of 14 doses.

Results: After the beginning of treatment, the median platelet counts increased from 15.5 (6.0 - 24.0) x 10(9)/L to 27.5 (16.0-47.0) x 10(9)/L, 35.0 (20.5-78.0) x 10(9)/L and 77.0 (41.8-119.5) x 10(9)/L on the fifth, seventh and fifteenth day, respectively (P < 0.01). After the discontinuation of rhTPO administration, the platelet count decreased gradually. On the twenty-eighth day, the median platelet count was 76.5 (35-120.3) x 10(9)/L, which was still significantly higher than the level before the treatment (P < 0.01). The overall response rate was 85.3%. The rate in the group with remarkable response (platelet count > or = 100 x 10(9)/L without bleeding) was 58.5% and that in the good response group (platelet count > or = 50 x 10(9)/L or 30 x 10(9)/L higher than the count before the treatment, without bleeding) was 26.8%. Only 3 patients had mild clinical untoward reactions. Low titer (1:5) of anti-TPO antibody in serum was detected with ELISA in one of the sixteen patients who received the test on the twenty-first and twenty-eighth day. Neutralizing test using TPO-dependent cell line showed that the positive serum had no neutralizing activity on rhTPO.

Conclusions: Consecutive subcutaneous injection of rhTPO for a maximum of 14 days was associated with a temporary elevation in platelet counts in patients with chronic refractory ITP with tolerable adverse effects.