Objective: To explore the clinical efficacy and adverse effects of GHA(G-CSF+homoharringtonin+cytarabine C) and new combined priming chemotherapeutic regimens(GHAA/GHTA) with high efficacy and low toxicity for treatment of relapsed and refractory acute myeloid leukemia(AML) and myelodysplastic syndrome(MDS), and to analyze the relation of above-mentioned regimens with the expression of co-stimuolating molecule B7.1.
Methods: Standard GHA regimen consisting of G-CSF: 100 µg/(m2·d) subcutaneous injection, d 0-14; homoharringtonine: 1.0 mg/(m2·d) intravenous drip, d 1-14; Ara-C: 7.5-10 mg/(m2·d) subcutaneous injection, q12h, d 1-14. Other regimens as GHAA/GHTA were combined respectively with aclarubicin 20 mg d 1-7, or pirarubicin 20 mg d 1-7. 74 patients with refractory AML and 46 patients with MDS received these priming chemotherapy. The clinical efficacy and toxicity of above-mentioned priming chemotherapy were compared with 56 patients received routine chemotherapy (MA/TAE) respectively. And the expression of costimulatory molecule B7.1 on leukemia cells in patients of different subtypes was also detected by immunofluoressence and its relationship with clinical efficiency was explored.
Results: (1) for AML patients treated with priming chemotherapy, the total remission was 67.56% (CR 54.05%, PR 13.51%), which was much higher than that of patients received routine chemotherapy (P<0.05). The CR rate of AML-M2 and AML-M5 group (65.51%, 61.90% respectively) was much higher than that of AML other subtypes (P<0.05), and the longest remission period lasted for 4 years; (2) for MDS patients treated with priming chemotherapy, the total remission was 60.87% (CR 45.65%, PR 15.22%), which was also significantly higher than that of patients received routine chemotherapy (P<0.05); (3) in comparison with patients received standard GHA priming regimen, the remission rate of combined priming chemotherapy GHAA/GHTA was significantly higher both in patients with AML (85.18%) and MDS (81.25%); (4) side effects after chemotheropy, including granulocyte deficiency, thrombocytopenia and anemia etc, lasted for 7-14 days; the severe infection rate was 1%, there were no severe bleeding, digest effect and damage of function in heart, liver and kidney. The therapy-related mortality was zero. Compared with routine chemotherapy, priming chemotherapy proved significantly safe and effective (P<0.05); (5) the expression rate of costimulatory molecule B7.1 showed large variance between AML and MDS, it was higher in AML-M2/AML-M5 and lower in AML of other subtypes (P<0.05). In the same case, B7.1 expression was positive correlated with efficiency of priming chemotherapy.
Conclusion: GHA priming chemotherapy, as well as other combination regimens GHAA/GHTA, are well-tolerated, effective regimens for refractory AML and advanced MDS, without severe side effects and therapy-related mortality. Especially the new regimens GHAA/GHTA has better efficacy, which are proved more efficient than conventional GHA. Efficiency of priming chemotherapy is positive correlated with B7.1 expression, its mechanism will be further explored.